Hello. I am just starting the conversion from Drums to Discs in the front. I am keeping drums in the rear for a while. The mounting brackets allow me to use rotors, calipers, and pads from a '74 Buick. Here are some concerns... Will the 8-16 psi residual pressure cause problems with the disc brakes? I am considering keeping the single reservoir original master cylinder. It has a spring inside of it that maintains the residual pressure. Has anybody ever experimented with eliminating this spring and adding a totally separate proportioning/residual/metering valve? If I eliminated the spring in the master cylinder, I would add a residual pressure valve and metering valve on the rear drum brakes.
Senior Member
You will need to go with a dual master clyinder set up for disc front and drum rear. Then you will also need a proportioning valve to set up the right pressure for both. Check with Master Power Brake, they have all you need. Good Luck [img]graemlins/thumbsup.gif[/img] [img]graemlins/thumbsup.gif[/img] [img]graemlins/thumbsup.gif[/img]
I just thought of something. That spring serves to return the pedal back when you take your foot off the brake. It's the check ball that traps the residual pressure. I think you're right. Dual Master is the only way to go.
Sergio,
I'm sure I've mentioned this before, the trouble is I read it so long ago (and didn't keep the magazine) that I can't remember the details.
However, I'm fairly sure that one of the larger suspension companies, possibly H-O racing, did a conversion on a sixties Riv utilising F-body components which vastly improved both the ride and handling, with lovely big brakes and lower stance. Sorry I can't be more helpful, but as I said, it was a VERY long time ago.
Best of luck,
Malc
It turns out that Corvettes have the dual-bail equal reservoir master cylinder. It also also super low profile. Perfect for the Rivi. I found a reasonable source for proportioning valves. One last question. The kit that I am putting together uses the front brake hardware from a '74 Buick LeSabre. Does the brake hose/caliper connection require (1) or (2) copper washers? If somebody out there could answer that for me, that would be great!
Senior Member
Make sure the Vette master has the correct depth for the rod that comes off the pedal or booster. Are you going with power brakes. If the Vette master is for non-power it has a deeper hole. You can`t use your old booster (if you have PB) it isnt designed for enough pressure to run discs. Discs take between 900-1000 to work as drums can run on 600. I would consult with Master Power Brake as to the system that will work with your car---just to make sure. [img]graemlins/thumbsup.gif[/img] [img]graemlins/thumbsup.gif[/img] [img]graemlins/thumbsup.gif[/img]
I have discovered that the vette master will not work with the stock '63 Rivi booster. The pushrod is way too long. The available vacuum or "volume" is way too small. The setup that Master Power Brakes uses a custom master cylinder that is nearly identical to the 'vette master cylinder. The 'vette master cylinder also has a 1-1/8" bore compared to the 1" bore on the stock M.C. The 'vette master also requires the use of a dual-diaphragm booster. Most later generation GM cars have these. I am planning on installing a pressure reducing valves for the rear drums. I will check pressures at every corner before I hit the street. BTW, for those wondering why I'm not getting a kit from all of these aftermarket companies... In short, there is no kit for the '63. All of the commerciallly available kits are for '64+ I think that I am making progress. I've spent about $300 and am close to disc brakes(for the front at least)!
One other issue... My '63 still uses the hydraulically actuated tail-light switch. The 'vette M.C. has the boss cast so that a 1/8" nptf hole can be drilled and tapped to accept the stock switch and connector. I modified the 'vette M.C. last night. It actually looks like The General actually intended this to work. The aftemarket kits do not have a provision for the stop light switch.
Senior Member
IF NEED BE YOU CAN RUN A TEE FITTING OFF THE LINE AFTER YOU LEAVE THE MASTER CYLINDER--I AM DOING THIS AS I AM USING A NOVA BOOSTER AND A CADDY MASTER---THERE ARE INFINATE COMBINATIONS USING STOCK PARTS--I USE THE GUYS AT MASTER POWER BRAKE CUZ THEY KNOW THERE STUFF--ONE GUY OWNS THREE FIFTIES BUICKS AND HAS BEEN VERY HELPFUL...GOOD LUCK. [img]graemlins/thumbsup.gif[/img] [img]graemlins/thumbsup.gif[/img] [img]graemlins/thumbsup.gif[/img]
BTW, the older Buick Mag wheels that are on my '63 Rivi will not fit the disc brake rotors! DOH! The hub part of the rotor is too wide in diameter and will not interface with the Buick wheel. Thankfully, I have located a decent set of wheels within 20 minutes.
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