Stan's Customs

I've searched the forum...can't find the thread. Unless I'm dreamin' there have been some post on using a manual master cylinder on 4 wheel disc brakes on a C1..

Anyone know where it is..? ...or how they turned out.?

Seems like maybe Bill and Herb both have or have tried the combination...?

If I am dreamin'... consider the thread started..
Does anyone have that set up?

Best regards..Stan..

Viking427

Are you referring to the modified Mopar master cylinder;

http://forums.corvetteforum.com/c1-a...-cylinder.html

1 inch bore & made for 4 wheel drums, so be sure to pop the brass seats out of the ports (gently pry out with a drywall screw & hammer claw) and remove the 10 lb. rubber residual valves & springs behind them or your calipers will drag. You probably won't need to replace them with the disc brake 2 lb. residual valves either unless you have too much stroke in your brake pedal afterward. 3/16" brake lines are recommended with discs (higher pressures).

ABSPowerBrake now has an OEM looking C1 master cylinder plumbed for dual ports on page 56 of thier catalog: http://www.abspowerbrake.com/maincat...ameset006.html
..but I don't think it's dual reservoir. They said it won't be ready until the end of the year, so it might eventually appear in production or it might not.

cbernhardt

I thought that the general consensus of the old thread was that the MOPAR used an external residual valve and no modifications were necessary with 4 wheel discs?

Charles

Viking427

The Cardone 101323M master cylinder referred to in that thread has internal 10 lb. (drum) Residual Valves directly in the ports of the master cylinder that can be easily accessed and removed by popping the brass seats out of those ports. Replacement with 2 lb. (disc) RV's are probably not necessary as long as the MC is located above the calipers since there should be adequate head pressure (elevated MC) to keep the caliper pistons extended and fluid from draining back into the MC. If you do in fact find you have slow pedal reaction, or you're using the newer "low drag" design calipers, 2 lb. RV's can be inserted into the ports to ensure all calipers remain full of fluid and the pads remain poised to grab the rotor. 2 lb. RV's are designed for disc applications and will (should) not cause rotor drag or premature pad wear.

Brass blocks located beneath/beside the MC, or down on the frame can house the brake light, hold-off/metering valves and residual valves ..or any combination of the above ..hence the name combination valve.

This particular MC (Cardone 101323M) has the RV's in the ports, so I assume it's OEM application specified the brass block housing only the brake light switch and/or hold-off/metering valves. The 1" piston is about the max you'd want in a manual 4 wheel disc application since the required pedal pressure (increases exponentially with increase in piston diameter) may be uncomfortably high. You can always locate the MC pushrod a little higher on the C1 pedal arm to allow for a lighter pedal (more leverage) by drilling another hole just above the factory one. This dual-hole arrangement is how it was done by the factory to accomodate both manual and power brakes and why power brake pedals seem to sit a little lower than manual brake pedals. Keep in mind, doing so will also increase pedal stroke.

toddalin

Why wouldn't you just go into the auto parts store and say, "Give me a master cylinder for a manual brake '70s Corvette."??? That's what I did for my '64.

Viking427

No can do ...different mounting flange style on C2 vs. C1 master cylinders. We're left to cobble contraptions of our own device

wmf62

Stan
i used the standard good oldfashioned regular single OEM 62 master cylinder on my 4-wheel disc brakes; worked fine.. just make sure you take the residual valve out of the front of the inside of the bore or the brakes will drag.
Bill

wmf62

Charles
i wasn't aware that there was any residual valve in the Mopar manual brake dual m/c we used for our conversions.
Bill

firstgear

yup, have that now. While it stops the car, I really want a different pedal feel so as we have discussed I bought the electric brake set up to install.

Here is what I have now...


Summit Racing


If you want to get a stand off, Meyers Racing has them as well as ABS Power Brakes.

Here it is installed in my car....

Stan's Customs

Thanks for that Bill..

How would describe the pedal feel/pressure....easy, moderate, firm pressure required. Normal or sorta strange because we are used to power assist...

Are hard fast stops easy to make..

I'm using 87 corvette calipers..

Thanks Stan..

Stan's Customs

That looks "really" good Herb. Nice! Have you driven it much yet...? How does it feel...is it what you were after..??

I like the idea of a remote pump very much. But I thought I'd look at all the old post once again before I dropped a grand. I like simple too....."if" it can be made to work well.

I remember you having some issues with the manual stuff. Hard pedal and slow stops or ...??

Thanks ..Stan..

Stan's Customs

[QUOTE=Viking427;1570869447]Are you referring to the modified Mopar master cylinder;

http://forums.corvetteforum.com/c1-a...-cylinder.html

Yep thats the one ..I don't know why the search didn't bring it up. Guess I didn't mention Mopar..

Thanks Viking....Stan

wmf62

Stan
very solid pedal; firm pressure required for hard stops because of no power brakes (we've been spoiled...).

the effort to stop using any non-power m/c, single or dual will be higher.

i have used the single m/c in 3 braking configurations, all with the same acceptable results:

1. 4-piston 65 front calipers with 62 drum rears





2. 4-piston 65 front calipers with Cadillac disc rears



3. single piston GM front calipers with the same Cadillac rear discs



Bill

Stan's Customs

Mornin' Bill..

Yep, I knew it would be higher..just wondered if it bordered on difficult?

Stan..

PS...I haven't been impressed with some of the so called power brakes with the small boosters. I've seen some manual brakes that worked about as well..

Stan's Customs

...are the dual master cylinders harder than the single m/c's for comparable stopping?

wmf62

Stan
i don't see any difference. in either case i have to 'stomp on it' harder if i want to stop quicker...
Bill

Stan's Customs

Well at least when you stomp on it it stops. Unlike some of the late model ABS stuff that just quits stopping early . I really diislike ABS brakes because of that....too much old school I guess. You learn to let off the brakes before you skid in the old cars..but you had ALL the car's braking ability at YOUR control.....unlike some of todays brake systems..

Of course when I started driving..most cars had manual brakes..especially those I had access too..Ha!

I don't remember them being hard to stop at all...or the pedal being particularly stiff.

I've got sooo much to do on this car...saving a grand on the brakes would sure help. Might consider doing manual brakes for now and change them later when I get it going...if need be.

Stan..

wmf62

Bill

cbernhardt

Well, I was not sure whether the MOPAR master cylinder had residual valves, but it does. Below is a picture of the one that I used. The insert shows the residual valve. The brass plug that covers the valve is a pretty hefty piece of metal. I assume that it needs to be put back into place for the brake line to seal.

Charles

wmf62

Charles
John just called me and alerted me of your post. about all i can say is: "i'll be damned"..

but, having said that; i have noticed no problem with my brakes dragging like they did when i still had the check valve in the original single m/c.
Bill