Backing plates

[Mopar Tom]

I am changing the axles in my '70 Duster to big bolt pattern. I have an 8 3/4 rear end. Will the backing plates from the small bolt pattern work? I have a set of rear brakes with backing plates off a '74 Dart that had an 8 1/4, should I use them?
Thanks for your help.

[ChargerMD]

I think- as long as you keep the same brake and drum size ( you will need different drums for the larger bolt pattern) you can use the same backing plates.

[SHY-PLY]

This could be interesting. I raced a '76 Volare' with an 8-3/4 rear out of a '69 Dart for years. I had the axle flanges welded up and redrilled to the larger bolt circle. I'm not sure what backing plates/drums that I used (multiple sets), but I had to use a 3/8" spacer between the flange and drum, always. If I didn't, the drum would set tight on the backing plate whenever I tightened up the lugs. I've read an explanation about this since, but I don't recall the details. Be aware, there is a difference between an A-body rear and others. Maybe someone here can help you out a little more.

[3bolt main]

on my duster i had to go to b-body backer plates and bigger brakes now i have the same problem with the drums tightening up also. i'm not sure if i got bad info or what

[Tarrbabe]

Where did you get your big bolt pattern axles? What are they from? Are they used from a B body? Are they the correct length for an A Body?

[3bolt main]

they are Moser Engineering axles A-body length but now im not sure about the brake set up if i have all the right parts in the right sizes i have to do some measuring

[Tarrbabe]

You may have to ask Moser but we were discussing this a few weeks ago on Mopar Alley Chat and some that had done it said you have to use B-Body or equivilant 2 1/2 brakes complete because the spacing is for B Body. Moser should know for sure but the guys over there have done it and said the A Body stuff won't match up.
I have not done this myself but feel I will in the future. If anyone knows more, please let us all know.

[Hammer 74]

From what I was told by Moser 10" drums and 11" drums have different offsets so the axles would be different lengths. I guess you could shim out the axle a little between the flange and the drum sort of like rim spacers.

[John Kunkel]

Moser will make A body large pattern axles two different ways
If the same A body overall length is retained, the original A body backing plate and shoes are retained and the drums are redrilled to the large pattern.
If the new axles are made longer than the originals, the drums, backing plates, shoes, etc. from a B, C or E body must be used. The drum always sits in the same relative position on the axle flange so, when wider shoes/drums are used, the backing plate must be offset inboard to compensate for the wider shoe/drum.

[The Dartman]

On my Dart Sport, I used all of the backing plates and brakes from my 8 1/4 and they were a direct fit onto the 8 3/4.

I think that the drum width will not work together for the small bolt pattern and the big bolt pattern drums.

[kudah440]

Hmmm I just wrote about this in another forum...heres what I did last weekend...
My wifes duster had a 8 3/4 with the re splined c-body axles and 10 inch drums with 4.5 bolt pattern. Last weekend I pulled it out and bolted on my 11x2 inch drum assembly (4.5 inch bolt pattern) from my 8 1/4 a body rear. Everything crossed over fine. (After that I put the 8 3/4 in my car). One small thing to mention though... every time I have gotten new brakes for the 11 inch, I have had to look them up for a Mirada or Cordoba.

[George G. Leverette]

3boltmain your problem could be caused by the length of the parking brake cable, if you use the 9" inch cables with the 10 or 11" backing plated with the 2 1\2" shoes they will probably not release properly. Any other comments on cable length?

[Mopar Tom]

I bought my axles from Moser, they are standard 30 spline 8 3/4 A-Body axles. It sounds like I can use the backing plates and drums off a '74 Dart with an 8 1/4?????????

[jimm II]

For what it's worth;the axle housing I put in my 74duster was out of a 1968-69 A body . The axle shafts I had made from Moser have the green bearings. The axle brake backing plates I HAD to use were from the Year 1972 Satilite /Roadrunner got these through the local dealership and the brake drums for the same..
The parking brake cables came from 1976 A body 8 1/4" axle with the 11"brake drums. this has and does work for me..
Jimm