Replacing Rear Backing plates.

[EU-avalanche]

Hello everyone,

I've lurked these forums for a while and found a lot of great answers to maintenance and repair problems for my previous repairs. But I haven't found an answer to my current issue.

I've got the two piece rear backing plates from rockauto.com.
The ones on my avalanche are completely rusted away. There's barely anything left.

I took off the wheel - removed the brake calipers - removed the disc - removed the e-brake assembly. : .now my issue.

There's four 18mm bolts that go into the axle housing. You can only get conventional spanners on them since the axle shaft is blocking access to put on a ratchet or impact.

On my vehicle these four 18mm bolts frozen solid into place. I put a spanner on there and hit it with a large mallet. Stood on the spanner (I'm 200lbs.) But they wouldn't budge.

Now, I know what you're saying. Whip out the torch and hear those buggers up a bit...
Yes, I'd like to, but if I break one off I'll need a replacement. My avalanche is my daily driver so I would like to have replacement bolts ready incase they do break.

So there is the actual question...

"What is the part number for those four 18mm bolts that go into the axle housing?" Or what are the specs on those bolts to get them from a hardware store?
I'll need to order four for each side.

 

[ygmn]

IS there not a hole in axle hub plate which when rotated allows you to put socket on these 4 bolts one at a time?

I have not had to do this yet as my baby has not out here TOE in any snow.

 

[frito]

IS there not a hole in axle hub plate which when rotated allows you to put socket on these 4 bolts one at a time?

I have not had to do this yet as my baby has not out here TOE in any snow.

No, the issue is that you'd have to remove the entire axle. Watch the video on the rock Auto part here. https://www.rockauto.com/en/catalog...94,brake+&+wheel+hub,brake+backing+plate,1628

OP, please post up the parts if you find them as I was going to order the same thing. I checked Rock Auto real quick and didn't see them listed.

 

[EU-avalanche]

IS there not a hole in axle hub plate which when rotated allows you to put socket on these 4 bolts one at a time?

I have not had to do this yet as my baby has not out here TOE in any snow.

Perhaps I could remove a bolt from the axle shaft, the one that the lug nuts go on. And stick an extension for an impact socket through it?

But I'm pretty sure even an ordinary wrench will do the job once the 18mm bolts have been heated and cooled a few times.

I just can't for the life of me find the specs of the bolts so I can buy new ones....

 

[ygmn]

Like frito says.
you need to remove axle shaft.

Good time to replace axle shaft end bearings and seals too while you have it part.

 

[ohiobellboy]

Like frito says.
you need to remove axle shaft.

Good time to replace axle shaft end bearings and seals too while you have it part.

No need to remove the axle if installing the two piece plates. Not a bad idea to and do the seals as you mentioned depending on mileage, but not necessary to remove them.

OP. Penetrating lubricant will be your best friend in this case along with a quality 6 point box wrench. Heat will help along the process.

 

[EU-avalanche]

Little update, found these bolts while going through some parts websites.

Full float axle hub bolt :. 1/2" x13. x1.25"

Dennys Driveshafts > AAM 40012104

When you are shopping for AAM 40012104, choose Denny's Driveshafts for the full line of AAM parts.

www.dennysdriveshaft.com

I ordered 8 of them. Will post again when I get around to getting the old bolts out.

 

[EU-avalanche]

Okay this Saturday I went ahead and got stuck in at 8am.
Took me all day mainly because I had to clean up a lot of rust with a wire brush.
One two piece backing plate was not quite shaped right so I had to bend and cut it so it wouldn't rub on the disc.

All bolts came out with a lot of WD-40 and heat, also an extra long 18mm wrench.

Thank you all for the advice.

https://imgur.com/a/KZJfNn6

http://imgur.com/a/w2r2jBI

 

[frito]

Nice job. I'll be doing the same in a couple weeks when I redo my rear brakes properly

 

[ygmn]

Glad you got it done and your truck lives on...

Nice to see AVYS in Europe....
not as many post any more since Loggie left.