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S197 2014 Mustang GT Premium - 6R80 Build Thread Profile - S197 Mustangs

Mad Hatter

Gotta go Faster
4,862
3,712
Santiago, Chile
Cos, was wondering if you have any problems with the brake pedal getting stone hard at the track. We have about 3 club members with the 6R80 and they all have the same problem after upgrading to Brembos from stock.
 
Cos, was wondering if you have any problems with the brake pedal getting stone hard at the track. We have about 3 club members with the 6R80 and they all have the same problem after upgrading to Brembos from stock.

My car is very similar to Coz's from a chassis development perspective. My engine is just running a tune but otherwise stock. I have 4 piston Brembo 14 inch fronts (2 piece Wilwood rotors) and the 13.8 rears with the single piston caliper. I am running Hawk DTC 30's on the front and Hawk HPS or Street/Race rears with Wilwood 570 fluid. I have no issues with hard pedal at all. The pedal effort is actually a bit lighter than I'd like. I use the unmodified ABS and tickle it a bit on track at times.

Since I have stock cams, I am not affecting the vacuum signal to the brake booster so there is plenty of boost. A hard pedal seems to indicate a booster issue. I track at sea level. Altitude could have some effect. I'd data-log manifold pressure (vacuum) to try an identify what the heck's going on when the pedal goes hard.
 

Mad Hatter

Gotta go Faster
4,862
3,712
Santiago, Chile
My car is very similar to Coz's from a chassis development perspective. My engine is just running a tune but otherwise stock. I have 4 piston Brembo 14 inch fronts (2 piece Wilwood rotors) and the 13.8 rears with the single piston caliper. I am running Hawk DTC 30's on the front and Hawk HPS or Street/Race rears with Wilwood 570 fluid. I have no issues with hard pedal at all. The pedal effort is actually a bit lighter than I'd like. I use the unmodified ABS and tickle it a bit on track at times.

Since I have stock cams, I am not affecting the vacuum signal to the brake booster so there is plenty of boost. A hard pedal seems to indicate a booster issue. I track at sea level. Altitude could have some effect. I'd data-log manifold pressure (vacuum) to try an identify what the heck's going on when the pedal goes hard.

I wonder if the base GT cars they sent down here have a different setup. All the S197 cars that got upgraded brakes from the stock Ford setup have this problem at the track... One has a set of Stoptech trophy calipers and his problem went away with a change to a manula setup, make one think its to do with the vacuum.
 
I wonder if the base GT cars they sent down here have a different setup. All the S197 cars that got upgraded brakes from the stock Ford setup have this problem at the track... One has a set of Stoptech trophy calipers and his problem went away with a change to a manula setup, make one think its to do with the vacuum.

My car is the second S197 I've owned upgraded to Brembos on the front. That earlier car was a 4.6 liter 5 speed. No issues with hard pedal on that one either. If switching to manual brakes solves it, then the vacuum booster and how much vacuum the engine creates would be under where I'd look. Maybe compare booster part numbers in Chile vs US domestic market.
 

Mad Hatter

Gotta go Faster
4,862
3,712
Santiago, Chile
My car is the second S197 I've owned upgraded to Brembos on the front. That earlier car was a 4.6 liter 5 speed. No issues with hard pedal on that one either. If switching to manual brakes solves it, then the vacuum booster and how much vacuum the engine creates would be under where I'd look. Maybe compare booster part numbers in Chile vs US domestic market.

Sorry, I ment to say switching to manual transmission. Will double check the part numbers, thanks.
 
1,250
1,043
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
Since I have stock cams, I am not affecting the vacuum signal to the brake booster so there is plenty of boost.

I have the L&M intake cams but my pedal feel was unchanged after the cams were installed.

The only other thing I can think of is if they also changed their brake lines to a version with a thinner profile banjo fitting. I hear that some Russell lines are like this. If you use the standard length banjo bolt with the thinner banjo fitting it may affect the flow of brake fluid through it?

But if its an intermintent problem, I doubt that would be the case. Unless either the caliper body or the banjo bolt expand in a certain direction just enough when hot to restrict flow of the fluid?

Just a wild ass guess...
 
I have the L&M intake cams but my pedal feel was unchanged after the cams were installed.

The only other thing I can think of is if they also changed their brake lines to a version with a thinner profile banjo fitting. I hear that some Russell lines are like this. If you use the standard length banjo bolt with the thinner banjo fitting it may affect the flow of brake fluid through it?

But if its an intermintent problem, I doubt that would be the case. Unless either the caliper body or the banjo bolt expand in a certain direction just enough when hot to restrict flow of the fluid?

Just a wild ass guess...
Hey Coz just read your build up, I’m buying Nitto NT01 275/40-18 tomorrow for my Boss. I ne
I have the L&M intake cams but my pedal feel was unchanged after the cams were installed.

The only other thing I can think of is if they also changed their brake lines to a version with a thinner profile banjo fitting. I hear that some Russell lines are like this. If you use the standard length banjo bolt with the thinner banjo fitting it may affect the flow of brake fluid through it?

But if its an intermintent problem, I doubt that would be the case. Unless either the caliper body or the banjo bolt expand in a certain direction just enough when hot to restrict flow of the fluid?

Just a wild ass guess...
Hey Coz, just read your build up, what do you think of the Falkens for track tire? I never considered them but the size and TW are interesting. I’m buying NT01 275/40-18 for my Boss track tires, they are a trade off of TW100 for relatively narrow width. Would rather have 285 or 295 but with 18’s the aspect ratio gives a pretty small diameter, typically <25”
 
1,250
1,043
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
what do you think of the Falkens for track
I just had one track day on them this past Friday. I like them but I was still trying to dial in pressures. It was a hot 90° day and after the first 20 minute session they were up to 41 psi. I was checking the tire temps across the thread, albeit only with laser heat detector, and I kept dropping the pressure over the next two sessions to 36 psi Each time the grip improved. And they give you good feedback. Next time I'll see what around 34 psi feels like. Maybe 35 front 34 rear.

Since this was my first time on this particular track orientation (Pocono SE Option 1) I can't compare it to any prior lap times. But they definitely felt faster and gave me more confidence. But now the G-LOC R12s up front may not be enough. I'll try to upgrade my rear pads first and see how that works. If needed I'll go to R16 up front.
 
I just had one track day on them this past Friday. I like them but I was still trying to dial in pressures. It was a hot 90° day and after the first 20 minute session they were up to 41 psi. I was checking the tire temps across the thread, albeit only with laser heat detector, and I kept dropping the pressure over the next two sessions to 36 psi Each time the grip improved. And they give you good feedback. Next time I'll see what around 34 psi feels like. Maybe 35 front 34 rear.

Since this was my first time on this particular track orientation (Pocono SE Option 1) I can't compare it to any prior lap times. But they definitely felt faster and gave me more confidence. But now the G-LOC R12s up front may not be enough. I'll try to upgrade my rear pads first and see how that works. If needed I'll go to R16 up front.
Ok thanks. I’m starting over with coilovers and camber plates from factory struts/springs so lot of new stuff. I had only one track day with these changes on “home” familiar track on used MPSS 275’s, so now the tires need to come along with the other changes. I’m a little frustrated with the availability of sizes and compounds with 18’s, in retrospect I should have gone with 19’s, live and learn.
 
I guess it depends what your ultimate goal is. If you eventually want to go competitive, there are more slicks, especially used, available in 18".
18’s were the correct choice when I made it 2 years ago and it is not wrong today. I need to keep my goals aligned with the mods, sometimes I (we all) can get carried away
 

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