RaceReadyRX7

My left front brake is not grabbing like the right front. Were talking big difference under hard braking. I just rebuilt both front caliper, replace the brake fluid with new dot 5 and bleed the system. At first both front brakes were grabbing the same, but after awhile the right front started grabbing a lot more. It almost puts me in ditch. Rebuilding the calipers didn't make any differences. The front pads are Hawk’s Black and are close to new about 85%. The rears are Hawks also. The rotors are also close to new, Brembos Zinc plated Cross Drilled and Slotted. I’m still running the stock brake lines, could the rubber lines cause by problem? I only have about 80k miles on this car. Anyone else had this problem, if so what fixed it?

C's-7

iTrader: (3)

Did you use DOT 5.1 or DOT 5?

rynberg

Exactly. Dot 5 is completely incompatible with other brake fluids and should never be mixed.

Also, you are running Hawk Blacks on the street? Very bad idea. I give those new x-drilled rotors about 2 months before they're toast, if that.

In any case, I would certainly suspect the left caliper rebuild....

RaceReadyRX7

Dot 5.1 if I remember right, it been about 2 months since I rebuild the calipers. Same has I had used the last time I replaced my brake fliud.

C's-7

iTrader: (3)

How was the rebuild performed on the calipers? Did you split the two calipers and if so did you replace the cross over seal and insure that it didn't shift before you tightened the bridge bolts?

RaceReadyRX7

The problem was there before I rebuild the calipers. I was hoping the rebuild would fix the problem.
I'll give the rotors a close inspection tonight.

RaceReadyRX7

I didn't split the calipers. Just replaced the piston seals.

DaveW

The stock calipers are sliding calipers. If they are not free to slide (needed to get equal force on the two pads) and therefore stick, you will get symptoms like yours - one brake not working the same as the other. The fact that it was OK for a while after you reassembled the system also supports that conclusion. Hose problems will not cause your symptoms - mushy pedal, yes, unequal braking, no, unless one hose is completely blocked.

RaceReadyRX7

So, maybe a little anti-seize on the pins might fix it?

C's-7

iTrader: (3)

If the front calipers were in fact giving you the problem then it would not be a sliding/floating issue. The only translation on the front calipers is the pads along the pad pins. It is possible for the pads to bind on these pins, which should give you noticeable taper wear just by inspection.

However, Dave W brings up a good point in the way that it may be a rear brake issue. Have you weighed this option out?

RaceReadyRX7

What can of rear brake problem are you thinking of? I have read Dave W reply several times and don't see anything about rear brakes.
I will check for uneven wear on the fronts.

DaveW

HMMM... Sorry, I didn't remember that the fronts had dual pistons (one on each side of the rotor)...

Do you feel pull in the steering wheel? If not it might indeed be a rear problem causing the car to pull, although the effect would be much less than what I think you are describing.

RaceReadyRX7

YES, the steering wheel does pull. Hard right.

C's-7

iTrader: (3)

Sorry for the confusion. What I'm trying to say is the rear brakes are designed to float/slide were the fronts are not. The bridge bolts on the front caliper clamp the two caliper halves together, which make it impossible for the front calipers to float/slide.

If the brakes are not floating properly then this would only pertain to the rear brakes.

Unless like I stated earlier the pads on the front caliper are binding along the pins.

mad_7tist

are you also sure the suspension is not worn? a shotty rack, inner or outter tie rod etc... that toes the tire out under braking. the car does not pull unless you hit the brakes right? trying to eliminate a draging pad /\.

RaceReadyRX7

The car is scheduled for an alignment tomorrow. I'll have them check out the tie rods for ware. It's set-up for autocross now. Going back to stock alignment tomorrow.

DaveW

Another thought:

Is it possible that one or more rotor surface is glazed (pad material transferred to rotor) more on one rotor than the other?
Although some pad types are made to transfer material to the rotor to create a compatible friction surface, I have had occasions when an excessive amount was transferred to just one rotor surface, causing uneven braking.

When you rebuilt the calipers, did you check the pistons for build-up, damage, etc., that could prevent a piston from extending as the pads wear? It still seems most likely that something in the caliper is not functioning properly.

Alignment (or play in a steering component) is certainly a possibility. Do you notice any strange front tire wear that would confirm an alignment problem?

turbojeff

iTrader: (30)

Try the brakes when they are hot, does it do the same thing? Auto-x alignment makes the car darty but I'm sure you know that since you've been running it for years.

If not there aren't many things it could be. Caliper rebuild might not be good...

RaceReadyRX7

I inspected the brakes again last night, no abnormal wear; no cracks in the rotors, the pad are not binding on the pins. Maybe it is the alignment. I just never thought that it could me alignment issues I'm having it set back to street spec per Pettit Racing website. I'll report back this afternoon after I pick the car from the alignment shop. If thats not it I'll have the rotors turned.

RaceReadyRX7

The new alignment fixed the problem. It must have been out of alignment. Thanks for all advice guys.

DaveW

Glad you got it fixed!