Parking Brake control module

[Larryjb]

Frozen park brake is usually because of age and crud in the outer cable casings or a kink or punch. Or hardware sticking.

That may very well be true. It would only freeze up when the temperatures dropped below freezing. I mashed a whole pile of grease into where the parking brake lever goes into the backing plate and that seemed to keep it from freezing up this winter. I figured that the boot had torn over the years, allowing crud, as you say, into the inner hardware, hence the reason for me replacing the boot and related hardware. What I did not know until a couple of days ago was that the backing plate had to be loosened by removing the four bolts. After that, I discovered that the backing plate has tabs that are bent over the heavier metal caliper mounting piece (the GM factory service manual doesn't give it a specific name, AFAIK). I'm not sure if I will be able to bend the tabs back, and with the vehicle in my garage I don't have room to pull the axles to replace the backing plate with the one piece backing plate. I have the 2 piece coming Monday and I will consider using that if necessary. I've already read the comments regarding the 2 piece backing plate, (and I can predict your comments Ron!), but if this truly doesn't work out I can pull the axles at a later date and replace the backing plates with proper GM ones.

Other comments I've read about the 2 piece backing plates seem to be if you install them correctly and bend the tabs right, they install just fine. We'll see. As I said, if I have to I can replace them with GM ones later if I need.

 

[OR VietVet]

Installing 2 piece backing plates is like replacing an outer cv boot with the ones that were split and you cut the old boot off and cleaned up and then packed new grease in there and wrapped the split boot around all that and reattached the split seems and installed new clamps at each end. POS is what they were. They caused so many problems. Can you supply pics of what you are saying?

So yea, you guessed right about what I feel and say about this stuff.

 

[Larryjb]

One of the problems people had when installing the Dorman, and I assume it will be a similar problem even with the one-piece backing plate, are the tabs. My backing plates aren't that bad, but one of them has a hole rusted through so I might was well replace it. If you look at the red circles, you can see some tabs. I'm sorry about the lousy image. I downsized it a little too much to make the size small enough. But, you can just make out the tabs I'm referring to.

These tabs are folded over the caliper mount bracket (the thing held with 4 bolts). I had to bend the tabs back to allow the caliper mounting bracket to separate from the backing plate. When installing a new backing plate, you will probably have to bend the new tabs into place after bolting the caliper mounting bracket into place. This is often the step missed causing the horrible rubbing people complain about.

If the backing plates are badly rusted, the tabs may not even exist anymore, resulting in such confusion.

Of course, I haven't started mine yet. I've probably got more of my own surprises to come, but I thought I'd share these images for anyone attempting to do this.

 

[Larryjb]

I installed the backing plates today and finished up to setting up the brakes. The biggest complaint about the Dorman 2 piece backing plates was fit. Everyone complained about scraping noises from the disk on the backing plate. Here's why: Just after installing the caliper mount onto the backing plate, you see two tabs circled in red:


Even in the 1Aauto video, showing the installation of these backing plates, they forget to fold these tabs over! I happened to notice that these tabs existed and were folded over on the original backing pates, so I was aware of this.


This is what the tabs should look like:


I used a punch to tap them flat. The disks are installed and there is no rubbing. They fit fine.

And yes, Ron, I should have used ACDelco backing plates. In fact, I almost always use ACDelco OEM or Professional line of parts, and usually avoid Dorman. I've had a lot of bad luck with Dorman stuff. But the truck was in my garage and no way to pull the axles right now. This truck is 18 years old too, and up here in BC with the salt they use on the roads, rust will claim this truck, probably in about 5 years. These backing plates should last at least this long. If, and only if, these backing plates don't work out, I won't be that upset to put ACDelco ones after. This is a case of me knowing what I'm getting into, a job that might have to be redone.

And I may have to redo it yet anyway. One of the screws that hold the spring clip that holds the parking shoe is stripped. Actually, it's the hole inside that's stripped. I put some loctite on the screw, but the previous owner had some one do some work once on it and must have overtightened it. In fact, the screw that was in there was oversized. I guess I could use one more oversize yet.



Now, back to one of the reasons I'm doing this job. Other than the parking brake not holding on a hill, the other reason is that in the winter months when it gets below freezing, the parking brake may freeze on. When I took the caliper mount off from the backing plates to remove the rubber grommet, I noticed that the rubber grommets were chewed up pretty badly. I suspect that water may have been able to enter the area of the parking brake lever and freeze overnight, freezing the parking brake in the applied position. I also noticed that the factory service manual method to remove the lever is to actually remove the backing plate itself. I suspect the reason for that is the danger of tearing that rubber grommet.

If you are ever in the situation of having to have the axles pulled, and you are not prepared to do that yourself, have the shop replace the backing plates AND the rubber grommet at the same time. This thing is a pain to remove.

 

[Larryjb]

And yes, those are nitrile gloves in the picture. And no, Trump can't have them! I might let him have a pair if he lets us have a mask.

Sorry, I couldn't resist!

 

[Larryjb]

Parking brake done, and it holds well.

 

[Larryjb]

Oh, and the 2 piece backing plates don't rub on anything. They're certainly a lot better than rusted out backing plates anyway.

 

[JonnyTahoe]

Mine were so rusted I took a hammer and bent them back and forth and they came off in pieces. Never replaced them just drove it with the bare Rotors completely visible from the inside.

 

[Larryjb]

My DS backing plate was partially gone. I also noticed a lot of caked on dirt entering the axle housing and brake area. So, the backing plates do something, but a lot of people are running with completely rusted backing plates for a long time too.

 

[JonnyTahoe]

Not many guys even notice or don't care if they are rusted and most think it's not worth the trouble to replace them. Most southern trucks don't have the rust problems like we do.