I am going to replace the original booster and master cylinder on my '56 Sedan DeVille with a dual 8" booster/dual circuit master cylinder. I will have to change the length of the rod to the booster, but other than that it will be all stock, no mods to the pedal or linkages. Keeping the stock drums, stock wheel cylinders. My question is, what size master cylinder bore should I use? I don't want to have to stand on it to stop, but it is a big heavy car, and I want stopping power. I am thinking a 1 1/8" bore, but I'd like to hear opinions, and results if anyone has already done it (and I know there have been lots done). Tried to search but no results. Thanks for any input, Greg
Well, I thought about that, but I don't know if that would be an apples to apples comparison. I don't have it apart, and it was hard to find the bore size of the original anywhere. It isn't even in the FSM.. I think it is 1 1/8" now. The dual master would, I think, move a different amount of fluid. Plus, I wonder if the amount of boost with the old style booster would be comparable to the newer style. I want a good firm pedal, and the Cadillac has a pedal that is already pretty close to the toe board already, so my pedal travel is a little limited. I'd just like to get it right the first time. Thanks for the reply!
it has been over 50 years but my caddies never had what you would by today standards a firm pedal.I owned 7 over the years (54 -72) and they all had the same pedal feel but never failed to stop.Bob posted a solution to your perceived problem.no guessing
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