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-   -   Brake Issues (https://www.corvetteforums.com/forum/corvette-c3-forum-15/brake-issues-10208/)

SuperHeroSmurf 09-29-2008 11:27 PM

Brake Issues
 
Brake pedal is traveling pretty far to apply the brakes. Warning light came on, so I swapped pads, checked fluid level. Problem still persisted so I bled the brake lines. Got some air from the left front, went through the cycle a little over a dozen times on this caliper so I assume I got most the air out, brake pedal is better but still requires significant travel to apply brakes. Brake system stops short just fine if you apply enough travel, and brake warning light went away after bleeding. Curious to see if anyone has any suggestions? Should I try bleeding again? Is there something else that could be causing the problem or causing the air intake. Have not noticed decrease in performance or travel since bleeding the lines. But still just too much travel. Rotors did not seem in too bad of shape but I haven't measured yet. Ran and pumped brakes significantly and did not observe and leaks at the calipers or along any of the lines. Not sure on the condition of the calipers but appeared in good shape and car brakes evenly no pulsating, no pulls. Any suggestions would be greatly appreciated. thanks in advance for any help.

pg 09-30-2008 12:42 AM

RE: Brake Issues
 
Hi SuperHeroSmurf and welcome again. You might want to bleed the whole system again. That will only cost you some time and break fluid. Start at the LF than RF. They have one bleeder each.
At the rear bleed the LR Inner than the Left outer, than the right inner and right outer.
Rotors have a limit that they can be turned if they were turned to much you will need excessive pedal travel to make the brakes work. Any shop can Mic the rotors, before you remove the rotors mark the hole thatone lug lines up with or you can end up with run out problems.
You may also have a master cyliner that is failing or the rod between the brake pedal may be out of adjustment.
A little history would help, year of Vette, have you always had this probem or did it just start? PG.

Wedge 09-30-2008 12:44 AM

RE: Brake Issues
 
[align=left]Has it been in storage for a while? If it has been sitting, I would suspect the seals in the calipers have gone bad, or the piston sleeves have pitted from rust. Look for moisture on the calipers and pads. If it has been in storage its not a bad idea to flush new brake fluid through the system to make sure it is fresh and clean.
I had a similar problem that was traced back to the Master Cylinder. One side went out, which left me with some, not much braking ability. It happened quickly when I was driving (over a mountain pass...), I had brakes but felt like they were going all the way to the floor (no rebound pressure), and the warning light would come on. Changed out the M/C and all was good.
[/align][align=left] [/align]

SuperHeroSmurf 09-30-2008 03:01 PM

RE: Brake Issues
 
Some more information... It's a 1981, hasn't been sitting for any excessive period of time. No visible moisture or fluid leaking anywhere that I can tell, dry around the pistons no brake fluid leaks that I've seen. The vehicle has always required lots of travel on the brake pedal since I purchased it about a year ago. Then the brake warning light came on a few weeks ago, bleed the lines and it went away, no there is a little more response to pressing the pedal (sponginess?) but still have to press as far as before.

SCHOON 09-30-2008 06:44 PM

RE: Brake Issues
 
If the light comes on again you know you are sucking air or low on fluid.
Could be a bad seal at the one of the calipers or the master cylinder is going bad.
If it was me I would replace the master cylinder they don't cost much and are usually the cause of the problem.
Remember your brakesare 27 years old.

SCHOON

78buckshot 09-30-2008 08:45 PM

RE: Brake Issues
 
I agree with the rest of the pack, bleed again on all four corners- if you still have too much peddle travel then replace the master cylinder.

73shark 09-30-2008 08:49 PM

RE: Brake Issues
 
I agree w/ replacing the master cylinder. Be sure to bench bleed it per the instructions.

Some "sponginess" is caused by the rubber hoses expanding slightly under pressure. Stainless braided lines can eliminate this.

Most manuals say to start bleeding at RR, then LR, then RF, and then LF. In other words, start at the farthest wheel and work your way in towards the master cylinder.

pg 09-30-2008 09:50 PM

RE: Brake Issues
 
Hi 73shark, your right on about the brake lines, on a 27 year old car its smart to replace them.

On bleeding: the Corvette manual on page 10-2 under "bleeding system"
"...proceed to the wheel cylinder nearest the master cylinder"...

Or in the 74 service manual page 5-18 under "Sequence for bleeding"
"...either front or rear system, start nearest the master cylinder first.

73shark 10-01-2008 12:05 AM

RE: Brake Issues
 
pg, you are correct. Not sure where I saw (or thought I saw) the reverse order. Will check thru some other service manuals and see if I've totally lost it (distinct possibility) or some brands do it differently. Anyway, good call and glad you caught it. :)

Flying Low 10-01-2008 09:10 AM

RE: Brake Issues
 

ORIGINAL: 73shark

pg, you are correct. Not sure where I saw (or thought I saw) the reverse order. Will check thru some other service manuals and see if I've totally lost it (distinct possibility) or some brands do it differently. Anyway, good call and glad you caught it. :)

Seems like I have allways done it backward myself. Glad you guys are here to keep me straight.


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