I NEED HELP brake problems

[easyrusty]

hi i have a 1982 vette i took it in for some routine maint and brake problems. i am now on the fourth master cylinder, each time the mc goes out any insight on this problem
thanks
darrell

 

[Copdogcorvettes]

hi i have a 1982 vette i took it in for some routine maint and brake problems. i am now on the fourth master cylinder, each time the mc goes out any insight on this problem
thanks
darrell

4 MASTER CYL. There something wrong with that. :W What is the problem you keep having; Why are you needing to get the brakes checked so much? Need a little more information.

Gary
SAVE the WAVE

 

[easyrusty]

4 MASTER CYL. There something wrong with that. :W What is the problem you keep having; Why are you needing to get the brakes checked so much? Need a little more information.

Gary
SAVE the WAVE

thanks gary i took it in because i essentially had no brakes going all the way to floor. he replaced the mc and they worked for a very short time. and they have done the same thing with all mc's.

 

[Copdogcorvettes]

In all cases was the master cyl. empty of fluid? trying to understand why the master cyl. needs replacing. There are many reasons for the pedal going to the floor.

Gary

 

[n8dogg]

You got problems besides the MC check all of your breaklines and break calipers for any sign of leaking then find someone new to work on it if you cant

 

[Bwmurph]

Easy,

I had the same thing - pedal all the way to the floor. Replaced one M/C and shortly after pedal to the floor again. THought I was having the "air getting sucked in because the runout on bearing was bad" thing. Then found I ahd a bad piston in a rear caliper. Repalced the caliper and bled the system with a Motive Bleeder and now have a "high and hard" pedal. (Had an accident with the Motive Bleeder and umped a bunch of brake fluid on the driveway, but that's another story)

Anyway, my guess is you have a bad caliper or even a pinhole in a brake line somewhere. No way you could get four bad M/C's in a row. It amy be alittle hard to find out which caliper is bad; mine wasn't leaking a lot, but just enough to draw air in to the system.

Good Luck,

Bernie O

 

[JohnZ]

thanks gary i took it in because i essentially had no brakes going all the way to floor. he replaced the mc and they worked for a very short time. and they have done the same thing with all mc's.

How long does it take for the brake system to go bad after replacing the master cylinder? Days? Miles driven?

 

[raybies]

It's in my opinion not the master cylinder.
I went through this when I first got my vette.
Turned out it was bad calipers and too much rotor runout which causes the calipers to go bad. If you check rotor runout first, that will more than likely lead you to the bad caliper.
Runout should be no more than .008" (eight thousandths of an inch)
You can have a bad caliper and not be leaking fluid. They just suck air back into the system and cause the pedal to go south.
Also I don't know if you bench bled the Master cylinder or not but you should do that before you install it and when you bench bleed it do not overstroke the piston.
Only move the piston in and out about an inch.
And using a pressure bleeder is advisable for bleeding the brakes, I've never had any luck with other methods.

 

[GTR1999]

It's in my opinion not the master cylinder.
I went through this when I first got my vette.
Turned out it was bad calipers and too much rotor runout which causes the calipers to go bad. If you check rotor runout first, that will more than likely lead you to the bad caliper.
Runout should be no more than .008" (eight thousandths of an inch)
You can have a bad caliper and not be leaking fluid. They just suck air back into the system and cause the pedal to go south.
Also I don't know if you bench bled the Master cylinder or not but you should do that before you install it and when you bench bleed it do not overstroke the piston.
Only move the piston in and out about an inch.
And using a pressure bleeder is advisable for bleeding the brakes, I've never had any luck with other methods.

Good points Ray only one thing,the runout should be less then 003" - 008 is too much, 005 is what the book calls for but I set all mine to under 003".

 

[nasajack]

Kinda having a brake issue...

with my '82 as well! ;squint:

I've have the front calipers replaced, all 4 sets of pads, the MC and the brake lines have no leaks...now the problem...the car pulls to the right upon braking.

I suspect something in the suspension might be failing...or it could be an alignment issue. I followed the wife while she drove the 82, and from behind I saw no 'dog-tailing' of the rear end and then would view the car from the front and found the car to follow true and straight from the rear-view mirror. The tires only have 10k on them and look evenly worn.

Any ideas?? ;help

 

[tmkassin]

with my '82 as well! ;squint:

I've have the front calipers replaced, all 4 sets of pads, the MC and the brake lines have no leaks...now the problem...the car pulls to the right upon braking.

I suspect something in the suspension might be failing...or it could be an alignment issue. I followed the wife while she drove the 82, and from behind I saw no 'dog-tailing' of the rear end and then would view the car from the front and found the car to follow true and straight from the rear-view mirror. The tires only have 10k on them and look evenly worn.

Any ideas?? ;help

Sounds like you have an air bubble in the left caliper. Try bleeding it out.

 

[BOB SWEETING]

Brake problem

Jack it up, and check for any loose wheel bearings, especially the rear. Those masters last 10 years or more. We use them all of the time for street rod and muscle carseyand never a problem. Rotor run out caused by improper set-up on a lathe will ruin rotors, sometimes they end up with .100" runout. The caliper pistons have to follow the rotor, and kills the seals. It also pumps air INTO the calipers. Any caliper boot not seated on the piston properly will also pull the piston back in. A secret on the Delco 4 piston caliper is that the pistons are so far apart, that they put pressure on the ENDS of the pads, and not in the center. This is why they squeak with no pedal pressure. The pads wear into a convex surface. Cutting out 1/2" of the center of the pads with a hack saw will prevent them wearing into a convex surface. The convex surface also makes the pedal low, because fluid volume is spent bending the pads flat.

 

[Vettehead Mikey]

The original poster hasn't been here since November 2009.

 

[herminator]

The original poster hasn't been here since November 2009.

Maybe was on a test drive? Hope not!