Which master cylinder bore size to use for power disc Kelsey/Hayes

cudajim said

My 67 Barracuda has stock Kelsey Hayes power disc brakes stolen were from a 68 Valiant. I got the brakes, master, prop valve all at once. Only problem is that the fronts don't grab well/rears lock up and the pedal is not so firm. The master also leaks from the top due to rust so it's time to change it anyway. My question is, what size bore should I buy and how do I get it to stop properly?

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Sounds like air in the system... And considering the fronts don't grab the air is probably in the front half of the system...

Rears grabbing can be a lot of things.... drums out of round, newer shoes with the lining in the wrong location, (very common these days) grease on the the brake linings.. Brake adjustment... Lots of things...

I believe the OE Master for that application is 1" & unless I've made 100% sure everything is working correctly and I still don't like the pedal feel I tend to default to the OE M/C size...