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8-3/4 Axle question

Paul Secoy

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Hello all, I have a question; I am contemplating using an A body 8-3/4" housing in my 67 Belvedere II, and will have to upgrade to the big bolt pattern axles. I vaguely recall from the last time I bought big bolt pattern axles that they stick out a little further from the axle housing to the wheel flange than the original small bolt axles. Am I remembering correctly, or do I need a nap?.. I am trying to see if this is feasible swap with existing wheels, or will I have to narrow a housing.

Thanks to all.
 
Paul, Tha A-body axle is narrower than the 67 B housing so you will be gaining outer tire clearance and losing inner clearance no matter.
 
You’ll have to move the perches as they are different center to center. The aftermarket axles have a different offset to allow you to use B body brakes, although you can buy aftermarket axles with the unique offset needed to run the small bolt brakes if you like.
 
Yup, the stock B axles stick out a bit further than the A body. Can't remember what the figure is but it's out there on the net....
 
The B and A are the same housing to flange. The difference is the backing plates. The B uses wider brakes than the A. The B backing plates are deeper. Install B backing plates, shoes, drums and it'll fit.
Doug
 
The B and A are the same housing to flange. The difference is the backing plates. The B uses wider brakes than the A. The B backing plates are deeper. Install B backing plates, shoes, drums and it'll fit.
Doug
I stand corrected....
 
The B and A are the same housing to flange. The difference is the backing plates. The B uses wider brakes than the A. The B backing plates are deeper. Install B backing plates, shoes, drums and it'll fit.
Doug
You sure? Don't know for a fact but here's a chart about housing widths.https://www.bigblockmopar.nl/tech/mopar-rearaxle-dimensions/
housing.JPG
 
Been a long time since having an A body rear end but could have sworn that the distance from the bearing fit to the flange face was different than the B axles.....
 
I'd buy custom axles with b-body bolt pattern. It's like having a narrowed rear. If your car is a 66/67 wheel/tire combos are better. Tire rubbing and wheel BS easier. MO.
 
From the Dr Diff site
A-body "big bolt pattern conversion axles" fit any '65 and newer, 5 x 4 1/2" Mopar spec rear disc or rear drum brake assembly. These axles will NOT fit 5 x 4" bolt pattern brake assemblies, backing plates or re-drilled drums.

I just worked on a 67 Cuda that had a locked rear axle. The customer installed 4 1/2" big bolt pattern Yukon conversion axles. He had also installed B body 10" drums. It still had 1 3/4" shoe backing plates. The drum was wedged into the backing plate. I swapped in B Body 10" backing plates and shoes, problem solved.
Doug
 
The difference in question is the axle flange "standout", the dimension between the axle housing flange and the outside of the axle shaft flange. The SBP A-body dimension is narrower than any other 8 3/4".

Mopar BBP Ends - 2.525"
Mopar SBP Ends - 2.22
 
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From the Dr Diff site
A-body "big bolt pattern conversion axles" fit any '65 and newer, 5 x 4 1/2" Mopar spec rear disc or rear drum brake assembly. These axles will NOT fit 5 x 4" bolt pattern brake assemblies, backing plates or re-drilled drums.

I just worked on a 67 Cuda that had a locked rear axle. The customer installed 4 1/2" big bolt pattern Yukon conversion axles. He had also installed B body 10" drums. It still had 1 3/4" shoe backing plates. The drum was wedged into the backing plate. I swapped in B Body 10" backing plates and shoes, problem solved.
Doug
I re read post I commented on, you were talking axle to axle flange. I thought it was housing.
 
The difference in question is the axle flange "standout", the dimension between the axle housing flange and the outside of the axle shaft flange. The SBP A-body dimension is narrower than any other 8 3/4".

Mopar BBP Ends - 2.525"
Mopar SBP Ends - 2.22

Yep, that is what I remembered, and I found it on BigblockDart.com. the big bolt axles stick out 1/4" more per side apparently. I thought I remembered a difference, just couldn't recall the measurement. I'll be using C body backing plates and drums off a parts car I have to save a little cash for this money pit.

I laid out the axle dimensions at work today with the wheels available to me. I have to try and get a measurement on the car, but if I can get right around 68" sidewall to sidewall, I'll be golden. Thank you very much for the responses.
 
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Yep, that is what I remembered, and I found it on BigblockDart.com. the big bolt axles stick out 1/4" more per side apparently. I thought i remembered a difference, jsut couldn't recall the measurement. I'll be using C body backing plates and drums off a parts car I have to save a little cash for this money pit.

I laid out the axle dimensions at work today with the wheels available to me. I have to try and get a measurement on the car, but if I can get right around 68" sidewall to sidewall, I'll be golden. Thank you very much for the responses.
Measure both sides of the car. They are not always the same.....even if never wrecked.
 
I stand corrected. Though .250" shouldn't make or brake wheel/tire fit.
Doug
 
I will do some measuring, I ran into issues with my 67 Barracuda with body measurements being off a bit. Yes, 1/4" isn't a huge deal, I just couldn't remember how much it was.

I am hoping I can find a wheel/tire combo that will work without resorting to narrowing a housing. I narrowed one years ago, and it worked out well, but it is a step I would rather skip.

Thanks again.
 
unless you already have the A body axle, and even if you do...

66/67 B body housings are WAY easier to find and WAY cheaper.

A body is typically around $300-$500 without chunk

66/67 B is typically $100-$200
 
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