how to PM rear brakes on a '99 C3500?

[coachjpg]

I did attach the brake cable to the arm at the beginning of assembly. There is a joint in the parking brake cable beneath the rear passenger side door. When I was struggling to get the brake shoe nails in place, I disconnected that joint in the cable so I wouldn't be fighting the parking brake so much. Now I can't get the cable reconnected at that joint.

I can take it apart again and start over with that cable joint connected, if that's the right thing to do. I understood that you're supposed to be able to disconnect and reconnect the parking brake cable at that joint.

 

[ak diesel driver]

try closing up the adjuster

 

[coachjpg]

try closing up the adjuster

If I understand you correctly, the adjuster has been closed tbe whole time. This is the screw with the knurled knob between the bottom of the shoes, right? It's closed in the photos, right?

Thanks again for your help.
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[btfarm]

The shoes should be tight against the backing plate. The damper spring with the tapered bottom goes on the front (non adjuster) side. It LOOKS like you have it assembled correctly otherwise but obviously something isn't right or the shoes would be tight to the backing plate.

One other thing: It's your stuff but I would NEVER use a concrete block as a vehicle stand. There are a zillion horror stories out there that involve that issue. We even have one here... JMHO

 

[radrian49]

Your are a great help! thanks

 

[coachjpg]

The shoes should be tight against the backing plate. The damper spring with the tapered bottom goes on the front (non adjuster) side.

OK. Switching the springs helped a lot. Now the front shoe lies flat against the backing plate. Thanks!

While I had things apart, I reconnected the parking brake cable at the joint below the passenger side door. Here's a picture of that joint:


Now the parking brake lever arm is keeping the rearmost shoe from touching the backing plate at the top. This photo shows the parking brake off, with the pedal all the way up.

This seems wrong to me. I can't install the brake bar or other springs with the lever in this position.

So either my parking brake cable is too short, or I'm missing a trick somewhere. Is this a common problem with these brakes?

Thanks,
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[btfarm]

Again, it LOOKS to be installed right. I usually assemble the 2 shoes with the adjuster & bottom spring. Hook the park lever to the rear shoe then spread them apart at top to get over the top anchor pin and onto the park brake bar/spring that I layed on the axle hub. Then I put the front damper together followed by the adjuster arm and damper. At that point I rattle 'em around to seat against the backing plate and get centered. Then install the lever return spring (short compression spring) followed by the rear spring ass'y and then the front spring.
I suppose it's possible he put in the wrong brake cable. Otherwise I'm stumped. Wish I were close so I could figure it out. I've done a bunch of these GM brakes over the last 30 years or so and they're all basically the same. And I've never seen the problem you have.
BTW, when you do go to put the drum on, manually run the adjuster out until you can just get the drum to go on with some light drag as it's rotated. Saves alot of hassle. And go buy a bleed kit. You won't regret it...
Bleed RR, LR, RF, LF in that order.

 

[coachjpg]

Does the position of the parking brake lever look correct for when the brake is released? I was thinking perhaps it should be much further to the right...

Thanks!

 

[btfarm]

Does the position of the parking brake lever look correct for when the brake is released? I was thinking perhaps it should be much further to the right...

Thanks!

It seems to me it should be farther right but the bar and spring usually push it over more. In any case, it definately is always closer to the center than the shoe frame.

 

[coachjpg]

The plot thickens.

I looked closely at the '99 C/K GM Service Manual. It talks about 2 kinds of drum brakes, leading/trailing and duo-servo. Based on the drawings in the book, it looks like I have duo-servo brakes except for the parking brake lever, which looks like the leading/trailing version. The parking brake did not work when I got the truck. Could it be that a PO installed the wrong part years ago and just lived with it? I re-used the parking brake lever that came with the truck, after treating the rust. It looked just as rusty as the other parts, so it was in there for a long time.

I just ordered a new parking brake lever from the dealership. Napa and AutoZone don't have this part. Chevy discontinued the right-side version of this part. We'll see what I find when I tear that side apart. They took my vin number in order to get the part right, so there is hope...

This was supposed to be a simple project...

 

[just a number]

nothing is ever that simple. just think though, by the time your done your know it inside and out.

What looks different between the 2 setups?

EDIT: I was looking at the pic of the cable joint. check it closely, buddy had one brake just when he needed it. It still looked fine. the end spread open.

 

[coachjpg]

What looks different between the 2 setups?

My brakes match the duo-servo drawings:

except for the parking brake lever, which matches the leading/trailing drawings:

You can see the latter image has totally different parts than my photos, except for the parking brake lever.

 

[coachjpg]

Here's another thought. The brake lever prevents the after shoe from sitting flush against the backing plate. Could it be that the lever should be outside the shoe, rather than behind it? The manual drawings are ambiguous on this point. That's not how it was installed when I opened up the brakes, but I'm not confident that they were right before. If I put the lever outside the shoe, I think the shoe might sit properly against the backing plate.

 

[btfarm]

The parking brake lever always goes behind the shoe. I'm beginning to think you have the wrong rear section of the cable.

 

[coachjpg]

The parking brake lever always goes behind the shoe. I'm beginning to think you have the wrong rear section of the cable.

OK. If the lever definitely goes behind the shoe, then either the cable or the lever is wrong. I pick up a new lever from the dealer in the AM. We'll see if it's different than the one I have.

I suppose the cable from the pedal could be wrong also. I'm only short a couple of inches...

 

[just a number]

I'd guess on the rear cable. If the front one was short neither (right or left) would reach. JHMO

 

[coachjpg]

I have 3 cables. One goes from the pedal to a joint beneath the rear passenger door. One goes from that joint to the left rear brake. The third ties into that rear cable about 3-4 feet behind the joint, and runs to the right rear brake. So any of these cables could be wrong.

 

[just a number]

could it be something as simple as the equalizer slid up? it's where the right and left rear join

 

[coachjpg]

I had a chat with the Chevy parts guy this morning. The part I ordered is exactly the part I have, so my problem is not an incorrect parking brake lever. In the photo below, I have the brake bar installed. You can see how the shoes are held apart at the top. My parking brake pedal is in the full up position. What you can't see in this photo is that the top of the right-hand shoe is not touching the backing plate. The parking brake lever is bearing against the raised central portion of the backing plate, which prevents the shoe from resting against the backing plate. My theory is that the lever is supposed to be more to the right, where it would not bear against the raised central portion of the backing plate. That would allow the top of the shoe to rest against the backing plate, and it would reduce the separation between the tops of the shoes.

The parts guy had an excellent drawing of my brakes, far better than what's in the Service Manual. It bothers me that GM has this excellent VIN-based parts information on-line, but they deny their customers access. So we go buy Chilton's manuals and Service Manuals etc., and we get generic info that is not at all specific to our vehicles. All the while GM's online systems have everything we need, but they deny us access. Grumble.

One thought would be to find the adjustment for the length of the cable and loosen it, but I find no such adjustment. This photo shows where the cable starts at the brake pedal.


This shows the equalizer, with an adjustment for the right-hand parking brake. I haven't even touched the brakes on the right side yet. You can see a bit of the black cable housing leading to the left rear brake.


Here you can see the rest of that black cable housing, leading to the left rear brake.


No adjustment.

What should I do next?

The parts guy gave me the part info for these cables, including the lengths. I could take out the cables and measure them. New cables are $25, $50 and $70 respectively for front, rear right, and rear left. Maybe I should just hold my nose and order a full set. Or perhaps you folks can point me to a way to adjust the length of the cables?

Thanks,
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[coachjpg]

I took another look at why my brake pads don't rest against the backing plate. The brake bar and parking brake lever bear on the raised area of the backing plate before the shoes touch. I looked at my photo of the backing plate before I cleaned it, and it shows no wear in the areas under the transfer bar and parking brake lever. There's a uniform layer of crud everywhere except the pads where the shoes are supposed to touch.

There was no way my pads could do that. I dug up the old pads, and sure enough, my new pads were too narrow. The parts guy had given me the wrong pads. So I tore it apart once again, and exchanged my pads for the right size. I presume the brakes will go together smoothly this time.

Before I removed the old brakes, I carefully compared them to the new ones. I checked for length, position and size of holes and fittings, etc. I never checked width. Oops.

This still does not address my parking brake cable issue. The manual tells me to adjust the parking brake cable to the point just before the parking brake causes drag, but I still find no place to adjust the cable. Any words of wisdom would be much appreciated.

Thanks,
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