What's the difference in a pb master cylinder vs. manual ?
 

like the title says is there a diff. between a power brake mc vs. a manual? This is on a 72 chevy if that makes a difference. I had a guy tell me he took a pb booster and just pulled a manual mc forward and added the booster and it worked with some tweeking to the rod that hooks to the pedal. just wondering if anyone knows of a diff. thanks

Re: What's the difference in a pb master cylinder vs. manual ?
 

The bore of the piston are different sizes

Re: What's the difference in a pb master cylinder vs. manual ?
 

All of the manual master cylinders that I have seen have a very deep tapered hole in them to keep the rod in place. The manual rod has a tapered end to fit the manual master cylinder. I am not sure how you would be able to match the manual rod to the booster or match the booster to the tapered hole in the manual master cylinder.

Jim

Re: What's the difference in a pb master cylinder vs. manual ?
 

I pulled the master off my blown booster and bolted it directly to the firewall.
i have been told that in these year of trucks they have the same p/n power or manual. I don't know if it is true, however, I have seen plenty of people on here pull the master cylinder off the firewall and slip a booster in there, and roll with it trouble free.

Re: What's the difference in a pb master cylinder vs. manual ?
 

There's no difference. On my 68 I pulled the master cylinder forward and installed a booster. Several year later the booster went bad and I took it off and rebolted the m.c. back to the original position. I bought a booster last month and again just pulled the m.c. forward and reinstalled the booster.

I did the same on my 69 when I converted it to p. brakes. From what I've noticed the only difference is in the drum/drum vs. disc/drum master cylinders.

Re: What's the difference in a pb master cylinder vs. manual ?
 

Can't speak for all years, but can speak to a 67 drum/drum setup (so my A$$umption is that it's common across all 67-72 drum/drum setups...). Anyhoo, the Non-power drum/drum master was different from the 67 power drum/drum master - the manual had the deep hole in the back of the piston vice the shallow one that fits the booster's intermediate pushrod. Yes, possible to go FROM power to manual with the same master - the opposite is not true in a bolt-on fashion - will take some modificaiton of the interface/intermediate push rod between the booster and master.

Re: What's the difference in a pb master cylinder vs. manual ?
 

Re: What's the difference in a pb master cylinder vs. manual ?
 

wow thanks for all the great replies! it sounds like it is deffinently a possibility so I'm going to try it. it will be a couple of weeks before I can try it I have to get the truck home first , but I'll let yall know my experience with it . thanks

Re: What's the difference in a pb master cylinder vs. manual ?
 

Yeah, some modifications are required. I did have to adjust the push rod on the booster to m.c. out some, change out the brake pedal pushrod and adjust the brake light switch.

Mine was a little tight but just long enough.

Re: What's the difference in a pb master cylinder vs. manual ?
 

Mine bolted straight in with no adjustments that I recall. Works great. 68 Drum/drum.

Re: What's the difference in a pb master cylinder vs. manual ?
 

Its worth remembering that Power Brakes were also offered as a dealer installed accessory. My '69 list shows two kits, one for C,K10 and another for C20-30,K20.

Re: What's the difference in a pb master cylinder vs. manual ?
 

Some manual brake master cylinders have a residual pressure check valve. This should not be used with disc brakes. The valve is behind the brass seat that the line seals against in the port. I had a 67 camaro in the late 80's that I installed disc on the front and removed the valve in the port for the front. I have heard that these were stop being used sometime in the early 70's.