I have a 54 Buick Special with power assist brakes. The master cylinder/booster is frame mounted under the driver's seat. It looks like the master cylinder is shot and I don't want to rebuild it again as this was already done 2 years ago and pretty all set with it. I'm not concerned with being period correct as am about reliably stopping. But, I am going to stay with the drum brakes themselves, not looking to convert the entire $ystem. Does anyone have suggestions as to a master cylinder/pedal assembly that converts nicely in this era GM. I'm cool with mounting on the firewall if necessary. I'm told mid 80s GM Van style masters work well, but not finding anything about that on the interweb. I thing 53-55 Olds and Caddy are similar set ups to what I'm currently running..so if anyone has experience with those (or Buick) and can help thanks in advance.
I'm in the midst of installing a dual master cylinder in my '55 Special, which is the same as your '54, I believe. The problem is, the original M/C is held on with 3-bolts and newer M'C's are 2-bolt. Because of the X-frame member, there's no room to drill for the right-hand bolt in the mounting pad and have room for the nut. (pic 1 - sorry the pics are a little fuzzy) I made an adapter that will bolt to the original mounting pad using 3- Allen Head counter sunk screws. I drilled & tapped the adaptor block (pic 2) for 7/16-20 bolts to hold on the new master cylinder. The adaptor block is 5/8" thick to allow enough "meat" for tapping (1½ depth x diameter of bolt). I used a 1970 Chevelle master cylinder (non power) (pic 3) as it has a 1" bore (same as the '55). I also had to increase the length of the actuating rod about 1-3/8" and I had to cut the access hole in the floor boards rectangular and back about 4" or 5" and fabricated a cover ( sorry, no pics). Not much of a tech article, but I've bolted it together for a trial fit and it all looks great. Hope this will help you. Any questions, feel free to ask. -Bob
Thanks Tag Man, Nice work! Was the original M/C standard(no power booster) and mounted of the forwad bracket (right under the reservoir "trap door" on the drivers side floor)? Or was it the power Treadle-vac set up and mounted on bracket about a foot farther to the rear with the resevoir filler under the hood ? What made you choose the 70 Chevelle M/C ? I assume mounting it on the Firewall and changing the pedal assembly was more work than fabbing the bracket ,and dealing with the rod and floor accesss? Thanks, Jesse
Yes, my M/C was a non-power unit, not the Treadle-Vac and the adaptor was made to mount the dual m/c in the same position. I like the look of the stock firewall and yes, making the adaptor was a LOT easier than changing the pedal assembly or so it seemed to me. Making the new rod was easy, as was the new trap door, just took some careful measuring & time to fabricate it. I chose the '70 Chevelle m/c only because it had the same bore as the stock one. I checked the specs at a couple of online sites and it looked perfect for my needs. -Bob
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