# 1987 Rear Brake Lockup



## larryn3 (Feb 19, 2011)

hi, I have a 1987 D21 4x4 with the usual discs in front and rear drums. The rear drums lock up on occasion, usually just the first few times that the brakes are applied after starting out. After a few stops, they work fine. Front brakes are working fine and have new calipers and pads. Any ideas on what could be causing this? I will be pulling drums off soon and appreciate any advice. I do recall the last time I pulled those drums off many years ago, a big sledge hammer was required to loosen them since backing off the adjuster and putting the screws in the drum didn't do anything. I'm not sure why these drums are so hard to remove? Never had that trouble with any other drum brake. Anyway, any help with the locking problem would be appreciated. larry


----------



## 4X4 (Nov 2, 2010)

First thing I'd check would be your Emergency Brake and Cable. Maybe it's hanging up somewhere.. then I'd check the springs inside the drum, on the shoes to make sure they're not sticking. Other than that, grease what you can.

I had a similar problem with an El' Camino I had, I replaced the drums and brake pads, also flushed and replaced the brake fluid. That fixed the problem.

I only say something about the E-Brake is because mine doesn't work and my cable was stuck, I pulled it out until I could replace it.

Good luck!


----------



## Grug (Aug 20, 2009)

Hey, Larry. Not too familiar with the '87 truck. But my '93 and '97 had threaded holes in the face of the drums where a fella' could screw bolts and they would push the drum off the hub. Kinda' clever, really.

Occasional sticking of the shoes seems odd. Do you use your parking brake regularly to keep it from rusting up?

I'd wanna' jack the rear end off the ground and have a partner apply the brakes to see how they grab (both with/without the brake applied). Maybe you can narrow it down to one wheel.

Like 4X4 said, maybe bleeding the brakes a coupla' rounds would help, too. Certainly couldn't hurt.


----------



## larryn3 (Feb 19, 2011)

thanks for the suggestions so far. I like the idea of jacking up the rear end and trying to narrow down the problem to one wheel. I know that the left rear is locking up, not sure about the right side. Like I said, the locking up only happens when i first start out, and then, only the first 3 or 4 times I apply the brake. After that, brakes work fine. Hand brake is ok as I use it all the time. Those holes for the screws is a good idea for getting off the drums, but didn't do me any good the first time I messed with the drums, however, I will try it agin as I suspect the drums will once again be hard to get off. 

I'm thinking that the return springs could be a problem. Perhaps they are not pulling the shoes off the drums as quick as they should although quite frankly, I've never had to replace springs on drum brakes on any car I've ever owned. Disc brakes are really a blessing. They are so easy to work on compared to the older drums. Will probably get to this next week.


----------



## Grug (Aug 20, 2009)

I hear ya' about disc brakes versus drums! Used to work on the old air cooled VW Bugs and they had drum brakes all round...uggh!

Yeah, hard to believe a spring wouldn't be doing its job...unless it flat out broke or fell out of the hole it was hangin' from. Still, seems odd that it only sticks some of the time.

The screws in the drums will ultimately get the drum off, but it might destroy the shoes in the process (assuming the shoes can't be backed down).

Maybe a bad cylinder on one wheel? I suppose you'll have to pull the drum to really get right down to the problem.

Good luck, man!


----------



## saudade (Apr 10, 2010)

Does it sit for while (like several days) when it does this? Has it been rainy/snowy/slushy where you are?

Condensation (or other water exposure) can cause the drum surface to rust fairly quickly. The grabbing could be due to that. Once you hit the brakes a few times, it cleans them off.

Are there any signs of a brake fluid leak?

In any event, you should pull the drums and check it out.


----------



## larryn3 (Feb 19, 2011)

It usually does sit for awhile between uses. Perhaps the problem is caused by rust (there is rain & snow here), although it still shouldn't lock up even though there is not a lot of weight in the rear. In a couple of days I will have a look and report back with what I discover. My guess is that I am not going to see anything out of the ordinary so I'll probably replace the springs which retract the shoes off the drums just to see what happens. larry


----------



## larryn3 (Feb 19, 2011)

Well, finished the job yesterday and this is what I found. One shoe on each wheel was worn down to replacement time, the other shoe worn but not too bad. All four shoes had a very hard glassy surface. Maybe thats why they were grabbing? I don't hardly remember how shoes got after being on vehicle for a while. Anyway, i changed them all out and so far they don't grab although I've only driven a couple of miles at most. I didn't change any of the springs as they looked fine. I must say it brought back memories having gotten to use my old drum brake spring tools again after many years on non use. 

For those who mess with these drums, there is a good reason why they have those threaded holes for helping to get the drums off. My passenger side drum came off rather easily. After backing off the adjuster, and screwing M8's into the holes, then banging the drum with a sledge got it off rather easily. The driver side was a different story. When I screwed in the bolts I recalled that the holes were stripped from many years ago. After about a hour of banging with a sledge and spraying PB blaster to no avail, I drilled new holes and tapped a 5/16 x 24 tread, screwed in some bolts and off it came. I'm not sure why these drums are so hard to remove and I've never had another vehicle with threaded holes in the drums. 

In any event, this job is done. Hopefully, that will resolve brake issues for awhile. Thanks to all who replied. larry


----------

