Brake Lockup question

Hi Guys,

Within the last 3 months I've replaced the following brake parts. Master Cylinder, Front wheel cylinders, front drums and shoes. After this I hired a mobile mechanic to help me bleed them. I didn't pre bleed the MC before R&R(didn't know). First they were super soft, then very very firm.

I noticed driving to work short drive, that by the end of the drive it seemed like the front right would be slightly rubbing to the point of a small squeak. Also felt a little resistance like the brakes were engaged. Didn't feel this for the first 3\4 of the drive. I thought no big deal must be the adjuster is a bit too tight and I needed to back it off. I got lazy and didn't do that.


I was driving last night and it was a bit longer than the normal work drive. I felt more and more braking build up. It then stopped me at a light and i couldnt move. I tried yanking the ebrake a few times, putting it in reverse and driving no go. I only produced burn outs. I had to get towed. When I got home the brakes had let up some and it was rollable again. I'm going to take the truck to a professional. I wanted to get some ideas of what it might be.

Maybe the new MC isn't good? Air left in the lines? Water contamination in the fluid?

Thanks for your knowledge and assistance.

Likely =NO Water-No Air!! = Possibly a set of shoes =installed backwards!! or just shoes adjusted too tight. You did not indicate whether was fronts or backs ?? Are both rears / fronts doing this lockup?? if so -id surely look @ the master cyl.!! residiual pressure valve bad or wrong master cyl??

The rubber hose to that wheel is bad internally.  It is creating a one way valve that is letting brake fluid through when you push the pedal and stopping it from moving back when you release the brake.

Internally the rubber hose has a liner.  When the out side of the hose starts to fail it allows the liner to expand which results in a split.  The split section then allows brake fluid to go between the liner and the outer sheath of the hose.  This closes the inner liner until you put pressure on the system.

Twinpilot001 wrote:Likely =NO Water-No Air!! = Possibly a set of shoes =installed backwards!! or just shoes adjusted too tight. You did not indicate whether was fronts or backs ??  Are both rears / fronts  doing this lockup?? if so -id surely look @ the master cyl.!! residiual pressure valve bad or wrong master cyl??

The shop i took it to found the following:

1. Mobile mechanic and I did the shoes backwards in the front.
2. One of the front adjuster cables snapped.
3. The shoes were adjusted too tight

Other problems
Back two wheel cylinders were beginning to weep.
One of the shoes was way to tight, so one was worn way low.

It was one in the front one in the back locking. I replaced the front hoses with new ones previously.

Expensive lessons learned.

LOL! multiple self inflicted wounds hurt the worst. Glad you figured it out. I bet it stops a lot better now!

AZ SuperVan wrote:LOL! multiple self inflicted wounds hurt the worst.  Glad you figured it out.  I bet it stops a lot better now!

Thank you! I should be a lot more safe now. I also have a good template if I have to take it apart in the future.

Sometime in 1977 my van ended up parked for the next 36 years. One resident of the shelter that owned the van decided he could brakes on it. He took everything off to the backing plates and then couldn't figure out how to put it back together. Soon about half the parts were missing. When I bought the van there was box with a set of new (36 year old) brake shoes in the back. I t wasquite the puzzle putting it all back together.

Picture in the shop manual would help with position of parts.

Bluelemon wrote:Picture in the shop manual would help with position of parts.

I had the page printed and in front of me. I also took pictures.

AZ SuperVan wrote:Sometime in 1977 my van ended up parked for the next 36 years.  One resident of the shelter that owned the van decided he could brakes on it.  He took everything off to the backing plates and then couldn't figure out how to put it back together.  Soon about half the parts were missing.  When I bought the van there was box with a set of new (36 year old) brake shoes in the back.  I t wasquite the puzzle putting it all back together.

This is kinda what happened to me. I knew the front right wheel cylinder was bad and I went to replace it and found a bad wheel bearing. I then had to source the new wheel bearing/hub drum. Then find a machine shop to put that together. It was apart for a couple of months. I then hired someone to help me finish it correctly and it didn't happen that way.

Good intentions don't always help in car work without the knowledge to back it up

It probably didn't seem fun when it locked up on you, but these old vans are just like giant jig saw puzzles with half the pieces put together wrong by previous owners. I have been running down "fixes" that really just traded one problem for another. Lots of different ways to do things wrong!