Project: 49 GMC, MII subframe, 70's GM midsize front brakes, 71 Nova rear axle and brakes. My donor car is a 91 Cadillac, and I was planning on using the brake booster and master cylinder, but have decided against it. The pedal setup is nice, but the booster is huge, 11 inch? , and the reservoir is sloped. My question, what is a good/cheap alternative brake booster - master cylinder that will work ? The reservoir needs to be flat, the booster needs to be smaller (if possible) and I would like to hook up easily to the caddy brake pedal. Speedway has a nice package, but it's all new parts and it's $180 Opinions? Is there an OEM setup that would work nicely? C1500? S10? Camaro? Thanks, Rich
I ***ume you are using a 11x1 front disc brake and a 9.5x2 rear drum brake. This system came from GM with a 1 and 1/8 master cylinder and a 9.5 inch single diaphram booster. Any 70's GM midsize car uses these parts, and are probably available rebuilt at your local parts store. The 9.5 booster is available on a lot of later GM stuff, including an S10. In 1978, GM intermediates (and the S10) went to smaller front brakes an a 15/16 master cylinder. You could also use the 8" tandem diaphram booster or the 9.5x8 tandem booster also used on a lot of GM cars. The 8"tandem is probably the most compact. The angle mounting depends on what car it is in - look around your junkyard and you'll find "level" ones. Hope I helped - if not, PM me ( I designed these systems back in the day!)
Good info. Measuring the booster, it's about 10 inches, and there's no reason not to use it, other than a smaller booster might look better. So, what's to keep me from just buying a dirt cheap mid 70's reman 1 1/8" power brake master cylinder, and throwing it on the caddy booster? Rich
That master cylinder pictured is out of a '57 chevy. Pick up one of those at the local Napa for about $50 and find the booster that fits it.
That master is NOT from a '57 Chev. They had single, not dual master cyls. It appears to be a '68-'72 or later Corvette master cyl. They are commonly used on streetrods because they have a large capacity.
I'll ask again... So, what's to keep me from just buying a dirt cheap mid 70's GM reman 1 1/8" power brake master cylinder, and throwing it on the caddy booster? Rich<!-- / message --><!-- sig -->
I did a 47 GMC several years ago, before all the catalog parts.... I used a Camaro, late 70's ealry 80's booster (looks smaller than what oyu have there) and master cylinder. Fit good looked nice. I even used the pedal hanger and column mount. Had to shorten the pedal/booster/MC bracket a little on the dash side and added a little length to the pedal arm to get it closer to the floor. All in all I thought it looked great for the $15 in junk yard parts. The truck stopped like a dream. I just thought it was easier to modify existing GM parts to get what you needed done. Hell I drove it for several years and never replaced one of the junkyard parts. Johnboy
In answer to your question, nothing. I think the Caddy booster is the "Metric" version of the 9.5 - but I may be wrong (the 90's are too new for me). The booster pictured for the Corvette might be a better choice (8x8 tandem), and they can be found in other GM cars in the junkyard - mainly Caprices,LeSabres and the like). The Corvette master is also a popular choice - 1" bore.
The Corvette master is available in 1", for manual brakes and 1 1/8" for power brakes. I use the 1 1/8" on my roadster with 4 wheel Corvette disk brakes and no booster. The pedal pressure is higher but I like the decreased pedal movement.
The bolt pattern and size of the opening are not the same, its easier to use the booster intended for that master cylinder. I have a 8" diameter one with a 70s mid size gm master in a 55 desoto with the same size brakes as what you are describing. I also have a combination valve installed, which I would recommend. I bought my stuff in a kit form, but it is all factory type stuff. just make sure the booster has the same size opening. I would guess vega/monza size cars had the small booster.
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