Grand Prix Brake Improvement

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Exactly. Even though the rear brakes only supply 20 percent or so of the stopping power, if they are not working (and they often do NOT with this design system), it is hard to stop.

I have rebuilt the front and rear calipers on these systems many times. Rebuild if cheaper, or buy new IF THEY NEED TO BE REPLACED.

Assuming that this is the same system I am familiar with, the self adjuster system on these rear disc brakes (assuming this is the system you have) are terrible about freezing up, and the brakes will not adjust properly, leaving them worthless.

If you use the parking brake every time you park, some of this problem can be eliminated.

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Thanks for the quick reply. This is what I found out. I loosened the caliper bolts enough to grab the slider/spacer piece with pliers. They all rotated freely.

HLS mentioned about using the parking brake for adjustment. I knew about this and usually use the parking brake. To try to fix the problem, I set and released the parking brake several dozen times but it made no difference.

With two lug nuts holding the rotor tight to the hub, I used a pry bar to move the caliper out so that the inner pad was touching hard on the rotor. I measured a gap of .036 on the drivers side and .025 on the passenger side between the outer pad and rotor. Is this normal? The outer pad on the passenger side has twice the wear as the other pads.

I should have mentioned that they are standard brakes without ABS. Disks front and rear. They stop straight with no pulsating. And no, they will not lock-up.

It feels like the master cylinder cannot displace enough volume of fluid to lock the wheels.

HLS

Please see my response to Shep.

Assuming it has them, are you familiar w/the difference in feel between standard and anti-lock brakes? The feeling when first making that change gives the impression of weak brakes. On a clean, dry road, with no traffic, try a panic stop (AGAIN! in a controlled situation/traffic, et al!) from about 35 mph. Does it stop straight w/o dragging the tires or locking the wheels? Sounds as if this may be what you are 'feeling'? Another feel it will effect will be an almost pulsating or pushing back against your foot on the brake pedal, as opposed to a cushioned stop against the pedal force--to be distinguished from that out-of-true rotors doing their own pulsating. Difficult to describe, but the feel, altho' similar, is definitely different. HTH, s

I don't think that it is the master cylinder because the pedal does not drop when holding it down for a time. It does feel mushy as if there is air in the system or something is expanding. Could there be air trapped that does not get removed by bleeding?

Your car should have sufficient braking to drag the tires. Can be so many causes; but since they seem to have done this since 7000 miles: if it calls for metallics and someone happened to complain about noise at less than 7000 miles and someone put on non-metallics to relieve the noise, they will NOT stop adequately. Were it mine, I'd go ahead and replace the rotors you said it needs. I'd choose a GOOD name-brand pad. I'd double-check and if it calls for semi-metallics or metallics, I'd be sure to use nothing but precisely that. If pedal still goes against a hard stop and it still fails to stop adequately, I'd replace the m/c. It should not need drilled and slotted rotors or stainless hoses. *You can check if rears are stopping adequately by applying emergency brake while rolling. If going much over 20-30 mph, they will probably--really should-- lock the wheels and drag the rear tires. s

Just to clear the air, you can set and release the parking brake hundreds of times, but if that adjuster is already frozen, you wont accomplish anything at all.

You have to manually free up those adjusters, if they are no longer working.

Proper bleeding will remove the air. My suggestion for m/c was only AFTER replacing rotors and installing proper pads ("If pedal still goes against a hard stop and it still fails to stop adequately, I'd replace the m/c.").

I think you have adequate info (from all responses combined) to proceed with proper repairs. It's not like you would be re-doing everything or even doing un-needed repairs. Inquire back if you experience further problems. Luck to you. s

Can the adjusters be freed up with out disassembly of the caliper? Does the .025-.026 gap under the pad indicate that they are not adjusting properly?

Thanks

difference.

You do not have to disassemble the rear calipers to free up the adjusters. The gap of pad to rotor does not necessarily mean anything important.

You MUST free those adjusters, if they are not free already.

The adjusters can be found at the end of the parking brake cable. You may have to spray these adjuster screws with aerosol lubricant, and further you may have to remove the nut from the end of the adjuster screw, and physically work the adjuster until it is capable of tightening the piston against the rotor when the parking brake is actuated.

It is not the easiest thing in the world, conceptually, to understand how these brakes work. At least, it took me a few times to get the full impact of what is happening.