82 brake woes

[buddaman]

HI, I'm a newbie to Corvettes and this forum as I just picked up a 1982. I'm looking for some advice on the brake system.

Symptoms are sporadic pedal, sometimes it will go to the floor, sometimes it's nice and high. When it's high, it doesn't seem to drop if I keep pressure on it, which makes me think the master cylinder is ok. The pads all around are good. I've bled both fronts and all 4 valves on the rears. Some of the initial fluid that came out was sort of dark, but I've essentially changed the fluid at this point on both master resevoirs with all the bleeding. No fluid leaks, in fact, with the bleeding the rubber master cylinder cover gasket gets pulled down and expanded as fluid is pumped out.

I'm stuck thinking that the master is indeed the problem even though once the pedal is high it doesn't drop with pressure, the classic sign I know of for master problems is the pedal dropping with pressure. The lines are good, no leaks, all 6 bleeders shoot fluid so I don't think there's any caliper probs. Just looking for any tricks before I spring for a master cylinder.

Thanks for helping the new guy!

 

[c4ever]

Welcome to the Dark Side. You can do a search and find a wealth of brake issues but these calipers and overall brake design is just plain lousey. I would replace all calipers or rebuild them and check for rotor run out. Simply put these calipers and brake design is notorious for sucking air into the caliper pistons. Not to mention squeel, pulling, etc,etc, etc, etc.
Keep us posted and welcome aboard

Carlo

 

[buddaman]

Cool, thanks. Master cylider would've been so much cheaper.... I just checked again to make sure I had it right and when the pedal is high it doesn't budge so I think the master is good. Rotors seem nice, pads are good. Car only has 44K miles and has been sitting for the most part of the last 2 or 3 years.

Do you think it might help to compress the caliper pistons a few times to try and move some air around or screw it and just replace them? Seemed like 1 wheel (passenger front) was the only side with noticeable air when I bled them. I'd like to make it work better short term without a complete overhaul but if I have to then I have to.

Thanks again for the assist.

 

[c4ever]

If car has been sitting, even better to rebuild or replace calipers and replace pads. It's important to check run out on your rotors. Pick up a service manual (e-bay, ecklers, etc) not a cheap imitation. It will be worth it's weight in gold before too long by allowing you to troubleshoot when necessary and not throwing good money after bad and it will walk you through the process. Do a search on Brakes and you'll find the run out tolerances listed here, I'm at work and don't have my manuals.

The 82's a great car. Enjoy the ride

Carlo

 

[JohnZ]

If the pedal goes to the floor occasionally, you need a master cylinder; if you only had air in the system, it would be there all the time and you'd never get a high pedal. I wouldn't want to be driving it when the pedal went to the floor..... ;help

 

[Stallion]

Is the master cylinder a big job to replace/rebuild? Besides having the bleed the system, if you don't have to replace calipers and rotors, it shouldn't be too bad, right? Isn't the master cylinder in a user friendly place?

 

[rpounds]

Just so happens that I just did this job on a '68 Firebird 400. Cool car . . . wish I had it sitting next to my vette. I've done this a few times and can tell you that there is no huge trick to it. Pretty straight forward. Check the power brake booster while you are there though. If the master cylinder has been leaking past the rear seal, it will probably be a matter of a short time before the power brake booster is toast. Easier to change them both at the same time than waiting. If the master cylinder has not leaked out the rear, then just replace the MC. Bench bleed the MC as per the enclosed instructions and then bleed the entire system until you are SURE that all air is out of the system. Should be a piece of cake.

Just my two cents . . . good luck, and congrats on purchasing your vette.

Ron

 

[MaineShark]

Whereabouts in the Northeast are you from, Budda?

Joe

 

[buddaman]

Master hasn't been leaking at all, in fact it doesn't appear the system leaks anywhere. I decided to replace the front calipers first, turns out they were only like $60 each. I've got the new ones in place but I gotta wait now for a pedal pumping volunteer until after work today.

The right from caliper looked a little iffy, cyliders all moved free but the rubber seals seemed out of place. This is the line that had lots of air in the beginning. Oh well, I'll post an update later today hopefully with triumphant news

Man, I had a 72 Roadrunner in the late 80's and did all my own work, I even worked as a local garage mechanic in the mid 80's doing tuneups and general work. It's been 12 or 13 years since I did anything more than change spark plugs but it's coming back to me slowly. Fun to get dirty again!

I'm about 30 miles NE of Boston and we finally got some warmth and sunshine today and my damn car is on jack stands!

 

[Bob Chadwick]

Is the master cylinder a big job to replace/rebuild? Besides having the bleed the system, if you don't have to replace calipers and rotors, it shouldn't be too bad, right? Isn't the master cylinder in a user friendly place?

TR,

A very easy job. Make sure you buy the special wrenches for the flare fittings on the lines. I think 4 bolts held the master cylinder in place. Make sure you bench bleed it before putting it on the car. I paid to have someone bleed the brakes. It was a PITA because you have to remove both rear wheels to get to the inside bleeders. I'm not sure if that was the case on the front lines. For $60 it wasn't worth the hassle.

Bob

 

[buddaman]

Well, front calipers didn't help but clearly needed replacing anyway. Today's fun will be a master cylinder!

 

[Stallion]

TR,

A very easy job. Make sure you buy the special wrenches for the flare fittings on the lines. I think 4 bolts held the master cylinder in place. Make sure you bench bleed it before putting it on the car. I paid to have someone bleed the brakes. It was a PITA because you have to remove both rear wheels to get to the inside bleeders. I'm not sure if that was the case on the front lines. For $60 it wasn't worth the hassle.

Bob

Oh I see what you mean. Yes, bleed does sound like a job that would be easier if someone else did it . I agree.

Thanks!!

 

[cruisin-davey-g]

Your Brakes

buddaman: One thing that should be noted about 'vette brakes. Alot of guys pedal bleed their systems. But the proper way is to pressure bleed 'em. That's how I do mine. I made up an adaptor out of an old master cylinder cover & when I bleed my system, I'll use slight compressed air & bleed 'em out that way. That's how they're done at the factory. I worked at Cadillac Motor Car Co. (GM) & the Cadillacs that had 4 disc brake systems were pressured bled & checked as they came down the line. Also, I had a similiar problem as you described on one of my 'vettes. Drove me crazy. I could drive around town all day with a good brake pedal. But if I drove at high speeds (freeway) & went to slow down & stop, my pedal went right to the floor & barely stopped the car. I would bleed the system & get the pedal back, but as soon as I did high speeds again, it would go down to the floor. Turned out to be a (very) slightly bent rear spindle, causing air to be pumped into the system. Changed the spindle along with the bearings & all was right with the world.

Dave

 

[Vette/Berlina-coupe]

-drive like your brakes are always of question...

Detroit Davy: -sure is great driving a car that is a potential accident ready to happen! No matter if you've got it all in perfect running order, --always leave plenty of space around you if possible, because you sure can't rely upon the C3's undersized 1920's parking-brake action to pull you out of a tight squeeze; --still, the rapid attrition of these venerable C3's certainly helps the supply & demand VALUE side... ~Bob vH
:dance

Dave further: -my feeling is exactly that which you have so well expressed on following page hereof, --sure wish there was a viable fix for the WEAK emergency-brake action, --maybe some member has knowledge of a more friction-exerting brake-shoe material enabling if desired for panic-stop purposes virtual(or nearly so) lock-up of the rear-wheels on our beloved old C3-"heffers". As expressed months ago herein, when my brakes went-out (-yep, rear-calipers pumping-in air! Wheeeeeeeeee!!), --I also narrowly avoided making mincemeat of several rice-burners... ~Bob vH

 

[buddaman]

Well, replaced the master cylinder, administered yet another bleeding and the pedal is nice and solid now. Got a good pedal, spun up the emergency brake cable a bit and it passed inspection with no issues.

I'm going to give it some time before I proclaim complete victory but I think I won this battle! Thanks again to all that offered advice, hopefully I can return the favor.

 

[cruisin-davey-g]

Re: -drive like your brakes are always of question...

Detroit Davy: -sure is great driving a car that is a potential accident ready to happen! No matter if you've got it all in perfect running order, --always leave plenty of space around you if possible, because you sure can't rely upon that 1920's parking-brake action to pull you out of a tight squeeze; --still, the rapid attrition of these cars helps the supply and demand side... ~Bob vH
:dance

Thanx, Bob, I know that these 'Vettes are not the most perfect car around (heck, what car is?) that's why I always want to try to improve on them, even if it means to modify 'em (vette) alittle. With all of the new technology out there today, it's nice to know that you can always update an older model, just for safety sake alone. The 'vette owner's that want their's "pure stock" without changing a thing, may or may not be putting their beautiful rides in jepodary when driving 'em (there's more drivers & cars on the roads today, then there were back when these classics were made). But I do respect these guys & gals that want to keep the Vettes just the way they were when new. I made changes on my 'vette looking at a safety standpoint & would never make any major mods to the bodies of these beautiful classics. Just my thoughts, that's all...............Dave