Big bolt pattern?

[Rob]

Can somone confirm what I'm hoping will work. I have a 70 Duster that I'm upgrading the brakes to discs from a 75 Dart, I assume that is a big bolt pattern and if so was wondering if I could use the backing plates from the 7 1/4 rear in the Dart in my 8 3/4?

 

[Longgone]

I have`nt tried personally , but I`ve heard that one of the bolt holes needs to be drilled to make it work.

 

[OldVart]

Even if you drill the extra hole in the 7.25" backing plate, I don't think it will fit properly on the 8.75".

 

[Longgone]

You know I had this same question about 3 months ago and I ended up using 8.75 backing plates. Lol, just easier that way!

 

[OldVart]

John, I did the same thing.

 

[340mopar]

If the bbp drums and backing plates from the 7 1/4 did work on the 8 3/4 what are you going to do about bbp axles.


Chuck

 

[Rob]

Well that's good to know before I start ripping things apart for no reason. I'm assuming that the 8 3/4 I have from a 70 Duster is the small pattern, can I drill them out and press in new studs or do I need to find backing plates off of an 8 3/4 that have the large bolt pattern?

 

[340mopar]

If it is an a-body 8 3/4 it only came with sbp. You can have them redrilled, that is what is in my Valiant but you need to redrill the sbp drums and use them also. To put large bolt pattern 8 3/4 backing plates and drums on an a-body 8 3/4 you have to change to aftermarket axles with a 2.36" offset. A-body 8 3/4 axles have approx. 2" offset so the brake stuff won't work.


Chuck

 

[Rob]

Thanks Chuck, that's the route I'll go :thumbup:

 

[Suregrip391]

I got my backing plates and drums, etc off a 79 Volare with a 7 1/4 rear. Large bolt pattern. Purchased new Yukon axles and it all bolted up to my A-body 8 3/4 with no problems. No drilling.