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Heavy Braking Front End Travel

Mad Hatter

Gotta go Faster
3,557
2,078
Santiago, Chile
Not sure I can point you in the right direction, only tell you how I solved what sounds like a similar problem. As I came up through the HDPE program, my braking was always smooth and firm. Of course no where near threshold, but I had lots of confidence in my braking. But as part of my effort to get better, I went from Hawk HP+ front and rear to a very aggressive Hawk HT-10 front and rear. That is where by problem started.

The car started to feel loose under braking, and one day while trying to chase down my buddy, I did a big swap under braking coming off the back straight at UMC to a hairpin. It made for some dramatic video. Luckily I went two feet in and the corner had plenty of run out. Lost the corner, saved the car kind of thing.

That led to about two years of trying different pads, different techniques to try to get my braking mojo back. Lap times stagnated. So I decided to go back to the basics, go back to a pad set that I knew would only be slightly more aggressive than my HP+ days. For the last year I have been running Hawk Blue fronts and HP+ rears. I know not a popular combination here at TMO.

Everyone on this forum will likely think I am crazy, but the step back has worked. It allowed me to work on my technique with a familiar feel to braking. The car feels more planted and as I have stuck with it, my braking has improved greatly. Lap times have dropped. Five personal bests in the last 5 sessions works for me.

I have a personal theory, that others can feel free to chime in on. I think that the ABS logic in my car could not keep up with the very aggressive pads, having been engineered for street use. Going back to a much less aggressive pad put me back in the happy place for my ABS and allowed me to work on the loose nut behind the wheel. Again, just a theory.

I hope you get it figured out because I know what you are going through!
The idea of the ABS being the culprit makes some sense, but then again, lots of Mustangs out racing with slicks and big brake kits with aggressive pads, that do not have this problem. I think Blacksheeps advice to look at something in the rear of the car sounds to me to be the most likely cause..
 
Another possibility is the front lower control arm rear bushing flex. Those hydro bushings are insanely soft and would create a toe out situation under heavy breaking and the more aggressive the pad and tire the more this will happen. When I removed my bushings I was shocked at just how much I was able to flex the bushing with just a screwdriver. I believe ford used this as a crutch because they couldn't figure out the EPAS calibration on the early cars hence all the nibble and issues when people put stiffer bushings in the control arms.
 

Norm Peterson

Corner Barstool Sitter
831
616
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Honestly Norm , G-Loc 10 up front is not enough pad in my estimation. I run R18 front , R10 rear and I recommend most folks to use a 16 up front , especially if going to fast tracks. Either way, the brakes on all my Bosses and the GT 350 worked quite well with some kind of stagger and a lower max. temp pad in the back.

PS note; all G-Locs or Carbotech pads should be purchased pre-bedded in my humble opinion.
I'm considering some stagger, just not sure how much or even which way. One thing I need to diagnose first is whether it is an ABS issue. First time the ABS light came on for me I actually set faster lap times with the ABS offline, but they weren't quite as consistent.

On the little 12.4" brakes, 10s aren't quite enough. So I moved up from 10s to 12s when the little front brakes were still on the car. When I moved up to 14" brakes I figured I ought to back off to 10s mostly due to the extra mechanical advantage of the 14". A secondary reason was that the 12s didn't last as long as the 10s.

My home tracks - NJMP - both space the heaviest braking zones out pretty evenly, and I've only got a 4.6L of about 2010-spec (FRPP tune). 125 mph is about it for me down the main straights - that's pretty much where redline in 4th gear happens - and I'm only having to drop about 50 - 60 mph for T1.


Norm
 

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