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S197 Should've bought a base GT Build Thread Profile - S197 Mustangs

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Bill Pemberton

0ld Ford Automotive Racing Terror
8,425
8,356
Exp. Type
Time Attack
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20+ Years
Blair, Nebraska
Nice clean look almost sleeper look, but with the big 19 inch Apex wheels and some RS4s I bet she sticks really well?! Lots of good stuff on the 14GT and sounds like your next mod is more seat time -- best mod you can make. Thanks for posting!~
 
72
65
Exp. Type
HPDE
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5-10 Years
New Jersey
Nice clean look almost sleeper look, but with the big 19 inch Apex wheels and some RS4s I bet she sticks really well?! Lots of good stuff on the 14GT and sounds like your next mod is more seat time -- best mod you can make. Thanks for posting!~
I've always been more of a function over form kinda guy, and I've always been a fan of sleepers.

They do have a lot of grip! Now I just need to adjust myself and the car to the extra grip. Mostly myself.
 
72
65
Exp. Type
HPDE
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5-10 Years
New Jersey
The item Should've bought a base GT has been updated:

Moved up to R12 pads on rear (instead of R10) and changed to GT500 rear rotors. Seems to have helped the braking stability quite a bit, but still not quite confidence inspiring.

I'm thinking I need stiffer front springs to reduce the dive and keep more weight on the rear.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,425
8,356
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Are you running R12s on the front? I would think you would want a more aggressive pad up front if so, and usually the 10s work well on the back since they come in with less temp and the rears don't heat up as fast. Not sure you will ever get rid of all of the dive in the front as it is a nose heavy car, and I don't think you want the brake bias to balance out where the rear could come in too soon. How did she run , time wise, the last time you were out?
 
72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
Are you running R12s on the front? I would think you would want a more aggressive pad up front if so, and usually the 10s work well on the back since they come in with less temp and the rears don't heat up as fast. Not sure you will ever get rid of all of the dive in the front as it is a nose heavy car, and I don't think you want the brake bias to balance out where the rear could come in too soon. How did she run , time wise, the last time you were out?
I was initially running R12s in front and R10s in back. When I upgraded to the 15 inch fronts, it made the instability worse despite moving the brake bias more to the front.
It was suggested to me to try a little more rear brake to help drag the rear of the car down, so I got some R12s to match the front and it seems to have helped some.

I think with fairly sticky 305s on all 4 and such huge brakes up front, it's too much tire and brake for my suspension setup (220lb in front is around half what any of the coilovers are running). I remember reading somewhere, probably a thread on here, that funky things can happen if your rear roll center gets above your front. Perhaps that's what's happening here when the car dives so much?
 
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@noldevina, I'm not clear exactly what you mean by brake "instability" but a couple things to keep in mind: First, stiffer front springs will reduce brake dive but they won't change the amount of weight transfer. The dive is the result of the weight transfer, not a cause. Second, I'm pretty certain the rear roll center is always higher than the front on these cars, that's normal. Good luck!
 
72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
@noldevina, I'm not clear exactly what you mean by brake "instability" but a couple things to keep in mind: First, stiffer front springs will reduce brake dive but they won't change the amount of weight transfer. The dive is the result of the weight transfer, not a cause. Second, I'm pretty certain the rear roll center is always higher than the front on these cars, that's normal. Good luck!
By "instability" I mean my car wants to rotate under heavy braking (at the end of straights), and on one occasion even axle hopped and almost caused a spin. It was made worse by increasing front braking power (upgrading to s550 6 pistons), and a bit better by going up a step in rear pad to match the front.
 
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I notice you have a lot of BMR suspension parts on your car. Too much anti-squat can cause braking instability, which would be made worse with too much rear brake bias. I would look into reducing your anti-squat and using a lower compound rear pad.

If your car wants to rotate under truly straight line braking, you may have a mechanical brake biasing problem left versus right??
 
65
104
Exp. Type
HPDE
Exp. Level
5-10 Years
Nova Scotia
By "instability" I mean my car wants to rotate under heavy braking (at the end of straights), and on one occasion even axle hopped and almost caused a spin. It was made worse by increasing front braking power (upgrading to s550 6 pistons), and a bit better by going up a step in rear pad to match the front.
I watched some video and realized that the instability I was experiencing was being induced by my hands. Putting more focus on getting the wheel straight during initial braking and then controlling the trail braking more intentionally made a huge difference. May not be your situation, but it’s always worth considering technique instead of looking at parts.
 
72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
I notice you have a lot of BMR suspension parts on your car. Too much anti-squat can cause braking instability, which would be made worse with too much rear brake bias. I would look into reducing your anti-squat and using a lower compound rear pad.

If your car wants to rotate under truly straight line braking, you may have a mechanical brake biasing problem left versus right??

The first thing I did after experiencing the issue was move the relocation brackets from the middle hole to the top for minimum anti-squat. I can revisit the upper mount as well, but it should be pretty low at this point. I never used drag settings for it.

I watched some video and realized that the instability I was experiencing was being induced by my hands. Putting more focus on getting the wheel straight during initial braking and then controlling the trail braking more intentionally made a huge difference. May not be your situation, but it’s always worth considering technique instead of looking at parts.
This very well could be the case. I don't do much trail braking, but will have to be more mindful of my hands when braking. I stopped doing in-car video a while ago but maybe I should revisit that idea.

Is it dancing around under heavy braking? Or more trying to rotate one way?

Toe/alignment can cause you to dance around under heavy braking, IME.
I haven't noticed it trending to one direction, but will have to keep a record on direction from now on. Alignment is fresh with a tiny bit of toe in. It has been mostly better since the alignment / rear brake pad "upgrade", they were done at the same time.
 
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CA
1.) What is your UCA?
2.) Instability in the front end (wandering) is caused by the front lower control arm rear hydro bushing. This bushing has a huge amount of deflection under braking. This is being exasperated by your soft front springs.
3.) Axle hop in the rear (as you have identified) is mostly caused by high anti squat %'s and brake bias. Your S550 6p calipers mean that your rear calipers are getting an additional 9% brake bias. This, combined with brake dive and high anti squat %'s can lead to brake hop. You should go to a less aggressive pad in the rear with relation to the front (ie R12's in front, R8's in rear).

Suspension wise, I think you have done all that you can do to counter the brake hop. You need to make brake component and then driving style adjustment.
 
72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
So I did an overhaul this spring and after a couple of track days I think I can say it made a major improvement in the braking instability that I've been experiencing, as well as the overall feel of the car. I did break the rules and make all of the changes at once, so I can't say which parts made the most improvement.
The changes:
  • Swapped out the Bilstein / BMR handling spring setup with Fortune Auto 510s. The spring rates are 560f/280r. The rear springs are on the short end, so I have a perch spacer for now, but will likely swap the spacer for a longer spring for better travel. With the spacer I was able to set ride height where it was previously, with about a 1.5" drop from stock. I also accidentally nailed corner balance just by eyeballing the ride height, which will probably never happen for me again.
  • Delrin FCA bushings, from Global West. Install kinda sucked but I could tell these were a huge improvement over the springy soft rubber bushings. Installed on a new set of OEM arms.
  • New outer tie rods, just for a "while you're in there" refresh.
  • Reduced front spacers from 25mm to 15mm, since the coilovers offered more inboard room for my 19" 305 setup.
  • Aligned to a hair of toe in and -2.6 degrees of camber. There's room for more if I want it.
  • Replaced BMR 38mm front sway bar with their smaller 35mm sway bar. The 38mm was way too stiff to begin with. With almost 2x the front spring rate I didn't want so much sway bar. Currently running on softest setting which should be similar to stock according to the spring rate post on here.
  • Replaced BMR poly rear arms with whiteline for better bushing material/shape for road course use. Should help the rear by reducing bind and since all arms are adjustable now, I can make sure geometry is correct.
  • Replaced goofy warped Stillen splitter with APR splitter and added front tow hook (not really related to any improvements, probably, but the warped fake splitter was bothering me and I got a killer deal on a used APR unit and tow hook) The APR splitter replaced the OEM splash tray, which leaves a pretty hefty gap between the splitter and radiator for air to just escape out the bottom, so I'm thinking of ways to seal that up and improve cooling.
I ran NJMP lightning and the HOD Pocono megacourse so far. At Lightning I played around with the rebound adjustment in the rear to see what gives the most braking stability. So far it feels good at 3-4 clicks from full soft, and I can max effort brake without the previous worrying wiggle or hop. Anything over 5 clicks and it gets massive axle hop under braking. I may try a little more rebound again with a less aggressive rear brake pad, since I'm still running equal front/rear compounds from before. I also still want to play with no rear sway bar.

On the street, ride quality is actually better than expected. It soaks up smaller bumps smoothly. Larger ones are still kind of jarring, as I would expect.

I'll post up some pictures and more thoughts later.
 
72
65
Exp. Type
HPDE
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5-10 Years
New Jersey
Fortune Auto 510 coilovers - I know they are not popular around here, and I was a little hesitant to try them, but the premium tier coilovers were out of my budget and a few of my friends who are running them convinced me they are decent. I like that they are valved to your spring rates and application and come with a dyno graph (even if I don't really know how to read a shock dyno), and that they are rebuildable and upgradeable in the US.
So far I am quite happy with the ride quality given the high spring rates, and it's nice to finally have sufficient spring rates on the track.
I will note that the rear springs are basically too short. I was barely able to get it to my desired -1.5" drop at max height, so I sourced a perch spacer to put it more in the middle of the adjustment range. I will probably end up replacing it with a longer spring for better travel.

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72
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Exp. Type
HPDE
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5-10 Years
New Jersey
I decided that it would also be a good time to replace my old front control arms and switch to a delrin front bushing set from Global West.
This was definitely the worst install out of this project, mostly for lack of having some of the proper tools.
I had a friend with a press take care of the bushing swap, but even he had a rough time getting them swapped.
The ball joints were quite stubborn and took a pickle fork to get them started and lot of BFH effort to get them the rest of the way out. The 2nd side took about half as long once I had the needed tools and figured out what worked. The delrin bushings allow the arms to rotate freely with little effort and no deflection, instead of springing around the center point like the rubber ones did.
I also used a Vorshlag jig to cut the strut towers out to 3," this made it much easier to access the camber adjustment and gave plenty of room for camber.
The coilovers provided plenty of extra room for my 19" wheel setup, so I was able to drop down from a 25mm spacer to 15mm. I think the locking ring might get in the way for an 18" wheel though.
I also ended up swapping out the OEM radiator support, mostly because I was swapping the sway bar and those clip-retained bolts are an absolute pain in the ass. Now it uses regular nuts and bolts which are accessible from both sides. It also weighs half as much, which is nice.
Finally, I changed out all of my BMR Poly rear arms for Whiteline adjustable parts. There was nothing wrong with any of the BMR parts per-se, but I was worried potential bind from the poly bushings was contributing to my instability issues. The Whiteline arms seem like a good comprimise between poly and metal joints. The bushings are shaped to allow more flex in the directions that would cause bind. Vorshlag seems to like them too, so good enough for me. I didn't bother to take any pictures of those, but they were all pretty standard arm installs, with everything except for the panhard bar set to stock length for now.

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72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
Finally, I got a great deal on a used APR splitter and ZL1addons tow hook from a friend who sold his car.
I decided it was time to swap out the floppy old Stillen splitter that definitely wasn't doing anything. It was convenient timing, as the bolt holes on my OEM under tray were ripping out and it needed replacing.
This unit not only looks much better but seems like it would be more functional too.
I will say, that crash beam is made out of some serious stuff (or I just don't know how to drill properly), it ate several cobalt drill bits while drilling for the struts.
The new splitter does leave a few inches gap between itself and the bottom of the radiator for air to escape. I will be figuring out a way to seal that up and improve cooling airflow next.
Overall though, I think it looks great.

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72
65
Exp. Type
HPDE
Exp. Level
5-10 Years
New Jersey
So this season has been... eventful.
The new setup was showing improvement, setting new PBs at each event, even while I was still getting it dialed in.
At Lime Rock I beat my previous best by about a second, despite it being a very hot greasy day in July.
And then.... a friend/instructor hopped in to give me some line suggestions and....
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So yeah that day ended a little early. He was not by any means pushing the car or showing off. We were starting to pick up pace a little after the out lap and the car got away from him over the crest of the hill. Both the car and the tire wall did their jobs beautifully, in that neither of us had so much as a scratch or bruise. The car drove back to the paddock under its own power, leaking only windshield washer fluid. Thankfully another friend had a free spot in his trailer and got the car home for me.

Also thankfully, the person who was driving is a stand-up fellow who made sure the car got repaired at no cost to me. A tall order, since I was not running with track insurance (I always assumed I would be the one to crash my car, and would figure that out if and when it came. I will strongly consider it next season after seeing that bill, though!). He definitely had no real obligation to do so, so perhaps take this as a reminder to be careful who you allow to drive your cars (and to use track insurance!).
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Oh, and my friend told me to throw the used Watson roll bar in the trunk for the shop to install, on him. So that's pretty cool.
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The repairs took about 3 months, and the shop missed enough small details that it was a bit disappointing, but I got her back and prepped in time for the NASA season closer at NJMP Lightning last weekend. I was happy to be able to sneak one more event in before winter, and the car felt good.
(At least, it didn't have any new issues. I still have some axle hop when close to max braking, which I will be taking a proper close and measured look at anti-squat over winter for. At least it does it in a straight line after now my last round of parts)
I didn't set any PRs last weekend as I was taking it easy, making sure nothing else was left loose or missed, plus the brake hop quite literally shook some confidence out of me, but I was within about a second of my PR so I'm good with that.

There were a few changes, to make things a little easier/cheaper. The Roush grille instead of the billet one, the Carter's Customs Splitter instead of APR, and a CSF radiator since the OEM Boss radiator was discontinued. Oh, and I had them put in a Racelouvers vent as well. Definitely looks a lot better than it did leaving Limerock.
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So this season has been... eventful.
The new setup was showing improvement, setting new PBs at each event, even while I was still getting it dialed in.
At Lime Rock I beat my previous best by about a second, despite it being a very hot greasy day in July.
And then.... a friend/instructor hopped in to give me some line suggestions and....
View attachment 91183
View attachment 91184
View attachment 91185


So yeah that day ended a little early. He was not by any means pushing the car or showing off. We were starting to pick up pace a little after the out lap and the car got away from him over the crest of the hill. Both the car and the tire wall did their jobs beautifully, in that neither of us had so much as a scratch or bruise. The car drove back to the paddock under its own power, leaking only windshield washer fluid. Thankfully another friend had a free spot in his trailer and got the car home for me.

Also thankfully, the person who was driving is a stand-up fellow who made sure the car got repaired at no cost to me. A tall order, since I was not running with track insurance (I always assumed I would be the one to crash my car, and would figure that out if and when it came. I will strongly consider it next season after seeing that bill, though!). He definitely had no real obligation to do so, so perhaps take this as a reminder to be careful who you allow to drive your cars (and to use track insurance!).
View attachment 91186
View attachment 91187
Oh, and my friend told me to throw the used Watson roll bar in the trunk for the shop to install, on him. So that's pretty cool.
View attachment 91188
The repairs took about 3 months, and the shop missed enough small details that it was a bit disappointing, but I got her back and prepped in time for the NASA season closer at NJMP Lightning last weekend. I was happy to be able to sneak one more event in before winter, and the car felt good.
(At least, it didn't have any new issues. I still have some axle hop when close to max braking, which I will be taking a proper close and measured look at anti-squat over winter for. At least it does it in a straight line after now my last round of parts)
I didn't set any PRs last weekend as I was taking it easy, making sure nothing else was left loose or missed, plus the brake hop quite literally shook some confidence out of me, but I was within about a second of my PR so I'm good with that.

There were a few changes, to make things a little easier/cheaper. The Roush grille instead of the billet one, the Carter's Customs Splitter instead of APR, and a CSF radiator since the OEM Boss radiator was discontinued. Oh, and I had them put in a Racelouvers vent as well. Definitely looks a lot better than it did leaving Limerock.
View attachment 91189
Wow that’s quite a story, fortunately no one was injured. The car looks great. I started reading the post from the beginning and your coilover selection piqued my interest. Then I finally got to the end. Good luck in ‘24.
 

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