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A-body 8-3/4 brakes v. others
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Author:  64 Convert [ Fri May 12, 2006 2:51 pm ]
Post subject:  A-body 8-3/4 brakes v. others
I seem to recall there is a difference in brake hardware/buildup for 8-3/4" A-body and other Mopars with that rear end, but I can't find it now that I need it.

I have all the gear and axle parts and pieces, including new Yukon axles with the big bolt pattern. But, I don't have any brake parts, except for the 10" backing plates from a B-body.

I'm trying to decide between going to the Scarebird adapters and rear disk brakes, or buying all the parts for a drum setup. The disk setup is simpler and the price is probably close since I have to buy everything new, but I'd like to get some opinions.
Author:  AndyZ [ Sat May 13, 2006 6:21 pm ]
Post subject: 
I am assuming you have 4" bolt pattern and if so, if you use the Scarebird stuff you will need to have a machine shop drill your new rotors to work. Also I have read in other postings that the installation doesn't work on A-bodies as easily as stated; something about one of the caliper bolt being blocked by the leaf spring (read the previous posting in this category). 10" drums work well on most cars. Good Luck
Author:  Joshie225 [ Sat May 13, 2006 7:15 pm ]
Post subject: 
A body 8 3/4s had 1.75" wide shoes and everything other 10" 8 3/4 brake setup I've seen was 2.5" wide. Were your axles made with the A-body bearing to axle flange dimension for the smaller brakes or to fit 2.5" wide brakes?
Author:  64 Convert [ Sat May 13, 2006 7:50 pm ]
Post subject: 
Quote:
A body 8 3/4s had 1.75" wide shoes and everything other 10" 8 3/4 brake setup I've seen was 2.5" wide. Were your axles made with the A-body bearing to axle flange dimension for the smaller brakes or to fit 2.5" wide brakes?
That difference is what I was trying to recall...and I don't know what I have. They are new axles with green bearings from Randy's, not machined from C-body or truck axles.

Do you know any place where I can find the dimensions to check?
Author:  Joshie225 [ Sat May 13, 2006 10:18 pm ]
Post subject: 
I don't have the dimention, sorry. Also, why the Green bearings?
Author:  chi/6er [ Sun May 14, 2006 1:53 am ]
Post subject:  8.75 rear end
the Yukon axle that you got for an A body should be around 27-28" long on each. With the green bearings I guess you dont have to adjust the bearing when you put on a new axle. Since you got the backing plate from a B body, you will be using the 2.5" brakes instead of the 1.75". I guess the only other way for better brake in your case is to get 11"brakes cost wont be as high as the disk brakes. I think on ebay there is a set of 11" backing plates for $9.99, so far nobody is buying so it may stikk be for sale.. I think with the green bearings you can't do hard cornering or auto crossing with them........
Author:  Patrick Devlin [ Sun May 14, 2006 8:37 am ]
Post subject: 
There is a difference between A-bodies and B-bodies in the backing plate to axel flange distance. This is something else that can screw up a brake swap. (I think the difference works out to be 1/4" per side, or something).

See http://www.autohobbydigest.com/8_75.html under "Axle Housing and Axle Dimensions"
Author:  Joshie225 [ Sun May 14, 2006 4:40 pm ]
Post subject: 
When I made my A-body 8 3/4 big bolt pattern I had C-body axles cut down. I used 10" F-body backing plates off a 7 1/4 and F-body wagon finned drums. 11" rear brakes are a lot heavier and are complete overkill for slant 6 passenger car use. I kept the original Timken axle bearings as Green bearings do not have nearly the thrust capacity of the original tapered roller bearings. The aftermarket axle makers don't like the Timken bearings as the axle length has to be right in order to get proper axle end play. Green bearings let them make axles to a lot looser length tolerance and that saves them money.
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