'77 Brakes locking up
Thread Starter
Heel & Toe
Joined: Apr 2011
Posts: 19
Likes: 0
From: Florence AL
'77 Brakes locking up
I'm having trouble with my right rear wheel locking up. I was driving at 60 mph last night and the wheel locked up causing an interesting transition from the far left lane to the shoulder of the road. After about 30 minutes the brakes had cooled down and I could drive the car again with no apparent resistance from the brakes.
This is the 2nd time it's happened and it only started after I bled the brakes last weekend. Does this sound like trash in the brake line or something with the proportioning valve? The previous owner rarely drove the car and obviously hadn't bled the brakes in a while. The fluid was old and I think it's very possible that something was dislodged when I bled them. It also appears to still have the original lines.
PS - After the first lockup I wasn't able to get fluid from the right rear line when trying to bleed it. Disconnected the line from the caliper and still no luck.
Is this a typical problem? Just trying to get an idea before I start replacing parts. Any suggestions would help.
Thanks for your help guys,
Brandon
This is the 2nd time it's happened and it only started after I bled the brakes last weekend. Does this sound like trash in the brake line or something with the proportioning valve? The previous owner rarely drove the car and obviously hadn't bled the brakes in a while. The fluid was old and I think it's very possible that something was dislodged when I bled them. It also appears to still have the original lines.
PS - After the first lockup I wasn't able to get fluid from the right rear line when trying to bleed it. Disconnected the line from the caliper and still no luck.
Is this a typical problem? Just trying to get an idea before I start replacing parts. Any suggestions would help.
Thanks for your help guys,
Brandon
Last edited by 77-Shark; Jun 11, 2011 at 03:59 PM.
Racer
Joined: Dec 2009
Posts: 380
Likes: 0
From: Glendale AZ
A lockup indicates that the calipers pistons were not able to retract for some reason. More than likely, they are corroded.
It is also possible that there is something blocking the line itself, if lodged well enough it would prevent the fluid from retracing and would cause the pistons to stick as well.
The "proportioning valve" only applies to front/rear bias it won't cause one side to lock up and not the other.
Now here's where it gets tricky, if you bled the left rear first you the proportioning valve may have cut off fluid to both rear wheels. To reset it after bleeding one wheel, usually a good firm stomp on the pedal will reset it.
It is also possible that there is something blocking the line itself, if lodged well enough it would prevent the fluid from retracing and would cause the pistons to stick as well.
The "proportioning valve" only applies to front/rear bias it won't cause one side to lock up and not the other.
Now here's where it gets tricky, if you bled the left rear first you the proportioning valve may have cut off fluid to both rear wheels. To reset it after bleeding one wheel, usually a good firm stomp on the pedal will reset it.
Thread Starter
Heel & Toe
Joined: Apr 2011
Posts: 19
Likes: 0
From: Florence AL
Thanks for the reply volition, I'll take a look at the pistons. Glad to eliminate the p valve as a possible source.
I started the bleeding with the right rear so I think I should be in good shape there.
I'm planning to pull the line off this evening and try to blow some air through it to see if it's blocked up.
Thanks for your help
I started the bleeding with the right rear so I think I should be in good shape there.
I'm planning to pull the line off this evening and try to blow some air through it to see if it's blocked up.
Thanks for your help
Race Director
Joined: Jul 2004
Posts: 12,681
Likes: 329
From: Scottsdale Arizona
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
Race Director
Joined: Apr 2007
Posts: 14,062
Likes: 602
From: Henderson Nv-Rohnert Park/Sonoma C o. ca/born in NY Rockaway Beach.
Cruising
Joined: Jun 2011
Posts: 10
Likes: 0
My 78 brakes were having problems. When I braked the car pulled right, and when driving without pressing brakes, car was pulling left. They changed the brake lines to stainless steel because the caliper locked up on the left side with original brake lines, my problems have went away.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
