brakes lock up
Thread Starter
Heel & Toe
Joined: Oct 2022
Posts: 16
Likes: 7
brakes lock up
Just got my '74 out for a drive and it did well until the front brakes locked up. I opened the bleeder screw on the pass.side and let the pressure off and started driving again for about 50 feet and they locked up again. Bled the drivers side, took off and made it the house where they locked up again. it has new all pads and have been bled. anybody have an idea?
Race Director
Joined: May 2006
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Le Mans Master
Joined: Aug 2017
Posts: 8,336
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From: Cool Northern Michigan
But why that would change just driving, it is not likely.
Normally this "lock-up" is a sure indication of rotted front hoses turning into one-way-check valves. But in your case I think I would just flush the front system.
I assume when the calipers locked a second time you applied pedal pressure. I suspect the front portion of the MC is gummed up somewhere in the bore.
Slight chance a proportioning valve has blockage as do the calipers. But hard to believe all 8 front pistons are stuck. I believe the issue is up stream.
Top priority now would be to pump the pedal several times, then using a turkey baster remove DOT3 almost to empty on the front rez. Refill.
Because you are only doing two bleeders, a Mity Vac or gravity will renew the front system. Avoid using the pedal until flush is complete.
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Team Owner
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From: Southern Cal Ca
St. Jude Donor '22
I would use washers to move m/c out.
I would be careful with seals and you could loose vacuum.
try to replicate the locking up.
continue with washer until sure it is helping.
if it does help, the washer/s thickness will be how much to shorten rod.
or buy adjustable rod to test and use
Instructor
Joined: Dec 2022
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From: Virginia
https://www.corvetteforum.com/forums...post1606436576
I had the same problem recently. Read my post.
I had the same problem recently. Read my post.
Is my vette stock?? HAHA
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Yours sounds like the calipers arent fully released . As you are driving you are heating the pads and calipers and when the fluid boils it expands and applies pressure to the brake pads. Make sure you have proper clearances
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
AAFliteTech,
Crawl under the dash and make sure there is nothing hindering the brake pedal from returning to the upright position. Work it by hand.
i.e. A new brake light switch? Some wiring blocking the pedal? Pedal return spring missing? Need some WD40 on the pivot?
Doesn't take much pedal drop to apply some braking.
Crawl under the dash and make sure there is nothing hindering the brake pedal from returning to the upright position. Work it by hand.
i.e. A new brake light switch? Some wiring blocking the pedal? Pedal return spring missing? Need some WD40 on the pivot?
Doesn't take much pedal drop to apply some braking.
Thread Starter
Heel & Toe
Joined: Oct 2022
Posts: 16
Likes: 7
74 Brakes
Installed a rebuilt master cylinder (old one had pits in the body) , replaced the front hoses and the rear steel lines, adjusted the m/c to booster rod, bled the brakes about 5 times and drove it around the neighbor for a while.....NO LOCK-UP......thanks guys.....
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Good job !. Then I will transfer you to Billing Dept.
Issue: Brakes
Outcome: Fixed
Posts: 19
That will be $129. How do you wish to make your payment?
And do you have any discount coupons?
Issue: Brakes
Outcome: Fixed
Posts: 19
That will be $129. How do you wish to make your payment?
And do you have any discount coupons?