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Discussion Starter #1
Hi folks this is my first posting. I have an 01 Mustang GT which I autocross, hillclimb and use for track days. My problem is, entering into a turn I apply the brake hard and it seems to function correctly (pulsates) for a few feet and then that sensation stops altogether and while still slowing the car some it does not do so nearly fast enough. Consequently I have to back up the corner and apply the brake earlier which of course wastes time. So far I have talked to the local Ford techs, Summit, American Muscle and Wildwood and haven gotten conflicting advice. I have been told "that is the way it is suppose to work" to "no it should pulse right down to complete stop". The system is pretty stock, but with new calipers, rotors and Hawk pads. I am currently running Hoosier A7s. It seems like the system starts to work and then cannot keep up. One Autocross race next weekend and then we are done, so a timely reply would be appreciated. Thank you for your time and trouble.
 

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Sounds a little like the dreaded "ice mode" that afflicts a lot of cars when you put stickier tires on, and the ABS algorithm thinks the fast rate of deceleration is due to lack of grip.

Key question: Does it seem like the car doesn't want to slow down even if you Fred Flinstone the brake pedal as hard as you can?
 

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Discussion Starter #3
Thank you MFE for your prompt reply. The Fred Flintstone thing is a wonderful analogy. After the first few feet of pulse it goes into almost a freefall, I know it is slowing some but not near fast enough. I either get off the brake to make the turn and loose the back end because of too fast entry or I keep the brake down and plow off the course, or I brake too early and give up time; none are acceptable. I don't want to disclose the various and conflicting advice I have received until I hear what you have to say. Thank you again.
 

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Have you tried disabling ABS to see if you can sustain the more powerful braking beyond the initial application?
 

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Hmmm . . . if your track tires are shorter than the car's OE tires, the ABS is going to think you're slowing down at a greater rate than is actually the case. Even if they were street tires. Still indicates taking ABS out of the loop.


Norm
 

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So far that is the one fix everyone agrees on,

I was going to say disable ABS, and if its a complete track car look into how much weight savings you get without in the car. I dont know how much of an advantage it is in lap time compared to non ABS, but i would feel like its one less thing to worry about, one less thing to break and have to fix.
 

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Without ABS you carry the risk of flat$potting a couple of expen$ive tire$. With it, there's some possibility of running into 'ice mode'. Pick your poison, I guess.

I doubt the weight difference or even where it's located is worth worrying about for HPDE. Can't be more than a few lbs.


Norm
 

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Discussion Starter #9
MFE, Patrick, Norm and Escort, thank you for your advice. Well after your sage advice and that of the professionals from the outfits I listed earlier, I disabled the ABS and the car performed the best it has in two years. Why did I not think of this earlier. I was able to go deeper before I applied the brake and still negotiate the turn. A little wheel lock up but not bad and certainly acceptable compared to how the car was acting with ABS on. Fuse #29 under the dash is indeed the racers friend.
 

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ABS should not cause this problem if working normally. Street tuned traction control on the other hand can do lots of weird stuff on a track car. If the car has traction control I would look into disabling that and try it again with the ABS working.
 

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TC should not be in the picture under any braking, let alone interfere during braking that started out being hard enough to get the ABS interested.


Norm
 
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