Can i see a Brake Plumbing Diagram (Drum /Drum) with proportioning valve location etc,,,, I seem to see a Disc /Drum but I lookin for Drum/Drum plumbing diagram with the proport. valve location.
Drum/drum systems never used proportioning valves. They did use residual valves up to the mid '70s, located internally in the master cylinders, and most vehicles used F/R distribution blocks that included a differential system pressure switch. That said, if you're using old non-servo fronts and modern duo-servo rears, a prop valve may be a good idea, because braking balance will be opposite what it should be.
See if this is what you're looking for: http://www.piratejack.net/index.php?option=com_content&view=article&id=11&Itemid=18 Kevin
I would fit an adjustable prop valve as no doubt front & rear wheels are different sizes, it makes a difference.
Subscribed! Having a nosedive problem with our 50 Chevy. It has the dreaded 72 Nova front clip & 76 nova rear. Drum drum power brakes. Running through stock metering valve, with no residual valves. Checked Pirate Jack's site just now and their info shows residual valves in both front and rear circuits. What do you guys think, or could this be a fauly metering valve problem? Thanks.
You don't want or need metering with drum/drum, but 10 lb. external or stock type internal (in the master) will be good.
Nosedive problem?? That's probably an alignment issue, unless your rear brakes are in need of rebuilding. Almost all post-war cars have been built with anti-dive characteristics, the Nova no exception. If it is installed incorrectly (ie: at an angle other than intended), it may dive when braking. Have the alignment checked first, before you start adding band-aids that may only make things worse. Cosmo
What I'm calling a metering valve may just be a distribution block. Came off the donor Nova. Located under the master, 2 3/16 lines for front, 1 1/4 " line for rear, probably sent brake problem signal to a dash light in its previos life. Pirate Jack's site shows a metering valve (their words, not mine) in a drum drum set up. Just wondering if there is anything to go bad on these.
That drum/drum diagram is really incorrect; only one residual needs to go to the fronts, and both F & R residuals should be plumbed closest to the master. More importantly, metering should not, and was never used on drum/drum. With a normal drum/drum, all you need is the front line out of the master going to front a tee, and the rear line going to the rear tee. If you want a dash brake warning light, use a combo distribution block and differential pressure switch, which you may already have from the Nova. Problem is most of these factory donor parts are 40 +/- years old! It's always best to use new brake components, and only the one's needed for a well designed brake system.
UPDATE; Orig question was because I got mixed advice when we did the brake system Update; There is no need for proportioning Valve with a Drum/Drum set up. With our dual master cyl all we need is a 10lb residual to be located less than 12" from front of master cyl forward toward front brakes. Our master cyl has a built in residual that takes care of rear brakes.
Any idea which 2 pot GM master has 10 lb residual valves built in? I was planning on using a Pirate Jacks 'Vette master and plumbing in a couple 10 lb valves in on our drum/drum '55 Olds. There has to be one I can buy off the shelf that I can use so I won't need the valves. We've moved the booster and master to the firewall so we could ditch the single pot master under the floor. Thanks, Kevin
There was a post on the proportioning and residual valve set ups by jimbo17 back on 04/03 and it explained it all from the TCI site
Nosedive under braking is caused when the rear brakes come on too soon or too hard (more or equal to the front)
Dual master cylinders had internal residuals from '67 (Cadillac a few years earlier) up to early/mid '70s, when better wheel cylinder designs, like cup expanders, and standard front disc brakes made them obsolete. It's best to use a matched booster/master combo, so use caution if you change masters.
The nosedive I refer to just feels like the front brakes are doing more than their share of work. Thanks for the replys/ideas. We drive the car quite a bit and get along ok, but have to go easy on the pedal. Did I mention these are power brakes?
The car wont dive if the front brakes do all or most of the stopping. When only the rears apply, the weight transfer shifts forward. The nose dives because the suspension settles forward, & the front tires continue to roll. You can test this with an ebrake that goes to the rear brakes.
Not sure how you arrived at the above ***umption, but the exact opposite actually happens. The vehicle (suspension) may squat, but there's very little weight transfer with rear brakes only, and the reason front-only braking will perform close to full system braking, because of weight transfer.
The dive is more pronounced because the front tires continue to roll. If you don't believe me, take your wifes car out & pull the ebrake & watch the nose drop Grab the bull by the horns, not the tail
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