Changing rotted backing plates/dust shields

[blue70chevelle]

So from what I understand, having the rear axle backing plates/dust shields rot out on these trucks is a common occurrence. When they rot out they often have shards of metal protrude and rub the disc rotor, or the insides of the drum and cause noise, squealing, uneven brake wear, etc. After listening to these things squeal for long enough, I finally decided to change them out. This how to will go through that process.
Be advised, this is not a terribly difficult operation, however you must be somewhat mechanically inclined. If you can change your own brake pads and discs, you could probably change these too, but I make no guarantee.

The items you will need are as follows;

(2) New backing plates (Dorman #924002, $11.57 at rockauto.com)
Tire iron
14mm wrench
18mm wrench
5/16" wrench
13mm wrench
flat head screwdriver
stick magnet
needle nose pliers
Large Jack
Large Jack stands
Oil catch can (drain bucket)
Diff gasket or Gasket maker
Diff Oil (depends)

The following items aren't needed, but if you have access to them will help a lot..

A Lift
Impact gun
Air Ratchet
Swivel sockets
Swivel Ratchets
Needle nose vice grips

Ok, First things first. Make sure if you are using jack stands and not a lift that you chock the tires! There is no parking brake on the front wheels and if the truck slides while you're under it, you're probably gonna get dead..
Next thing, Make sure to leave the truck in neutral during the entire operation, you'll understand why later.

So finally we can get started. Get the rear end of the truck up in the air whatever method you can. Take your trusty tire iron and take the tire/rim off. now you will be looking at the brake assembly.

On the rear of the caliper there are two 14mm bolts. remove these two bolts (circled in red)

Next you will be taking off the two 18mm bolts holding the caliper bracket to the axle flange (circled in red)

Now the front off the axle should look like this

Next, grab hold of the rotor and pull it straight off. It might be hard to pull off as the emergency brake might be hung up a bit. you might have to rock it back and forth or pull with some brute strength. It will come off though!

I'm not going to go into it, but now would be a good time to check on the condition of your emergency brake..
now were going to go to the rear end housing for a bit. Take your 13mm wrench and starting at the top, remove the 10 bolts holding the differential cover on. If the gasket is still good, it shouldn't leak yet and it should have to be pried off. keep your drain bucket close by just in case.

Once all ten bolts are out, grab your drain bucket and your flat head screwdriver and slowly pry the cover off.

The inside off the diff should look like this

The next step is why the truck is in neutral.
Rotate the axle until the cross shaft and the bolt holding the cross shaft in are present.
The bolt is a 5/16" bolt. remove this bolt

and slide the shaft out.

Slowly rotate the axle until the opening in the diff unit comes around again
Next, push the axle in towards the center of the diff. This will reveal the c clip holding the axle in. With your magnet on a stick, grab the c clip.

It is important to note, When the rear is apart like this, it is important to not turn the axles or drive shaft. you risk having the spider gears fall out of place, then it will be a mess to put back together.
Next pull the axle out. Make sure to support the axle good. If you pull the axle out at an angle you can mess up the axle seal!

Now we will go back to the brake side of the axle.
With the axle removed, it will look like this. Remove the 4 bolts pictured. They are 18mm bolts.

Next remove the 5/16" bolt that holds the top of the e-brake drum in place

Now remove the e-brake drum. It may need some finesse, but this is what you'll end up with

Now for the pain in the ass part. You can do this any number of ways. I used a needle nose vise grip and a normal needle nose to pull the spring back. The only reason it is a pain is because this spring has a lot of tension and needs to be pull pretty far to release the cable off the brake mechanism. The spring will not come off the cable, so have no fear that it will shoot out and hit you in the eye. Regardless, get that thing off!

Once it's off, unbend the tabs holding the backing place in place, and pull off the outer axle flange thing

Now rip off the backing plate/dust shield and beat the hell out of it for making you go through this stupid long process to replace it.

 

[blue70chevelle]

This is what you're left with.

And this is what the rotted old one looks like in comparison to the new one..

Now it's time for reassembly. It's basically dis-assembly in reverse, so I'm not going to go through all the pics again, just some.
Put the new backing plate on along with the outer axle flange. Remember to bend the stupid tabs on the new backing plate to hold it onto the outer flange, I forgot and had to go back!..

Using your needle nose, or whatever you finally got to work for you before, reattach your e-brake/parking brake cable

Slap your e-brake drum back up into place and secure it using your 5/16" bolt and bracket.

Gently, while supporting it, slide the axle back in. Try not to turn it once the splines are seated! (sorry no pics)
push the axle all the way in, and reinsert the c-clip, then pull the axle back out a bit to seat the c clip.

Then reinsert the cross shaft and the 5/16" bolt holding the cross shaft in.
A word to the wise, put lock tight on the bolt! Mine was loose when we removed it earlier. That's not a good thing..
I'm out of pictures for the rest, but it is simple.
Grab a new rear end gasket or some gasket maker, and put a generous bead on the rear end cover.
Pop the rear end cover up and put all 10 bolts back in.
Fill the diff with the proper oil until it comes out the fill hole. (I didn't buy new gear oil, because the royal purple I had in there was only a month old)
Finish putting your brakes back on and voila!
Your done.

For reference, this is how rotted those damn plates were..

^^ That's supposed to be solid!

I know this was a long read, but hopefully it helped those of you with the same problem, who are looking to do it by yourself.

The total time it took was about 3 hours using a lift, but the power went out half way through and we lost the compressor, so we had to do most of it with hand tools as a result.

The total cost was $23.14 plus shipping. If you have to buy a gasket or gasket maker and diff oil, it could get a bit more expensive (especially if your using royal purple) but I had this stuff on hand so..

any questions please ask.

Shane

 

[NJ04HOE]

Good job, this is a nice addition to the tech section since a lot of us have the rotted shields.

 

[blue70chevelle]

Thank-you. I figured I'd dive into myself. The book hours alone for this job at the average $75 an hour labor rate (NY ) came out to a ridiculous amount to have a shop do it for me, and I'm somewhat handy and I have my dad to show me the ropes when I get stuck, so it was a no brainer. I'm just glad it is finally done and I don't have to listen to that awful scrapping anymore

Book hours show the job as 3.3 hours..

 

[Xowner]

Great write up! Only thing to add is somtimes the small pin that holds the bigger pin in the diff breaks! Becarful with it!

 

[Narco]

awesome write up...now THIS is what belongs in the Tech sections!

 

[Bailey-Hoe!]

awesome write up! Might I suggest getting the new plates bedlined! You can buy that stuff in a can at home Depot. It might buy some more time.

BB

 

[blue70chevelle]

You might be able to bedline them, but they are very close to the rotor, so any added thickness such as a bedliner material might cause some rubbing. It's something to try though. You might be better off with rustoleum or POR15...

 

[denalianyone]

Damn, that is a long process just to remove a backing plate!

 

[jaysandy]

when you pull the cross shaft pin out what do you need to do to get the other side axle out at the same time

---------- Post added at 08:14 PM ---------- Previous post was at 07:58 PM ----------

Shane... nice job on this with the pic's and all... but what about the drivers side... when inside the rear end and after pulling the pin for the axle is a c clip also accessible for the drivers side axle and pulling one axle out at a time ??? thanks,, JOE