Power Disc/drum conversion by ...unknown

[64plybelvwgn]

I purchased a 65 Belvedere from an elderly gentleman who had no details about the car other than it has a 70 440 ( verified ) , modified a/t, and 3:55 suregrip. Somebody at sometime put in a power disc front / drum rear conversion with a proportioning valve. I've done this myself before with a Jeg's kit and a SSBC proportioning valve for the rears, but don't know anything abut this set-up. What I do know is that the rear wheels / tires appear to lock up before the front...which is not the way it's supposed to be. I also wanted to install a Hurst Line-Loc but someone separated the front left & right so I would have to re-plumb that into a Y then into the Line-Loc anyways.
Any suggestions on what this set-up is ? ( Please see pic ) And how I may be able to readjust the bias between the front and rear brakes.? If there is an adjustment for the Prop valve, where is it hiding ?

View attachment 403260 View attachment 403260 View attachment 403260 View attachment 403260
Thanks in advance. Any help is sincerely appreciated.
Ted

View attachment 403259

 

[Kern Dog]

That looks like a common "Corvette"master cylinder that was popular in kits from Master Power brakes. They often had a 1 1/8" bore and really needed that booster to avoid an excessively hard pedal. The proportioning valve seems to be a generic unit common to the swap too. I was given one from a buddy but have not tried to use it.
Many ways to reduce rear wheel lockup. Personally, I'd consider an adjustable valve with a knob. You could also look into smaller wheel cylinders for the rear brakes. You'd have to google search the different sizes but I do recall that some minivans and Dakotas used an 11/16" wheel cylinder that was supposed to be the smallest cylinder known to physically fit with the right inlet thread size and pitch.

 

[dan juhasz]

That is common GM stuff, no way the I'm aware of to adjust. You can either limit pressure with the adjustable style in line valve, and or experiment with pressure hold off valve that are usually preset.

 

[6-david-5]

I purchased a 65 Belvedere from an elderly gentleman who had no details about the car other than it has a 70 440 ( verified ) , modified a/t, and 3:55 suregrip. Somebody at sometime put in a power disc front / drum rear conversion with a proportioning valve. I've done this myself before with a Jeg's kit and a SSBC proportioning valve for the rears, but don't know anything abut this set-up. What I do know is that the rear wheels / tires appear to lock up before the front...which is not the way it's supposed to be. I also wanted to install a Hurst Line-Loc but someone separated the front left & right so I would have to re-plumb that into a Y then into the Line-Loc anyways.
Any suggestions on what this set-up is ? ( Please see pic ) And how I may be able to readjust the bias between the front and rear brakes.? If there is an adjustment for the Prop valve, where is it hiding ? View attachment 403261 View attachment 403260 View attachment 403260 View attachment 403260 View attachment 403260
Thanks in advance. Any help is sincerely appreciated.
Ted

View attachment 403258 View attachment 403259 View attachment 403262

Ted

I'll bet this is the valve you have:

http://www.ebay.com/itm/361824239593?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

I have been taking a hard look at that valve and have been investigating it for my other car. There is even a guy on A-bodies only selling that set-up. Other speed merchants online advertise that proportioning valve by itself as being universal and that it "would work for a disk/drum setup".

However, on my '65 Belvedere, I use a '73-'76 A-body proportioning valve, stock 10" drums/wheel cylinders on the rear and 11 3/4" rotors in the front with slider calipers from a '79 Chrysler Newport. NO adjustable valve. That setup has NEVER given me a minute's problem! I've driven that car like an animal more times than I should mention and have stopped the car hard to make the first turn-out at the end of the 1/8'th-mile before. I am duplicating this setup on my '67 when that time comes because I know it works.

I would probably replace that valve with this one similar to this:
http://www.ebay.com/itm/70-74-Mopar...ash=item25b8dda09d:g:BJ4AAOSw2ENW8aWP&vxp=mtr

I have also used a valve similar to this one successfully on my son's dart with a Scarebird brake conversion:
http://www.ebay.com/itm/Adjustable-...id=100005&rk=5&rkt=6&mehot=ag&sd=122259425088
....... I never even adjusted the knob, and the rears don't lock up!

I'm making the assumption that your rear brake condition is good. I hope the above was helpful, and that you reach your solution soon!

David

 

[64plybelvwgn]

That looks like a common "Corvette"master cylinder that was popular in kits from Master Power brakes. They often had a 1 1/8" bore and really needed that booster to avoid an excessively hard pedal. The proportioning valve seems to be a generic unit common to the swap too. I was given one from a buddy but have not tried to use it.
Many ways to reduce rear wheel lockup. Personally, I'd consider an adjustable valve with a knob. You could also look into smaller wheel cylinders for the rear brakes. You'd have to google search the different sizes but I do recall that some minivans and Dakotas used an 11/16" wheel cylinder that was supposed to be the smallest cylinder known to physically fit with the right inlet thread size and pitch.

Great ! Good info... I'll look into the adjustable valve as well as the smaller rear cylinders. Thank you.

 

[64plybelvwgn]

That is common GM stuff, no way the I'm aware of to adjust. You can either limit pressure with the adjustable style in line valve, and or experiment with pressure hold off valve that are usually preset.

Thank you. Was afraid of that . May just tear it out and start from scratch with an adjustable valve like I did on my 64.

 

[64plybelvwgn]

Ted

I'll bet this is the valve you have:

http://www.ebay.com/itm/361824239593?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

I have been taking a hard look at that valve and have been investigating it for my other car. There is even a guy on A-bodies only selling that set-up. Other speed merchants online advertise that proportioning valve by itself as being universal and that it "would work for a disk/drum setup".

However, on my '65 Belvedere, I use a '73-'76 A-body proportioning valve, stock 10" drums/wheel cylinders on the rear and 11 3/4" rotors in the front with slider calipers from a '79 Chrysler Newport. NO adjustable valve. That setup has NEVER given me a minute's problem! I've driven that car like an animal more times than I should mention and have stopped the car hard to make the first turn-out at the end of the 1/8'th-mile before. I am duplicating this setup on my '67 when that time comes because I know it works.

I would probably replace that valve with this one similar to this:
http://www.ebay.com/itm/70-74-Mopar-A-body-plymouth-dodge-Duster-Dart-brake-valve-proportioning-meter-/162015322269?fits=Modelart&hash=item25b8dda09d:g:BJ4AAOSw2ENW8aWP&vxp=mtr

I have also used a valve similar to this one successfully on my son's dart with a Scarebird brake conversion:
http://www.ebay.com/itm/Adjustable-Brake-Proportioning-Valve-with-Built-In-Distribution-Block-Fittings/141659328950?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIC.MBE&ao=2&asc=41451&meid=87f263de89af4b74a4f2d5686d1292fb&pid=100005&rk=5&rkt=6&mehot=ag&sd=122259425088
....... I never even adjusted the knob, and the rears don't lock up!

I'm making the assumption that your rear brake condition is good. I hope the above was helpful, and that you reach your solution soon!

David

David. Excellent ! Thanks very much for your reply. I'm going to look into those mentioned options before I tear into it...or discard it and start from scratch. Ted