Rear brakes locking up???

[scampbel98]

Every once in a while, my rear brakes seem to lock up. Nothing violent, pedal gets hard, engine struggles.
I don't think its the e brake hanging up. Ive got new/rebuilt calipers, steel braid lines, new compensator, new master cylinder. All bled until clear wheels down....

Have to on off the ebrake, try reverse etc until it lets go...

I'm at a loss

[lglade]

I rebuilt my rear calipers recently including the parking brake components. On one of the calipers, I incorrectly assembled the e-brake actuator which caused it to drag the pads against the rotor. A quick check of the rotors to see which one was hot told me which side needed to be fixed. I took that caliper apart (again) and reassembled it, paying more attention to how the e-brake went together, and that solved my problem. I think the first thing you need to do is to see if both of your rear wheels are locking up or just one.

[124JOE]

go thru every thing
make sure all is tight and correct

[bobplyler]

If the pedal is hard, and engine struggling, I'd check for a vacuum leak at the booster.

[scampbel98]

Bob.. definitely locked up brakes. Can't even push it out of gear

[Rambo]

If your pushrod from the booster to the master cylinder is incorrectly adjusted it will drag the brakes and they will eventually lock up.

[scampbel98]

If your pushrod from the booster to the master cylinder is incorrectly adjusted it will drag the brakes and they will eventually lock up.

What's the fix or repair on that Rambo.
As I've replaced the M/C.... it might be that

[Exit98]

It's a very long story, but I'll spare you the ugly details.

Back in the day, my brand new 1972 124 Spider would lock up its brakes at random times. Once at 85 MPH. Scary stuff. Back to the dealer they say nothings wrong, didn't do it for us. Finally it happens when they have it. Bad booster they say. Don't have any got to get it from Italy. 45 days later I got the car back. Sorry for the delay they say.

I'd check your booster.

[Rambo]

If your pushrod from the booster to the master cylinder is incorrectly adjusted it will drag the brakes and they will eventually lock up.

What's the fix or repair on that Rambo.
As I've replaced the M/C.... it might be that

There is a rod that comes from the booster to the master cylinder that actuates the piston. There is a adjustment nut on that rod. you have to loosen the adjustment nut then thread the rod down. You might be able to do this without removing the brake lines from the master cylinder. Once you see the rod it will become apparent of how to adjust it. If the rod is adjusted to far out it will constantly push on the master cylinder dragging the brakes. If the rod is to far in it will require too much pedal travel to stop. There should be a small amount of free play between the rod and the piston. When i replaced my booster and cylinder i adjusted the rod all the way down towards the booster and for some reason the brakes were still dragging. I had to make a spacer to go in between the MC and booster to give the right amount of free play. But just look at the rod and see how much adjustment you have. I was driving and about 10 minutes later i was fighting my brakes then finally they locked up. Although, if this were the case i think the front brakes would lock and not just the rears. Hope this helps.

[scampbel98]

Thanks Rambo, so working from memory (it's been awhile since I cursed out the booster install (and had to deal with ripped firewall due to clutch), I only need to loosen the M/C for access? Hopefully the whole booster doesn't need to come off.....

sigh.... I'm betting the 2017 doesn't have this problem.

[Rambo]

Thanks Rambo, so working from memory (it's been awhile since I cursed out the booster install (and had to deal with ripped firewall due to clutch), I only need to loosen the M/C for access? Hopefully the whole booster doesn't need to come off.....

sigh.... I'm betting the 2017 doesn't have this problem.

No, to remove the rod all you have to do is remove the master cylinder far enough away from the booster. You may not even have to remove the brake lines but im not completly sure.