Dual Diaphragm booster for 1964 Chrysler (smaller firewall bolt pattern)

[xander18]

Ross and others have covered this but I'll throw my two cents in to say that you definitely need the correct booster. Part of the reason is because disc brakes require higher forces. Drum brakes are somewhat self-energizing because as the leading edge of the shoe contacts the drum it gets wedged in, requiring less braking force (also why they don't stop as well in reverse). But disc brakes are all squeeze with no mechanical advantage. To get that higher force you usually need higher line pressures but that also depends on the relative bore sizes of the calipers and master brake cylinder. Hydraulics only get you so far and the additional force of more booster surface area is almost always gonna be required.

But proof is in the pudding: with a single diaphragm booster in good condition (no leaks) the car stops like garbage.

 

[C-440-300]

Just for the record, my 66 New Yorker had a disc booster off a 69 300. If I had to guess I'd say the booster had the same bolt pattern on the firewall side as a 4 bolt master.

I would think if you have to redrill the firewall to fit the later booster, as long as the rod is centered the same as the 64 was, the stock pedal should work. Assuming the rod length etc is compatible.

Kevin

FYI, my '66 300 booster was replaced by Booster Steve (Booster Dewey Exchange at the time - BTW, I understand they both retired and the new outfit is in WA state?) with the mid-70s COP car Midland dual 9". He had to shorten the rod on the Midland Ross single that I used for exchange (was the original 4-drum booster). Booster had power! But, I learned my 1" 1/32" MC not cutting it. Went to 1". Now, the prop. valve has an effect on the rear (4-disc). I still wonder if I go to smaller bore. 'Just my experience. Cheers!