[Schurkey]

Originally Posted by Tim Corcoran

Schurkey,
Thank for the info much appreciated, but now the quest to find a B-Body in the salvage yards, like I said now days most of what they have left is late model stuff cars made in the 70's are all mostly crushed a long time ago.

There's lots of those cars around here in the Treasure Yard.

Because I'm cheap, I intended to use everything but the shoes and some springs from my A-body brakes. But all you'd really need are the backing plates from the Yard, you'd be able to buy everything else new--shoes, springs, adjuster pieces, hold-downs, etc.

[Schurkey]

I will hit the yards and see what I can find wish I had a more complete list of donor cars. I know I'm looking for a GM with 11" drum brakes years 65-70 so if I pull the drum off and it's got 11" drum I'm good?

I'd rather you hear this from an actual expert like Ol' Pinion Head, but...yes. Far as I know, '65--'70 B-body, and '73--'78 A-body, that have 11" rear drum brakes should be adequate donors. There may be other years, other models. The big deal would be the bolt spacing on the backing plate needing to match the backing-plate bolt hole spacing on the axle you intend to actually use.

[bob prichard]

Originally Posted by Half-Inch Stud

Yes, 10-Bolt plates, drums, T- bolts and brake stuff being far superior.

Use the 65-72 Big Car Pontiac Yoke on 12-Bolt for better results.

I found a 65-72 big car Pontiac yoke for sale on ebay, from Frank’s Pontiac Parts. His ad states it has 28 splines, my Chevy 12 bolt has 30, so I don’t think that setup will work.

[A Schab]

Isn’t the the pattern of the 4 bolts on the end of the axle tube larger on B body’s than A body’s ?
I believe that A,F,G and X body cars use the small pattern and B,Y and truck use the larger pattern.I think that the 1965 Z-16 Chevelle is the only A body 12 bolt that will take the B body brakes.
Old’s Vista Cruiser’s and the Buick wagons with the glass tops both have larger rear brakes that will bolt right on. I think that the shoes are 2.5” wide compared to the regular 2” shoes.

[Schurkey]

That's why I was hoping for a confirmation/denial by one of our axle experts.

[Half-Inch Stud]

Originally Posted by bob prichard

I found a 65-72 big car Pontiac yoke for sale on ebay, from Frank’s Pontiac Parts. His ad states it has 28 splines, my Chevy 12 bolt has 30, so I don’t think that setup will work.

30-splines sounda like the Axle-Diff side gears. 30-Spline pinion-yoke for real?

[OG68]

I have a rear set of, if I remember correctly, 69 Vista Cruiser drum brakes.
The shoes are 2 1/2". Same as the front. They require the VC backing plates to work.
I ran them on my 68 for a number of years but had issues with the rear brakes locking up before the front drums. During the restoration I toyed with the idea of using them with a front disk setup but decided to keep the original drums with Muscle Car Brake Shoes.

And IIRC the 73-77 A body wagons had 11" brakes along with a select few Monte Carlos. Again, OPH can confirm.

[bob prichard]

Originally Posted by Half-Inch Stud

30-splines sounda like the Axle-Diff side gears. 30-Spline pinion-yoke for real?

Yes, unless I counted wrong. I also bought a Moser yoke for it with the same spline count.

[Tim Corcoran]

It appears that no one knows the answer to my original question. I have swapped the backing plates from the 10 bolt Pontiac rear housing and installed them on my 12 bolt rear housing. I will be installing the Pontiac 10 bolt brake details shoes drums etc. onto the Pontiac 10 bolt backing plates that are now on my Chevy 12 bolt housing. So, the answer to my original question is YES. Thanks for everyone's thoughts but it looks like I answered my own question.

[Half-Inch Stud]

On the 12-bolt Yoke deal: There is a Chevy Kingswood 454 "12-Bolt that is an "oversized freak; more like Dana60 proportions with 12-Bolt looks.

65-70 BOP big Car Yoke should/will spline nicely into the stock Chevelle-GTO-formula400 4-speed 12-bolts.

[grivera]

Originally Posted by Tim Corcoran

It appears that no one knows the answer to my original question. I have swapped the backing plates from the 10 bolt Pontiac rear housing and installed them on my 12 bolt rear housing. I will be installing the Pontiac 10 bolt brake details shoes drums etc. onto the Pontiac 10 bolt backing plates that are now on my Chevy 12 bolt housing. So, the answer to my original question is YES. Thanks for everyone's thoughts but it looks like I answered my own question.

That’s good news -

HIS and OPH answered yes early on

['ol Pinion head]

Regret I contributed to the "off in the ditch" discussion concerning backing plates. Last Soring & early Summer I went through several dozen original GM 9.5" drum rear backing plates, & though I knew there were 5 or 6 different functional styles, I was surprised by how many addition different cosmetic styles there were. That's where my mind was wandering when answering Tim's post.

On the normal width 9.5" drum rear shoes, I've been a continual buyer from both the original Praise Dyno Brakes, then its successor (same bunch) www.musclecarbrakes.com. Have also bought their wider front front shoes for several A-body (manual front drums). While, MCB's special matrix shoes are expensive, they do resist fade better than any parts store shoes. That noted, for each side, one of the higher tension return springs & one small stamped steel bracket in their brake in a box kit are an absolute nightmare to propeerly install. Would love to see MCB assemble those small pieces in house, & band them together, so they can be easily assembled on each backing plate. Its just 3 small pieces.

[400 Lemans]

The holes in the center of bop drums are slightly smaller than the chevy drums.You can get them to go over the axle ends but you will play heck getting the drums back off. They will hang up. Ask me how i know.

['ol Pinion head]

Originally Posted by 400 Lemans

The holes in the center of bop drums are slightly smaller than the chevy drums.You can get them to go over the axle ends but you will play heck getting the drums back off. They will hang up. Ask me how i know.

Been there too! One of the reasons the factory axles used in the Buick, Olds, & Pontiac usage McKinnon built 12 bolts are different than the common stock "68-72" A-body/ 70 F-body 12 bolt axles. The McKinnon plant also cast & built 12 bolts for some Malibus, Chvls, Elco's, & Monte's, but they will have Chevrolet specific axles, drums, & backing plates.

[Tim Corcoran]

I think the smaller 9.5 brakes from the Pontiac 10 bolt are plenty strong enough to stop the car if you have front disc brakes. I have been using them on my 65 LeMans low 10 second drag car for years and it stops on a dime. If you were running 4 wheel drums it might improve your braking

[Tim Corcoran]

Pinion, I see your post now your correct, I found out that the 10 bolt drums don't fit on the Chevy 12 bolt, fortunately I had some 12 bolt drums in my stash. Everything else bolted right up backing plates and all the brake details. I have the car running now with new engine and 12 bolt in place. I did put new wheel cylinders on the 12 bolt but now the brakes are not working correctly. Nothing to do with the 12 bolt I think it may be the M/C because the car has been sitting a long time. Even with power brakes it takes a whole lot of foot pressure to stop the car kind of dangerous to drive it like this. I'm going to bleed the front brakes and see if there is any improvement.