Have to ask....what exactly are you wanting to accomplish? for a car/truck that weighs about what a Camaro does, 12" brakes would be a pretty aggressive brake, even with narrower shoes that the stock Buick 2 1/4" or 2 1/2" width. That could be moderated with wheel cylinder size, but it's a LOT of brake. The reason I emphasize that so much is that rear wheel lock up is a very dangerous situation. It will cause a vehicle to go sideways or do a complete 180* turn around when you least want that. The answer to your question is....probably......with a change in backing plates. So, what's your goal here? Ray
Building a model a 1930 Tudor sedan with Buick drums up front,just thought it would be cool to have the same drums all around,if I only had to change the backing plates to 12" Buick rear backing plates.just wondering if anyone has done this.
Here's an off -the - wall suggestion....See if the Buick drum would fit over the whole Chevy drum /backing plate setup...in other words , just use it as a cover...might have to do some trimming ,etc ...Might have to get longer wheel studs I'm sure the engineer-types will think of a million reasons not to do it....but ......just sayin'...
The inside of the Buick drum is not flat past the diameter of the hub. There is not enough material to machine them flat before going all of they way through. Just get some GM G-Body drums, they go right on:
Yup. I have a set in my garage now that I pirated from an early 80's 4 cyl camaro. Probly never use them but they were finned aluminum drums....
Using an s10 rear in the roadster I'm currently building. Have Buick 45 fin up front with 58 Buick backing plates. I also wanted rears to match, removed a quarter inch of Buick lining from the top inch and s10 drums slide right in. Bolt pattern matched!
The bolt pattern on the S10 is 5-on-4-3/4". The bolt pattern on the Buick 45-fin drums is 5-on-5". The center register hole in the Buick drum is much larger than the registration shoulder on the S10 axles. Remove your wheels and take a picture of the the registration hole. There is a significant taper to the inside of the Buick drum that will prevent the inner drum from sitting flat against the outer drum:
We put the buicks on a brke drum machine and turned the top inch of lining out. My friends a machinist, they are still at his house, he must have redrilled the bolt holes and turned the centers of the buicks. When I placed them in they looked close and he called and told me they were done. Sorry for any misunderstanding. I hope to pick them up this weekend. Will let you know. NAPA has a book of wheel studs, have to measure and find a set that fit both drums and my wheels to press in.
Wouldn't hurt to cut ALL the iron liner out. It would reduce rotating mass (flywheel effect) and reduce unsprung weight. Both would be beneficial in minimizing performance loss due to "style over physics" Ray
Yes, like Ray said, if it's just cosmetic, cut out the whole liner and thin the aluminum till you can almost see through it.
s I agree that on an average street car with the same size tires on all four corners, and likely 60 front 40 rear weight distribution, that 12" rear brakes would be aggressive or even dangerous. On the other hand, a Hi-boy roadster, with small 165R15 front tires, big 265/60R15 rear tires, and close to a 50-50 weight distribution, can we still assume that the front brakes will/can do most of the work??? My slide rule says that on a highboy, with big and little tires, the rear brakes will have to do a lot more of the work than one might expect. On a Hi-Boy having the big Buick drums on the back might make sense. (besides looking cool).
I am fitting 90 fin drums to a 9" Ford, using Buick backing plates. the 90 fins and the 45 fins will work on the same backing plates. The question becomes how good a machinist are you and do you really want to deal with that much brake on the rear. GM put aluminum finned drums on some Malibu wagons in the '80s. If I had a Camaro rear that is the direction I would take unless I was a pretty good machinist and already had the Buick parts.
And I agree with the conclusion you reach, given the variables you selected. I think what both our posts suggest is that there are many factors to consider when choosing brake components for a well thought out, safe system. At the time of my post, the OP had not revealed his exact plans. But, this being a forum dedicated to traditional hot rods, it seemed likely he would be building a fairly lightweight vehicle. He did indicate he wanted to use 12" brakes on both ends, but did not say what respective tire sizes would be used. Ray
The Jalopy Journal
