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S197 JDMac's Autocross GT Build Thread Profile - S197 Mustangs

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It may have to do with squeezing the 315 onto an 11" wheel. It will fit but it's a little squeezed which will want to make it roll over more. That tire mounted on an 11.5" or 12" wheel would probably roll over less at lower pressures.
I'm sure that this has something to do with it. According to Flaken, the approved wheel width is 10.5-11.5" so my 11" wheels are within spec.
I'm sure that this has something to do with it. According to Flaken, the approved wheel width is 10.5-11.5" so my 11" wheels are within spec.
For sure they're within spec, but you typically want to be on the wider end of the scale than the narrower end especially for the type of usage we're putting them through. I used to run 315's on my 10.5" wheels on my old SN95, but the sidwall bulge showed it wasn't the optimum solution. I am only on 11's as well and I will probably move to 11.5's or 12's before looking to go wider depending on what tire manufacturers offer. Would love to run some 19x12's with a 325 at all four corners.
For sure they're within spec, but you typically want to be on the wider end of the scale than the narrower end especially for the type of usage we're putting them through. I used to run 315's on my 10.5" wheels on my old SN95, but the sidwall bulge showed it wasn't the optimum solution. I am only on 11's as well and I will probably move to 11.5's or 12's before looking to go wider depending on what tire manufacturers offer. Would love to run some 19x12's with a 325 at all four corners.
I was originally looking for 305s but there didn't seem to be any RT660s in stock anywhere at the time. I'll try again once these are worn down

Bill Pemberton

0ld Ford Automotive Racing Terror
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Keep in mind what works on an autocross course is not necessarily what one wants to run on a road course. Try lower pressures next time on the track and I would begin around 30 lbs., cold, to start. I would not be surprised if starting even lower than that might be where you begin after testing. Check when you come in hot at pressures of 34-37 for example.

Tires ( various brands ) do not all run at the same temps, but get back to us on how the Falkens feel starting much lower.
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The test and tune went well. Again, it was cold and rainy for most of the day but I did learn some things.

This event was held at a parking lot that my region used to use for everything. The lot started to get a lot of potholes so we moved to a different one while they repaved it. The pavement is about a year old and this was the first time that there was any spirited driving on it. It was pretty smooth, but new asphalt can be slick in the rain, and this was. Below is a video from the same lot when I first got into autocross in my basically stock V6 New Edge.

I set the rear sway bar to the softest setting and the shocks to an even balance before the event and the car really liked that. It felt like I could push it a little further and was a little more predictable when trying to drive at the edge of traction. The tires started off at my regular pressure of 36 psi. Since it was cold and the track was slick, I kept the shocks set at 4/32

The morning session was really cold and really slick. Any time that I would try to turn into a corner hard the front would begin to push. As soon as I even looked at my throttle pedal the rear would slide out. My tires didn't get a lick of heat in them and the pressure stayed the exact same. The major thing that I learned in this session was that the car really liked the rear sway bar adjustment. I didn't have any oversteer that wasn't throttle-induced.

The afternoon session started right as the misty rain stopped. The track was still wet but dried up as we went. I was very annoyed with the cold tires so I decided to waste a run to get an opportunity to try and warm them up. The starter kept asking me for an overly aggressive launch, so I made sure to spin the tires through second gear. My rear tires were up to temp entering the slalom, but my fronts definitely were not! I plowed right into the second slalom cone and tested out my new splitter; it worked! After doing everything that I could to warm up my tires, I was ready for the afternoon sessions.

I tried lowering the tire pressures to 32 psi for a run and it didn't seem to like it. The track wasn't completely dry yet, which I'm sure had something to do with it, but it seemed to lower my overall limit of traction. I tried marking the tires to see how close to the sidewall the tire would wear, but the track was still too wet for that. I grabbed my air pump and brought the tires back to 36 psi for my next runs.

My run times were around the 50-51 second range all morning and early afternoon. I had a couple of 49 second runs as the track started to dry and finished the day with a 48.8X and a 48.00 second run. Here is my best run.

After comparing my run to others, I think that I have a decent idea of where I excelled and where I need to improve. I seemed to do well on the slalom and kink in the back (0:00-0:15). I probably should have tried braking harder and later at the end of the straight (0:19). The part where I really struggled was the Chicago box (0:23-0:27). I probably could have entered with a little less angle so that I could carry a little more speed through it. Personally, I think that I set up for the slalom (0:27-0:31) really well the second time. There were a lot of cars that were too focused on exiting the box that they would blow that turn. I braked and turned in a little bit later after the straight (0:45). I hit a cone entering the finish line last time, so I took that part (0:49) easier than I probably could have.

I have another test and tune Saturday with a points event the following day. I hope that the weather will cooperate and that I'll be able to actually test tire pressures with some heat!
Well, it's time to do some more maintenance. I've had 3 events since last posting and the car did okay but not great.

First is brakes. I finally had my first event of the year where it was dry and learned that my ABS system doesn't like HPS 5.0 brake pads. I had those in the front and back and ABS would seem to be triggered way too early in the rear and not let the fronts do their job. That was at the test and tune last Saturday. I swapped out for my DTC-60/30s that night and the brakes worked WAY better at the points event the next day.

Second is the front control arm bushings. I noticed that my rear passenger side bushing had a small crack in it a few days after that track day but it got worse after the points event last Sunday with the good brakes. I ordered all the parts to replace them with poly bushings as well as new ball joints. After a little more research I learned about the 2011 EPAS issue so I also ordered a steering rack from a 2013 car. I almost started that job but realized that the rack was going to be a pain in the [butt] to change and I didn't have time to do it all before the next event. There weren't any voids in the rubber, and I didn't hear any weird noises, so I decided to run the car again. It made it through the event with my dad co-driving the car with me but it looks worse now. Now both rear bushings have a crack all the way around but the passenger side is starting to come apart. I started pulling the car apart last night and realized that I need a few different tools to do it right.

Third is the engine problems. I've been working with Lund to revise my tune and have been having issues. Apparently the revisions were under the impression that I had a PMAS CAI instead of the Ford Racing CAI that comes with the Cobra Jet intake manifold. I would get a System Too Rich (P0175) code when the car would warm up but it wouldn't come back once the code is cleared and the car is up to temp. Those tunes felt great, but they sent me another after looking at my datalogs. My O2 sensors were giving weird data so they sent me a safe tune and suggested that I get new upstream O2 sensors. Those are on their way and will go in the car as soon as they show up. I went to move my car out of the garage yesterday afternoon (20 ish hours after getting back from the last event) and it was not happy; see the video below. I shut it off and started it again and it seemed okay. The idle had a little lope, but nowhere near as bad. I'm guessing that the O2 sensors are shot. Any suggestions other than what Lund sees?

So I have a busy week this week. Below is a list of parts that I plan on swapping out before the event on Sunday:
  • Poly Front Control Arm Bushings
  • Extended Ball Joints
  • Steering Rack from 2013 GT500
  • Bump Steer Tie Rod Ends
  • O2 Sensors
  • Spark Plugs
  • Fresh Tune
Late update, but all that work was wrapped up that Wednesday night with plenty of time to get it to the alignment shop that Friday. I decided to take my control arms to work and have one of those guys help me get the old bushings out, and I'm so glad that they did. Every comment that I read said that they are a pain in the arss to remove and they were definitely right. We ended up having to burn the rubber out and cut the inner sleeve with a death wheel. I was able to get the old steering rack out without lowering the k-member or heating up the bolts. Once the new bushings and ball joints were in it was fairly smooth sailing to get the car back together.

I was really surprised at how different the car felt afterward. As I was turning into a corner the car would take a fraction of a second to plant then it would turn hard; now it's instant. I don't have any weird shakes and can actually feel the difference between the standard and sport steering feel.

After putting in the new spark plugs and o2 sensors I was still struggling to get a smooth idle. I took the MAF sensor out to try and clean it again and realized that the housing on that cheap sensor had broken and was only held on by one screw. A new quality MAF sensor, some tune revisions, and it was much better!

I did an autocross last weekend and ended up kicking butt. I beat a lot of corvettes with very competent drivers in raw time. The only cars in CAM that beat me in raw time were a C5Z that was driven by last year's A-Street Nationals camp (sadly by 1.6 seconds) and a C6Z (by 0.5 seconds). Since that group combines all CAM classes and goes by PAX, I got 2nd in class with my 32.563-second run. I have room to improve, but I'm doing pretty damn well in my mind.

I love this car!
Another event down! This was my second time with the Steel Cities Region SCCA outside Pittsburgh. There are many skilled drivers there.

The course had a tight start, deceptively tight slalom, a few smooth turns, pretty normal slalom, and a fast finish. I thought that I did pretty well leaving the event, but am realizing that I was a little late on most elements. I have room to improve, but I'm happy with how I did.

After comparing my times to others that I consistently race with, I did better than usual; however, I did not place well. I got 3rd of 7 in class (CAM-C), 67th of 129 in Raw time, and 77th of 129 in PAX.
It's been a while since I've updated this. One winter project is adding an oil cooler to the car since I'd like to start competing in Time Trial events. As I'm piecing everything together I'm realizing that most of the older posts regarding oil coolers revolve around -10AN hose, but the newer posts claim that -12AN hose is the way to go. I bought everything for -12AN hose but just realized that the Mishimoto sandwich plate has M20 ports instead of M22.

It looks like I have 3 options:
  1. Use -12AN to M20 fittings for the sandwich plate - I'm worried that the ID of the M20 fitting portion will be too small and either cause pressure loss or heat the oil due to the velocity change.
  2. Switch to -10AN hose and fittings - The smaller diameter hose would result in more pressure loss, but it might be better since it wouldn't have such a harsh change in velocity as the oil goes through the fittings.
  3. Switch to a different sandwich plate that allows for M22 fittings - I'm not sure what other sandwich plate would offer a thermostat and fitting ports for sending units that would fit a Coyote engine.
If anybody has suggestions for which way to go and what parts to buy, I'm all ears.
With regards to the wheel width thing, we are going through this in IMSA right now, they have given the new Gt4 Mustang a smaller front tire and it has a narrower track. This on a car that tends to be pushy to begin with.
If you are allowed optional wheel widths, you can sort of " fake" the tire out by using different widths. As an example a 10 in wide tire on a 10in wheel might be neutral, spread that over an 11 in wheel and you will prolly decrease adhesion in turn in and turn out, put them on a 9 in wheel and they will turn in and out, but roll over in the center of the corner


Dances with Racecars
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
A little update from this winter's shenanigans.

As stated above, my main goal was to install an oil cooler for the anticipated track days and Time Trials that I want to do this year. I went with a Setrab 934 heat exchanger, Setrab thermostatic sandwich plate, spacer (for gauge sensors), and -12AN hoses and fittings. The exchanger was reasonably easy to mount; more on that later. The hoses were a pain to run. I ended up going the long way (around the passenger side of the radiator) to avoid sharp bends. The temperature sender is in the spacer plate and reads the engine oil temperature before it goes through the exchanger. The engine oil pressure sender is T'ed into the stock oil pressure sender location, which (I think) is reading pressure after the exchanger and filter.

I went with Autometer Ultra-Lite gauges inside the Ford Performance gauge pod. I opted to mount my pod at an angle so that I could accurately read the gauge from the driver's seat. It looks a little odd but is functional. I'll likely fill the 3rd gauge spot with a wideband or coolant temp sensor, but neither of those is high on my priority list right now. The pressure gauge worked right away but the temperature gauge read very low. Apparently, the spacer that I used wasn't conductive enough, so I had to add a ground to the sender base using a ring terminal and high-temp grommet to keep constant pressure for good contact.
IMG_7508 (1).JPG

While planning this, I decided that I might as well get 3 birds with one stone and buy the Ford Performance bumper bar. The goal was to provide a lower mount for the oil cooler, add chassis mounts for the splitter rods, and add a tow hook. As a bonus, it helps offset the extra weight added by the oil cooler. The new hole in my bumper cover could have been cut better, but it was a learning process! The bar that I bought didn't come with the tow hook, so I made one that matched the Ford design.

Another small project was to increase the spring rate in my front coilovers. I did have 7 kg/mm (390 lb/in) and swapped them to 12 kg/mm (670 lb/in) springs to better match the 5 kg/mm (280 lb/in) springs in the rear. I'm still using the Pedders dampers, which I've had good luck with, but the internet seems to dislike. I'll keep rocking them until Vorshlag brings back their "Track Pro" setup for S197. I'm loving the spring upgrade so far.

My brakes need a little bit of attention too. The front rotors are wavy (not warped) from the extreme wear of using DTC-60 pads on the street and at autocross for a month or so before I switched back to HPS 5.0s. I will be throwing some new StopTech rotors on and will make sure the swap pads before and after track days. As I was looking at the rear rotors, I noticed that the uneven wear that was mentioned in a post last year is still present. The rear pads seem to be wearing unevenly also, so it's probably time for new rear calipers. New (not remanufactured) OEM rear calipers have been ordered and should be here next week.

I need to redo my numbers to include my time trials class. Unfortunately, the splitter puts me in M2, but everything else on the car seems to fit really well into T2. I don't plan on being super competitive in time trials, so it's not worth taking that on and off to me; autocross is where I want to stay competitive. I removed a lot of the stickers from the car while I was at it. I'd like to have the numbers and class be a little more subtle, but the Sterling Gray paint seems to make numbers without contrasting backgrounds or borders very visible. I'm open to suggestions, but right now I'm planning on doing the same thing that I had but with M2 and CAM-C stacked on top of each other. Looking back, I probably could have kept what I had and used reusable vinyl with M2 to cover the autocross class for time trial events.

Finally, I'm doing routine maintenance. Fresh oil change, transmission fluid, differential fluid, and brake fluid. I've been taking my sweet time, but everything should be good to go before my first event. If the weather looks good, then my first event will be Track Night in America at Nelson Ledges next weekend. Can't wait!
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1 Track Night in America and 1 Time Trial into the season and the car is doing great! However, there was some drama leading up to and into this weekend's TT at Pitt Race.

While driving back from Nelson Ledges 2 weekends ago I must have hit a bump that knocked my alignment out of wack. I looked over the car and didn't see anything damaged, so I scheduled an alignment at my buddy's shop. While it was getting realigned the shop found a control arm bolt that was a little loose which caused the misalignment. They also pointed out that my brake pedal felt funny and performed an ABS bleed; holy cow it feels awesome now! Unfortunately, the same bolt slipped again as I was driving home Friday night after picking the car up.

I was supposed to attend an Autocross Test and Tune on Saturday but canceled my registration with hopes that I could get the car ready for the Time Trial on Sunday. I got the car up in the air and removed the bolt that had been giving me problems. It was the front bolt on the driver-side front control arm. After a quick inspection, it looked safe but had absolutely no thread-locker left. I cleaned the bolt, added plenty of blue loctite, and reinstalled it. While I had the car in the air I did a bolt check for all suspension components and everything felt good. Wheels went on, car back on the ground, and I was ready to go!

Sunday, my first ever Time Trial:

It ended up being way hotter at Pitt Race than anybody would have expected for April. I still had to take a mid-session cool-down lap every once and a while, but the oil cooler kept temperatures in check. A lot of cars were getting 3 hot laps before they saw high temps, but I was able to get 5 hot laps in before I would see the gauges rise. I probably could have gone a little longer, but I appreciated the opportunity to gather my thoughts before I'd get back on it again.

The practice session went well. I took it easy and learned the track. It felt familiar because of my time on the simulator, but the elevation changes and blind turns were things that I was not expecting. I picked up the pace as I got more and more comfortable and ended up with a best time of 2:10, which was my generous goal for the day. My tires gained way more pressure than I expected, so I took that data and came up with a game plan for the timed sessions.

The first session was very similar to practice. Since it was a competition, I was thinking that more people would be going all out right away. I was surprised and relieved when they didn't; everybody eased into it and progressed at a similar rate to how they did during the practice session. My best time this session was a 2:06.9 - a decent improvement as I started to trust the car and myself more and more.
IMG_7807 (1).JPG
My hood must open the wrong way!

As soon as I parked in paddock I heard a hissing noise coming from one of my rear wheels. My valve stem (not the core) was leaking badly. At this point I was not concerned about competing and focused on how I was going to get home. After asking all of the locals, I called a nearby race shop and he was able to help me out. If you are ever at Pitt Race and have an issue, call Race Protocol! He was awesome.

Everybody that I talked to said that the second session was greasy from a hot track and that they matched their first session time, but that was still ~2 seconds off-pace from what they usually run.

I went into my third session calm and confident. After a few laps I had barely improved my time from the first session and started to fall off pace. The majority of the group ended their session early, so the track was pretty open. I took a cool-down lap and decided to give it one more shot. I ended up getting my best lap of the day with a 2:05.0. I pushed the car harder than I had before but finally started to feel comfortable doing it; it was a great feeling of accomplishment.

Overall, it was a ton of fun. The relatively small issues leading up to it made it that much better.
I came home from work last night to see another one of my tires flat due to a ripped valve stem. It looks like I'll be replacing all 4 with metal ones this week. I might as well have them flip the tires while they have them.
In preparation for the back-to-back Solo National Tour and ProSolo in Cleveland, I dropped my car off at the shop to get new metal valve stems, new tires, and a fresh alignment. I didn't get a chance to drive the car too much that week, but it felt better than ever the little bit that I did.

My car was wrecked in the front right corner before I bought it and has always had about 0.7° of cross-caster. My coilovers don't have caster adjustment in the top hat, and it didn't drive that bad, so I haven't been worrying about it. My tire delivery was delayed so while it was waiting I had the shop take care of that using Ford's service procedure for adjusting the caster by moving the rear control arm mount using a cam bolt. I'll probably have to check that bolt more often. Now that it's fixed I'm amazed how much better the car feels. My current alignment specs are: 3.0° of camber, 7.2° of caster, and 0 toe.

When looking for new tires, I debated going with the 295/35R19 Yokohama A052 or 305/30R19 Bridgestone RE-71RS since both seem to have more initial grip than the Falken RT660s I have been using. The yoks are the lighter option, and the 295 size seems to measure about the same as most 305s, but I heard that the stones tolerate heat a little better. I ended up going with the stones to try something new...and maybe because my ego couldn't handle having a tire size that started with a 2! 😆

The tires were heat cycled by Tire Rack before they were delivered. My plan was to utilize the Test and Tune course before the National Tour to relearn the car and scrub in the new tires. I was amazed at how much more grip there was! Right out of the gate, the tires felt better than what I was used to. The steering feel wasn't as tight as what the Falkens had, but the grip was noticeably higher. I was running 37/36 psi with the Falkens and was able to drop the Bridgestones down to 34 psi before I started to get tire wear on the sidewalls. Time to kick some butt!

Bill Pemberton

0ld Ford Automotive Racing Terror
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
I love TireRack but I personally do not recommend heat cycling 200 TWR tires because in most cases the cars are driven on the street some as well as to the track. Getting that initial molding release gunk off is great , but the extra bucks can be saved with many folks. If going directly to the autocross course it might be helpful , but this is one item I have not found very beneficial with street tires over the years, imho.

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