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Unread 10-02-2012, 06:51 PM
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Default Re: Vorshlag BRZ Project Build Thread

Project Update for October 2, 2012: Well a lot has happened in the last four weeks since my first BRZ post. We've been super busy with some big race weekends, and have been working on several LS1 swaps in-house among other cars. Still, we have made some strides on this FT-86 project. First, the SCCA classing news.

FT-86 Twins Classed In STX!

If you are interested in SCCA autocrossing this FT86 chassis, there were some notable things said and seen at the 2012 SCCA Solo Nationals. We noticed a number of FR-S/BRZ cars entered in C Stock and a few in Road Tire, but the car was not classed in Street Touring category for this years Nationals, which was held last month in Lincoln, Nebraska.


Left: We saw seven FT86 cars at Nationals in CStock and RTR. Right: Our ESP Mustang did all right with four months of ESP development

I went to the SCCA Town Hall Meeting and it was said there that the FT86 twins would be classed in Street Touring soon after Nationals. It was inferred to me personally that the twins would go to STR, racing against the S2000, 3rd Gen MX5, and the other roadsters in that class. I felt this was a bad idea and that it belonged in a slower class, STX, which is made up of heavier 4 seat cars like the FT86 chassis. Behind the scenes the SEB and STAC (the two groups that class cars in ST) were split down the middle, and I "read the tea leaves" as they would be conservative and put this car in the faster class.


There's two things you don't find in Nebraska: good Mexican food and predictable weather

I made predictions soon after Nationals that the twins would go to STR, but was thankfully wrong, as this October 2012 FasTrack notification a couple of weeks ago placed the BRZ and FR-S into STX class. There are very few preparation differences between STR and STX classes, with X having a 265mm tire width maximum and R being 255, but both are limited to a maximum of a 9" wide wheel. The rest of the rules are identical - header-back exhaust, high flow cat, cold air intake is somewhat unrestricted, outer fender contours cannot be changed, but suspension has lots of allowances. You can't use metal bushings or move pick-up points (avoid those silly "anti-lift kits"!) but you can use coilovers, camber plates, poly/plastic bushings, and more. Great classing choice b the SEB and STAC, and I commend both on their choice and apologize for ever doubting their wisdom.


These are your typical STR (S2000, left) and STX (325 & 328 E36, right) front running car models

I made some statements on roadraceautox forum (aka: The Sandbox) that, if I was wrong about these cars going to STR, I would eat crow, dance a jig and prep Matt's car for STX. Ran out of time today and didn't get to take a video of me "dancing a jig" but we will do it this weekend at the NASA event. I have never been happier to be wrong, too. The SEB still has a 12 month window to change their mind when they first class a car, so if the FR-S or BRZ proves to be dominant in STX they said that they will move it to STR, potentially before the 2013 Solo Nationals. So if you prepare your car for STX just... be careful not to go TOO fast at a National Tour or ProSolo.

This STX classing for the twin has already made a big impact on racers - just today a long-time SCCA Solo racer called me and said "As soon as I saw the STX classing I bought a car that week!" Again, I don't feel the FT86 twins will be a threat to STX, but they should at least be competitive here, unlike in STR, where they would have been cannon fodder.

Whiteline FT86 Parts Going On

We at Vorshlag were already an Energy Suspension and Powerflex bushing dealer, but picked up Whiteline products last month as well. This was because they had some new bushings, Watts Link kit, control arms and relocation brackets for our twin 2011 & 2013 Mustang GTs that we needed. We put them to the test at the Solo Nationals and Global Time Attack events last month and did very well at both. When one of their reps came to our shop before the GTA event, he saw that we had a BRZ project and offered up some new goodies to test straight away. The early FT86 items from Whiteline available right away were two of the WRX/STi holdover parts that made it to the FT86 unaltered.



The first thing we installed was the Whiteline transmission mount bushing insert, part number KDT926, shown above. We have these ready to sell, of course. This kit is a polyurethane shifter bushing insert that fills a massive void in the OEM transmission bushing. Installing this bushing took minutes from underneath and it really tightened up the shift feel, but added a tiny bit of NVH in the process (noise/vibration/harshness).



You can see the gap in the OEM bushing above left and the Whiteline insert installed above, right. The main bolt from the bottom secures the insert in place. Very easy install and very worthwhile for anyone wanting a better shift feel or anyone doing competition events where this is allowed. Matt says it has a little extra vibration at 750-800 rpm and a little more engine noise at 2500-3500 rpm. It isn't too harsh and I barely noticed it myself, but just wanted to warn anyone. He says it has become less noticeable since he has been driving it for the past week.



Next up was the Whiteline polyurethane rear crossmember bushing insert kit, part number KDT922. We also have this ready to sell in our FT86 model section. This kit has two-piece polyurethane inserts for the rear crossmember bushings, which are made of rubber and also have BIG voids in them to make it all squishy and sloppy. Again, the OEM has to make these cars 100% smooth for every single type of driver on the road, but enthusiasts and competitors are going to want firmer bushings in several places.


Left: Stock bushing installed. Right: Whiteline KDT922 kit installed

This rear crossmember insert kit prevents the rear differential housing from having to "wind up" against those big, open rubber bushings. They are easy to install (and easy to remove later, if the car gets sold) and tighten up the reaction time from when you mash the throttle to the car accelerating forward. Once the car was in the air, the rear subframe was lowered an inch or so and these inserts were bolted above and below the rubber bushings, removing the gap and firming them up. It took about 45 minutes.


Here is a animated GIF showing the installation of the KDT922 kit

Swift Lowering Springs, Test 1


Left: OEM ride height reality. 15" from fender lip to center of wheel, F&R. Right: Photoshopped ride height goal, about 1.5" lower?

One of the most visually irritating things about this car, after we replaced the OEM skinny wheels and tires, was the tall stance. Again - Subaru and Toyota had to make the FT86 twins work on almost any sort of road or weather condition (think: heavy snow drifts), so they made it sit up tall and have relatively soft springs. We measured Matt's BRZ at 15" from center of wheel to fender lip on all four corners. Measuring this way will not change with tire height changes, so it's how we measure all cars that have unaltered fender lips.

One of the first and most popular suspension upgrades on many sports cars is a change to "aftermarket lowering springs". These usually lower a car 1 to 1.5 inches and stiffen up the rates 10-30%. There are several brands and options for the FT86 and we carry both Eibach and Swift. Most lowering springs have a variable rate design, where the first inch or so of travel is OEM soft, but then the coil spacing changes and they get stiffer after that amount of displacement.


Left: OEM rear spring next to Swift Lowering Spring. Right: OEM rear shock and Swift spring.

Swift heard about our BRZ build and sent us a prototype set of lowering springs for the FT86. Well, it was more like we begged them to send us their first set (after they had done their in-house testing on them) so we could at least show something going on with this car (because our coilover shocks are very late). They warned us that this set of Swifts was not the final production version and that the ride heights were not what they targeted, so I'm not giving any stats or impressions on these just yet. We were just happy to get the first test set on Matt's car and will revisit this when the revised production springs are available.


Left: Front Swift spring on OEM strut. Right: Rear OEM shock and Swift spring.

The ride height is a bit lower, but it is not dramatic. I suspect that the production kit will be closer to 1" - 1.5" below the stock 15" number. We raised the front a tick with our prototype camber plate + OEM perch solution, which I will explain below.

Vorshlag Camber Plates for OEM Spring Prototypes

We have already been selling camber plates for the FT86 for a few months, but so far we only support the coilover offerings that use a 2.25", 60mm, or 2.5" ID linear springs. This is because our Vorshlag camber plates always come with a new upper spring perch with an integral sealed radial bearing inside - it is a long story, but this is why our plates don't wear out or make noise or have funky steering feedback. Whenever we make a new camber plate design it gets the coilover perch first, then we tackle the OEM perch second. The FT86 uses many Subaru GD chassis parts and our high caster Vorshlag camber plates work perfectly on this car. But the Impreza GD's front OEM spring diameter is very different than the FT86's spring diameter, so we had to make something custom.



Making the OEM perch for our camber plates is a lot more involved than just fitting it to the factory diameter spring (which aftermarket lowering springs all match). To do it correctly it requires a lot of calculations, modeling and some testing to get the final camber plate + perch assembly to match the factory ride height. What we don't want to ever do is raise or lower the ride height in the new camber plate + perch assembly for an OEM/aftermarket lowering spring application. For a coilover car we actually try to minimize the stack-up height, to increase total stroke; ride height can be adjusted with the adjustable spring perches inherent to coilovers.



We took Matt's car apart a couple of weeks ago and measured the factory spring diameter and modeled the OEM top mount and upper perch, but have not had time to do the full 3D design work necessary to make an all new upper perch explicitly for this chassis/spring. But we had just finished all of this design work + prototypes + testing phase for the BMW 1M OEM perch and had an extra pair of early 1M prototypes sitting on the build table when the BRZ Swift lowering springs arrived. Lo and behold, they were almost perfect fit to the FT86 front spring diameter!



So when we did the Swift spring install on Matt's car we machined a custom set of BRZ upper perches in the lathe from a 1M prototype set and - viola! - we had our first BRZ OEM spring perch solution. After installing them it looks like it needs some more tweaking to be the perfect solution for the FT86, but for now it allowed Matt's BRZ to get up to -3.0 of negative camber in the front! His BRZ started out with -0.2 to -0.4 on the front end (and we verified this OEM camber setting range on a friend's FR-S also) so that is a big gain, and it can go right back to the stock setting (and a little beyond) for a big range of adjustment.


Here's how it sits with our prototype camber plate + OEM perch and prototype Swifts.

Again, please ignore the ride height of this car in the picture above. This has both prototype Swift springs and prototype Vorshlag plates with OEM perches. Both designs are not quite 100% yet - we still need to tweak the front OEM style Vorshlag perches a bit, and the lowering springs are not production lengths either. The raised front relative to the rear is from our camber plate, not the Swift springs, too. We will readdress this in a future post when both production parts are ready. Should be a matter of weeks. These Vorshlag OEM style upper perch + Camber Plates are not for sale at this time; we are only supporting coilover spring diameters for our FT86 plates right now.

Issues With The Car

Matt's BRZ has logged a tick over three thousands miles on the odometer now and two small issues have cropped up. First thing we noticed visually was the right rear taillight housing is showing water inside. This is likely from a crack in the foam rubber seal between the outer lens and the tailing housing itself, and condensation has entered. My brand new Mazda RX8 did this when it was about the same age (two months old). Matt will have the Subaru dealer replace the leaking housing under warranty.


We over-filled the blinker fluid!

The second issue is the 3rd gear synchronizer seems to be shot, and it hasn't been abused. This started happening weeks before the Whiteline transmission bushing insert was installed, which had nothing to do with the synchro failure. I drove the car when it was a week old and it shifted smoothly into each gear, with fast or slow gear changes. Matt has only been daily driving this car to work and on a couple of trips, he doesn't speed shift or drive like a maniac, and almost every car he has ever owned was a manual. I don't think it is user error. But today when I drove it with 3000 miles the synchro is snicking badly unless you shift 2-3 like a grandma. It takes a "1....2....3..." count to get it onto 3rd without crashing. It doesn't seem to occur below about 4k RPM, but above that it will grind even with the most gingerly shift. Again, I just saw this first hand and was shocked. This will be another thing to mention to the dealer for repair under warranty.

Not trying to spook anyone - these are not necessarily unexpected issues with a brand new design like this. And also I had a then brand new model 2005 RX8 showing more issues than this - a blown strut, end link fell apart, taillight housing was full of water, and it got horrible gas mileage - so just be ready if these issues pop up. We are seeing a sample set of one here, so these two problems do not necessarily mean this is a trend.

What's Next?

We have more production FT86 Whiteline parts coming right after the SEMA show next month, hopefully. We have a three track events at Eagles Canyon Raceway coming up int he next 6 weeks (NASA Oct 6-7, SCCA PDX Oct 13-14, Five Star Ford Open Track day Nov 17) but Matt is out of town for two of those. Hopefully we can get it on ECR (our main test track here in town) at the November event and get some baseline test laps in.

Thanks,
__________________
Terry Fair - www.vorshlag.com

Vorshlag project cars: $2010 GRM Challenge E30 V8 + E46 DSP Autox Build + 2011 Mustang GT autox/track car

Last edited by Faerus; 10-03-2012 at 11:59 AM.
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