Forums / Off Topic / Vette Brake Problem

5 years 10 weeks ago, 5:20 PM

cbxjeff

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Vette Brake Problem

My son has been helpng my sister-in-law get her Vette ready to sell. There has been a long going brake problem. Allan has found and replaced 3 leaking calipers. As of last weekend, there are no leaks. Unfortunately the pedal still is bad. He says that he can get a steady stream from each caliper when bleeding. I feel that elimates the master cyl.

I thought my working on cars ended 15 years ago but here I am. I hardly remember, but think I have read that the brakes should be blead w/ the engine running (P.B.). Also I think I remember that the caliper most far from the master cyl should be blead first.

Any ideas guys? She REALLY needs to sell this car as her truck is over 200K and needs a new one.

Thanks,

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5 years 10 weeks ago, 5:55 PM

samD

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Probably a small, hardly noticeable leak in it. If not, a hard jab on the brakes may make it pop or lock up. Try, if there is an adjustment on the brake rod to the master cylinder. Invest $9.95 for a set of brake bleeders, so no chance of air back in.

5 years 10 weeks ago, 6:54 PM

Redheadusmcwife

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Vette Brake Problem

cbxjeff
What is wrong with the pedal on the vette?

Here is what I would do first with the brakes:
I have found that using the old hose in a jar of fluid (trick),allows some air back into the system,thru the threads of the bleeder screw try this and see if it works, you may also be picking the air up at your connection to the caliper. Does this happen on any of the other caliper on the car? If not it maybe a piston seal on the caliper. You also should have a Vette master which has integral residual valves for the front and rear which can prevent the calipers from picking up air by having positive pressure at the caliper seals. Corvette calipers are very efficient pieces but at a cost of complexity and they are also sensitive to water contamination which can cause corrosion in the piston bores and leaks. Any true performance car has similar calipers. Brake fluid has a very high level of hydrocicity and picks up water like sugar draws bees. I don't know the condition of your calipers but you can get rebuilt ones with stainless steel liners! and then run silicone fluid (DOT 5) which pretty much makes the calipers last forever. That again has its own cost, it makes the pedal a bit spongy but you can make up for that with braided brake lines. Corvette calipers are not the best with lack of use. When they sit for long periods they sometimes start to drip but then you pump them a couple of times and they seal up and work fine but not always. I believe this is caused by the residual pressure easing off and letting the seal relax and collapse. There are also brake rod adjustments that may need to be done which would give low pedal but if that is not it let me know. Also if your master cylinder does not have the residual valves you will need to install them on your brake lines as close to the master cylinder as possible.
Also for $10.95 a one man blead kit has worked the best. This is a clear hose with a recovery bottle, designed so that you do not have to close the bleader valve when you let up on the pedal. The trick is to place your recovery bottle HIGHER than your caliper when your bleading. Keeping your master cylinder full, pump the pedal up and down slowly with the recovery bottle up high. You do not have to close the bleader valve each time the pedal comes up as you do with the conventional method.If there are no leaks in your system your caliper will normally blead out with about 10 to 12 pumps depending on how much air you have in the system. Start with the longest brake line and work to the shortest. If you have two bleader screws on one caliper, blead the inside one first, then the outside.

Hope this helps if you need any more help just ask. I love working on sport car and race cars, I have been around race cars all my life......
Thank you, Stephanie - Redheadusmcwife

5 years 10 weeks ago, 1:41 AM

Anonymous

vette brakes

as said by redhead above,it may be the unreplaced caliper but as a professional mechanic i question the condition of the master cylinder due to the fact you are replacing leaking calipers.loosen up the master cylinder mounting bolts at the booster and look for signs of leakage at the back of the piston and inside the vacuum booster.even if the master cylinder isnt leaking it does not mean that it is in serviceable condition,if an o ring for the front side of the master is bad it can force brake fluid to be pushed into the rear of the cylinder and/or vice versa causing lotsa headaches by not being easily detectable like a leak is.more info could help as well.what year is the vette?power brakes?let us know what happens!

5 years 9 weeks ago, 6:09 AM

Mark3030

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vette brakes

same conclusion as red head & greasypaws, replace the the fourth cliper and check, if same prob, replace master cylinder.

"the thrill of the hunt"
5 years 9 weeks ago, 3:10 PM

cbxjeff

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Thanks for the replies. It's a '78 w/ P.B. The pedal goes almost but not quite to the floor. Allan did start bleeding at the rear but I'll have to ask about inside/outside. I'll get a 1 man bleed kit tomarrow and maybe go to the lake (sister-in-law's cabin) with him Sunday and watch the race since we are blacked out in Indy. I'll check the rear seal on the master. I used to run into that when I was rebuilding Mercedes diesels. The master would leak and the fluid would eat the booster diaphram. I didn't think about the hoses. If many of them were week that could cause the whole thing.

The saga continues.

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5 years 9 weeks ago, 6:55 PM

runawaygun762

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cbxjeff

Try taking out the master catalytic convection plug and then run it on the highway. If the flux capacitor makes a whining noise at high RPM, then you need to replace your continuom transfunctioner sensor. Just a thought.

"I have always been a soldier. I have known no other life. The calling of arms, I have followed from boyhood. I have never sought another." From The Virtues of War, by Steven Pressfield.
5 years 9 weeks ago, 3:25 PM

cbxjeff

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762,

Dude - you have seen way to many Star Wars pics. Time will heal!!!

It's too late for me, save yourself.
5 years 9 weeks ago, 3:29 PM

runawaygun762

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cbxjeff

flux capacitor is Back to the Future, and continuom transfunctioner if from Dude Where's My Car. Although I did put the whining noise thing as a deficiency on my HMMWV's maintenance sheet and the mechanic signed off saying he replaced it.

"I have always been a soldier. I have known no other life. The calling of arms, I have followed from boyhood. I have never sought another." From The Virtues of War, by Steven Pressfield.
5 years 9 weeks ago, 1:15 PM

cbxjeff

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Vette Brakes

WE GOT BRAKES!

Allan just called to say that he bled them once again using the inside & longest line first routine. Checked the hoses, fired it up and there they were. Thanks for all of your help guys (even 762!!!). This has been a real hassle since the car is about 50 miles from us and has required many week-end trips for him.

Thanks again

It's too late for me, save yourself.

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