CT Rear Brake release prob

[Jon41W]

Hi, I am new to the group so hopefully im posting this in the right place.
I have a 1968 M35a2 duece and as I was driving last week I came to a stop and went to take off and noticed the rear brakes were locked up. The brake pedal was at the complete top with no free play. The only way I was able to get the brakes to release was to drain the air out of the system. I limped it home with the drains open. It seams that once the system builds air pressure the rear brakes stay applied and the brake pedal gets hard and high. Any suggestions on a repair for this? Thank you

 

[M35A2-AZ]

Sounds like you airpack (brake booster) has gone bad.

 

[G744]

Another cause may just be the shoes are adjusted too tight, or the master cylinder pushrod is set too long.

Then they rub a bit, get hot & expand, then lock up.

DG

 

[Jon41W]

Sounds like you airpack (brake booster) has gone bad.

Anyway to check that or is that a common thing to happen to these?

 

[Jon41W]

Another cause may just be the shoes are adjusted too tight, or the master cylinder pushrod is set too long.

Then they rub a bit, get hot & expand, then lock up.

DG

I checked the brake adjustments and found all that is ok. This has been a truck that has been driven daily until this happened. Thank you

 

[G744]

The AirPak may be the cause, but they usually work for many years without problems.

DG