The Stovebolt Site Forums The Shop Area General Truck Talk Sticky Brakes

I have a 1951 chevy 3100 series pick-up and lately I've had some problems with the brakes. On a couple of occasions this summer, the brake on the left rear has started dragging. I don't really notice it when I'm driving accept that I can sometimes hear it when I hit the brakes. I'll check the wheel and it will be hot. I remove the drum and don't find anything wrong. If I crack the bleeder on that wheel the brake shoes will open up and everything will be fine for a while. But then in another month or so it happens again. Three years ago I replaced the wheel cylinders, shoes, springs, and all the hardware on all 4 wheels. I have not done anything to the master cylinder or brake lines. Does anyone have any idea what might be causing this?

Hy Joe M, did you replace your brake lines and flex lines? Something may be check valving and causing pressure to build up in that particular wheel cylinder.

Make sure that the shoes spring back away from the drum without hanging up. Spray the moving parts and friction areas with WD-40. Perhaps even a little bit O grease. You may find that only one shoe is rubbing. This can happen if the shoes are not "locked" into place when installed but should be evident when adjusting them.

Readjust using the star wheel then get back in the truck and hit the brakes. Repeat this process a few times until the shoes are seated properly.

Sounds like a flex line that is collapsing. Had the same problem when I bought my truck. Changed the flex lines and everything was fine.

Also check to make sure your master cylinder pushrod is adjusted correctly. If you don't let the piston in the master cylinder uncover the compensation port pressure gradually builds in the system and the brakes start to drag.

Joe, check to make sure your emergency brake isn't hanging up... that's what happened to me....

I appreciate the the input from everyone. I have not replaced the brake lines or flex lines. My best guess is that something is "check valving" as 3B says or trapping hydraulic pressure in the line. I'll plan on replacing the old flex lines in case this is the cause. It was on my list of things to do anyway. The other possible cause is the master cylinder. Any advice on adjusting? My shop manual is a little vague on this. Thanks. Joe

Joe, are you sure that the master master cyinder hasn't been rebuilt recently, and that they put the pushrod stop plate in backwards. It will all fit together fine but this will keep the cup from clearing the compensation port, therefore not relieving the pressure in the lines. The cup should clear the port by 1/32", this is documented in the service manual.
Denny Graham
Sandwich, IL

I had mine adjusted up too tight once and the heat from the drivetrain and from the brakes expanded the fluid to the point that it was applying the brake, making even more heat. I had to let it cool down before I could even move it again,
Scott

Denny,
It is unlikely that it was rebuilt. But I wouldn't rule it out. I'll add that to my list of things to check out. Thanks. Joe