Track day - rear wiggle under heavy braking

NeverSatisfied

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That is curious. Forgive me if you already stated it, but what drive mode/advance track settings do you use? I ask because it’s possible the stability control systems are engaging rear brakes quite a lot without your knowledge.
I run full off.

It’s a combo of the bias, small brakes, and shitty reverse rotor vent design on the rear.

 

K4fxd

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and shitty reverse rotor vent design on the rear.
Steeda makes 2 piece rotors for the rear base model and they work great. I have a set of both front and rear.

With these rotors I don't feel the need for the 6 piston brakes even with Hoosiers.

Whatever I lack in brake power I make up from less weight.
 

NeverSatisfied

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Steeda makes 2 piece rotors for the rear base model and they work great. I have a set of both front and rear.

With these rotors I don't feel the need for the 6 piston brakes even with Hoosiers.

Whatever I lack in brake power I make up from less weight.
At $950 for rear rotors only from Steeda, I'll keep throwing Centric $55 rear blanks at mine every time I replace the pads!

Same on the front--Centric 15" blanks on used PP 6 piston Brembos is a hard upgrade combo to beat for consumable cost.
 

K4fxd

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Yes it's expensive. But they work very well.
 


Egparson202

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At $950 for rear rotors only from Steeda, I'll keep throwing Centric $55 rear blanks at mine every time I replace the pads!

Same on the front--Centric 15" blanks on used PP 6 piston Brembos is a hard upgrade combo to beat for consumable cost.
Sounds like you’ve found a strategy that meets your needs. If you’re pleased with the performance and the operating cost, done & done.
 

luc

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A few note
Same thing happened to me a few times at the braking zone for T2 at Laguna
Solution was to use a more aggressive rear pads
I used to love Glock (18/12) until i tried Cobalt… day and night
I run nt01, 305 squared
Cheapest blank rotors are totally up to the task
You can be (and should be) very hard on the brakes and smooth at the same time
Car is a 17pp1 with ford racing suspension, camber plates and pp2 tune
 

GTP

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A little rear wiggle under hard braking at the end of the straightaway is kinda fun, and advanced drivers have confirmed this. It can be in the nature of any car because the back end gets light in that situation.

Having said that, your rear toe numbers are both negative (toe out), and I understand that a tiny amount of toe in is what provides sufficient rear end stability under hard braking.

Put +0.1° toe in at each rear wheel and try that. That's my 2¢.
 
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RocketGuy3

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I'm sure you've gotten better advice than I'm about to give by now since I haven't even tracked my Mach 1 (yet), but I just want to say that this is a very common complaint about the GT4, and an issue I've experienced myself in that car on the track. The most commonly prescribed solution is to just be smoother with the brake pedal. Not less force, but apply the force more smoothly rather than an immediate stab right after lifting.

... That said, obviously things like tires and alignment will make a difference as well.
 
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Techapma

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Had my first opportunity to go back to the track since having the alignment corrected - night/day difference!

Still algae a little wiggle, but nothing like before.
 

WCRookie99

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Had my first opportunity to go back to the track since having the alignment corrected - night/day difference!

Still algae a little wiggle, but nothing like before.

Looks like you have it fixed, few comments:

As LUC says about Turn 2 at Laguna and certainly Turn 5 at Road America, both very fast down hill into slow corners (140+ to 55mph or higher). ABS will come on and I've always had slight wiggle (not ABS issue) under extremely hard braking.

IMHO, Street Mustang corner balance is the issue, as they're at BEST (1100/1100 front 850/750Right rear, lbs) balance plus driver, so I've always noticed a slight wiggle to the left (rear of the car moving to the left) under extremely hard braking.

So, very normal if slight movement.

Last thing, also agreeing with LUC, stock rear calipers and rotors are totally fine, no need to spend $950 on rear. (Front is worth it for both weight reduction and cooling)

Glad you're enjoying the M1
 
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