Editing 1937-1957 Buick Oldsmobile Pontiac suspension upgrade (section)
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===Notes=== *Your original drum setup used 1/4" brake lines. 3/16" is recommended for disc brakes. *Many aftermarket master cylinders have metric fittings. You may find yourself putting different fittings on each end of your new lines to convert from metric to inch. There is a direct metric match to the 3/16" line size, so that is not a problem. *Master cylinder size is important, but slightly flexible. One option is the Corvette-style master cylinder, with ports located on either side. This makes installation easier, and they're fairly cheap. *The 1" bore will do the job, but expect the pedal travel to be a bit long. On the other hand, a 1-1/4" or larger master cylinder will move the fluid faster (shorter stroke), but the small 7-inch booster might not be up to the job, the result being a too-hard pedal effort. Your original master cylinder may push the discs fine as far as volume goes, but pressure could be another matter. *Virtually all cars will need an adjustable proportioning valve. Any change from the original setup – front or rear weight change, tire sizes, line sizes, rake or tail drag, disc conversion, etc., has the potential to throw your brake system out of balance. *Most disc conversions will require at least 15 inch wheels; check it out before you order. *The project in this tutorial used a Corvette 1" ID master cylinder, and a 7" single stage booster. This combination turned out to be "close enough". The brakes are a vast improvement over manual drums, but not perfect. Stopping power is great, until about the last 20% of pedal travel, as several test panic stops revealed. At the very bottom, you just can’t push hard enough to lock them up. The system probably needs a 9 or 10 inch booster to be perfect. There simply isn't enough power in a 7 inch booster to lock up a set of 215/75x15 tires on a 3500 pound car, on dry pavement. ====Improvements two years later==== Never really happy with the 7 inch booster. Moved some things under the hood to get more room and installed a 9 inch dual diaphragm booster from a mid 1990s Camaro. Now it stops like a new car. I'll never use a 7 inch booster again.
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