Vorshlag 2011 Mustang 5.0 GT - track/autocross/street Project

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Project Update for Nov 16, 2012: Wow, has it been a month since my last update to this build thread? We've been buried and posting on our other build threads, but I neglected this one. We had an autocross two weeks ago (last one of the year) and have a track event tomorrow that we're loading up for. And the eBay auction on my 2001 BMW 330Ci is still going strong (ends Tuesday Nov 20th at noon!). Anyway - busy busy, so let's get caught up with a quick update.

SCCA Autocross, Crandall, Nov 4, 2012

Two weeks ago we had the last autocross for the year lined up. We had the 315/35/18 Kumho V710s still mounted to the Forgestar 18x11"/18x12" race wheels. Hmm, swap to the Hoosiers for this autocross or not? It was the last event of the year and I had the regional class championship wrapped up, so I blew off the extra work of swapping tires and had the guys here at Vorshlag leave those on the race wheels and the 315/30/18 Hoosier A6s stayed on the tire rack. If it was even remotely warm they would probably do all right, and I doubted Madarash would show up to two SCCA regional events in a row (my main ESP competition in this region - the reigning and 8 time ESP National Champion who is brutally fast every time).



Well, I was wrong... he did show up, but didn't run his car. Opie Viets brought his '84 3rd gen Camaro down from his region and ran with Madarash co-driving. And they ran Street Mod, in an earlier heat. Opie's car was similar to Mark's in many ways, and even had Madarsh's old double-adjustable Konis and some other parts of the set-up were the same. But it wasn't Mark's actual 3rd gen, and he told me this past week that it still needed some work. So yea, "I beat Madarash", technically, but it wasn't a real victory - it wasn't his car, running in the same class or heat. But.... I never get to say that much, so I gotta sneak it in whenever I can!

• PAX Results: http://texasscca.org/2012_solo_results/tr12_9_pax.htm
• Overall Results: http://texasscca.org/2012_solo_resul..._final.htm#ESP
• Photo and video gallery: http://vorshlag.smugmug.com/Racing-E...andall-110412/

Strangely I did place 2nd out of 112 in PAX, which was a first for this car. It was frakkin working WELL on those Kumhos!?! So Amy and I drove together in ESP and ran in the last heat of the day. Temperatures were mild all day and there was water on two parts of the course for everyone's runs. It was there in the morning and kept seeping up through some cracks in the concrete pad, so we all had to deal with it. Oh well, could have been in worse spots.



The course was the same as two months ago for the first 1/4, then it had some tight turn-arounds with short acceleration zones coming out, with lots of tight TIGHT transitions. Walking the course I feared losing to street tired Miatas in STR or the narrow slalom buggies in STX, but luckily that didn't happen. Putting 2.5 seconds on STR and 4.5 seconds on STX was unusual for us, but it felt gooood. Even with a lot of tight stuff the big S197 did all right.



Everything seemed to work well that day, for once. The shocks worked brilliantly, as always, but so did the brakes. No "ice mode" or lack of power assist, like the last time we ran here (we put in the 2nd replacement brake booster vacuum hose grommet before the NASA event). The tires were pretty cool all day, but we finally got some heat in them after our 4th runs, which seemed to help. With the new stiffer spring rates we added after the Solo Nationals, and the stiffer swaybar settings that seemed to work best in our private test, the car corners flatter and transitions violently.



A nice surprise was Amy getting interviewed by a camera crew shooting for "Mobil1 The Grid". The interviewer even rode through with Amy and was all smiles after hopping out. They interviewed a half dozen racers so it might not "make the cut", but she put on some good runs and did great on camera, and the car looked and sounded great. She was a tenth off of Madarash's time, and a second quicker than the 3rd place ESP entrant, also a Solo Nationals veteran. The Mustang was just stinkin' FAST that day. So ... we will know if she made the cut when the show airs on Speed (or FoxSports1?) next March, I guess.



An old college buddy and my current engine builder (HKRacing Engines), Erik Koenig, was in town delivering two LS1 engines to Vorshlag, so he stuck around and came to the autocross. We watched some of the event from atop the drag race bleachers then he rode through with me on three of my runs. He taught me most of what I know about autocrossing back from our TAMSCC college racing days, and was the first person I ever rode through with in an autocross run with on race tires - which totally ruined me, and led me to go to college at Texas A&M University in the first place! He used to race well against Madarash in ESP in the early 1990s, so he got to talk to him again after being away from the sport for the past decade. It was good to see him out again and I hope he gets one of his Mustangs back into autocross worthy shape soon. Big shout out to my buddy Ed from Pirtek, who came out to "crew" for Amy's and my runs. When you're driving with two folks in a small heat, with numbers to change, tires to check, shocks to tweak, passengers on every run, and a TV crew shooting video of all of that, this really helps - so thanks!



Above is the in-car video from my fifth and best run. It had a huge mistake in one of the tight 180° turn-arounds, and I blew off the run after that. The right rear started spinning after that flub and I just matted the throttle, pissed off at my mistake, and just drove like an idiot to the finish. And dropped almost 9 tenths?! I am still scratching my head over that one. I guess all of my other runs were worse - and they all did have mistakes. I never claimed to be a good driver, but sometimes I luck into a good run. I didn't hit a cone all day and Amy was also pretty clean with only one cone, and we were stepping on cone bases. She managed 2nd in class and 11th in PAX, also a good placing for her.

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This was our last autocross planned for the year. We have lots to work on over the winter to this car, mainly turning it into a more track-worthy car, with the compromises of running "autocross and track and street" down to just "track and street only", as the 2013 GT is getting closer to ESP set-up. We have another set of coilovers on hand for the '13 (AST 4200RR), as well as a Watts Link kit (Whiteline, of course), and some other bits and pieces that we will show in that build thread (I will link it from here when I start it).

Preparation for Five Star Ford track day



So that was two weeks ago and today we're prepping the 2011 GT for another track event. This is an informal HPDE put on by the Five Star Ford of Plano dealership where we got our '13 GT, and the dealer we got that car from is setting this up (Corey White). This is the same group that did this back in June. Weather for tomorrow looks nice and we should have 40-50 cars. Amy will be driving the '11 GT and Matt will be in his BRZ (which got 255 Hankook R-S3s on the 17x9" wheels, Carbotech brake pads, and an oil change today, too).



One of the biggest changes to the '11 GT was a height reduction on the rear wing element. After hearing from several aero experts about the poor placement of our APR 3D wing element ("it doesn't work above the roofline!") we finally got around to shortening our custom built wing uprights. Ryan took 5 inches out of the height and the element now sits below the roof line.

Ryan, and our new tech that started this week Olof, got the Mustang and BRZ cleaned up, inspected, tires swapped, brake pads swapped, and the red car is being loaded into the trailer now. We will be out at Eagles Canyon bright and early tomorrow morning to put in some solid laps in both cars.



The differential in the 2011 GT is fried again, so we'll order another carbon clutch pack rebuild kit from Ford and get that installed in the coming weeks. The left rear outer axle seal is weeping a tiny bit of fluid, so that needs to be changed. The next event for this car is another ECR track event December 8th - the annual "Toy Run" event.

2012 Mustang Boss 302-S Prep

During the week of Nov 5-9th we worked on American Iron racer Mark Smith's Boss 302-S race car here at Vorshlag. Figured I'd show this car, as it has some pretty cool parts and capabilities as delivered from Ford. I will show more on this car in a future post, too.



After setting a track record at ECR in October, he brought the car to Vorshlag for some more tweaks, updates, and repairs. We had discussed some weight saving items we could tackle for a good 75+ pound drop in weight. American Iron runs with a power:weight formula, and the 302-S can run a variety of restrictors to go up and down in power. With a lower weight he can run less power, then add ballast to use a larger restrictor for more power at bigger tracks. Flexibility...



The big update we made was a new custom mandrel bent exhaust, to replace the nearly stock parts that these cars come with. We left the stock exhaust manifolds in place, as much as it pained me, and concentrated on a lightweight, high flow race exhaust that included 16 gauge Stainless Steel mandrel bends, two 4" round Magnaflow stainless mufflers, and a custom X-merge, all made in-house here by our fab guru Ryan. The new system stopped just below the rear axle and the car dropped about 45 pounds - and picked up a lot of power.



The entire system is tucked above the bottom of the frame rails and shouldn't ever scrape anywhere, unless it runs over something off track that only hits under the middle of the car. Ryan added heat shielding to the tunnel near the tips, built custom hangers with poly mount bushings, and it looks and sounds amazing.



With the stock air filter/box in place and the stock exhaust manifolds, power jumped from 365 to 420 whp! The old number had a home-brew air restrictor in place, which was changed for a proper restrictor in the throttle body. LG Motorsports dyno'd the car with three different size restrictors and now it has 365 whp again, but a lot more torque than before. He can also run the car at three different weights now and has the dyno charts and restrictors needed for each AI legal set-up.



Ryan built a custom bracket for this sub-3 pound battery Mark wanted to try - and the dang thing works! It charges fast and will start the car at least 5 times in a row with the same charge. Dropped 30 more pounds with this battery, and the old one can be swapped in quickly to add ballast or if the new wiz-bang battery craps out. New front wheel bearings, a strut repair, lots of clean-up work, new fluids in the diff/cool and trans/cooler, and a sound test rounded out our work for the week. Mark was very pleased with the car, the exhaust still managed to only blow 95 dB, and he did well at two races at NOLA last weekend.


Video of the drive-by in the 302-S with a sound meter at 50 feet.

A rear main seal leak (that we warned him about) became worse in those two races at NOLA and a slipping clutch ended his weekend early, after the second race. He managed to secure 2nd overall in AI for the year for NASA Texas, so he was happy with that (he only ran about half of the races). Next year - look out! I suspect Mark's 302-S will likely win even more AI races.

Anyway... this quick post grew a bit! I better sign off and help get the trailer loaded. Until next time!

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Project Update for Nov 30th, 2012: We had a track event in the Mustang since our last update and Amy set her new personal best lap at ECR. We've also finally modified the 2013 GT with real suspension bits, but that will be covered in that car's own thread. And after a considerable wait we finally have AST 4150s in stock for the S197 Mustang (and Vorshlag bought the entire order)!

Five Star Ford HPDE, ECR, Nov 17th

In our last project thread installment, we were preparing the 2011 GT for a Ford-centric track day at Eagles Canyon, our local 2.5 mile road course that is bumpy, but fun. This is where we do a majority of our testing and where Five Star Ford (a local Ford dealership - and where we bought our 2013 GT) had their first HPDE event back in June. This track is a brake intensive track, as I have mentioned before, and Amy drove the car exclusively all day and took the rear brake pads down to the backing plates. The pads were marginal when we got there and she still managed to get three HARD track sessions in before they started making racket and she brought it in.

Vorshlag Picture/Video gallery: http://vorshlag.smugmug.com/Racing-E...ar-ECR-111712/



Our photo guru Brandon went with us and took some great pictures, and Ed from Pirtek Plano South joined us out there as well. Matt brought his BRZ with our camber plates, some fresh 255/40/17 R-S3 tires and Carbotech brake pads and was tearing it up as well. I came out to watch, ride along and instruct, and to maybe take a few laps in one of our cars. In the picture above, I was riding through with Amy and it looks like I am yelling, but I'm probably saying "Gas! Gas! Gas!", to try to push her to faster lap times.



Ed and I (above right) got Amy's and Matt's cars ready, plus helped a few racers adjust camber or fix some small issues. I rode along with a number of other racers, including Matt in his BRZ, another FR-S driver Stephen F, and Amy in the '11 Mustang. After my ride along with me that day, plus Mike Patterson's in-car instruction from the NASA event in October, and maybe with some help from the new (more effective?) rear wing location, Amy lopped a second off her previous best lap to the tune of a 1:57.7.


Click above for in-car video from Amy's 1:57.7 lap.

This was again a pretty cold day (50s), very similar to the NASA event the month before, and she was pushing her braking zones and using more of the track on both corner entry and exit. She gave ride-alongs to Ed, me, and event organizer and Five Star Ford super dealer Corey White. Everyone had a blast riding along, the spectators loved watching/hearing her car on track, and she had the fastest car on track that day by a good bit. But as one onlooker said, "It ain't got that whistle!"



Vorshlag/AST tester Ken O and another Vorshlag/AST customer Jason had their E46 M3s out there in the Advanced group with Amy, both running Continental road race slicks (made by Hoosier). Ken normally runs 1:57s on Hoosier A6s, but could only get a best of 2:01 on these Conti's. I went out in a session in Matt's BRZ and had a BLAST, getting a 2:10.5 best after getting blocked on one of my few laps (AIM Solo showed a 2:09.5 predictive before that). Matt knocked off a 2:11.0, which was still damned quick especially since he hasn't been on track in about two years! That light, little RWD coupe is fun, with tons of grip and lots of brakes, but just very little power.



At the end of the day, the rear brakes were finally used up and it looked like we had a rear axle seal leaking a little (it melted), so we loaded up the Mustang and headed home. Amy had a grin from ear to ear and couldn't wait to get back out on track! I think we've created a monster - if I could convince her to let us build her a W2W car, I would love to get her out there mixing it up with the AI boys. The next day I unloaded the car at the shop and went to buy a (basket case) '97 M3, for parts, then unloaded that, so it turned into an all around busy weekend.



Repairs from ECR

So at this event the Porterfield front and rear brakes got used up, and then some. We already had a compromised pad set-up on the car, as we wanted to get rid of all of the rest of the Porterfield pads we had on hand, and Amy took care of that. The rears were to the backing plates and the fronts weren't much better off at day's end, but they were worn to begin with. On Monday after the event we swapped on some street pads, turned the rotors, and bled the system.



We have mentioned the Porterfields brake pads in the past, and we have had decent results from them, but when Ryan and the crew have switched from track (R4) to autocross/street (R4S) pads, the pads coming off tend to crumble and fall apart. This has happened to three sets of pads, which each had more than 50% pad life left... we pulled them out of the caliper and the friction material crumbled, fell off the backing plates, and were then junk. This was getting ridiculous and expensive, so we have now switched to another brand. We had even worse luck on Hawk brake pads. Not knocking these brands, just didn't work well on the Mustang.


Carbotech pads going on the '13 BRZ

Before the November 17th ECR event, we ordered some Carbotech pads (XP12 front, XP8 rear compounds) for Matt's BRZ. The pads themselves LOOKED really good - and yes, you can see quality differences in brake pads. After driving the BRZ myself for a session at that event, beating on the brakes relentlessly, and then seeing the lap times and data I logged on this car under braking (1.4g!), I am a believer. The Carbotech pads didn't fall apart or wear the rotors funny either, like the Porterfields have been.

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I liked Carbotechs so much we have since become a dealer. Now we have ordered their track pads for the 2011 and 2013 Mustangs and we'll see how these do next weekend. XP20 front and XP10 rear for the '11 (race tires, Brembos, ducting) and for the non-Brembo equipped (ugh) '13 we got XP12 front and XP10 rear (street tires, small 13.2" front brakes, stock power). We will see the results soon enough but I've had several American Iron racers tell me Carbotech were the best pads they have ever used. After seeing the results on the BRZ, I believe them.

So the '11 GT's front Brembo calipers have been rebuilt already, as the dust seals had burned and melted mostly away. They lasted almost two years under abusive braking on this FAT ASS car, at a lot of track and autocross events. After the latest ECR event, Ryan noticed the rear dust seals were melted, along with the caliper guide pin dust boots and rear axle seals. The rear calipers and guide pin dust seals have all been replaced and the rear axle seals will be swapped out for new ones next week, when we rebuild the Traction Lok differential once again. We debated going to a better aftermarket differential in the '11, but decided to "punt" on this decision (we won't race again until late January or early February) and instead ordered another $110 FRPP carbon clutch pack replacement kit. The '13 GT will get the better differential first (likely a T2-R), as it is more important for autocross use than on track.

AST 4150 Coilovers for S197 in Stock

After almost a year of waiting, they are here! The 4150 is a new shock model from AST that is a single adjustable monotube coilover strut/shock combination that we have been waiting for since late 2011. I won't bore you with all of the details, but the development and then initial production took longer than expected; the first sets arrived yesterday. I also won't bury you with too much sales talk, as you can see more details about the 4150 at this link.



There I go over the history of the 4100, the changes to the 4150, and explain how Vorshlag helped in our small way to both develop and get these made. It turns out that Vorshlag was the only AST dealer who was patient enough and who believed in this product enough to put in the orders, and we just received all of the 4150s likely to be delivered in 2012. We have a number of S197 and BMW E36 models in stock, ready to ship.



To allow for the maximum amount of travel in the rear of the S197, we had AST make the rear shocks completely different for us than what they normally do. We've tested these rear shocks three different ways and the configuration we went with allows for maximum total stroke and no in-board wheel interference. We keep the (replacement, coilover style) spring in the stock location, use some AST supplied adjustable rear spring height platforms, and machine our own Nylon adapters to make these platforms fit the S197 chassis. We're making these adapters in house now (I made the pair in the above left picture on our lathe yesterday) and supplying them with each 4150 kit at no additional cost. It is highly unlikely that you will see another AST dealer selling AST S197 shocks made to the Vorshlag spec.

Again, you can ready more about them in this link.

Prizes and Kudos

Just found out moments ago that our red 2011 Mustang won 1st Prize ($400) for the Street Prepared category in the "Black Magic Shine Awards" at the 2012 SCCA Tire Rack Solo National Championships. And can you blame them? That Mustang looks GOOD. :P



Also received all of the prizes from the Global Time Attack event at TMS. Ken O picked up my Ducati Limited edition Oakley Sunglasses, which are pretty sweet (below, left).



We also won a $300 Whiteline product credit at GTA for the class win, which I put towards another Watts Link kit for my 2013 Mustang GT. They also made this video (click here or above, right) where they interviewed me at the GTA event, which they showed in their 2012 SEMA booth on a loop. Pretty cool surprise, even if I look like a bog dork on film.


What's Next?

We have another track event December 8th at Eagles Canyon Raceway once again, but this will certainly be our last track event of 2012. We are taking four cars out there this time: the 2011 GT, the 2013 GT (with a full "Stage 1" AST/Whiteline/Vorshlag suspension installed), Matt's 2013 Subaru BRZ and the 1998 Firebird ChumpCar for its maiden track voyage. This is their annual "Toy Run" event, which the owners of ECR hold in December of each year to raise money and get toys and foods for charity. It is also very very affordable for the racers: $50 + a $10 unwrapped toy + 2 canned food items. As you can expect, it brings out a LOT of people, and many of them are new to track events, or are autocrossers. We go to the Toy Run event every year and ALWAYS have a blast, seeing lots of friends that are track junkies and cone punchers alike. If you are in Dallas, come join in the fun!

MORE INFO........
Contact: Maggie Williams
Organization: Eagles Canyon Raceway
Link: www.eaglescanyon.com
e-Mail: [email protected]
Phone: 817-992-9774

We also have been modifying our 2013 Mustang GT with what we are calling our "Stage 1" track setup. This car is now equipped with all of the most important bits we recommend in our "S197 Mustang Handling Guide" (which will be published soon). See details below.



Vorshlag S197 Stage 1 Suspension Set-up: AST monotube adjustable coilover dampers, stiffer rate coilover springs and a lower ride height; Vorshlag camber/caster plates and upper spring perches; Whiteline Watts Link kit; adjustable front sway bar; Vorshlag/D-Force lightweight 18x10" wheels mounted with 295/35/18 Nitto NT05 tires; Carbotech brake pads. All told this is about $6000 in parts, but it makes a HUGE difference in on-track performance. Ideally this car would have the 14" front Brembos but we are eventually turning this into an autocross-only car, so the big brakes were skipped on purpose. Anyone tracking an S197 would be FOOLISH to not get the 14" Brembos.

This set-up is 100% street friendly, with a great ride that should even get the "wife approved" status. Notice - we have made NO power mods to this Mustang at this stage. The 5.0L equipped S197s already makes 380 whp bone stock, so adding more power should not be in your first round of modifications to these cars. It will only make the car harder to drive until you step-up to larger R compound rubber. Ask me how I know this. Of course nobody listens to that, and modifies for more power first... Oiy!

We will run my black 2013 GT equipped as shown above next weekend at ECR. With a data logger and on-board video we will see how much improvement (if any) we have made over the "baseline" set-up we ran in October (which was these wheels/tires + camber plates only, with a best of 2:07 laps). The Vorshlag crew is also going to be driving Cadillac CTS-Vs at COTA on December 7th - the new Formula 1 track in Austin - the day before the ECR event. Should be another fun weekend!

More soon,

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Originally Posted by GT Muscle I've been reading this build for few days now, with some skimming and skipping I finally finished. There are several weight reduction I haven't seen you try yet, BMR's K-member and arms(31 lbs), MMR tranny CF tunnel (they claim 75+ lbs), MMR CF trunk (25lbs), and if you're going hardcore, JPC offer ligher axles and final drive.

Wow, those are some pretty extreme weight saving mods. Let me address them each in order:

• The K-member is not allowed in almost any SCCA racing class so we didn't look at this. I have installed tubular K-members on several Mustangs and they are not a perfect, no-compromise mod. The suspension geometry is often altered in these, and if the unit is built for weight savings (drag racing) it can even have more deflection under load than the stock steel piece. The road race versions are often only 10-20 pounds lighter, which isn't much considering their price, complexity, and time to install.
• A CF trunk is also a costly one, and wouldn't work at all with any sort of wing mounted to it like we run on track. You would then need to brace the wing all the way down to the frame, adding structure and weight along the way. And CF trunk wasn't legal for the racing class we used to run in this car (SCCA ESP) so we couldn't do it. Now we could, but it is a costly mod for the weight lost.
• CF Tunnel? What the.... you mean they cut out the stamped steel unibody floor and bolt or bond some CF replacement in there??? That sounds like a nightmare on many levels. First, you would lose all sorts of structural rigidity. I suspect this is for fully caged race cars only. That isn't at all what we have.
• Lighter axles would probably mean weaker, too. Sure, you can probably get a gun drilled axle as strong as stock, but at what cost?

Originally Posted by GT Muscle Few Questions: -Have you done the rear seats yet? -Since we can fit a 315mm tire on the 18x10 is there a need for an 11"? I see you didn't like the 345 because that was my plan.

Yes, the rear seat is under 28 pounds.



Seat belt hardware is also around 8 for a total weight loss potential of 35 pounds. But removing the rear seat adds a TREMENDOUS amount of rear axle and road noise. It kind of sucks on a street driven car. Have been driving my 2013 GT like this for 2 months and it sucks.



And mounting a tire to a narrower than optimal wheel is "possible", it isn't great for performance. Squeezed tires don't sit square on a narrow wheel, and the actual tread section gets cupped up on the ends, effectively making the tire narrower in use than it really is. The 315mm tire mounted to the 18x11" wheel (front) is even a bit squeezed compared to when it is mounted on the 18x12" wheel (rear).

Cheers,

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Quick Update for Jan 18, 2013: I've been waiting for something to be published before I posted again, so I'll hold off on a big thread update for maybe another week or two. A lot has been going on in the background.



NASA Time Trial classes had a bit of a shake-up for 2013 but it was only minor tweaks and things worked out in our favor, for a change. We've gone from TTS (now called TT2) essentially down one class to TTA (now TT3), and we can run now run this car at the limit of the power to weight ratio. No more "well, it was overweight/underpowered", it is maxed out. Apparently this new mix-up has made TT3 the most popular class, at least for this first NASA Texas event. We have 9 cars signed up in the TT3 class, so far.



We're loading up the trailer right now to take the red 2011 Mustang down to the NASA Texas event at MSR-Houston later today for races on Saturday and Sunday. Amy and I are splitting up the driving duties over both days. Will post a much more detailed pre-/post-race report when we get back. Well, then I'm flying to New Orleans for a couple days to drive on some new BFGoodrich tires, so it might be late next week or the following. Hoping to get some good intel on this new "Rival" street tire they are making (for autocrossers and track guys that need a 200+ treadwear tire) as well as bend the ear of tire engineers about the R1 and R1-S race tires.

More soon,

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Project Update for January 29, 2013 : We have a lot of ground to cover on the S197 Mustang thread. so look for several updates over the next week or two. Our last real S197 thread update was in November, and a LOT has happened behind the scenes since then - with respect to future competition in our 2011 and 2013 GT's in SCCA Solo ESP for 2013, plus several track events. We will also cover the new NASA TT3 classing and our first 2013 competition (with a track record + double-win), a track event in December with both of our S197s, the whole Watts Link/SCCA debacle, a new shock/spring set-up we've been testing on S197s, and then the BFGoodrich Rival tire launch event that I attended, where I got to test with four different types of cars and seven types of tires at the NOLA Motorsport park, including FR500S Mustangs (former Miller Cup cars). This set of updates will be broken up into multiple thread posts over the next several days, otherwise it will be too long and I won't get any sleep - and I've been on the road, racing various cars for four of the last five days, then sick with a stomach bug, so I'm beat. Let's back up and start with the preparation on the 2013 GT before the December track event first...

2013 GT Coilover Shock Install

The last time we took the 2013 Mustang to ECR, it was on the OEM shocks and springs and the handling was "frightening", to say the least. The car was hopping and flopping around, like a fish out of water. Lots of lean, roll, dive, and all that bad stuff we are used to on OEM sprung/damped S197s. Our long term plans at the time still included SCCA E-Street Prepared class preparations, but we would still do a track event or two before we got too far down the rabbit hole of autocross-only modifications.



Obviously a big improvement we could tackle that worked for both autocross and track use was to add our normal monotube adjustable coilover upgrade. Since Vorshlag sells AST and Moton monotubes, plus some others, we had several options that would work. We picked up some AST double adjustable coilovers with remote reservoirs for an S197 (AST 4200-RR), a custom test set made by AST-USA for a former employee. These were built with racing style "eye-to-eye" rear shocks, just like the Motons on our 2011 GT. On this car, however, I wanted to keep them "pin" style on top, to allow for the rebound knob to be located in the trunk for easy rebound changes (see above, left). An eye-to-eye shock tends to have the rebound knob located under the trunk floor and, like in the case of our Moton CS shocks on the 2011 GT, we have to remove a rear wheel to adjust rebound. It is a hassle, and that adjustment almost never gets tweaked. so we end up using the same setting for street and track use (which is a shame). So we asked AST-USA to re-work the rear shock shafts to have a traditional top pin and used it with the OEM style shock mount. They swapped out the shafts and adjusters to our favored eye lower/pin upper style and now the rebound knob is easy to access.



Once these were built to our liking, Vorshlag fabricator Ryan fashioned some reservoir mounts for the rear shocks, and cut holes in the trunk floor "spare tire well" to route the reservoirs through without disconnecting the hoses (which is a PITA) - just like on the 2011 GT. I asked him to tweak the angle of the reservoirs to be able to see the knobs easier from behind, which he did. The reservoirs were mounted into the spare tire well using the 2-piece "Seals-It" brand grommets to make this hole water tight. He mocked-up the seals with temporary Clecos, then used small machine bolts and nuts to hold them in place. If the shocks need to be removed from the car, the 2-piece grommets can be unbolted then the reservoir can slide right through the now open hole... no mess, no fuss. The other mounting/routing option for shock reservoir hoses is to drill much smaller holes/grommets and add (very costly) quick-disconnects on each shock line. Even then you still have to bleed off the Nitrogen charge before disconnecting the hoses, and re-fill the N2 when reinstalling. We feel this "big hole/2-piece grommet" arrangement is easier to deal with in the long run, and it is less expensive - but there are a dozen ways to skin this cat.



The front struts were not that unusual, being a typical non-inverted 22mm shaft monotube with rebound knobs on the strut shaft top and the compression knobs on the remote reservoirs (just like the rears). The hoses were long enough to route underneath the inner fender structure and mount the reservoirs just about anywhere in the engine bay. Ryan made some additional reservoir brackets for the front struts, but unlike our 2011 GT this car still had the factory airbox in place (everything is still bone stock under hood, for the lower 380 whp output). This meant we couldn't mount the reservoirs in the same place as on the '11 (which was blocked on this car by the giant OEM airbox), so we thought about it and placed them vertically in the airstream behind the headlights.



Shock reservoirs need to shed heat when they are working (they turn motion into heat), so we always try to keep them cool. Mounting them so that they get cool air from the front end seemed like the best idea. This location doesn't "show them off" as well as elsewhere, but so be it. I've seen some racers place remote shock reservoirs near the worst sources of under hood heat - like above a turbocharger (I've even done this myself) - but you really have to think about where you mount these things to keep them cool. A boiling hot reservoir will not allow the shock to perform nearly as well as one that stays closer to ambient temperature.



As you can see in the "Before and After" shots above, the ride height on the 2013 GT is significantly lowered, with the front dropping 1.25" and the rear dropping nearly 1.75". This gets ride of the huge front-down rake these cars come with and lowers the CG significantly. The spring rates we used were somewhat mild, with 450#/in in front and 225 #/in in the rear. This makes for a very decent ride on the street, but still a sizable bump in spring rates over stock, for better track handling (well, at least the front rates). See the updated spring charts below for the base 2013 GT OEM springs, the 2011 "Brembo GT" OEM springs, and the '07-08 Shelby GT spring rates (equipped with the FRPP M-5300-P springs).



Click the charts above for larger image... LEFT: 2013 Base GT. CENTER: 2011 "Brembo" GT. RIGHT: M-5300-P/'07-08 Shelby GT.

Since I first posted several OEM S197 Mustang spring rate tests, we noted two problems: first, we weren't compressing the springs nearly far enough. We were barely getting them compressed enough to even approach static ride height. So we upgraded our digital spring rater to a new "ram" to allow for 15" of spring compression vs the 4.5" it came with, which let us test over a wider range. These newly tested Mustang spring rates then become much more linear as we tested them over a wider displacement range. Second there was an error in our calculations for "rate at compressed height" that has also been fixed in our default spreadsheet. The measured force numbers never changed, just how we were showing them (rate of rate change vs rate at position). Sorry for the confusion.

So as you can see, we've upped the front spring rate considerably more than the rear on this car once again, which we have found - from a lot of coilover testing - works better with an S197, both on track and on the street. The bigger rate increase up front cuts down on brake dive, body roll and camber loss under cornering forces. It also reduces understeer caused by bottoming out of the front suspension. This 450#/in spring also makes the car transition much faster than with the ~100 #/in rates. Luckily the adjustable AST monotubes do a fine job of managing the 4.5 times increase in front rate. You won't see OEM-lowering springs in this spring rate range because the typical shocks these are used on (OEM style) cannot deal with those spring rates.

continued below