Hey Guys, my 55 Buick Special finally runs really good.I took it out for its first ride above 10mph, and I'm a little concerned about the brakes. It has the factory drums, with the Treadle Vac. The brake system has been completely rebuilt. When driving the drums start to engage at light maybe 1/4 pedal but don't really do much until 1/2-3/4 pedal any more than that the front drums lock up. I feel like there should be a little more bite at lesser pedal. I tried to adjust everything the way the shop manual says, I'm wondering if the rod from the booster to the pedal needs to be adjusted, or maybe the brake shoes need to be adjusted. I figure there has to be something I missed. I've bled the brakes multiple times.
I'm not familiar with 51 buick brakes, specifically, but would start with readjusting the shoes. Also take a look at the arc of the shoes to the drums -are they contacting evenly across entire arc, or just at the ends or center ?
On those brakes I'd do just as I was taught in 1962. Tighten the brakes up untl you can't turn the wheel/tire by hand and back it off 11 clicks. That has worked for me for 61 years. I had a 65 Buick in 1966/67 but am not sure if it had the Tredle Vac or just regular brakes. I always thought it stopped pretty well and I drove the **** out of that car.
I had some early 1960s Oldsmobiles and Caddys, those stopped on the proverbial dime. I'd go with the adjustment advice above. One thing is to make sure the shoes and drums are not glazed up. A common error was cutting drums and leaving too-fine a finish.
Have the drums been turned? Oversize drums need to have the shoes ground to contact the entire surface (arced) and shims behind the linings if needed. Max safe drum diameter is normally .060" oversize. More than that can cause overheating, "bell mouthing" and possible breakage. There is much more to having good brakes than just changing parts. Unfortunately, with the advent of disc brakes and the decline in real brake shops you may have trouble finding some place with the knowledge and equipment to properly fit the shoes to the drums. Make double effort to prevent even a tiny amount of grease on the shoes. It can cause them to lock up. Even a greasy finger print can ruin a brake job.
Some older front drums could be turned .090 over, not sure when they started casting the # into the drums. A Motors Manual should be the answer. In short of having shoes arced, I bevel the leading and trailing edges with a wood rasp to help the break-in period.
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