does anyone know if the 8.2 buick backing plates will work on a chevy 12 bolt axle? Also wondering if it dosen't work is it worth the time and $$ to put disc rear brakes on a street car? -nate
Nate.... It was my plan to use a 12 bolt chevy rear & reuse my 8.2 backing plates & drum brake set-up on my lesabre... However, if my memory serves me, the axle flange to housing flange dimension is different between the 12 bolt & 8.2 rears. Keep in mind this was a 8.2 out of a 65 lesabre. I think the 8.2 had a 1 7/8" flange to flange dimension & the 12 bolt was larger. This difference would not allow the drum to slide on far enough in order to engage the brake shoes, when braking. Since I had the 12 bolt narrowed I went with new style big bearing ford type housing ends & Moser axles. Tom:TU:
I know the backing plates I had on a 1970 8.2 Buick rear worked on a later installed Chevy 12 bolt without modification in my case.The thing is though that these backing plates may have originally been off the 8.5 Buick rear which came in my '71.The latter rear was switched over to the 8.2 about ten years ago and memory has failed me.Sorry I can't be of more help. Rod
The 8.2 backing plates are direct bolt on on all GM 12 bolt rears, except '65-70 Impalla & '65 Z16 Chevelle. Should fit nearly all 8.5 A-body rears. A10 axle bearing 8.5 A-body rear is the exception. Basically there are 3 different backing plates used on '64-72 A-body rears. -Std BOP 9 1/2" drum backing plate -Chevy 9 1/2" drum backing plate, has spotwelded on sheetmetal flange on back side around the OD. -BOP A-body stwgn 9 1/2" drum, but has deeper step, so wider drum can be run. Also has larger diam centering hole to clear 2.9" diam axle bearings. Got Posi? :3gears: Roger
Nate, You would be better of building an 8.5" rear from a 71-2 Skylark/Cutlass. Install 3.08 gears, posi, add rear sway bar and boxed lower arms. The rear disc brakes are really not needed for a street car. You can see my article on our site about the rear disc brake conversion.
hehe.. well i have a 12 bolt axles stock, and housing (less posi with 3.31's I may try to reuse) I may choose a lower numeric rear ratio. I've already boxed rear arms and swaybars. i'm guestimating my setup will be between 520hp and 560 hp at the crank when completed. with a switch pitch th400 I'd like to try to keep the rear drums mostly for :dollar: reasons unless to fit new brakes on the 12 bolt.
Nate.. If the 8.2 backing plates don't work for you...I have a set of chevy 12 bolt backing plates, no drums though...they are off of a 68 or 69 chevelle... Tom:TU:
tlivingd With 520-560 hp at the crank, may I suggest on your 12 bolt buildup, upgrading to new Moser axles, & if your posi carrier is oem Eaton carrier, install specially heatreated 10-17 spider/side gears & solid cluch plates (Tom's Diff), along with 400lb springs & thicker spring plates. Just sticking with oem Eaton carrier & stock axles, once you get the car to hook, easy to find the limits of a stock Chevelle 12 bolt posi rear, & it won't be a pretty sight . Got Posi? :3gears: Roger
thanks for the info Roger, I was afraid to hear that but i'd rather be safe than sorry. With moser axles are those then also converted to C-clip elims as well? I would be going with aftermarket posi unit (Eaton) hopefully it's already built to handle that. I was never planning on running slicks to help hook up, but some day somone may convince me to run their extra slicks at a track for a pass or two. Gernading the rear would be the last thing i'd want to do. guess the price for new axles isn't too bad now that i look at them. -nate
Its so you can bolt the axles to the housing instead of relying on the c clips that are in the center section holding the axles in...I have seen some c clip axles fly out of cars when the clips fall out...
with the axles with c-clips the only thing holding the axle into the axle housing is a little c clip on the end inside of the differental. these c-clips are pretty weak or the end of the axle shaft is pretty weak and under high horsepower and side loading (cornering hard for example) will cause the end of the shaft or the c-clip to deform and/or break and the axle will litterally roll out from under the car leaving the axle housing. the eliminator is a bearing that is pressed onto the axle (near the wheel flange) and has a bolt in bracket that holds the axle bearing assy to the axle housing.
