GM 1989 GMC C-2500 Rear Drum brakes not working!!

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Okay the rear drum brakes have everything new and the parking brake has new cables. BUT the rear drums still drag and shudder. Everything is new drums,pads,springs,and cylinders. What is wrong?? Any help would be great!! This is a 1989 GMC C-2500 3/4 ton truck.
 
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Okay the rear drum brakes have everything new and the parking brake has new cables. BUT the rear drums still drag and shudder. Everything is new drums,pads,springs,and cylinders. What is wrong?? Any help would be great!! This is a 1989 GMC C-2500 3/4 ton truck.
Do you have the primary brake shoe in the correct location?

Did you adjust them properly per the FSM?

Did you really become a mamber on a Land Cruiser forum just to ask this question abot an old Chevy?

Should try "www.67-72chevytrucks.com"
 
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This forum is GMC/ Chevy where you getting land Cruiser??
If you go to the "home" page you will see this is primarily a Toyota site.

I'm just bustin your balls

The Chevy and other sections are secondary sections for those if us that have lots of vehicles.
I've got many and one is a 70 GMC K2500.

I have also done all my own work on everything for the last 40+ years.

So, if the rear brakes are shuddering, then they're dragging.


New drums:. Did you clean out the varnish from the manufacturer?

Is the primary shoe to the front? This is the one with the shorter pad material.

Did you get the adjusters back in on the same side and in the correct location with the spring?

After installation, did you do the back up hard brake, then forward and brake at least 10 times so the adjusters would do the final adjustment to the shoes?

Is the parking brake pedal fully released?
Is the PB cable loose enough to not cause dragging, yet tight enough to lock the brakes for parking?

Shuddering is from the pads rubbing continuously. Out of round drums or air in the brake lines can cause this.

Bleed your lines again to make sure all the air is out.
RR, LR, RF, LF
Always bleed everything, even if you only did the rear.

Do you know what I mean about primary and secondary brake shoes?
 
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If you go to the "home" page you will see this is primarily a Toyota site.

I'm just bustin your balls

The Chevy and other sections are secondary sections for those if us that have lots of vehicles.
I've got many and one is a 70 GMC K2500.

I have also done all my own work on everything for the last 40+ years.

So, if the rear brakes are shuddering, then they're dragging.


New drums:. Did you clean out the varnish from the manufacturer?

Is the primary shoe to the front? This is the one with the shorter pad material.

Did you get the adjusters back in on the same side and in the correct location with the spring?

After installation, did you do the back up hard brake, then forward and brake at least 10 times so the adjusters would do the final adjustment to the shoes?

Is the parking brake pedal fully released?
Is the PB cable loose enough to not cause dragging, yet tight enough to lock the brakes for parking?

Shuddering is from the pads rubbing continuously. Out of round drums or air in the brake lines can cause this.

Bleed your lines again to make sure all the air is out.
RR, LR, RF, LF
Always bleed everything, even if you only did the rear.

Do you know what I mean about primary and secondary brake shoes?
Everything is done, everything is new and it still is doing this.
 
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Everything is done, everything is new and it still is doing this.
It's new, but is it in the right place?

I have seen people out on a lot of NEW parts, but in the wrong order.

Obviously, it's right.

Why ask if you know it's right?
 
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It's new, but is it in the right place?

I have seen people out on a lot of NEW parts, but in the wrong order.

Obviously, it's right.

Why ask if you know it's right?
my mechanic did the brakes And they say it's adjusted right. I'm asking because if everything is right then what the hell else could it be?? maybe bad flexible brakes lines on the rear?? I mean there is not much left it could be. That is why I'm on here asking Duh.
 
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my mechanic did the brakes And they say it's adjusted right. I'm asking because if everything is right then what the hell else could it be?? maybe bad flexible brakes lines on the rear?? I mean there is not much left it could be. That is why I'm on here asking Duh.
OK, so you're NOT doing this yourself?

Refer back to my list above.

I've been doing brakes and driveline work on Studebakers, Chevy's, Internationals, and MOPARS for a LOT of years.

Even if the mechanic says it's right, it's not if it's shuddering. That means they are catching and releasing in some manner. It could even be new drums that are out of round.

Keep taking it back to him until the brakes work properly.
 
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OK, so you're NOT doing this yourself?

Refer back to my list above.

I've been doing brakes and driveline work on Studebakers, Chevy's, Internationals, and MOPARS for a LOT of years.

Even if the mechanic says it's right, it's not if it's shuddering. That means they are catching and releasing in some manner. It could even be new drums that are out of round.

Keep taking it back to him until the brakes work properly.
No not myself. Oh I did take it back 3rd time this time. And I agree obviously it's not right. it's only so many things it could be. Don't get me wrong this mechanic has been good. But this time it's been frustrating to say the least. I just thought I'd put it on here to see if it was anything else it could be. it just seems they don't release the whole way or something. Not good for gas mileage.
 
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No not myself. Oh I did take it back 3rd time this time. And I agree obviously it's not right. it's only so many things it could be. Don't get me wrong this mechanic has been good. But this time it's been frustrating to say the least. I just thought I'd put it on here to see if it was anything else it could be. it just seems they don't release the whole way or something. Not good for gas mileage.
Take the truck out on a road, back up and stomp the brakes.

Pull forward 5 ft and step on the brakes hard.

Back up 15 ft under a lot of acceleration and stomp the brakes. The front tires should squeal.

Repeat this whole process about 10 times. This rotating action actuates the self adjusters in the rear axle in order to set them in the correct location.

It may take more than 10 times, as the little teeth can be pretty fine and only move one tooth at a time.

Another thing they may not have done is to "Bed The Brakes".

Drive the truck about 45 MPH.
Apply the brakes hard and firm enough to stop as quickly as possible, without locking the wheels, and slow it down to about 5 MPH.
Then speed back up to 45 MPH and do it again.

Repeat this part at least 3 times.

Yes, you will see and smell smoke from the brakes. This is part of the correct process.

Then, drive around WITHOUT STOPPING COMPLETELY (like roll up to lights and roll through stop signs) for about 15 minutes to let them cool down.

Then, drive at 45 MPH and apply brakes smoothly and "ride the brakes to 5MPH applying medium pressure down to 5 MPH.

Repeat this process at least 3 times.

Then drive around for another 15 minutes without stopping to allow them to cool.

This whole process heats up the brake pads and drums to remove oil and debris, it heats and hardens the glue as well as the compounds in the shoes (or pads).

If you think I'm full of shyte, look it up online about Bedding the Brakes.

I do this on all my vehicles and I get long life out of my brakes. It seems counter-intuitive, but it is very effective and big trucks do this too.
 

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