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Unread 08-31-2016, 03:44 PM
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Fair! Fair! is offline
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Default Re: Vorshlag BRZ/FRS Project Development Thread

Project update for August 31, 2016: It has been 3 years since I last updated this thread. When we left off in August 2013 I had just autocrossed Matt's '13 BRZ on the newly installed set of MCS coilovers and 255mm Rivals. Matt left Vorshlag shortly after my last post, so we lost our "in-house" 86 test chassis. We have of course worked on many more 86 chassis cars since then, and have even developed some new products. I will cover all of that, plus introduce another 86 into the Vorshlag shop - my wife Amy's red 2013 FR-S (see below) which she bought a week ago.

Vorshlag 2013 FR-S which we tracked in stock form last weekend to get a "Baseline Lap Time"

We've already weighed it, fixed a number of worn or broken items, then tracked it at Motorsport Ranch to get a "baseline stock lap time", which we will use to gauge improvements over time. We bought this car to test fit "some new items" we just moved into production for this chassis, and we will also use it to develop and test more new products over the next year or two. Let's get caught up first, then cover the product developments we've made for the 86, then show our new shop car and the track test.


Yes, I am doing an event write-up from 3 years ago - but it was a very memorable event for several reasons. This event happened during a hectic series of weeks, as we were developing and track testing a new aero package for our NASA TT3 classed Mustang, which we took to the NASA National Championships at Miller Motorsports Park a couple of weeks later (where the car did OK, trophied 3rd in class - we changed the aero package further soon after and made even bigger gains).

August 2013 was a hectic time at Vorshlag - working on a lot of cars & prepping for NASA Nationals

This August autocross was also the first and last time I competed in Matt's BRZ, as he turned in his notice shortly after this event (moving on to a higher paying job outside of motorsports, which we wished him well with). The local autocross clubs lost this site shortly after this event, and it was the last time I ever got to race at Crandall. Just a bunch of reasons why I lost track of time and never did this event write-up in the BRZ after adding the MCS coilovers.

Event Photo and Video Gallery:

At this August 2013 autocross, Matt ran his BRZ in Novice class with an STX pax and I ran it in the open STX class. The car at this point had a few Whiteline bushings & swaybars, MCS coilovers with the rates we have since spec'd on dozens of 86 cars, Vorshlag camber plates, and the ever popular Enkei RPF1 wheels in 17x9" with 255/40/17 BFG Rival tires (this was long before the Rival-S or RE71R arrived on the "200" treadwear autocross scene).

Right off the bat the handling felt so much better than with the stock dampers and lowering springs. This clean concrete parking lot had a busy layout, but similar to several events we had run at this now defunct site. As they typically did, this course had lots of turn-arounds, slaloms and offsets.

We made only a few damper and tire pressure adjustments and swept both the STX and Novice classes. Matt took first in novice out of 29 cars at this, his first autocross event in the car. My entry in STX was 1st out of 4, 13th out of 111 in PAX, and compared well to other STX and STU cars that ran that day.

There were other STX cars running in other classes, like Brad in "X" class (for pro level drivers), and Sipe who ran in SMod that day. Sipe was ahead of us but that was in an RX8 with possibly the highest STX level prep of any car in the nation at the time, and he also run in a later heat. So with a car that was just setup on MCS coilovers the BRZ was pretty dang quick, and we were happy with that.

That same day Amy and another autocrosser Mark Council both drove very well prepped Mustangs in STU class - as a test. Amy was driving our 2013 Mustang GT (on AST remote doubles, bars, brakes, 18x10" wheels, more) and Mark was in his even more prepped 2012 GT. Their two drives provided two more pieces of data to show that the pony cars didn't belong in STU class. Mark and I both raced his car in STU the month before at this same site, too.

At that August event they were both on competitive tires and drove well, but they both still brought up the bottom of the STU class and were 3.5+ seconds behind my STX time in the BRZ. Remember - STU is supposed to be faster than STX. I've co-driven with both of these drivers many times - they are both fast, and Amy even has the National Championships to show for it. This data from this and some previous events was what we used when we wrote in for new rules allowances for the stick axle cars in Street Touring... which led to a letter writing campaign... which eventually led to the formation of the STP class (right after CAM was introduced, terrible timing). So their drives were worth noting and comparing to the STX times of this BRZ, if you follow those classes.

In-car video of my fastest time that day

The in-car video above was my fastest autocross time of the day in the BRZ, but there were still a number of "qualifiers" from this run that I have to note. First, I had Mark Council riding with me, and he is no dainty little boy. Second, there was a lost car randomly driving around on course, which I noted so I backed off briefly... to make sure he wasn't going to swerve in front of me (the corner workers red flagged the course, behind me). Lastly, STX ran in an earlier session that day and the course had about a dozen spots of water seeping up through the concrete (from a recent rain) that slowed us down a tick. The course dried out in later sessions and those drivers were generally faster. So the car could have been even quicker without these issues.

I remember that autocross vividly. The BRZ handled so well, just did everything right - rotation/corner entry, stopping, slaloms - other than not having much horsepower (100% stock drivetrain, making 166 whp). This was before everyone and their brother started autocrossing the 86 chassis, and the BRZ really crushed it that day. Good fun that day, and I aim to make our FR-S handle as well as Matt's BRZ did, if not better.


We have sold a good number of MCS coilovers for the 86 chassis but the price point does put some people off. We have been selling more and more Bilstein monotube coilovers and in early 2016 we reached out to a local autocrosser, Chase Reeves, to see if he would test a modified version on his BRZ. He jumped at the chance to become a Vorshlag Tester, and even though he's only been autocrossing for 2 years he goes to a LOT of these events, as well as road course club trials.

The Bilstein PSS10 kit for the 86 chassis is shown above. This kit has adjustable damping, uses an inverted strut and a 40mm shaft housing, and works well for "spirited street use" with the springs provided. There is one knob that adjusts both Rebound and Compression, but the Rebound changes are significantly larger. This is not the type of valving adjustment what you'd see in a true Motorsports monotube adjustable, but the price is often $800+ less than the entry level MCS TT1 kit - and the Bilstien kit also comes with ride height adjusters and springs, so the price difference is even larger.

Like we do with all shock kits that come with unmarked springs, the spring rates were measured here at Vorshlag (the right way) and we found them to be too soft for even semi-serious serious autocross or track use. The rates were almost the same as stock, to be honest. The spring rate charts we measured on our digital spring rating rig showed a front spring rate of about 172 #/in, and was somewhat linear. The rears had a more variable rate, from 175-275 #/in (avg rate of 207).

We tend to see these somewhat soft rates and oddly shaped "Tapered" springs on most Bilstein "PSS series" kits (PSS with non-adj valving and the PSS9 and PSS10 adjustables). The included springs are usually 60mm ID at one end (the bottom) and the OEM diameter at the top (huge). We almost always ditch these springs, for two reasons: softness and size. The rates above are too soft for use with a grippy 255mm tire - the car would have too much roll and dive when driven in competition.

To fix this we converted this kit with a 60mm coilover spring rate upgrade front and rear, which allowed us to ditch the giant OEM strut top mount and use our Vorshlag camber plates. We chose a linear 350 #/in rate Hyperco spring up front, with no tender spring. This works in conjunction with our 60mm upper perches and camber plates to convert this from an "OEM" style upper spring diameter to a much smaller 60mm spring. The smaller diameter spring allows for more inboard camber travel, as the 60mm spring takes up much less space laterally and allows the top of the strut to travel inboard more than the stock spring ever could. The 60mm sparing is also about half the weight of an OEM or the Bilstein kit's "tapered" spring.

Out back we used another 350 #/in spring from Hyperco We coupled this with a prototype set of Vorshlag spherical rear upper shock mounts (RSM) shown below, which we made on our CNC machines while the car was here for installation. We coupled the new spherical upper shock mount with our 60mm upper perches and an integral single-row sealed radial bearing, which deals with any spring rotation during compression. These have been used for testing on Chases BRZ since early March 2016 with zero issues, so we will move these into production soon.

If you look at the post above this one we have the spring rate charts for the factory BRZ and FRS springs. The stock BRZ had springs with rates of 162 #/in Front and 201 #/in Rear. The stock FRS curiously had a stiffer Rear rate at 221 #/in but a softer Front rate at 125 #/in. Like we have done in the past with PSS10 Bilsteins, we "about doubled" the spring rates, to get to what we felt would work right off the bat and within the PSS10's damping adjustment range. With an MCS coilover we tend to start with triple the front rates as our softest option, but the PSS10 damping doesn't have quite as much range as a Motorsport level shock like the MCS.

Since this was Chase's daily driver, car we kept the ride heights almost identical to stock, which he asked for. Normally that is tough on a Motorsports damper, and we could have gone an inch or more lower, but this is what he wanted and the Bilstein's adjustable ride heights allowed for this. We did gain a lot of negative camber and some positive caster with the camber plates and smaller diameter springs, and the total negative camber goes up with lower ride heights.

The setup sheet we did for this BRZ, like we do for all cars we install suspension on, shows the before and after ride heights and camber measurements. With camber maxed out (and front toe set to .125" total toe out, to minimize tire wear but still allow for a razor sharp turn-in) we saw -3.5 camber up front. With his 255/40/17 Dunlop Direzza Z2 tires on the 17x9" wheels above we knew this would work well, and camber adjustment is easy if he wants to change it.

The damping adjustment was also easy to dial in for street use, and Chase uses 2 out of 10 clicks from full soft for daily driving use. The rear knob is visible in the trunk, as shown above. The front strut's damping adjustment is at the bottom of the strut, since it is inverted. This means to access that knob you have to turn the wheel to full lock and reach in under the strut to get to it.

That is a picture of another PSS10 strut, from a Porsche 996 install we did a week before this BRZ. The strut's damping knobs are marked well and have very distinctive clicks, so once you visualize which way "soft" is, you can do this adjustment by reaching in and turning it blind.

Chase has been co-driving a Corvette for autocross this summer, but recently competed in two events in his BRZ. But he moved up to 245mm Hoosier A7 competition tires. This really wasn't what we designed this modified PSS10 kit and associated springs for, but damn if it isn't doing well anyway! He won CSP at his first event on A7s and came in a close second this last weekend, narrowly missing out on another win by .020 sec. That was running against some dedicated CSP Miatas (see in frame above) with flares, big tires, built motors, serious levels of prep and some of the fastest drivers in the region.

Not bad for 350#/in springs and PSS10s on an otherwise stock BRZ. Well he has a 20mm front Whiteline swaybar and the 16mm Whiteline rear bar as well.

Here is Chase's best autocross run from the most recent SCCA event, where he came in a close 2nd in CSP. Once he gets back to doing more road course events, mostly SCCA Club Trials, I'll try to get some lap times from him on the new Bilstein / Vorshlag suspension.


So I'm caught up on the last autocross I did in Matt's BRZ, and showed the PSS10 kit we modified and installed on Chase's BRZ. Now let's take a look at our new shop car - this 2013 FR-S. We had some pressing deadlines on some 86 parts we have built which we needed to verify on an 86 chassis - a car that we could take mostly apart - so a tester's car on loan wasn't the solution here. There were also some new suspension bits we have dreamed up that it would help to have a stock 86 on hand to test with, too.

Amy has been wanting an 86 for the past year and a half. Strangely enough she never drove Matt's BRZ, but about 18 months ago she test drove a new 2015 FR-S one random Saturday - and she loved it! There was a series of cloverleaf exits next to the Scion dealer, she did all 4 of those twice each, and she was hooked. Even with the skinny Prius tires they come with it was still fun. The seats, greenhouse, visibility, stock handling, ergonomics - it all worked for her.

continued below

Last edited by Fair!; 01-25-2017 at 06:36 PM.
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