About 2 months ago I replace my rear brake pads and rotors. My truck has the rear disc brakes with the drum in hat for the parking brake. Almost every other week, my left rear side keeps adjusting itself tighter. It gets tight enough to the point where it starts dragging and heats up that side. Had it smoking a little bit the last two times, and my disc temperature was just over 400 degrees today.

My right side has not been affected. I used to use the parking brake every time I parked (carryover from when I had a manual transmission) before the brake job. Now I only use it when needed, and at home because of the sloped driveway. Truck felt fine on the way to work this morning, one the way home I started feeling it drag again, and I had not even used the parking brake all day.

I am stumped why this keeps happening. Any ideas on what I need to do?

 

I am not familiar with that drum in hat brake but perhaps the adjustment is held in place similar to the shoe brakes on the earlier models.

The star adjustment wheel sits against the spring to hold it in place, if the spring is weak or on backwards the wheel can move causing the brake to self adjust.

That may not be possible on yours but thought it might give you something to look at

 

My guess is that either the emergency brake cable or the lever pivot inside the drum is starting to seize and doesn't release completely when you release the brake.

 

Adjuster and star wheel in backwards would seem obvious.

When mine are too tight she starts vibrating and I have to get out and back it off a notch.

Mine didn't have the self adjusters when I did my rears, but now won't stay tight so I need to get them.....

 

The spring is in place and holding against the star wheel. And I cycled the brake a few times with the rotors off and did not see any binding of the lever and springs.

The funny thing was is that yesterday I didn't even use the parking brake and it found a way to drag. Very strange. When I had the rotor off I looked at it good and saw that where the parking brake shoes ride has been slightly blued from the heat. Thankfully the rotor has not warped from this.

I also checked rotor thickness where the main disc pads are just to make sure the caliper isn't sticking. That part looks fine and also measured the same as my right side rotor.

I don't know if the parking brake is self-adjusting like a true drum brake. The service manual I have is kinda vague on the details for the drum in hat setup. Mine just seems to have a mind of its own.

 

I wonder if the springs are getting weak......

 

You may want to search this and find my past headaches on this. I ended up replacing everything, the cables and all the brake components and mine still wouldn't hold, still doesn't by the way.
I found out a couple weeks ago mine didn't even have the adjusters, I just figured it was a new design the first time I got in there.

I have about an inch of threads showing on both star wheels, one more nock on the wheel and they drag, parked on a 10% incline with a full mash on the pedal and she groans down the hill....the drivers side spring is fully compressed. the passemger side about halfway, which leads me to believe the driver's is the loose one, but that isn't the case when I adjust and set them....

Any thoughts appreciated.

 

No they aren't self adjusting. The starwheel has to be adjusted manually, and the spring going past it serves as the detent, providing that "click" feel when you adjust it, and also holds it from spinning itself and losing adjustment.

I find them very troublesome as far as adjusting through the slot, and providing enough friction to keep the truck from rolling especially with a trailer on. I am actually really glad to have rear drums on mine. Hope you get it sorted out soon.

 

Lary, I don't think the springs are getting weak. They seem to be holding the star wheel in place fine. In fact, when I pulled the rotor the other day, the adjuster only had about 1½ threads showing (almost adjusted all the way in). My right hand side shows about 6 threads, which is about ¼" wider than the left. Both sides have a similar amount of material on the shoes.

Very puzzling, used to work just fine before I did the brake job. Although, just beforehand it was having trouble holding the truck on inclines. I really don't like knowing that I can't trust the parking brake anymore.

 

It did it again!

And I have not touched the parking brake at all for two days (since my initial post). It is also adjusted all the way in.

I am starting to wonder if that caliper is sticking. It's the original caliper, with the original brake fluid, and I just recently replaced the original set of rear pads. Also, with my infrared temp gun, the hottest temperatures are on the disc, and not the hat part. Caliper is hot too.

 

That is what mine did that led to all the repair work and new parking brake.

Sounds like you may have found your problem, new calipers aren't that expensive.....do them both.

Meanwhile, I still have inoperative parking brakes!!!!

 

I plan on replacing them after the Power Bleeder I ordered arrives. I'm going to change all of the brake fluid while I'm at it.

After I knock that out, I'll mess with the parking brake again.

 

Just wanted to update this thread with the results.

I changed out both rear calipers and the problem is now gone. Luckily with all of the overheats I did not damage the axle seals or warp the rotors.

Was able to change out the fluid in the master cylinder resevoir and the rear lines. The front caliper bleeder screws are corroded in place, and I'll deal with them the next time I service the front brakes.

While I was at it, I readjusted the parking brakes(again), and they are working just fine.

Lastly, I highly reccomend buying a Power Bleeder, makes these jobs much easier!