Weird brake issue

[NO LIFT]

After removing my street brake pads, and installing my Hawks for an upcoming track weekend, my '88 911 wants to turn right when I push on the brake pedal.

Caliper, right? My first inclination.

But, this has happened before and have replaced the calipers (all 4).

Tonight I will try pushing the pistons back into the calipers to see if anything hangs up, and will bleed the brakes, although I'm confident that there is no air in the system.

Any other ideas?

[djpateman]

It may be that the rotors are getting a better bite on the right side, slowing the car a bit more on the right, thus causing the turn to the right. You might want to grind the rotors a little to remove any glazing of the surfaces.

[kidrock]

what condition are the brake line hoses in? If you still have the original rubber ones, they may be degraded and could use replacing...especially if you're gonna track the car.

[Green 912]

Check for seal pull back. Easy check and fix. Remove both pads from one corner and push the brake pedal just enough to push the pistons in a little past the pad space. Now push the pistons back just enough to friction fit the pads in. If the pad slides in easy stop and push the piston back out some using the brake pedal. The pad needs to be snug on the piston and rotor and pushed back to make the space. This removes seal pullback. Do this to all 4 corners. This is also a cure for new / rebuilt caliper soft pedal issues. Good form to do this whenever changing pads to maintain a consistent pedal stroke and feel.

[80-911SC]

i think kid got it , brake bis to the one side if the calipers are newer check the lines

[jsmithcds]

+1 on Green 912's suggestion. Same thing happened to me. Just easy on the pedal or you will be taking the caliper completely off to reasemble..... trust me when I say this. Block of wood inside caliper to stop pistons from pushing out is not a bad idea either.

nice write up Green 912

[NO LIFT]

Green 912, I think you've enlightened me.

I tried a similar deal last night, I retracted the caliper pistons, pumped the pedal to re-seat the pads, and then bled the fluid. It is better, but not what it should be.

I will try your suggestion tonight, and I'm confident it will work.

Thanks for the tip!

[djpateman]

Well, considering that a whole different set of calipers and a whole different set of pads did not change the underlying issue, then I'd say the calipers and pads are not prime suspects. An alignment issue would generally be constant. Loose components such as wheel bearings, tie rods, ball joints or strut top bushing might shift under braking causing an alignment change. Brake lines might leak and lose pressure causing uneven braking, and thus a steering change, but leaks are generally noticed. Brake lines that are old tend to pinch off, thus becoming one way valves, but this generally causes longer term braking/steering issues; the brake pads drag on that caliper for a long time causing excessive pad wear, and generate lots of heat, both of which are noticeable. If the effect is just under active braking, then the cause is more likely to be a friction difference in one side; if the calipers and pads can be eliminated, then it only leaves the rotors.

[ShakinJoe]

Warren Hall explains this perfectlt in this post.

Spongy brake pedal, even after ....

[911st]

Any leakage on the side that is not holding?

Air in line on non holding side and or pads need to be re bedded in.

I assunm this is not a turbo look.

[burgermeister]

I've had a similar experience with a used set of PFC97's. Put my old pads back on, all is normal. I did notice uneven wear pattern of the rotor when I took the PFC's back off. Chances are, the pads need bedding to the rotors.

[NO LIFT]

Thanks, ShakinJoe!

I followed the procedure, but it is now dark and raining, so I'll have to drive it tomorrow. I'm confident that the pistons were not contacting the pads as they should.

Just to make us all feel better, no problem with brake lines, etc.

Thanks to all for your help and advice, y'all are great!

What a wierd deal, I've never come across this issue in 20 years of cars, DE, and racing. I think I may have purchased all new caliper when this happened before and I didn't really need them...oh well.