10 inch rear drum brakes

[jawbone]

Can someone take the time to answer this question. Am in the process of trying to convert 7.25 rear end SBP 9 in. drums to BBP 10 in. drums for 8.75 rear end. Question is what years will suit my needs. Looking for 10 in BBP 10 X 2.5 backing plates. Is backing plate for 10 X 2.5 SBP different than 10 X 2.5 BBP?

 

[69FBCuda]

Are you saying that you want to use the drums from a 8.75" on a 7.25" ?
Are you switching to or re drilling the axles?
My 7.25" came with 4 bolt backing plates

 

[66fs]

There are no 10 x 2.5 SBP backing plates. Original A-Body SBP rear 10 in brakes are 10.75. Original 73 up BBP 10 in A-Body rear brakes are 2.5. The backing plates are different than the SBP backing plates. But the 10 x 2.5 brakes came on most other platforms including PU Trucks.

 

[72bluNblu]

The backing plate offset from SBP to BBP brakes is different, because the axle flange offset is different between SBP and BBP axles.



So if you’re switching from SBP brakes to BBP brakes, you also need to be switching from SBP axles to BBP axles (and not just a re-drill either)

 

[mvh]

There are no 10 x 2.5 SBP backing plates. Original A-Body SBP rear 10 in brakes are 10.75. Original 73 up BBP 10 in A-Body rear brakes are 2.5. The backing plates are different than the SBP backing plates. But the 10 x 2.5 brakes came on most other platforms including PU Trucks.

66fs mistyped his reply... he meant to say, SBP 10in rear brakes are 10 X 1.75". That is, 1-3/4 inch wide, not 2-1/2 inch wide. The width is measured on the shoe, not the full depth of the drum, FYI.

 

[jawbone]

Are you saying that you want to use the drums from a 8.75" on a 7.25" ?
Are you switching to or re drilling the axles?
My 7.25" came with 4 bolt backing plates

It's nothing about drums or axles. It's about whether backing plates are interchangeable between 7.25 with 10 x 2.5 and 8.75 with 10 x 2.5 inch brakes. Think you just answered my question. The 7.25 is only 4 bolt. Never knew if 7.25 even came with 10 x 2.5 inch brakes.

 

[jawbone]

There are no 10 x 2.5 SBP backing plates. Original A-Body SBP rear 10 in brakes are 10.75. Original 73 up BBP 10 in A-Body rear brakes are 2.5. The backing plates are different than the SBP backing plates. But the 10 x 2.5 brakes came on most other platforms including PU Trucks.

That's what I needed to know. Thank you.

 

[jawbone]

The backing plate offset from SBP to BBP brakes is different, because the axle flange offset is different between SBP and BBP axles.

View attachment 1716220200

So if you’re switching from SBP brakes to BBP brakes, you also need to be switching from SBP axles to BBP axles (and not just a re-drill either)

Thanks for the response and information. Again, just the information I need to know. Keeping me from making mistake.

 

[jawbone]

66fs mistyped his reply... he meant to say, SBP 10in rear brakes are 10 X 1.75". That is, 1-3/4 inch wide, not 2-1/2 inch wide. The width is measured on the shoe, not the full depth of the drum, FYI.

Thanks for clearing that up.

 

[69FBCuda]

When you talk about SBP vs BBP if you switch from one to the other the lug hole locations change along with the hub bore. So yes you are talking about drums and axles unless you plan on re-drilling the ones you have.

 

[jawbone]

When you talk about SBP vs BBP if you switch from one to the other the lug hole locations change along with the hub bore. So yes you are talking about drums and axles unless you plan on re-drilling the ones you have.

Thanks. I was not at that level of understanding. Thanks for responding.