Check valve in 64 master cylinder?

[Paul J.]

Re: Check valve in 64 master cylinder?

James,

Power steering and power brakes are two nice upgrades but I certainly don't see anything wrong with drum brakes. I installed P/S on my 67 and I love it..

I don't understand why some people change out there drum brakes to disc but the reason may be to use a dual circuit master. It's a nice safety item but a well maintained drum brake system should be fine.

I think we've been told for the last 40 years that disc brakes are far superior to drum brakes without anyone qualifying that statement. It depends on the design and application. But as long as people have money to throw at their projects the aftermarket will be more than happy to step in.

[John H.]

Re: Check valve in 64 master cylinder?

Stu,

I was a little confused also as most check valves or limit valves are external of the Master Cylinder.
JR

Not really. RPV's (Residual Pressure Valves) are always internal to the master cylinder in GM production drum/drum or disc/drum systems, and, other than the '66-'67 Corvette J-56 HD Brake option with the Kelsey-Hayes rear proportioning valve, no Corvette disc system had any sort of external valving until the brass "combination valve" appeared later in the C3 era when the car got heavier.

The '67-up distribution block which includes the differential pressure switch for the "Brake" warning light in the cluster isn't a valve at all, and performs no fluid valving function - it just contains a spring-loaded spool that provides a ground.


GM Disc/drum systems on steel passenger cars from '67 through the early 70's DID have external valves - a metering/hold-off valve in the front disc system, and some also had an external proportioning valve in the rear drum system (in addition to the RPV in the master cylinder drum outlet). In the early 70's, all three disc/drum functions (metering/hold-off, proportioning, and differential pressure switch) were consolidated in the brass "combination valve".

Here's a link that covers the details of 1960's GM disc/drum brake system valves:

http://www.camaros.org/brakevalve.shtml

[Stuart F.]

Re: Check valve in 64 master cylinder?

I should have known better about the RPV valve in the 63-64 masters. Although it was 3 or 4 years ago that I changed out my brakes, I also changed the master back to a correct dated 63. So, while I was at it, I put a kit in the 64 master that I removed in order to have a spare on hand.

Stu Fox

[James B.]

Re: Check valve in 64 master cylinder?

I think we've been told for the last 40 years that disc brakes are far superior to drum brakes without anyone qualifying that statement. It depends on the design and application. But as long as people have money to throw at their projects the aftermarket will be more than happy to step in.

Are disc brakes superior ? It is really a moot point- bottom line is that if my 64 L84 was a 65 L84 it would be worth about twice as much as it is (65 l84 rarity counts for a little of the difference but 64 is relatively rare as well).
re throwing money at Project, I collected 65-7 disc brake suspension parts over 4 years at swap meets and did the conversion myself. I doubt that I have $300 in the conversion and when I go back to drums will probably make the investment back.
Yes, like the rest of the public I got sucked in reading car mags in the 60s. As I remember the big thing was fade resistance to repeated hard applications. Of course driving a manual disc brake 67 today compared to a C6- feels like no brakes at all.

[Stuart F.]

Re: Check valve in 64 master cylinder?

I really liked my sintered metallic brakes when they were working well years ago. The drawbacks, for street use, were mainly poor braking when cold. When hot, they were great. In fact, the hotter they got the better they got. I guess the racing drawback was that they were erratic and perhaps inconsistent. For long races, well, anything that required lining change during a race the vote went to disc brakes hands down. Back in the mid 60's, the head engineer at the company I worked for told me that if the auto industry wanted to change over to disc brakes on all models it would take up all the foundry capacity in the U.S. to meet the demand. Hummm, I wonder how that worked out?

Stu Fox