disc/disc master cylinder?

[ocbaud]

anyone have the link for what is a good m/c to get for a disc/disc setup???

i know mike did it and some other stuff has to be done, but if i'm buying a new master cylinder, and i plan on getting a rear disc kit, i might as well do it once.

[swervin ervin]

Eric,

I used a disc/disc combination valve and disc/disc master cylinder from Master Power Brakes. Here is direct links to them. My brakes work fantastic BTW.

http://www.mpbrakes.com/products/pro...product_id=613

http://www.mpbrakes.com/products/pro...product_id=537

[low sierra]

I bought mine from http://www.performanceonline.com/sto...tomer/home.php
really liked price and service.

[ocbaud]

Originally Posted by swervin ervin

Eric,

I used a disc/disc combination valve and disc/disc master cylinder from Master Power Brakes. Here is direct links to them. My brakes work fantastic BTW.

http://www.mpbrakes.com/products/pro...product_id=613

http://www.mpbrakes.com/products/pro...product_id=537

have you seen the $599 rear disc kit in chevy duty??? i was thinking about picking that up when it comes time for it.

would you also recommend getting a new booster? mine seems fine, but if its apart, might as well replace it if something else is better.

also, with that master cylinder, would it be possible to use it with the stock drum brakes in the back? the truck is drove maybe 20 miles a month, if that, so i'm just wondering if it would be drivable with that m/c until i get the rest of the rear disc parts.

[72C203503ONTHETREE]

When I put disc brakes on the rear of my 66 Chevelle(fronts to) I used a Corvette master cylinder from the early 70's. They will bolt up the same and of course are made for four wheel disc brakes and are cheap from the parts stores. You would need a proportioning block but can also get an adjustable one like I did from Summit racing. Barkes worked great for not a lot of money.

[swervin ervin]

No, you can't use a disc/disc master cylinder with drum brakes. As far as the booster goes, it depends on what you are after. I replaced mine when doing my brakes but I didn't really have to, just wanted to.

[ocbaud]

Originally Posted by swervin ervin

No, you can't use a disc/disc master cylinder with drum brakes. As far as the booster goes, it depends on what you are after. I replaced mine when doing my brakes but I didn't really have to, just wanted to.

what happens if you do?

last month, i honestly probably went about 10 miles, to either go to the store or pick up some food.

[swervin ervin]

Disc/drum masters have built in 10 lb residual valves. This is to keep pressure on the drum brakes since they have to move the shoes so far before making contact with the drum. If you didn't have the built in residual valves the spring from the drum brakes would collapse the wheel cylinder when the shoes released. The next time you hit the brakes you wouldn't have any rear brakes, unless you pumped them a bunch of times.

So without a residual valve, as disc/disc masters don't have, you would have some pretty sorry brakes, as in almost none.

I know what you are trying to do but rebuilt master cylinders are pretty cheap. Just replace yours and save on trying to get by with the wrong parts.

[magnethead]

or just leave the rear brakes unhooked.. not fun but feasible.

[ghetto_superman]

i just bought a stock '72 chevy style reman booster/master cylinder setup.. havent put it on yet, but will it work with my 4 wheel discs? or do i need to return it in favor of a corvette unit? also what kind of prop valve is best for this? sorry- dont mean to hijack this thread, but ive been wondering and were on the topic.. thanks,
-Mike

[swervin ervin]

For disc/disc brakes no proportioning valve is needed. Only a combination valve. As I said above, stock disc/drum masters have a built in residual valve that holds pressure on the rears. If this master is used in a disc/disc setup the rear brakes will drag. I know a lot of folks will say they used an external proportioning valve to reduce pressure to the rear brakes to help overcome this but the only correct way of doing this is with the correct master cylinder. I guess almost anything can be made work but the questions is does it work correctly. I don't like taking shortcuts with my brakes.

Oh, to answer your question, yes, the booster will work but the master isn't the correct one.

[ocbaud]

Originally Posted by swervin ervin

Disc/drum masters have built in 10 lb residual valves. This is to keep pressure on the drum brakes since they have to move the shoes so far before making contact with the drum. If you didn't have the built in residual valves the spring from the drum brakes would collapse the wheel cylinder when the shoes released. The next time you hit the brakes you wouldn't have any rear brakes, unless you pumped them a bunch of times.

So without a residual valve, as disc/disc masters don't have, you would have some pretty sorry brakes, as in almost none.

I know what you are trying to do but rebuilt master cylinders are pretty cheap. Just replace yours and save on trying to get by with the wrong parts.

sweet, just figured i would ask to see why it wouldnt work

i'll probably end up gettnig the refurb one for now, i have a lot of other stuff to do before i worry about the rear brakes.

[ghetto_superman]

ok sweet i think ill just return my huge 11" booster/MC setup and get one from a corvette. whats the best years of corvette again? id like it to look as "era correct" as possible.. (ie.. not plastic and such)