Drum brake issues

[jfabert]

I have been having a problem with my rear brakes ever since I replaced the shoes and all hardware. Before they worked normal just the shoes were getting low and the springs were starting to get pretty ugly. I replaced the shoes, all the springs, the adjusters and the wheel cylinders. Ever since then they have acted like they are not working anymore. I then replaced the master brake cylinder, bleed a couple gallons of fluid through them, replaced the distribution block, adjusted the hell out of them and also had the rig to two different shops and neither found a problem that would be causing it. I just starting thinking that maybe the parts store gave me the wrong shoes. I looked them up on LMC truck and the older trucks, 73-75 had 11" drums and my 87 should have 11 5/32" drums. So I guess my question is could the smaller shoes be installed on an axle that require the slightly larger ones. My rear brakes act like they are not getting enough pressure to work to their full potential? I even use to be able to lock up the rear wheels while driving down the road and engaging the e-brake but after the swap it hardly slows the truck down. I'm not able to check my rig out and measure them until next week when I get home just was wondering if this makes sense and if this has happened to any one? Sorry for the long post I have just been fighting this for a couple of years now and really need it working right to be safe. Thank you.
Jason.

 

[4X4HIGH]

IIRC the width of the shoes is also different between the 11" and the 11 5/32" diameter drums. It sounds to me like you don't have the shoes adjusted up properly. Also in case you didn't know there is a short shoe (Primary shoe) and a long shoe (secondary shoe) and the short shoe ALWAYS goes to the front.

 

[1BEATK5]

im with 4x4high
try this

loosen the parking brake adjuster

adjust the brakes till they drag a bit.

tap the drum with a hammer to get the shoes centered in the drum,
adjust the shoes till they drag again. making sure the drum is fully seated against the axleshaft flange when checking the adjustment.

repeat a couple times untill the shoes drag abit. not just hearing them drag, but actually cause a little bit of drag

then adjust the parking brake again. but make sure you dont adjust it too much and make the shoes drag too much.

i bet thet fixes the problem

 

[4X4HIGH]

I like to adjust the shoes then with both drums on I hit the brake pedal a couple times to center the shoes up and then recheck and do this as many times as required.

 

[jfabert]

Right, they are 3/4" wider. It just sounded like that if they can be installed that it may cause something like this.

Both shops told me they adjusted them also but it never changed anything. I will try that as soon as I get home. Thank you for the help.

 

[4X4HIGH]

The first thing I would check is the proportioning valve to make sure it doesn't need to be reset. There is a button (under a rubber cover) that you simply push in.

 

[jfabert]

I replaces the shoes again cause I ended up installing the drivers side wrong causing that side to wear out allot faster. Just a little improvement but still not like it use to be. The valve did not need to be reset and I see no way to adjust the brakes with the drums on. The backing plate does not have a hole or a spot to punch out either. From hat I have read they are self adjusting when going in reverse and hitting the brakes over and over a few times. I just cant figure this out. My next step when I get the cash is to replace all the hard lines with new stainless and the flex lines with extended braided stainless. The only thing I can think of now is maybe I have a little flap coming off the flex brake line causing a little blockage. The lines is the only thing that has not been replaced in the braking system other than the booster. I'm ready to give up on this thing and just deal with them not working right.

 

[Fordum]

It has been a long time since I had to work on a GM drum brake. But, from what I remember, if you don't have the hole in the backing place, or one in the drum, you pull the drum, adjust the brakes out until you can just get the drum back on.

Then back up, stop, pull forward, stop, a few times to adjust them the rest of the way.

Some, like my Ford, "get a bite" when you back up, but only turn the adjuster when you stop going forward.

One problem is that if the shoes are loose enough when you start that they don't hit the drum when you stop, then they will never adjust since the adjustment occurs when the whole shoe assembly twists on the backing plate.

One other thing that will cause you to not have rear brakes is when you do both sides at once, and manage to swap the adjusters from side to side.
In most setups, they turn opposite each other.
If you mix them up, they will unadjust when you do the forward/back thing.

You may think that is very unlikely, but I have seen it twice.

Once, the guy actually got them mixed up when the truck sat for a couple of weeks before he got around to putting it back together.

The other time, the parts house gave a guy the wrong adjuster.

I wish you could post pictures. There are guys here who do drum brakes in their sleep.

Course, I'm not going to let them work on my truck, I want someone awake....

 

[jfabert]

I did make sure the adjusters where on he right side. After I noticed that I installed the shoes backwards on one side i triple checked everything before I put it all back together. I did adjust them so I could barely get the drum back on then drove back and forth in the drive way to adjust them. I keep thinking about putting discs on the back but I don't want to put that money into 10 bolts. i would rather save up and do it with a 14 bolt.

 

[dhcomp]

I did make sure the adjusters where on he right side. After I noticed that I installed the shoes backwards on one side i triple checked everything before I put it all back together. I did adjust them so I could barely get the drum back on then drove back and forth in the drive way to adjust them. I keep thinking about putting discs on the back but I don't want to put that money into 10 bolts. i would rather save up and do it with a 14 bolt.

Guys have lots of issues with Disk swaps too. Definitely wouldnt' consider that an "easier" thing to do than fix your drums.

And really, i'm in teh same boat. I totally rebuilt my drums, and they haven't felt right since. Need to try and get a "pro" on here to help me out when i finally have time, and get the hydraulic issues fixed.