I installed a dual reservoir master cylinder in my '48 18 years ago. The MC was originally for a 67-70 Chevy (NAPA 36239). The bracket was from CPP. The adjustment of the plunger rod has always been incredibly touchy.
If the plunger rod is screwed in a bit too far by maybe only one fine thread, the brake pedal will rise while driving and braking and possibly make the shoes to drag badly, possibly a lot.
If the rod is screwed out a tiny bit too far, the brake pedal will go almost to the floor (but still stopping).
34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
What brakes on the truck? Disc drum, drum drum, orig huck or later bendix? Do you have separate residual pressure valves installed for each end? of appropriate pressure? Think it’s residual 10 psi for drums….2 psi for disc I used a corvette manual brake master from 1970, 1” bore, on my 46 (huck) Chuck
Last edited by Hanks custodian; 04/14/20228:09 PM.
Couple of things though. The new master cylinders no longer come with pressure residual valves, even on the master cylinders that are specificed for manual drum drum applications. Factory masters all came with the little rubbber duck bill valves. So to mimic that pressure, you might consider installing say Wilwood red pressure residual valves in line for the front and rear brakes.
Are you running a distribution valve or porportioning valve?
I have drums; Huck on the rear and Bendix from a '57 1-ton on the front. No power. The MC is bare bones with nothing additional. No residual pressure valves or proportioning valve. Sounds like I'm valve-deficient.
I notice Cletis' Tech Tip on upgrading to a dual reservoir MC does not mention the valves. Is there a diagram-for-dummies around?
34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
Typical recommendation is to install as close to master as practical, I put mine below the top of the master, seemed to make sense….I also have a adjustable proportioning valve on the rear brakes, not sure if you need one with bendix front/huck rear, you’ll find out when you test drive a panic stop to see if the rears lock up prematurely.
Last edited by Hanks custodian; 04/14/20229:11 PM.
