I just put new rear rotors and Hawk HPS all corners. I have Yoko A008RSII tires on the car right now.

I went to test the brakes and they are great, just like air brakes. So anyways, the problem arises when I lock up the back tires. The car tends to swing to the driver side, is this normal? Or do I have a seized caliper on one of my rear

Thanks.

 

I'm not for sure, but I'd say you have a 150+ pound individual sitting on the "driver's side" of your car. This may be the problem?

 

Does the car swing out from the rear? or does it feel like it's turning when you brake?

I'll assume the problem is coming from the rear of the car... I'd check the condition of both calipers and bleed the system just in case. This could also be a suspension problem... remember, your car has variable toe in the rear, so if that isnt as tight as it should be, it could cause some instability problems under braking. Both these problems should appear under hard braking wether you lock up or not though. If your car is only acting stupid when locked up, chances are one of your wheels isnt locked up at all. Give the brake system a check in this case.

If, on the other hand, if you feel like the rear end of the car is simply unstable under braking and has a tendency to swing out on either side, you probably have too much brakes in the back. Many people who run high performance pads on stock setups only use them in the front and keep the stock pads in the rear... the last thing you want is the rear wheels locking up under hard braking!

 

It is possible that one of you rear calipers is siezed, but your symptom does not reflect this possibility. If one of your rear calipers is siezed, your car would pull to one direction while you were NOT braking. Also, you would experience brake dragging. That is when you release the brake and you still feel your caliper(s) grabbing.

 

Well, I just did more test and the rears seems to lock up, but not together. Sometimes the right and sometimes the left. Verify by white smoke floating towards the front after hard braking from 100km/h to 0km/h.

Could this be to much braking on the back?
Or bias on front/rear, left/right screwed?

Thanks

 

I would try bleeding the rear system first. If that doesnt work, then slap your old pads back on the rear wheels and give it try. The only way to adjust bias on the car is with the pads, so it's entirely possible that your new Hawk pads are providing TOO MUCH rear braking compared to the front pads. This is a common problem... that's why most people stick to stock pads in the rear (unless you do major brake mods in the front).

 

Don't you have flat spots in your tires now???:p

 

Ok, i had the same thing. It was on a 88 NA base though, and it has single piston calipers in front.

The problem was that the front piston tops were dished toward the pad (from exessive pressure/rust?) So im guessing cause of this when the pedal was pressed the front pistons would travel less than their original travel due to the larger volume in there. The back was still good so it would push like normal. Thus too much rear brake bias. Hope u can understand.......

But u have 4 pot fronts so could it still be?

Cheers,
Jakob

 

Actually, I had some stuck pistons up front, but I've manage to free them up. Would they still be the problem??

If the rears are locking up, do that mean that they are ok and functional?

thanks

 

If you can lock up the rears, I'd say they are functional lol. Fixing your front calipers added more front bias (more front braking). Did this fix your probem??

 

I finally gotten around to getting new calipers, x-drilled rotors and new pads. See if this will solve my problem