Drum keeps locking up...

[da_raabi]

So I recently re-did the drums on my C30 (Dana 70 FF). Here is what was replaced:

Wheel Cylinders
Spring Kit
Shoes
All rubber lines replaced with stainless
Removed the load sensing valve

I kept the original drums for maybe 200 miles then just replaced those as well. My problem is that since I have owned the truck, I have had issues with one or both drums "over-adjusting" and locking the drums up. If I back them off they are OK for a while, then they lock up again. I completely loosened the e-brake thinking maybe that was sticking too. Any ideas why this might happen? The tires are trash and shake like mad, could that cause the drum to wobble or something and over-adjust? I'm getting sick of this!

 

[77 K20]

I have one of my rear brakes that has been doing the same thing. Haven't gotten around to it but I was told that the backing plate can get some notches worn into it and then it can cause issues like that. Can buy new backing plates or just take an angle grinder or something and grind the worn area smooth.

Hopefully someone here can add some details to that- as I haven't tried it yet.

 

[87sierra]

i have had the same issue as well it started after i replaced the back drums and shoes but it has not occured recently and i would like to know what the problem could possibly be

 

[J Knight]

This is probably a longshot or a guess at best but did you istall the brake shoe with the longer pad to the back and shorter pad to the front? They are suposed to adjust when you apply the brakes in reverse, maybe if the shoes are backwards(long in front, short in back) they might be adjusting everytime you stop. Like I said just a guess.

 

[chengny]

2X what J Knight says. But any improperly assembled parts might cause this issue. Here are some images to compare your brakes with:

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In case you are concerned that the above images don't apply to your truck, here is my right rear brake fully assembled (1986 K30). It is the same:

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[da_raabi]

From what I could tell the shoes were the same size, am I wrong here?

 

[chengny]

Look closely, the lining material extends higher up on the rear (trailing) shoe. And trust me - it makes a difference:

 

[da_raabi]

Damn... That might be my problem then. Can I reuse the shoes if I go ahead and switch them all around? I've only put maaaayybbbe 1000 miles on them. I dont drive the truck very far.

 

[da_raabi]

Look closely, the lining material extends higher up on the rear (lagging) shoe. And trust me - it makes a difference:

Are those the 13x3.5 or 13x2.5 brakes?

 

[chengny]

Can I reuse the shoes if I go ahead and switch them all around?

Yes - they should be fine. The front lining is lower so that the rear catches first when the pistons move out. It somehow prevents the brakes from grabbing ID of the drum and opening everything up.


Are those the 13x3.5 or 13x2.5 brakes?

Those are 3.5" brakes. The drums are huge.

 

[da_raabi]

Ok, chances are pretty good thats what I did. I wanted to make sure you had the 3.5 brakes like mine. Looks like I know what I'm doing this weekend!

 

[da_raabi]

Forgot to post up results... It turns out I installed everything correctly but get this: after a ton of troubleshooting I figured out that the e-brake cable bracket to get it over the pumpkin from the driver side had broken, allowing the cable to drop behind the dumped exhaust. Since the cable is shrouded in plastic, the exhaust would melt it, letting it move and wiggle, then when it cooled it would stick, making it stick further and further up as time went on. Disconnected/removed the cable and everything seems to work fine. Who knew???

 

[da_raabi]

So this problem has persisted since the last time I posted on the topic. I still have the odd lock-up, particularly in high-heat (long drives) and in the rain. I decided I wanted to get greasy yesterday and went ahead and pulled both back apart. Low and behold... I had put the driver's side drum together backwards. The short shoe is in the back... Nice. Its been a solid year of driving (daily) on these shoes. Should I replace them at this point?

 

[da_raabi]

Here are some pics of the current setup. Please take a look and see if anything looks wrong.

Driver's side:

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Passenger Side

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[chengny]

Please take a look and see if anything looks wrong.

Low and behold... I had put the driver's side drum together backwards. The short shoe is in the back...

Other than that - no, I can't see anything wrong. But that's just me.

I can't see any reason why you can't just switch them front to back and keep right on using them.

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