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View Full Version : Cobra rear disc brake problem - RR Track car


Vnemous
03-10-2010, 05:17 PM
Hoping to get some ideas... I have a 93 Fox Mustang that has been upgraded to rear Cobra 11.65" rotors, calipers, etc. Housing is original 93 but every other part is new. This car is used for road course events (HPDE, open track, etc).

Problem: The rotor is rubbing the caliper bracket in hard turns both directions. I have replaced the differential (Ford Racing), axles (Moser), studs (ARP), axle bearings and seals. I am running Nitto NT01 tires so have lots of grip with Maximum Motorsports Torque arm, spring and panhard bar. When the car is just setting there, I have about 1/8" clearence between the rotor and caliper bracket. Other than the housing flexing, I am out of ideas. Hoping somebody has heard of this before and has some ideas. Thanks.

Larry95
03-11-2010, 08:39 AM
What type of differential are you running? I had a similar problem with the FRRP OEM differential in my track car. I replace it with a T2R -- problem solved.

Philcsag1
03-11-2010, 09:03 AM
I have run across this problem also.<O:p</O:p

I have a theory of why it occurs but no definitive proof

<O:p</O:pThe bracket that the caliper sits in may be slightly different GT to Cobra.
<O:p</O:p
What I have done on 2 of the mustangs we own with this brake set up is to place a standard thickness washer in between the axel mount caliper bracket and the caliper bracket the caliper sits in. The washer is placed in-between the 2 pieces where the attachment bolts go thru.
<O:p</O:p
This has solved the problem and we been running the car like this for over 5 yeas.
<O:p</O:p
We do have a T2Rin the rear so that is not the cure.

Larry95
03-11-2010, 02:44 PM
We do have a T2Rin the rear so that is not the cure.I think my OEM had such worn clutches that it was causing my problem.

Vnemous
03-13-2010, 09:34 AM
It is the original 8.8 from the 93 LX 5.0. not sure I know what a "T2R" is...

I will give the shimming of the caliper bracket a try. Seems like this could be a common problem when the car is track driven so was hoping others had a solution. Thanks for your help.

Admiral
03-25-2010, 08:27 AM
Are you running the anti-moan brackets? I think alot of folks forget to add these when the do rear brake upgrades, usually not a problem unless you road race or do OT in the car, then axle flex can cause the contact issues you mention.

Here's a link to he Ford Racing upgrade kit, you can see the brackets in the pic:
http://www.latemodelrestoration.com/item/M2300M

Hope this helps you find the solution!

Vnemous
04-13-2010, 12:39 PM
Yes, I am running the brackets. Did some grinding and they still rub. This is all leading me to the new Moser Axles I installed. They are the only common part. I am guessing the diameter is to small where the bearing rides allowing the axles to flex more. In comparing my car to many others, I have much more axle movement.

Thanks.