Loose Rear End on Hard Braking - Fix?

[Greg35]

I understand my pressures are way to high for optimum performance....but these kinds of pressures will save your tires and get the most track life out of them. Thanks for the info.

I respectfully disagree ....and feel Stuntman is right on. Your tires track grip ( and subsequently tire life) will indeed suffer w/ such a higher than recommended tire pressures.
As you are surely aware , FP recommended Cold pressure is 32lb street and 28lb track use.
I suggest you may want to TRY a couple different settings @ lower psi ....just to compare ride comfort, grip, and more even tire wear across the tread. It's amazing what just a 2-3 lb difference will make to ea. of these ! Just my 2 cents. Best regards.

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[Stuntman]

I understand my pressures are way to high for optimum performance....but these kinds of pressures will save your tires and get the most track life out of them. Thanks for the info.

No they don't.

MAYBE slightly reduce premature outer shoulder wear if you don't run Ford's recommended camber settings.

 

[firestarter2]

Circling back to this. My unstableness under braking is gone. I had the alignment redone and changed tires to Sport Cups 2. I am not sure which did it.

 

[nastang87xx]

Interesting you mention this. I had a wet track day recently and it was TERRIFYING under braking. Every time I went to the brakes even lightly, the ABS would activate and the rear end felt like it was going to come around. Wet didn't help. Cold didn't help. But it was a perspective nonetheless. I think the ABS might just be very much tuned for dry surfaces? Or that the brakes are so aggressive that it actually overwhelms the ABS in situations where the friction coefficient between the tires and the road is super dicey? I'm not sure. But it was truly one of the scariest things I've ever experience in an automobile. It took me a whole session to trust the car.

 

[Caballus]

Interesting you mention this. I had a wet track day recently and it was TERRIFYING under braking. Every time I went to the brakes even lightly, the ABS would activate and the rear end felt like it was going to come around. Wet didn't help. Cold didn't help. But it was a perspective nonetheless. I think the ABS might just be very much tuned for dry surfaces? Or that the brakes are so aggressive that it actually overwhelms the ABS in situations where the friction coefficient between the tires and the road is super dicey? I'm not sure. But it was truly one of the scariest things I've ever experience in an automobile. It took me a whole session to trust the car.

What made you eventually trust the car. Did you determine that it only felt like it would break loose but really wouldn't?

 

[JAJ]

...I had a wet track day recently and it was TERRIFYING under braking. Every time I went to the brakes even lightly, the ABS would activate and the rear end felt like it was going to come around...

What alignment settings and which tires and brake pads were you using? I had a set of Conti's that I ran this year that were fabulous in the dry, but I had to stay under 65MPH on the highway if it rained because the tramlining went from non-existent in the dry to vicious in the wet. No other tires in my shockingly large inventory were even remotely like this.

...it was truly one of the scariest things I've ever experience in an automobile...

At least you were in control - the scariest things I've experienced in an automobile were when someone else was driving.

 

[Epiphany]

I have tracked my car 4 times with just using as much as I can get out of the stock setup....-1 degree neg front, -.75 degree rear and 5-5.25 degree pos caster.

Why did you dial out so much caster?

 

[shelbyman]

Why did you dial out so much caster?

I'm not sure any adjustment to caster was made. What does the supplement booklet call for? I'm not lazy but been laid up a bit so not easy for me to get in the car and get the supplement out.

 

[Epiphany]

You were talking about the track numbers you have been using for alignment. Your positive caster should be just shy of 7 degrees.

 

[shelbyman]

You were talking about the track numbers you have been using for alignment. Your positive caster should be just shy of 7 degrees.

Yes I see that on the setup notes. I'm not sure what it is actually so when I have the camber plates installed I'll get an update on what it actually is. Thanks for posting that pic of the setup sheet. For a compromise setup are you running toe out or pretty much a neutral setup for toe? Want to mitigate tramlining as much as possible.

 

[Epiphany]

Tire choice is probably the biggest factor with respect to tramlining. What are you running?

 

[shelbyman]

Tire choice is probably the biggest factor with respect to tramlining. What are you running?

I'm running the stock Michelin Pilot Super Sports.

 

[nastang87xx]

What made you eventually trust the car. Did you determine that it only felt like it would break loose but really wouldn't?

Exactly. I had some space at one point and just kinda stomped on the brakes to see what would happen and it didn't swing around, just was super super skiddish.

 

[firestarter2]

Interesting you mention this. I had a wet track day recently and it was TERRIFYING under braking. Every time I went to the brakes even lightly, the ABS would activate and the rear end felt like it was going to come around. Wet didn't help. Cold didn't help. But it was a perspective nonetheless. I think the ABS might just be very much tuned for dry surfaces? Or that the brakes are so aggressive that it actually overwhelms the ABS in situations where the friction coefficient between the tires and the road is super dicey? I'm not sure. But it was truly one of the scariest things I've ever experience in an automobile. It took me a whole session to trust the car.

Funny a rain session will take me a long time to recover from to get confidence back in the car.

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