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One day this week I plan to replace my original master cylinder with repro MC. It looks fairly straight forward, but for those who have done it, any surprises or challenges I should know about. Looks like the clevis pin will be the hardest part to get at. Any tips? Thanks
PS, I forgot to mention that it has disc brakes on the front.
After losing my brakes on a steep hill years ago in a 1961 Pontiac convertible with a single master cylinder because of a blown brake hose , I always convert to double master cylinder . Our safety and the high value of these cars is too much too risk if you actually drive them . NCRS should make an exception for safety reasons .
Agree on the conversion to the dual master cylinder. Perhaps 65GG you already have a dual master cylinder if you have disc brakes on the front?
I just completed the conversion from the single master to the dual and so far am very pleased with the change. Very solid braking and additional safety.
I'm not converting to dual now. I'm just looking for information on replacing the original with an original type. I've been reading the forum about disc brake conversions, should I also disassemble the new one and remove the residual valve before install? I'm just asking if there's anything unusual about the removal and replacement and not an upgrade. I appreciate any advice in THAT direction.
I converted my '60 to front disc using the original single master cylinder. There was conflicting information about residual valve removal with this conversion. The majority recommended removal of the valve. I removed it and had barely any braking and it was just with the rear brakes. I reinstalled the residual valve and the car stops great.
Frankie, did you have front discs? If you did, did you remove the residual valve?
Wow that’s been a while but I’m pretty sure I left it in.
My 61’s front discs were converted with 73 Camaro parts. Worked superbly. Delco-Morraine calipers.
Last edited by Frankie the Fink; 11-12-2018 at 06:53 PM.
Well I have the new M/C now, but I don't know whether to take out the residual valve. I have strong advice both here and by PM from forum members I respect and trust split about half and half between take it out or leave it in. I understand the reasoning both ways, so I guess I'll have to decide something and try it and change it if it isn't working right. My inclination is to leave it in and drive and see how the brakes work and if the pads are dragging and decide from there unless someone has some compelling reason besides the dragging pads. I can take it out later I guess. Does anyone know for sure if it can be removed by disconnecting the brake line and the end plug without removing the m/c again? In the ST-12 it looks like that can be done fairly easily from the front end.
The residual valve maintains about 10 psi of pressure in the hydraulic system to minimize pedal travel with drum brakes (helps overcome pull-back spring pressure and parks the shoes closer to the drums); without the residual valve, a single full pedal stroke may not be enough to apply max braking power. Conversely, disc brakes don't use a residual valve, as constant 10 psi hydraulic pressure will fry the brake pads (Corvette disc brakes are a constant-contact design, and the springs behind the caliper pistons keep the pads in light contact with the rotors by design).
That's why master cylinders used on passenger cars with disc front and drum rear brakes only have a residual pressure valve on the outlet that feeds the rear drum brake system.
Thank you John, very clear explanation. I have a 61 FI car that I want to put a dual master cylinder on. The car is a big brake car so it still has drums all around. Do you have any suggestions for a supplier on this kind of setup? Jerry
Don't know where my original text went - the photo uploader ate it. At any rate, although Mopar and Wilwood probably have pieces that will work, so will '67-'69 Camaro/Nova dual drum/drum master cylinders - they already have the residual pressure valves in both outlets (Item #2 in photo).
So I looked up this master cylinder and it can be had in different bore diameters. My car is a HD brake drum option car and the wheel cylinders are all stock diameter. I believe the original bore diameter of the master cylinder was 1 inch , so my assumption is that i would use a 1 inch bore diameter with the dual master cylinder. The mounting for the original master cylinder used three bolts. The Camaro dual master cylinder from 67 thru 69 were a two bolt mount. I can machine a three to two bolt mount. I think someone on this board must have done this before, is this what you did and how did it work?
Well I decided to try it with the valve in. After the first brake press, I could barely roll the front wheels. The pads were very tight. I had to take the master cylinder back out and remove the valve because the replacement did not have the large end nut to remove to get to the valve. It's all back together, but it's rained all day and I did not drive it yet. If I need to, I'll add a residual valve in the line to the rear drums only.
11-11-2018, 10:50 AM
1960 Master Cylinder Replacement
At any rate, although Mopar and Wilwood probably have pieces that will work, so will '67-'69 Camaro/Nova dual drum/drum master cylinders - they already have the residual pressure valves in both outlets (Item #2 in photo). 
