Brake problems 24 may05

[Roy]

Had my 98 SL1 in to have rotors and pads changed. Since I got it back every
once in a while the front brakes will tighten up. The pedal gets really firm
and when I push in the clutch it is like the brakes are being applied
lightly. It only seems to be affecting the front, if I hit the brakes hard
when it is tight all the braking seems to be in the front. And it is even
the car and wheel don't pull to one side. It only seems to do this when the
car is warm (not necessarily when the brakes have been used a lot).
Could it be that when they pushed the calipers in they pushed too fast or
hard?
Could they have done something to mess up the master cylinder?
Or could it be that I had a defective caliper to begin with and the movement
made the problem apparent (the shops story)?
Anybody had this problem and know what was done to fix it or can tell me
where to start looking?

I usually do my own brake work (20 years now) but I had to get it done and I
didn't have any free time. Last time I make that mistake

 

[MrTimm]

I had this exact problem and posted the ongoing saga of how I got it
fixed. It turned out to be very simple.....

The brake light switch was sticking.

It presses against the pedal arm from the top. When the pedal is pushed
it travels away from the switch. When the piston in the switch is fully
extended it turns the brake light on.

When the pedal is released, it pushes the piston back into the switch
and turns off the brake lights.

When the switch gets old, it will sometimes not retract into the "off"
position and hold the brake pedal partially down. It makes it feel like
you're driving around with the brakes on.

Once we figured it out, the mechanic cleaned the part up and it's
worked fine for over a year. Cost of the actual repair $0.

MrTimm

 

[Roy]

I've tried hooking the pedal with my toe and pulling it up. It is all the
way up. I'll check that out more.
It's not that the pedal is partially down, the pedal is all the way up and
the car slows down more than it does when this isn't acting up. When I take
off on level ground it feels like I'm taking off on a slope. And if it stays
that way too long the brakes will start to stink (burn).

 

[MrTimm]

That's exactly how it felt to me. You won't be able to lift the pedal.
It'll feel like it's up. Check that switch plunger and make sure it'll
move up and down the whole way. You'll have to check it when it's
working to compare.

Mine didn't do it ALL the time. that made it harder to diagnose.

Good luck,

MrTimm

 

[private]

Had my 98 SL1 in to have rotors and pads changed. Since I got it back every
once in a while the front brakes will tighten up. The pedal gets really firm
and when I push in the clutch it is like the brakes are being applied
lightly. It only seems to be affecting the front, if I hit the brakes hard
when it is tight all the braking seems to be in the front. And it is even
the car and wheel don't pull to one side. It only seems to do this when the
car is warm (not necessarily when the brakes have been used a lot).
Could it be that when they pushed the calipers in they pushed too fast or
hard?
Could they have done something to mess up the master cylinder?
Or could it be that I had a defective caliper to begin with and the movement
made the problem apparent (the shops story)?
Anybody had this problem and know what was done to fix it or can tell me
where to start looking?

I usually do my own brake work (20 years now) but I had to get it done and I
didn't have any free time. Last time I make that mistake

FWIW My first suspicion would be to check for corrosion on the caliper
slide bolts. I am a big believer in the use of high temp nevr seize on all
brake bolts but especially on the caliper sliders. If this is not the
problem I would suspect corrosion in the caliper piston bore which is a much
more serious and expensive problem usually caused by moisture in the brake
fluid. PM brake bleeding in order to remove old moisture laden fluid is a
good PM practice that is not normally done by brake shops and is another
reason to always DIY.

Brake fluid is hygroscopic and will suck moisture out of the air which is
why the brake fluid reservoir should not be opened unless REALLY necessary
and why you should NEVER top off with fluid not from a NEW factory sealed
container. If you need to add fluid use it as a good opportunity to bleed
the system to purge the old fluid.. Buy fluid in small size containers and
use it all, do not store opened fluid for later use, especially if you are
in a humid climate.

The suggestion from Mr. Timm to check the brake light switch is a good one
and should be done first as this is easier but I would suspect that this
fault would not present itself only after a rotor pad replacement.

Just my .02