1993 Pontiac Grand Prix SE coupe. 115,000 miles. W-body, same as Lumina,
Regal and Cutlass.

The brakes perform pretty much the same now as when I bought it with 7000
miles in 1994. In normal driving they work fine. During a "panic stop" they
don't work well. There is not much more stopping power than normal driving.
The pedal will go to a hard stop and scare the crap out of me because I
think that I will hit the car in front of me. The wheels will not lock. When
the car was under warranty the dealer told me "That is the way the brakes
are on these cars."

I know that the brakes are not hot when this happens so it is not fading. I
pretty sure that it is not air in the lines because it was like this new and
I have flushed the brake fluid every several years using a pressure bleeder.
It is not leakage in the master cylinder because when holding the pedal, it
does not drop.

The front rotors need to be replaced. While working on this I want to try to
improve the problem that I described above. I've read about after market
parts that claim to help. I want to learn from your experience before I
spend a lot of money on parts that do not help.

Stainless Steel Brake Hoses: Hype or help?

Drilled and Slotted Rotors: Hype or help?

Any other suggestions?


Thanks

Usually ther rear brake system is a problem on these cars, the lower slider
pins rust up and freeze and at times the upper, this limits the clamping
action of the caliper resulting in little or no rear braking, check this
out.
"Commuter" <t120rv (AT) pacifier (DOT) com> wrote




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"Shep" <djsljsrn (AT) capital (DOT) net> wrote


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.

HLS, on the money!
"HLS" <nospam (AT) nospam (DOT) nix> wrote




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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.



"Shep" <djsljsrn (AT) capital (DOT) net> wrote

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.


"sdlomi2" <sdlSPAMomi2 (AT) yahoo (DOT) com> wrote

HLS

Please see my response to Shep.


"HLS" <nospam (AT) nospam (DOT) nix> wrote

"Commuter" <t120rv (AT) pacifier (DOT) com> wrote

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?


"sdlomi2" <sdlSPAMomi2 (AT) yahoo (DOT) com> wrote

"Commuter" <t120rv (AT) pacifier (DOT) com> wrote

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