Backing Plate Differences

[RustyRatRod]

Are 10" backing plates from a B body 7 1/4 the same as the A body 10" backing plates for the A body 7 1/4? Thank you drive through.

 

[fishmens67]

Yes, they will swap

 

[Dana67Dart]

Question...

I assume the b body are large bolt pattern axles, on SBP 8 3/4 vs LBP 8 3/4 the axel back spacing is different by about 1/4 inch. Does the same apply to 7 1/4"

 

[cudamark]

Are 10" backing plates from a B body 7 1/4 the same as the A body 10" backing plates for the A body 7 1/4? Thank you drive through.

Nope, different. The B-body 7 1/4 backing plates (6 cylinder car with the 10 X 1 3/4" brake shoes) are the same as the A-body with an 8 3/4, not the 7 1/4. The A-body 7 1/4 only uses 4 mounting studs.

 

[RustyRatRod]

Ugh. I seem to be gettin conflictin answers. Can someone nail it down for me, so I don't get the wrong thing?

 

[cudamark]

What year is the donor B-body car? '65-7? What do you need to "nail it down"? I can give you the part numbers of the backing plates in 1966 if you want.

 

[RustyRatRod]

What year is the donor B-body car? '65-7? What do you need to "nail it down"? I can give you the part numbers of the backing plates in 1966 if you want.

My car is a 64 Valiant and I am unsure of the B body 7 1/4.

 

[cudamark]

Why not just get some 10" ones off an A-body 7 1/4? There should be plenty of those around. The B-body ones are a 5 bolt mounting, like the 8 3/4.

 

[RustyRatRod]

Why not just get some 10" ones off an A-body 7 1/4? There should be plenty of those around. The B-body ones are a 5 bolt mounting, like the 8 3/4.

That's what I want and am looking for. S'why I asked about the interchangeability.

 

[yellow rose]

That's what I want and am looking for. S'why I asked about the interchangeability.

I just pulled a 7.25 out of an A body. I’m going to use the backing plates off it for my D60. While the 7.25 only has 4 studs holding the backing plate on, it still had 5 holes so it will work for the 8.25, 8.75 and D60.

As I understand it, as long as the 7.25 has a BBP it’s all the same.

I was told the SBP A body 7.25 has a different backing plate, but I can’t verify that.

 

[Dana67Dart]

SBP 7 1/4 has a smaller diameter center hole, bearing is smaller, than 8 3/4

In the last 3 years someone posted a photo of a SBP, 7 1/4, 10 x1 3/4 backing plate next to a SBP, 8 3/4, 10 x 1 3/4 backing plate, center home was different.

 

[yellow rose]

SBP 7 1/4 has a smaller diameter center hole, bearing is smaller, than 8 3/4

In the last 3 years someone posted a photo of a SBP, 7 1/4, 10 x1 3/4 backing plate next to a SBP, 8 3/4, 10 x 1 3/4 backing plate, center home was different.

Hmmmmm. When I get home Friday I’ll measure what I have. I’m 95% sure I checked the hole size when we swapped out the axles and they were the same.

 

[Dana67Dart]

I’m 95% sure I checked the hole size when we swapped out the axles and they were the same

Could be for BBP 7 1/4.

I was told 7 1/4 and 8 3/4 SBP 10 X 1 3/4 would swap. The photo posted proved otherwise.

 

[yellow rose]

Could be for BBP 7 1/4.

I was told 7 1/4 and 8 3/4 SBP 10 X 1 3/4 would swap. The photo posted proved otherwise.

Yeah...I thought I looked at hole sizes but maybe I didn’t. It was a BBP 7.25. I’ll measure it when I get home and see if my cheese is off the cracker again.

 

[cudamark]

BBP 7 1/4 A-body rear ends use 10 X 2 1/2" brakes, SBP 7 1/4 rears (with 10" brakes) measure 10 X 1 3/4". The backing plates won't interchange for that reason alone.

 

[RustyRatRod]

Thanks yall. I think we've established the backin plates are different. Now I need to post a wanted ad.

 

[yellow rose]

BBP 7 1/4 A-body rear ends use 10 X 2 1/2" brakes, SBP 7 1/4 rears (with 10" brakes) measure 10 X 1 3/4". The backing plates won't interchange for that reason alone.

Cool. I have the BBP plates so I’m pooping in the tall cotton for once.