? about what master cylinder to run.......

[Pro Fleetline]

Looking to update my single master cylinder to a nice dual peice with out the huge booster i have seen some that are a nice bolt in replacement. Any idea what peice would work on my 56 2-10 still has drum brakes just looking for a nice upgrade nothing to exotic. is there a GM peice that will work or an aftermarket? Thanks for any input

[Rick_L]

Go to the auto supply and get a master cylinder for a 67-68 Camaro, Nova, or Chevelle with manual drum brakes. It will bolt to the lower pair of bolt holes that your original used. Then all you need to do is connect your old brake line to the front port on the m/c (or a replacement line). At the tee at the right front brake, disconnect the line to the rear brakes and plug the tee where you disconnected. Now run a new line from the rear port on your new m/c to the rear brake line that you disconnected. You should be able to get all you need at the auto supply, but it might be nice to cut and flare the new line so it fits nice and looks good. Now would be a good time to get new hoses if they are aged.

[Pro Fleetline]

Thanks sounds just like what im looking for thanks again

[henrys57wagon]

You could use a 71 Nova drum brake M/C also. Good day, Henry.

[JLS]

Does anybody know what the piston diameter is on the manual drum brake Camaro M/C? Are they small diameter like manual disc M/C's? I know they have Vette manual disc brake M/C's that are 1" bores but were Camaros available with manual discs? What is the bolt spacing of those M/C's that fit on the firewall?.......wow that's a lot of questions...I need a nap!

Joe

[Rick_L]

1" bore is the answer to all your questions. There were manual discs available on Corvettes, I have no idea about Camaros.

The only functional difference between a disc brake master cylinder and a drum brake master cylinder is the possible presence of residual pressure valves on the drum brake models on 67-70 model cars. These can be removed if present.

The other difference in master cylinders is that drum/drum units usually had 2 small reservoirs, disc/drum units had a large reservoir and a small reservoir, and disc/disc (Corvette) had 2 large reservoirs. While the large reservoirs are nice, you can run a small reservoir master cylinder with discs - you just need to check the fluid level more often.

[henrys57wagon]

Again on our disc/drum 71 Nova we have a manual M/C off same application. Good day, Henry.

[Black 55]

Where are these residual pressure valves located on the master cyl? Thanks, jim

[Rick_L]

They are a rubber "duck bill" type valve located under the brass flare seat cone. You can insert the blank end of a drill bit in there to see if you feel a rubber part.

You don't want them in there if the line is connected to a disc brake, as it will cause the pad to drag on the rotor.

You can remove them by tapping the cone for a 6-32 thread. Then put a 6-32 screw about 1" long in the hole, and pull the cone out with a claw hammer. The residual valve just sits in there, remove it with your fingers. Clean everything, remove the burrs from the cone, and replace it.

In the past I've found new cones at the auto supply, but I haven't been able to recently.

I've also purchased rebuilt master cylinders recently that should have had them, but did not (A-1 Cardone brand).

[bigbopper]

Hello,
Late 60's master cylnders are the way to go like several others have stated. That was the beginning of the disc brake option on GM cars, so there was some nice 1" bore MC's with the drum/drum avaiable. There was also disc/drum non power assisted options available clear up to the early 70's. My favorite MC for disc/disc setups is the 1968 Corvette non power assisted. What I suggest is you go to your favorite jobber and tell them you would like a MC for ????? late 60's GM car with the set-up you have disc/drum for example and let GM engineers figure out the design you need.
If you have your brake lines off and look into the port where your lines attach. Your drum brake port will have a thin brass cover hiding the port opening and behind it is a rubber wafer and this is what GM used for a residual pressure valve. It is always a good idea to check this prior to installation and make sure it fits your application. If you later want to add disc brakes, all you have to do is remove this "check valve". I just use a thin srew driver and work it out.
I hope this helps