21st Century Fox - Vorshlag suspension development for Fox and SN95 Mustangs

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Project Introduction: July 10, 2025 - This is the first in a series of forum posts that will chronicle our development of suspension parts for the Fox and SN95 Mustang chassis, the 3rd and 4th generations of the Mustang line. And then our explanation of why we are doing this, and what we hope to prove.



Some history: I have owned now eight different Fox generation Mustangs, plus worked in 1998-99 as a technician at a shop that specialized in upgrading Fox and SN95 Mustangs - suspension, power, and braking. I tracked and autocrossed Fox Mustangs through college, and even worked some long term tests at Texas World Speedway in (then new) Fox Mustangs. Most of the suspension and brake development for these two generations of Mustangs is still stuck in the 1990s, with very little being developed for these older cars that is inline with even the OEM level of parts from modern 5th to 7th generation Mustangs.



We love the last 3 generations of Mustang models, and we have owned and raced all of them. We spent a lot of years running in Coyote powered S197 competitively, then jumped to the S550 and then on to S650 chassis cars. We have learned how to make these cars handle with thousands of suspension customers for these generations. We want to bring these older cars into 21st Century with some newer suspension designs.



For some reason - probably having to do with when I was born and having grown up with these cars - the 3rd gen Fox and the 4th gen SN95 Mustangs have a hold on my heart. I have wrenched on these cars, driven the Fox and SN95 Mustangs, so I know first hand how compromised their suspensions are, their brakes, even their engines - their everything. But the heart wants what it wants. We cannot change our past, but hopefully we can make these older cars better!

MAKE GENX CARS GREAT... AGAIN?

This is not a one-off project, this is part of a series of development cars we purchased and are upgrading. In 2023 we started putting a concept of a plan to take cars that GenX folks grew up with - from the 1980s to 1990s - and develop 21st century solutions for each.



We want to adapt modern suspension geometries, better hubs and uprights, stronger differentials, the latest in OEM based brakes, modern aluminum engines and EFI tuning, the latest in tire technology stuffed under the stock or enlarged fenders, world class ABS and electric steering, and Motorsports traction control that we have utilized in our late model race cars.



It is a big project, but we have gathered 4 cars at Vorshlag that we own to use for these development plans - because from past attempts at using customers' cars for this sort of "alpha" development, we now know that WE have to own and direct these builds, not someone else. This was a hard earned lesson, and we have lost some very valuable development work with flaky testers.



We have already completed some level development work on all 4 of these cars: 1991 BMW E30, a 1995 BMW E36 M3, 1989 Chevy 3rd gen IROC Camaro, and this 1988 Fox Mustang. This forum thread covers the Fox and SN95 work we have planned, and I will link the other cars' development threads below as they are created:

• Vorshlag E30 Development
• Vorshlag E36 Development
• Vorshlag 3rd Gen F-body Development (TBA)

This will be the place we show every step of the development on these 3rd and 4th gen Mustangs, every track test, every step of fabrication and engineering, hopefully capturing your curiosity - and we will even be requesting advice in some areas. These things are also covered daily on our socials - FB, IG, and YT. Ultimately we want to make parts that we can sell that are better than what is out there for these cars - and The Market will let us know how we are doing, in addition to the lap times we can help create in our and customers' cars.

FOX TEST MULE - 1988 MUSTANG LX - #THEOCHO

In May of 2020, this cream puff 1988 Mustang LX 5-speed car was essentially "abandoned" by Jason at Vorshlag, with the intention of spurring along a plan we have had for a while: to get a donor Fox to use for new suspension development.



He had purchased this to be a daily driver on his commute to Vorshlag, but it only took one or two commutes to realized - this 2.3L powered Mustang was dangerously under powered and not suited to a highway commute where speeds often reach 80+ mph. This car cannot reach 80 mph without a long hill and a tail wind. He knew I cannot resist a notchback Fox and after sitting under a car cover for a bit, I fell for the bait and dove head first into a major development project using this car.

EARLY REPAIR WORK

We brought this car into Vorshlag on Sept 11, 2024 and spent a few weeks tackling some deferred maintenance. Jason even supplied a gaggle of restoration parts he had purchased that were to pretty up the exterior and interior.



After sitting for almost 4 years the old battery was completely fried, so I got this 33.5 pound wet cell battery at our local O'Reillys store. While there I also got a new positive battery cable to replace the crusty stock one that was 36 years old.



I then ordered some "C-tek metallic" brake pads for the front and a new fuel filter. Christian cleaned out the stock tank of old fuel and it looked good inside, so we had hope it would start - and it fired right up.



The stock 15x7" wheels were an iconic part of the 1985-1989 Fox Mustangs, before they moved to the 16" Pony 5-star wheels later on. I wanted to keep these wheels, but the old tires were rotten and needed replacement. After a long search I realized that 15" tire options that fit this car (225/60R15 and 215/65R15) were essentially non-existent. When Myles sent me a Marketplace deal on 17x9" 4-lug replica wheels that were 10 miles away for $275, that was an easy purchase.



The 17" wheels had even more tires choices than the 15" or 16" options and I found a set of 245/40R17 Firestone Firehawk Indy 500 tires on closeout for a steal. These were easy to fit without any real body mods, but 255mm tires are sort of pushing it with stock suspension and bodywork. These 300 TW tires would be light years better than anything we ran "back in the day", and they mounted up without issue.



The stock steering coupler was rotted away so that was replaced, and the last thing I wanted was to disable the factory steering wheel lock in the column. We do this for any car that goes on track so that we can safely turn the engine off at the key and not lose steering while driving at speed.



Christian did the surgery and the steering column lock was removed. All of the work above was accomplished within one week in September of 2024.

PRELIMINARY SEAT BRACKET DEVELOPMENT

The stock seats in this car are abysmal and I had hoped to have a fixed back racing seat in this car for the first track test. We pulled the driver's seat, measured the stock seat centerline and the steering column center - and while not too far off, there was some centering of the seat we could accomplish.



We came up with a plan but we had a lot of other development going on with other cars and customer builds, and this got put off.

GAME ON!

The little Fox sat in our lobby for 8 months while we thrashed on customer builds and development work. But it came back into the Vorshlag shop in early June of 2025. Two big customer builds had just wrapped up and left, so we finally had time on our schedule to tackle more development work. We had also just bought a new 3D scanner we need to do some design work.



First thing we did was to rack in all of the front negative camber on the stock suspension, then reset the front toe to zero. That was about all we wanted to modify before the first track test.



We took the car to an alignment shop we don't trust and told them to NOT touch anything, just give us a readout. And the front was sitting at -2.0 deg of front camber, which was a nice surprise. The +1.0 deg of caster was actually pretty worrying, as that is well outside of the +6 to +8 deg caster range we want to see. Now we see why people swap in the offset lower control arms, which move the wheel forward and add a lot of caster.



We also pulled the "trunk junk" that day and got a starting weight with the iron block 4 cylinder and aluminum T-5 transmission at 2810 lbs with 1/2 tank of fuel.



The temporary spare, jack, and tire iron was 36.6 pounds and later on we weighed the four cylinder + T5 at 481.8 pounds, without the A/C compressor, P/S pump or alternator. I'll get those weights shortly and add them to the total.

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SN95 CAMBER PLATE + REAR SHOCK MOUNTS

In May of 2025 we had Chris' 1995 Mustang GT in our shop getting a set of MCS remote double adjustable coilovers installed. But these were not the typical "eye to eye" rear shocks that most folks order, which we've sold many times for the Fox or SN95 cars. We ordered a eye-lower and pin-upper rear shock to be able to make a proper spherical shock mount for the upper mounting position - which we have released for the SN95 and will soon make a Fox version of.



This uses a derivative of our C6 Corvette Z06 / NC MX5 spherical shock mount, which we CNC machine in-house here at Vorshlag. This design is unique in that it moves the spherical bearing above the sheet metal - which requires some modification to the car and/or to a mounting tower to make work. These have proven to fix some issues on those two chassis which otherwise are almost always using a rubber or poly upper mount - which is never desirable in any sort of Motorsports use. The sloppy bushing movement soaks up damper travel and delays them from doing any work.



We made this new mount and a drilling fixture to help add the 45mm dia hole, and offset the mount away from the tire for more clearance to use a real coilover shock. This includes a reinforcement plate that is tack welded to the car, and we stitch welded the rear shock tower to the wheel tub and frame rail to reinforce all of that for suspension loads vs damper-only loads with the stock "divorced" spring.



Another major development we made for this car was a radically different camber plate for the SN95 chassis. Unlike virtually all offerings from the past 30 years, our design does NOT sit above the strut tower. This means we don't need to drill a 4th hole and mount the plate above the tower. This also means that there are not "point loads" from top mounting - so the bolts are NOT in tension. Instead, the normal impact loads from bump travel go through the main plate from underneath - doing a better job of spreading these loads to the tower. This design also gains a substantial amount of shock travel over "eye" mounts with a conversion adapter that sits under the shock tower.



We started with a new design idea, made the main plate and lower bolt ring out of steel quickly, then test fit these to the SN95's right front strut tower. On this one we did add the 4th hole but our production unit will not need that. After testing this mock-up design on the car (above) we noticed that the previous camber setting of -2.5 deg was nearly doubled to -4.7 deg - without modifying the strut tower. We immediately moved to CNC production of an aluminum main plate and top pointer ring.



Since our main camber plate design is not placed ABOVE the strut tower, our included radial bearing spring perch just sat on the top step of the strut - without the need for inches of spacers. We did it the Vorshlag way, which has worked great for 20 years and tens of thousands of camber plates on other car models. The spring length is super long for coilover Fox/SN95 cars, so thse don't need the extra strut travel up front, meaning the "above tower trick" for camber plate mounting is not needed.



We still have one more design iteration to get this to production, but it should be ready by Q3 2025. While the Mustang was here we did a few other tasks beyond the MCS install, prototype camber plate install, and rear spherical shock mount install. When it was all wrapped up we took the car to get an alignment check at a nearby shop.




We increased the front camber from -2.5 to -4.4 deg of camber, which made the 345mm Vitour P1 tires on 18x12" wheels fit a bit better. Chris is planning on some flares in the future, but for now the fat tires just hang out in the wind a bit.



The customer Chris was so happy with the MCS + Vorshlag parts, and he left our shop to go run a track event at Hallett (a 1.8 mile track in Oklahoma). Straight away was 3 seconds faster than his previous Personal Best, and never touched a knob on the MCS dampers! Now he's looking to tackle an ABS upgrade (his SN95 ABS was deleted long ago), which we're working on with this Fox - we will have something for the SN95 in the future as well.

THE GENERAL SUSPENSION PLANS FOR THE FOX

Without being cagey, I'm not going to share much about our plans other than the obvious - we're going to make a Fox camber plate design that hopefully fills a niche and solves some problems. We've already scanned the strut towers of our 1988 Fox and have a design in the works, which we will install in the coming weeks.



Another thing we want to tackle is a new tubular K-member design using some 21st Century uprights and design aspects - unlike anything on the market today. The factory Fox front crossmember is very large and restrictive in many ways (like header clearance) but it very strong. All of the front suspension lateral loads and much of the engine torque and braking pass through this steel assembly.



As we've found out in some early engine swap research, none of the current long tube header designs will fit the stock crossmember. There used to be a Hooker header that did, but parent company Holley ditched all exhaust related components a few years back. We bought some cheap eBay headers but can clearly see that, like the offerings from Speed Engineering, ARH and others - they only fit with a handful of "drag race oriented" tubular K-members, which leave a lot of strength out of the equation in the search for weight loss.



We have worked with some of these drag race crossmembers and they tend to break in real road race Mustangs, like the Fox shown above. The lack of structural support in these crossmembers is crucial, and we have repaired and upgraded more than a few of these. For drag racing these crossmembers can work fine, but for road course or autocross use with modern tires that can reach 1.5g without aero loads, those will flex and bend too much to be useful.



The existing Maximum Motorsports K-member (above) is MUCH stronger, and it has been the go-to for corner carvers for the Fox and SN95 for ages. We have purchased and installed these on cars to replace the drag race versions. But as great as the Maximum unit is, we want to do something with newer uprights and suspension geometries that haven't been done yet.



Out back the 4-link OEM suspension and solid axle are just so, so bad. This was a cheesy suspension design even in 1977 (from the Ford Fairmont). The auto-bind geometry of the opposed 4 link is well known and I'm not gong to rehash that here. When I worked at Houston Performance in the late 1990s we often installed a panhard bar and torque arm - suspension design fixes dating from the 1960s - and that improved handling a bit, but brought their own negatives. We have even done some of that at Vorshlag (above right), Again, I'm not going to go into all of that, but even the best solid axle Band-Aids have big downsides.



The popular "upgrade" for a long time was to yank the stick axle and swap in the complete 1999-2004 SN95 Independent Rear Suspension, or IRS. Sadly, the geometry of this is still pretty compromised - they axle hop pretty badly under power, so much so that the drag racers of these later Cobras would pull them and sell them to track folks.



Out back we also want to adapt 21st Century designs to fit the Fox chassis without much if any cutting or fabrication by the end user. I love the S550/S650 rear IRS setup, due to some very favorable geometry and much less unsprung weight. There is both camber and toe adjustment, and we can actually USE negative rear camber to make these cars faster. Also, IRS doesn't make the rear springs on both sides "additive in bump", so we can run a stiffer rate without wrecking ride quality.



Compared to the Fox's solid axle, however, the S550 IRS setup is just SO FREAGIN WIDE. And it isn't just as simple as narrowing the subframe or arms to fit the much narrower Fox chassis - that wrecks the rear suspension geometry, and this route may prove impossible. We have three rear subframes and suspensions from modern chassis (including the S550) at our shop, which we are 3D scanning and modeling. We'll get something proper designed and fabricated, just stay tuned. I've wanted to do this for a DECADE and now we have the resources to complete this.



No lie, this is a big engineering task (the IRS and the front suspension work), but we are investing the time and money to do this - new 3D scanning tools, more engineering manpower, more fabrication equipment. We're going to have the entire fox chassis scanned as well as the the 3 rear subframes and IRS setups modeled soon. This major suspension design work will happen after we complete a quick V8 swap, get that running and tuned, and perform a series of baseline and track tests on the existing 245mm Firehawk 300TW tires. We have to do this because our first track test with the 2.3L was SO BAD as to be completely meaningless.

WHAT'S NEXT?

We always do a baseline track test at the same track, going back 20 years - Motorsport Ranch Cresson's 1.7 CCW course - my home track, where I have driven thousands of laps and set probably ~15 class track records. I was going to include the first track test in this first installment, but it was SO BAD that I will save that for next time. Embarrassingly slow!



If I can find another stock Fox Mustang V8 from 1987-1993 to take out and get a baseline, I will. Otherwise we'll do it with the 500 hp LS and TKX installed, in the next 6-8 weeks. We do have our 2nd and 3rd journal entries for the 21st Century Fox Diary on YouTube, and the 2nd is linked below.



You can click the image above for the linked video - matter of fact, ALL images in my forum posts going back 25 years can be clicked for higher res images (these always look better on a larger PC than a tiny phone). Before you turn your noses up, yes - our engine swap will be an aluminum LS1 made by General Motors (well, a hotted up one built by HPR). I like to call the LS a "Gen2 Windsor", because they share more geometry with the 351W than earlier Small Block Chevy engines - heck you can swap LS and Windsor cylinder heads across the respective blocks.



The 2.3L + T5 is already out and an LS with a Tremec TKX is already installed, just needs all of the plumbing and wiring. We will have mounts for our new front crossmember (and possibly swap headers) to fit the LS V8, Coyote 5.0L, and 302/351 Windsor engines. And soon we will have a proper transmission crossmember for the TKX (the current offerings aren't great). PLEASE don't get hung up on the engine - this V8 is a necessity right now, as our 2.3L died in our first track test, and it was too slow to give us a meaningful baseline to compare to.

We will share more next time - thanks for reading!

Terry @ Vorshlag

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Project Update for October 6, 2025 - Lots to catch up on for the last few of months. We have nearly completed a V8 swap and a lot of other tasks, much of which has nothing to do with the engine swap - and might be worthwhile for some viewers on their own project cars. The first post in this thread was a bit long, and had a lot of "plans" - this is all tech, which we will start off with the first track test in June of 2025 (which was pretty awful).



Some of you might read this and think "Hey - I could have finished this V8 swap faster", and you might be right. The difference here is that we're finishing each system we touch to a pretty high level - think "car show worthy + highest levels of Motorsports safety", and that takes time. We are also in the middle of four other shop builds, plus customer work, and we attack this project as time permits.



So let's kick this forum update off with this car's first track test, then dive into the many systems we are upgrading, repairing or throwing away and replacing.

"BASELINE LAP" TRACK TEST - JUNE 8, 2025 - MSR-C 1.7 CCW

We took the little Fox to the track to get a baseline lap at Motorsport Ranch Cresson's 1.7 CCW track, which I have been driving at for 25 years and have made 1000+ laps on. Not a brag, just that I know this track well and "learning the lines" isn't an issue for me here. I have set many class track records here in dozens of cars, and have a club membership here - so I can go on "member days" and get laps without much traffic (like I did on this Friday morning).



I like testing here because on member days they do 30 minute sessions and at 1.7 miles it makes for a short out lap and in lap, so I can often come into the pits and make changes and go back out several times in a session. I will sometimes swap cars during a session, and only get charged for one session fee ($25).

As stated before, the only changes to the stock 1988 Mustang (covered last time) were fresh 245mm Firestone Firehawk 300 treadwear tires on 17x9" wheels and some RockAuto semi-metallic front brake pads. We replaced or fixed things like the battery, some wiring, new fuel filter, pushed some brake fluid to bleed the system, but otherwise it was stock.



Number one thing I noticed right as I was going out on track - the oil pressure gauge was not working (above left - see the engine, running but oil pressure is near zero). Hmm, I don't remember that on a test drive earlier, but who knows? It is a 37 year old car, probably a flaky sensor. We had half tank of (really old) gas, tires were set at 34F/28R psi on these sticker new Firestone Firehawk 500s (300 treadwear). Ambient temps were 77F, and Amy was there with me shooting pictures.



I drove for 3 full laps and pushed the car hard each lap. The lack of power was SHOCKING and it would not exceed 74 mph no matter what I did. Redline is 4000 rpm with this 2.3L tractor motor. I've gone faster around here in my tow vehicle, this was just DISMAL. I was Wide Open Throttle in many corners not normally possible, just barely needed the brakes, but when I did have to slow the car would brake dive hard. Ahh... memories. The roll in the rear was painful, but the 2.3L car had no rear swaybar.



I am kind of amazed at how slow this car is. Most modern pony cars will do a 1:25 lap here and I've run 1:18 in our '24 Darkhorse and 1:13.2 in my S550 Mustang on Hoosiers. This 1:52 lap is an outlier - I have nothing to compare it to. "Luckily" the engine crapped out on my 4th lap - I panicked thinking I had hurt the engine. I realized this engine is barely worth scrap metal cost anyway, no fluids were pouring out, and I managed to re-fire it and limp it into the pits and back in my trailer.

I had planned on making more laps, coming in to check and bleed down tire pressures, but it just didn't matter. It was painfully slow and this "baseline" lap is just not worth comparing to. We talked about it back and the shop and decided to put a V8 into this car, make no other changes, and come back to get a true "stock suspension" baseline lap with real power.

PLANS FOR A V8 UPGRADE

Now the powerplant upgrade was not supposed to happen at the beginning of this project, and it will never be the focus of this Vorshlag build. The main goal is to develop some 21st century suspension options (both front and rear) for the 1979-93 Fox chassis. To quantify any changes we always start with a Baseline Lap at MSR Cresson 1.7 CCW, then test things at every stage of development.

But our baseline laps from June were completely useless, due to the 2.3 liter four cylinder, which might have been putting out 80 hp at the start of the track test. In hindsight we made a clear mistake. While we replaced the brake pads, tires, and brake fluid, and even changed the fuel filter, we neglected to clean out the fuel tank. I had forgotten that it had been sitting outside under a tarp for close to 4 years - and gasoline doesn't sit that long and work well. Even with an unclogged fuel system, however, the 4 cylinder power was never going to put down any meaningful lap time to compare to.



I loved the Small Block Ford (SBF) and Coyote engines I have owned over the years, but they have downsides. Instead of finding a period correct 1987-93 Ford 5.0L engine, changing everything to make that work in this car, we're short cutting a bit to a lighter all aluminum LS V8 and Tremec TKX 5-speed manual. We had always planned for some sort of aluminum V8 - Coyote or LS - and an 383" LS from another project was almost complete at HPR so we're going that route.



I'm not here to sell anyone on any sort of engine or swap. I've got a lot of years using SBF engines, like above left where we were swapping in a new longblock into my 1987 LX in 1993. That pic has engine builder Erik Koenig (HPR) where lots of engines of all makes get built. The issue with any Ford engine options are simple: weight and size. The Fox shown above right is one of our customers' with a Coyote 5.0 swapped Fox, and the engine takes up the entire engine bay, with no room for a traditional vacuum brake booster. The smaller SBF is heavier because it has an iron block, but you can spend $$$ to build an all aluminum Windsor that can make similar power (the Ford Z351 aluminum Windsor block is a staggering $7000!)

ALL-ALUMINUM GEN2 WINDSOR V8!

Some people get real funny about cross make engine swaps, which is funny to me - because the OEMs do these things all the time. The Toyota GR86 has a Subaru engine. The Mazda NC MX5 has a Ford engine. I could give 100s of examples, and you folks only get your feathers ruffled when some hot rodder does what hot rodders HAVE ALWAYS DONE and perform an engine swap that isn't blessed by some auto maker. WHO CARES!? The time clocks on a race track sure don't give a fig what is stamped on a valve cover. Get over it - or call this GenIV LS a "Gen2 Windsor", as these things share more geometry with the Windsor than they do with the old Small Block Chevy. You can swap the cylinder heads back and forth without much effort!



We are using an all aluminum LS mostly because 1) this car had a dreadful four cylinder and 2) because the LS is light, compact, and we already had one in process at HPR. If we had started with a 5.0L SBF powered car we wouldn't be messing with the LS swap we are doing now (but we would have still done it eventually). We will make our planned new front K-member available with engine mounts and header options for the big 3 options: SBF, Coyote, and LS.



The original 2.3L + T5 drivetrain was removed June 26th out and a mock-up LS1 and the Tremec TKX were installed July 1st. The Tremec 5-speed transmission (with 600 ft-lbs of torque capacity!) was in another project that has been back burnered, and will work nicely in the little Fox chassis.

OIL PAN AND HEADER TESTING

On July 1st we had the old 2.3L + T5 drivetrain out and it was time to test some parts to see which headers and oil pan needed to go onto the LS1 engine we have planned.



We bolted up the Tremec TKX and bellhousing we had in another project to a "mock up" LS block and heads, which are made from a windowed block and some old heads. We added a 4th gen Camaro (1998-2002) oil pan to this engine for our first mockup.



The 4th gen F-body pan does not fit - as expected and shown above. We were told this wouldn't work with the stock Fox crossmember, but I am always of the mind of "trust but verify" if someone cannot show me pictures - like the two above. So many forums where this level of detail might exist are sadly gone. I was otherwise happy with the overall fit of the drivetrain, and the shifter on the normal TKX location lined up with the hole in the floor of this manual car.



At this point we just made some wooden shims and set the engine and transmission in place - at the wrong driveline angle and lateral placement, but its a close approximation. With a spare intake installed we could finally see we had more hood clearance than we had hoped, and a few other things could be checked. I might go with a taller intake than originally planned, to utilize this vertical space.



Jason had spoken to the Holley tech while they were developing their swap parts and knew that Holley had a pan with minor changes that fit the stock crossmember, which was verified on an Ls swap mustangs FB group that this Holley 302-5 oil pan would work with the stock crossmember, and sure enough, it is stated to be made for this exact swap. Holley used to offer lots of things, like long tube headers and a transmission crossmember, which were made for an LS in a Fox with the stock front suspension crossmember, but they got spooked (by the EPA?) and dropped most of these parts. The oil pan was still available, so I bought that.



On July 7th we received the 302-5 oil pan and an ARP oil pan bolt kit for an LS and we got it bolted to our mock-up LS engine, and stuffed that back into the Mustang. Now we could test proper driveline angles and do more detailed driveline placement tests.



This Holley pan was the perfect wet sump oil pan for this LS engine, in the Fox chassis, with a stock crossmember. The engine was offset to the passenger side in some of the above pics, trying to make some headers fit. Again - most folks would immediately swap to an aftermarket front crossmember for any sort of track or drag race build in a Fox, all of which add loads more clearance.



But here, we are just trying to get this on track with the STOCK SUSPENSION, and the tubular crossmembers all require coilovers, as they ditch the stock inboard spring mounting pockets. We're stuck with the chunky Ford crossmember for now. We will be making a new tubular crossmember soon, of course, and it will become obvious why we're doing that when we finish that.



Earlier I took a gamble and ordered these $217 long tube stainless headers made "for a '79-93 fox and '94-04 SN95 LS swap". I found these from several vendors and they are all clearly Chinese built. It was so cheap I figured it was worth a try, and nowhere did any of these entries say what is really needed to make these possibly fit: an aftermarket, tubular crossmember. They looked pretty good, to be honest. How does anyone in this chain of manufacturer + reseller make any money at this price? Sweat shop labor and cheap materials is how.



Of course $200 eBay headers will absolutely not fit without the tubular crossmember or major rework, but that was a low risk gamble. We don't feel like chopping up these headers and "making them fit".



This $217 header purchase was still a very low risk gamble. All of the folks on socials saying "just make them fit" or "just build custom headers" as we were showing this in real time have done neither tasks. Making an LS swap kit is absolutely NOT our goal here. We've done this level of rework on cheap headers on other projects before, and it was always a huge time suck - figure 20-30+ hours minimum to modify these and make them hold vacuum, and possibly more hours than that. We are not going to burn those sorts of hours modifying $200 eBay headers.



That day after testing I made our 3rd journal entry video (linked above) - it is less than 2 minutes, showing much of what I just explained above about the oil pan and header testing.



I rolled the dice a second time in early July when the header test fit went sideways and ordered these $114 cast iron "LS3" manifolds. They are heavy but they actually fit, and the LS1 and LS3 exhaust ports are close enough in shape and size to not matter. We now know that these do fit and those in in late July with the actual built LS engine, no longer needing this just mock up longblock. I'll show that further down with the exhaust work.



Once we knew the 302-5 Holley pan was the right option, I ordered an Improved Racing baffle kit, made to fit this 302-5 pan and the 302-3 variant (with oil drain back holes for turbos). After test fitting the baffle to the pan (below left), I took the 302-5 Holley oil pan + pickup and the Improved Racing 302-12 baffle kit to the guys at HorsePower Research, who were wrapping up the little 6.3L LS engine.



At HPR, Alec modified a stock LS windage tray (above right) to clear the very short front section of the oil pan. There is no windage there because this oil pan just clears the 4.0" stroke crank. The Holley pickup screen was checked for depth with clay - it had the .250-.300" clearance to the bottom of the oil pan we want. The Holley pan was installed and buttoned up along with a new front cover.

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FUEL TANK REFRESH AND UPGRADES

This was the crucial step we skipped in the earliest stage of this build, and that could of at least allowed the 2.3L engine to run wide open and possibly achieved more than 74 mph terminal velocity. Live and learn! Like I mentioned above from our June track test, we should have dropped and cleaned out the tank earlier, but instead we just swapped the fuel filter and sent it. On July 14th, we finally dropped the tank to properly clean it out.



The fuel sock from the stock pump was completely disintegrated. And now the lack of power on lap 4 of our track test with the 2.3L makes more sense. I mean, sure... the oil pressure gauge read zero the entire time, and I thought it was a busted gauge. Until it started working on lap 4, and showed the low numbers. But the engine never made any clatter, just felt way down on power.



Now I suspect the fuel injectors or new filter were simply clogged from the sock coming apart - and the engine stopped making power. Here we drained the stinky fuel and power washed the insides of the tank and it looks spotless. I ordered a "drop in replacement" Aeromotive pump kt and a new level sensor, which will be installed next.



The stock tank looked pretty solid, but it had one busted spot weld for the "fuel pump basket" mounted inside - if you shook the tank the basket would bang against the top. Myles fixed that with a small drilled hole through the spot weld, then TIG welded the tank to the basket. And covered up the hole with a rosette weld. Brad wire brushed the exterior of the tank, then sprayed it with self etching primer.



He then hit it with a coat of Duplicolor aluminum silver "engine paint with ceramic", and it looks good as new. Would it have been smarter to buy a new tank from Summit for about $130 delivered? Probably, but you never know what you are going to get with the cheap import replacements. This one was good for 37 years of service - and now should be good for 37 more.



Here the Aeromotive 340 lph pump assembly was installed. The new pump assembly drops into the high spot on the right side in place of the stock pump. Above left, Brad is looking inside the tank to see which way to clock the fuel sock filter, so it lines up in the "basket" properly.



The images above were taken through the fuel level fill hole on the side, and the above left image shows the top of the Aeromotive assembly bolted in place. I show these because the instructions suck and we couldn't find good pictures, and this took some trial and error. The right side picture above shows the stainless steel arm holding the pump and sock, which are nested down inside the basket. The black corrugated return hose drops right into the basket - which acts almost as a surge tank, but not quite.



We replaced everything that went into the tank - because 37 years submerged in fuel will rot anything. The new RockAuto sourced fuel level float assembly went into the center opening, which is on a lower level on the top of the tank.

I showed some images of the tank going together on a FB group called "79-04 Mustangs Road Race-HPDE-AutoX" and a user there pointed out (that's his picture, below left) that the replacement fuel tank vent we have - OEM sized - might be insufficient for the 340 lph pump that we're using.



Instead of finding out the hard way, I ordered the Breeze Automotive "big bore vent valve" kit he recommended for $49. It is considerably larger and we will plumb this to a custom charcoal canister we are building, which I will show below.



The last item that touches the stock fuel tank is the filler neck. This was removed from the chassis and cleaned up, then a new rubber gasket that mates the steel tubular neck to the tank was installed. The best advice is - if you have to drop the tank and you don't remember if the gasket is new, you should just replace it.

WEIGHTS OF ENGINES

I have an obsession with weights, and of course we weighed the engine + transmission coming out as well as what went back in. I thought this was interesting



We will get into more on this engine in another section, but you might notice that the all aluminum LS V8 + TKX weigh less than the 2.3L and glass T5.

STICK AXLE FUN

This 1988 Mustang had the 2.3L 4 cylinder, which means it came with a 7.5" ring gear axle housing and an open differential. We plan to design a new IRS setup out back (not '99-04 Cobra based) but want to complete a couple of track tests with V8 power and the stock rear stick axle, and I don't want an open diff that might explode with the power we're adding.



We went hunting for a 4-lug 8.8" ring gear 1987-93 Mustang stick axle out of a V8 car. This means FB Marketplace, as every other local used parts selling platform is dead (RIP Craigslist).



First one I found for $250 was impossible to meet up with the guy, but the second one for $300 (talked down from $400 once we arrived) worked out well. This one has the super common 3.08:1 gears, the limited slip still works, and it came with all of the arms and even the qudra-shocks. We power washed and weighed it at 236 lbs as shown above, and the open diff 7.5" came in at 172 pounds - shown below, but without the 4 shocks and no rear swaybar.



The 8.8" limited Slip rear axle was checked out, cleaned, and installed into the 4 cylinder car. Adding the rear swaybar that came with this is a nice bonus, as this suspension is super soft and has tons of roll. We checked the original 4 cylinder rear springs on our digital spring rater at 142 #/in and the V8 springs (it only came with ONE with the axle) at 185 #/in. We only had a complete pair of 4 cylinder springs, so those went in for the "stock baseline" track tests.



The above two pictures show the 8.8" axle with two different brake hard line setups. At left is the setup that normally comes on the V8 cars, with the junction for the rear circuit on the driver's side. We swapped over the rear brake hard lines and junction from the 4 cylinder's axle to line up with a hard line to the front on the passenger side of this chassis. That won't affect hydraulics at all, just makes it easier to use the lines on the chassis for the next track tests.



Another discovery (re-remembering?) was finding that the 4 cylinder shocks (the dirty ones, above left) are different, and have a thicker "eye" at the bottom and mount with a different bracket perpendicular to the axle. The V8 shocks have a different bracket at the axle and a thinner eye. The 4 cylinder shocks were completely blown.



So I bought the cheapest pair of Fox V8 twin tube rear dampers from RockAuto at $17.84 each, and those are on the car for the next two track tests. Nothing but the best for #TheOcho!



The shocks arrived and that allowed the 8.8" to finally be bolted up and ready for a driveshaft mockup and measurements.

REAR CHASSIS 3D SCANNING

When we had the axle out in the step above we took the time to do some scans. Myles added a bunch of our magnetic tracking dots and some talc + alcohol spray for a matte finish on the surfaces. Then the Einstar Vega was used once again to pick up details on the rear frame sections, floor, and all pick-up points.



We also had rounded up several modern OEM Independent Rear Suspension subframes and we mocked those up in the bare rear chassis. This has ruled out one of the hopefuls, but we do have some good ideas of where to go next. We never planned to just "stick a subframe" out back and make it fit, no we will make a subframe. This mockup just gave us some ideas of potential interference.



The goal is to use rear uprights and basic geometries from a 21st century chassis' IRS that has an abundant supply of the OEM parts we will build around, aftermarket support for arms (that we will make or have made to our specs), and use the center differential housing we want (Ford based). Rear hubs with the same 5 x 114.3 bolt circle and better rear brake caliper and rotor options is a plus. More on this after the next two track tests.

FLOORPAN CLEANUP + REPAIRS

If you noticed a filthy floorpan in the pictures above, you are not alone. 37 years of a leaking rear engine seal and valve cover coated the middle of the chassis in oil and grime. This is the nastiest part of this chassis, as we've power washed the engine bay and front subframe to be spotlessly clean.



The mock up engine and transmission were out so we rolled the Fox outside on a hot July day and Brad jacked up one side at a time and power washed it, after soaking it with degreaser.



The underside was now "clean" but about half the undercoating is still attached. If you look at the top pic when it was greasy, the undercoating is gone only where the oil spot used to be. That gave me an idea - let's soak it for 24 hours with WD-40!



Plastic drop sheet was taped under the car and a full "big blast" can of WD-40 was sprayed on the remaining undercoating. This mild solvent was sprayed on liberally and allowed to soak and drip overnight. The hope was this would soften the undercoating so it could be removed.



The next day Brad used some plastic scrapers and grout brushes to soften the WD-40 soaked undercoating, but it took plenty of elbow grease. The reciprocating saw with a grout brush attached was the most efficient method of removing the softened undercoating, but it was all overhead work. We just don't see extra undercoating sprayed onto Texas cars, so we're not super experienced with its removal.



After a half day of scrubbing and some time spent with the pressure washer (again), real progress was made - and it showed us some important issues we needed to address.



The bottom of the floorpan was remarkably clean for a 37 year old car. The trunk area, floorpan, tunnel - all pretty clean now. This allowed us to see some sins that needed repair.



There was evidence of tearing at both transmission crossmember brackets that are spot welded to the floor, likely from a front end impact which was otherwise repaired fairly well. The above left pic (taken while cleaning) shows a gap along the top of both flanges. The above right pic (driver's side) shows another gap as well as a tear, plus some floor deformation that needed to be addressed.



We tagged in Christian at this point, as Brad was assembling the HPR built engine to the Tremec trans. He removed the interior to get the carpet out, as we had some welding to do underneath - and with any insulation or carpet above it, that just leads to fire. There was the stock carpet + jute insulation, another layer of some aftermarket insulation, and then the glued down asphalt OEM insulation inside that he removed from the front seat area.



The old carpet was disgustingly dirty and smells like a dirty sock, so I ordered new black carpets from LMR that day. Christian weighed 7.2 pounds of stuck on insulation that he removed just from the floor section, with a heat gun and scraper, and it came out relatively quickly. There's still more to remove on the tunnel and back seat area, but we'll tackle that later.

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With the very clean floor we could see the damage and work it with a dolly and hammer. Christian straightened out slightly some bent sections of floor (drivers side, from above) moving the mating transmission mount brackets up to meet that.



He flattened the mounting faces of the brackets front to back, then a few holes were drilled to replicate popped spot welds with new rosette welds, and the MIG was used to stitch weld the seams as needed.



With those brackets bent back to the stock shapes and then stitch welded to the floor, he hit these areas with self-etching primer. We will likely paint the underside of the car when we respray the engine bay, but that's for later - now we can get back to building a new transmission crossmember to fit the TKX.

HPR BUILT 383" ENGINE ARRIVES

Skip this section if you care nothing about this GM LS engine - nobody will blame you. This was an engine built for another project a few years ago that was repurposed for this build back in June of 2025. This engine has a forged 4.0" stroke crank, forged rods, and forged Wiseco pistons with 3D milled pistons for a lighter total mass.



An aluminum block, with a spicy hydraulic roller cam (.643" total lift with 246/253 deg duration at .050" lift on a 110 deg centerline) and single pass CNC ported 241 cathedral port heads. Nothing crazy, more of a budget build that you could replicate for $6-8K.



This engine was originally built in 2020, used briefly in another car, and then put in storage. Before it was repurposed for this car it was disassembled, a few things were changed and then I picked it up only July 23, 2025 in my little Maverick. We quickly got to work putting this together as a complete engine.



The clutch and flywheel were robbed from yet another project with an LS swap - same car we took the Tremec TKX from, as that car is going to a ZF 8HP. We discussed using the 8-speed ZF automatic in the Fox, but the extra cost, complexity (tuning, adapters, wiring), size, and weight were deemed inappropriate for this build.



This Fidanza flywheel has been used in at least 3 cars in the past, going back to 2007 in our original BMW E36 LS swapped "Alpha" car. The steel mating surface still looks good and it still weighs the same 12.9 pounds that it did back then. Brad installed this to the crank with new ARP bolts and Loctite.



We used this ACT "GM9-SPSS" street performance clutch kit as well as the RAM Heavy Duty hydraulic throw out bearing kit with shims and alignment pin shown above, which are both suited for use with the "GM" splined Tremec TKX transmission. This is a heavier than stock clutch, but not by much - and attached to this fairly mild 383" LS it should be fine.



This full diameter, single disc clutch and pressure plate are hefty at 29.2 pounds. I was tempted to use a lighter, smaller diameter twin disc clutch and flywheel I had from another project, but I remembered how "not fun" that thing was to drive and went with the fill size, sprung hub ACT. This was bolted to the flywheel with more ARP bolts.



We of course checked the TOB depth and stand-off distance (.155-.200" to the pressure plate fingers, per RAMs spec) before we put the transmission on. This is the same bellhousing we have used on many TKX LS swaps paired up with a RAM TOB kit with custom lines we had in the other car. We added a remote bleeder and a quick connect to tie into the hydraulic master cylinder line. Brad then shimmed the TOB to get the right stand-off gap.



I rounded up the standard AC Delco starter we settled on years ago - it just works, is lighter than most, and it's new instead of rebuilt. The "early" LS7 water pump was bolted on, along with the thermostat housing, ICT Billet manually adjustable belt tensioner, and timing pointer. All we're missing here is the alternator and intake manifold, but it was time to bolt the complete engine to the Tremec transmission.



This weight was with our new "hanging scale" that makes drivetrain weight checks super easy. That engine tilter / chain setup weighs about what the plastic intake manifold does, so the 471 pound weight is still worthwhile.



And again the aluminum V8 is LIGHTER than the 2.3L that came out. All aluminum V8s are pretty amazing, and coupled with a light flywheel and 3D milled pistons it all adds up.

MAKING ENGINE MOUNTS



On the last day of July 2025 we were ready to finally install the completed engine into the little Fox, and it was time to dial in the drivetrain alignment and make some mounts.



With these completed engine + transmission installed, the drivetrain shimmed with wood again. Brad lined out the engine bay with strings to show centerline down the middle of the chassis, then a line between the struts to give us a fore-aft alignment marker.



We always shift any "V" engine away from the steering shaft towards the other side by 1/2" to 3/4" - as do most OEMs. It is VERY rare for a V6 or V8 engine to be dead centered in the chassis. The down angle on the back was more than I liked, but we would adjust that when we built the transmission crossmember.



The transmission is offset the same amount towards the passenger side as the engine, so it is parallel with the driveshaft and centerline. With the engine in place we also test fit the cast iron exhaust manifolds, which fit perfectly.



We had some block-side engine mounts from Holley we built around for this early stage, and decided to make some simple brackets that would be welded to the subframe on the bottom. Why weld them on? To save time - we're not trying to make an LS swap kit here, and this subframe isn't staying very long (two track tests, tops). Myles CNC cut and bent some pieces and the crew tack welded those in the car.



You can see the block-side mounts above, under the exhaust manifold. These were part of Holley's former LS swap catalog for the Fox that they have mostly abandoned due to many concerns and changes at the corporate level. Really wish we had some of those Hooker long tube header kits that worked with the stock crossmember, as I hate log manifolds - but again, this is just temporary.



With the engine out of the way, the new mounts were fully stitch welded, masked, primed, then painted in a matching white paint. It was super tempting to paint the whole engine bay at this point, but there is a lot of welding and clean up work (so many holes) that have to happen before we pretty it up in there.

DESIGN AND BUILD TKX CROSSMEMBER

Before you ask, yes we looked at what was out there to adapt the Tremec TKX transmission to the Fox chassis. We saw some crossmember designs but they were for the original SBF, and not the LS engine we are using. We also have some design parameters that somebody else likely doesn't share. So we're making our own crossmember for this swap - with this engine at this positioning.



Now that the chassis brackets are repaired and properly welded we can tie into those for a prototype crossmember. This crossmember could go into production, but it likely will get a revision before that point. Myles used another set of strings for reference and designed this in CAD using methods we have used on many previous transmission crossmember mounts we have made in the past.



The CNC cut main arms were mocked up in the car with the self-jigging components. Instead of having the big bushings at the chassis mounts, we incorporate a common Energy Suspensions poly mount at the transmission. The idea was to give the exhaust more ground clearance than the factory mount does, so the "humps" are taller than the OEM crossmember.



The basic design was tacked together in the car, and the driveline angles now matched our design goals. The assembly was removed and went to the fab bench to be final TIG welded and reinforced with some sheet metal sections.



Myles added these two panels with dimple die holes, then welded those in. The finished design was test fit, removed, and primed for a good stopping point on this design. It is bolted in the car and will get painted before we go to the track.



Overall we are happy with the design, and it ended up being lighter than the factory stamped steel unit and has a LOT more exhaust clearance. We noted one small change for a production part we will make, which I will talk about below.

LIGHTER CARPET AND INTERIOR

We keep saying - this is to be a real street car, but we also want to make it as light as possible. Why is that so important? Memories.

I remember my 1987 LX notch back that I raced through college as a 3050 pound street car, with an iron block & heads, and I think we can meet or beat that goal in 2025 with a lot better suspension, more power, better interior materials, and still have carpets. But we're still chasing pounds wherever we can find them.



When Christian tackled the floor pan repairs he pulled out the carpet and also scraped out 7.2 pounds of tar paper glued to the front seat area, but there was still more of this stuff to come out. After seeing the nasty stock carpet I ordered a new set of black aftermarket carpet from LMR, and that finally arrived so Brad tackled more tar paper insulation removal at the end of July.



The rear seat is practically useless in these cars. I sat in the back seat of too many Fox Mustangs in college, going to parties or dinner or whatever, because that's all my friends had. Literally nobody had a 4 door in my racing group of friends. I don't ever want to sit in that cramped back seat ever again - so it is coming out. We'll make some sort of "rear seat delete" kit with upholstery to cover up the sheet metal, and a firewall to the trunk, at some later date. For now, we removed the back seats (23.7) and factory jute insulation underneath (9.4) for a total 33.1 pound savings.



Brad spent the better part of a day with a heat gun, drywall putty knife scrapers, WD-40 and shop towels removing more tar paper and cleaning the adhesive, going into the trunk area (see below). Was it worth this work? Let's check the scales.



Brad ended up removing another 16.7 pounds of tar paper from the tunnel and back seat area, so that makes (16.7 tunnel and back seat + 7.2 from the front) a full 23.9 pounds of just tar paper insulation removed. Racers often remove this stuff to both save weight and to allow for clean sheet metal to weld to - for roll bars, roll cages, subframe connectors, etc. We'll have some combination of those safety and bracing options added to this chassis in the future, of course.



The factory carpet in this car is 37 years old and stanky, and it weighed in at 28.7 pounds with the factory jute insulation underneath. We're going without that jute, and the ACC aftermarket carpet came in at 8.8 pounds. Once we finish the seat bracket base design I'll show weights of the aftermarket seats vs the stock seats, then the new carpet will finally get installed. For now we're (28.7 - 8.8 lbs) 19.1 pounds ahead on carpet and 23.9 pounds lighter on tar paper and insulation, for a total savings of 43 pounds in the interior so far. I'll gladly take 43 pounds of weight savings while still keeping carpet and the rest of the plastic bits, we damn sure will.

CUSTOM CHARCOAL CANISTER

This is more "street car stuff", but done because the factory charcoal canister is long gone and we hate stinky race cars that smell like fuel. The stock tank needs to vent if pressure increases, and it needs to suck in air as fuel is consumed, otherwise it would suck in the tank closed.



The 37 year old system for trapping fuel vapors is long gone, so Jason showed me some off-the-shelf solutions, then came up with an idea he wanted to try - making one from a catch can and some charcoal pellets for a fish tank filter. I'm game, so we ordered both the tank and a huge bag of the charcoal, then took a look at the parts.

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The imported aluminum catch can kit came with a lot of aluminum machined barb fittings, plus an internal screen that would keep the charcoal in the main chamber, and a bronze vent filter that will allow air to pass both ways. It also included an external vent filter, which we planned to place "outside of the car", and outside of the cabin. When the charcoal arrived on a weekend I took it all apart, configured it how I felt would work best, and added as much charcoal into the main chamber as it would hold.



We had the "big vent" in the fuel tank from Breeze, and that kit came with some appropriate fuel vent hose - which we plumbed from the top of the tank into the trunk. We just drilled a hole (see below left) to feed into our charcoal canister. That hose was shoved through a simple hole with a grommet, and had some slack as the tank was raised in place - should allow for tank removal without a bunch of hassles.



Normally I'm against plumbing through sheet metal without bulkhead connectors, but this is just a vent line - zero pressure - so we let it slide (literally). The restored fuel tank was raised in place and mounted with the stock straps and black abrasion shield, with the level sensor and wiring for the tank connected.



The external vent filter was installed in the "top" of the catch can at a 90 degree angle, and that was then mounted outside of the plastic fuel filler splash guard (see above left). The charcoal canister was plumbed at the bottom side (the chamber with the charcoal pellets) from the tank vent and Breeze check valve.



Brad then made a simple aluminum bracket that attaches to the trunk with a rivnut. That's it, that's the whole system. Less than $45 spent and it should keep the stink outside of the car (venting to the filter behind the fuel door flap, which isn't air tight) and allow the air inside the fuel tank to expand and contract without any damage to the tank.

HEATER CORE REPLACEMENT

Why show this step? Well to prove that we're building a real street car and not some dedicated race car. And also, heater cores were a common failure point for the Fox models when they were new. We're changing this one out suspecting it leaked - and if you could smell the carpet, you would agree. As soon as we saw the heater core out of the dash, it showed evidence of leaking.



The cooling system work we're going to perform would be pretty silly to then plumb into this old mangled heater core, with crushed hose nipples sticking past the firewall. This thing was chewed up and was begging for replacement with something fresh and better made.



We needed to drop the dash down anyway to tackle a hydraulic clutch system conversion, so we had this all aluminum heater core on hand to swap in. There was squirrel debris and other nastiness under the dash, so all of that was cleaned up.



The old heater core unit was brass and shaped exactly like the aluminum version (see above left), and the new one weighed half as much. Most OEMs have gone away from brass to aluminum for heater exchangers since the 1980s, and we're doing the same under the hood, too.



I replaced a leaky heater core in my Fox around 1992 or so, and I didn't have the patience to remove the dash - so like a hack, I just "cut a hole" in the HVAC box to gain access. I'm so glad we did this one the right way. This was a relatively easy one to check off the list, if you ignore the hassles of dropping the dash.

DESIGN AND BUILD DRIVESHAFT + SPEEDO ROUTING VER 1

It was August 2025 at this point and we needed to make a driveshaft to connect the Tremec TKX and the 8.8" axle out of a V8 Fox. The transmission crossmember had been painted with the same silver ceramic engine paint as the fuel tank, as you can see. I went through some of our "returned" driveshafts from our other swap kits to piece this one together.



In the past we sold swap driveshafts made to our drawings, designed for a specific chassis, transmission and axle for BMWs and other cars. Some people have reading comprehension problems and just order a driveshaft and hope it fits their random swap. We get so many angry returns from folks that we just stopped selling driveshafts last year - people cannot follow directions. That meant we had a few new ones leftover, and we robbed them for parts - including the front yoke and both machined aluminum ends for the U-joint connections. The TKX shares the same front yoke as the T56, that was installed it in the car (see above right).



We didn't have an original V8 Fox driveshaft to steal one from, so we ordered this axle flange yoke adapter for a 1350 U-joint from Denny's Driveshafts, then mounted that up. With those two ends complete, we could measure for the 3" tubular driveshaft and have that built to spec (made a drawing, spec sheet, PO, etc).



I went to a local driveshaft shop to have this made, and even using the aluminum yokes and all the supplies we offered up, and all they did was supply the main shaft + welding and balancing, wow they charged me a lot. But hey, it was done, and we aren't offering driveshafts for swaps ever again, so I don't need to worry about finding a new supplier with better prices.



This is when we went to put the stock speedometer cable into the TKX, which is setup to take a mechanical cable to drive the speedometer. We had ordered the "yellow" drive end to work with the 3.08:1 ratio rear end, and well... the prototype crossmember needed a bit of a tweak to line up. And later on, it needed more work still. We'll show that next time!

SECONDARY SENSORS FOR STOCK GAUGE FUNCTION

We're going to have a digital dash in this car, but it will be mounted off to the side - the main gauges I want to look at while driving on track are the original gauges from 1988!



These include the big 140 mph speedometer, the 8000 rpm tack, fuel level, oil pressure, coolant temp and voltage meter. To make all of those gauges function with the LS engine (which we're controlling with a Link ECU) we're running a parallel set of factory 1988 Mustang 2.3L sensors.



We could have pilfered the old sensors off the old 2.3L engine, but instead of re-using nearly four decade old sensors (and the oil pressure sensor was highly questionable) I splurged for new versions of the coolant temp and oil pressure. Jason found the right adapter for the M12-1.5 thread in the LS cylinder head to adapt the Ford temp sensor, and the oil pressure sensor will be tied into a remote hose and dual sensor package off the back of the LS block, with one going to the gauges and the other to the Link ECU.



Brad started thinning the factory engine bay harness to the bare essentials in September, including these two sensor circuits. The speedometer cable will still work, the tack signal will come from the Link, the fuel level circuit will go to the tank and the voltage is easy. The stock gauges will work in all of their 1980s glory!

RADIATOR AND FAN

When it comes to cooling, I've always been of the "overkill everything" mindset, and will take any small weight penalty that this brings. While we are focused heavily on weight, under-sizing the radiator or fan is not in my DNA. As we found out on our 800 hp LS powered S550 Mustang, you can have enough radiator cooling for track use at speed, but idling or driving slowly forces the need for a big electric fan.



After I took some measurements of the engine bay, I did my searches and ended up with the EXACT same radiator I picked for Trigger - it will also fit the Fox. That's great, because that thing is a BEAST. That also means that the same fan we use on the S550 - this S197 Mustang factory electric fan - will also fit. This combo solved my idling temp issues, and we can let the 454" LS idle all day in Texas summer heat now without issue. Coolant stays at 175-185F on track and cycles on the thermostat at 190F at idle in the paddock, with the fan going on and off as needed.



This Howe two-pass core was significantly taller than the "bolt in" aftermarket Fox radiators (most of which were $600-700) but we've got our tricks - namely, a slight radiator roll. I had hoped to push the top of the radiator under the stock radiator support (like we did in the S550) but the opening was too narrow to tip it forward, so we just pushed the bottom of the heat exchanger rearward and down a bit.



Without the massive mechanical fan and shroud the V8 Fox has, we have plenty of room. It helps that we pushed the LS as far back toward the firewall as we could. Lots of room. First, Brad drilled out the spot welds for the lower mounts, and those were removed to give us clearance. Then he added rivnuts at the lower portion of the front radiator support to hold some new "rolled" lower brackets. We used the same method and series of parts we have used many times before to mount radiators.



Brad made a pair of aluminum lower new brackets and added lower radiator mount bushings from a 1st gen Subaru BRZ, mounted inside these aluminum brackets. Those were then bolted in place at the lower radiator support with the rivnuts from above. This lets the bottom of the radiator slip down just about an inch.



Myles then machined some round aluminum stock on the lathe to fit these bushings, and he TIG welded those pins to the lower tanks, just like countless radiators factory are mounted. We did the exact same on the S550, and its worked well for 4 years. That gets the massive Howe radiator located at the bottom, with a tilt, so all we need to do now is locate the top.



Brad took some aluminum sheet, sheared that and bent it on a 90 degree angle. Some "clamp" mounts were built into this with foam cushions to hold the outside of the upper portion of both side tanks. This upper panel bolts to the upper radiator support on the Fox.



Of course the upper bracket is brush finished and has dimple die holes, because why not? The lower mounts are cushioned and the whole unit is supported at the tanks. We'll add front facing ducting panels to force the air from the grill through this radiator - later in the build.



This is how the finished radiator mount came out - it is a MASSIVE unit that the front fin areas see all of the front end airflow, thanks to the slight roll. We still have ample room in front of the engine, as you can see with the front accessories in place, above.



The S197 fan was mocked up a few weeks later, and of course it was weighed (9.7 lbs). It is a significant amperage draw, but we remove the 2-speed switch it comes with and run it wide open, with a trigger from the ECU through a relay.



It mounts exactly like the factory S197 Mustang fan mounts - with two bolted fasteners at the top and two slip in mounts at the bottom (with the two plastic lower fins). Brad made the little fin mounts and Myles welded those on, as well as some threaded aluminum bungs for the upper bolts. All TIG welded onto the tanks, and the fan fits perfectly with zero mods on this setup. If it ever dies, another $100 fan can be slipped in place and bolted down. Easy.



That's what the fan looks like bolted in, with some most of the cooling hoses in place - I'll show more of that next time.

WHAT'S NEXT?

This is a great place to stop, as this post is running long - but at least it got us into September 2025 work.



We're much further along and I will share more next time - hopefully with the engine running and the car moving under its own power again.

More soon,

Terry @ Vorshlag