Could I use a porportioning valve set up off of a later model full size car that has a Drum/Drum brake set up, on my under the floor brake pedal setup on my model A? Basically I would be trying to use it instead of buying all the little check valves and stuff I was told I would need to use my pedal set up and not have ****py pedal pressure. I'm going to use a dual master cylinder on it but I'll still be running drum brakes on the front and back. Thanks for any help.
While we're on this subject.(Sorry I don't know about the stock valve) I just put all new disc/drums and under floor master cylinder, complete with residual valves, adjustible proportioning valve, the whole works. That they said that I needed.....yadda......yadda.......yadda. NOW I CAN"T GET IT TO BLEED!! I think I've tried everything. Any helpful hints out there? Thanks in advance, Don
not to sound obvious, but did you bench bleed the master cyl? also on my APV tightening (clockwise) the knob makes it wide open. logic would say the opposite, maybe you arent getting any pressure to the wheel cylinders because of that. are you getting fluid to any one bleed point, or none at all?
IMO it might cost a few extra bucks, but i'd just go with a brand new adjustable proportioning valve. it is a brake system, and streetrodder or not, i tend to go overkill. i dont want to f*#k around with my brake system.
Yes I did bench bleed the m cylinder. I havn't moved the proportining valve though. It was on 9 of 10. I am getting good clear fluid form all bleeders and every fitting. I've cracked them all with someone holding pressure on the pumped up peddal. The peddal will pump up after a few pumps. When you leave it alone it goes down on the first few pumps. When you start the car it goes down even quicker. The peddal is lazy coming back up when it's running. I sprayed brakleen on everything and let it sit. Everything is dry. No leaks. Everything from front to back is brand new. I am a firm believer that new stuff breaks too. So I'm not shure if everything is perfect. Any other help would be great, Don
Hey I agree that an adjustable proprtion valve is a good and inexpensive remedy to balance front and rear function but more isn't necessarily better. It allows experimenting for best result. Bottom line is whatever works for you.
Been there done that and learned the hard way. Sounds like you do not have any clearance between the adjuster rod and mater cyclinder. If so you will have no pedal or very soft pedal
Sorry, didn't mean to hi jack your post. If it's offensive than don't remember any of the tips to bleed your brake system after it's installed. I'll start another thread and you can use the ideas off of that. I only figured it would help the both of us. Don
If you buy a drum/drum dual circuit master cylinder (look for something off a late sixties car), it will have residual pressure valves built in to both outlets. These will work fine for under floor setups as well as firewall mounted setups. If you have the correct size wheel cylinders front and rear, then that is all you should need. If you have problems with the rear wheels locking up first, you can either fit smaller diameter rear wheel cylinders or fit a proportioning valve. I think the odds of a factory proportioning valve being correct for your setup are fairly small, so it is probably better to go for an adjustable proportioning valve like the Willwood version.
donzillia jack the front then rear of the car up as far as you can so that the bleader is way past the master then bleed ....might be trapped air.....that come from wilwood
simonsez is right. you dont need proportion valves 2lb and 10lb valves. all you need is what he says the right m/cyl and wheel cyls. brakes worked just fine on late 50,s and early 60,s cars. the valve stuff is a fix for a screwed up combination.
"Valves" are NOT bandaids for screwed up combinations. When you mix and match parts you are at times left without key features - Proportioning valves - Residual Pressure Valves - Metering Valves are used by the factory - they are also sold separately for us hot rodders mixing parts. 2 PSI RPV's are available because it's RARE (if they ever even did it) for the factory to do this - why?? Because the factory normally mounted the M/C much higher than the calipers. FWIW a drum/drum proportioning valve (when sized properly) will ALWAYS outperform a system that doesn't have one - exception possibly being an adjustable balance bar system. That's teh beauty of a proportioning valve (even a non adjustable one) is that they allow the pressure rise to the rears to be a function (proportion) of the fronts. It's a dynamic system - that's why they use proportioning valves. Bleeding a new system is a pain - ***uming you have no combination valve (or others) your problem could be that there is simply too much air in your lines to get an effective bleed. Pre-bleed lines - then re-bleed as normal. For the drum drum proportioning valve (combination valve) - choose one from a car that is as similar (in weight and brake system) as your own) . You won't need add on RPV's if you get a drum M/C with them built in.
What mastercylinders came with the valves built in? Perferibly GM stuff. I have some new mastercylinders for late 60's novas will one of these work?
You definitely need a proportionong valve. In your little model A if you have too much pressure going to the rears you WILL lock them up. You need to cut the pressure to the drums. An OE prop valve wont work as good as an adjustable one from Speedway or Wilwood. An OE one is set up for a car with drastically different dimensions than a Model-A, meaning it probably still send too much pressure to the rear brakes. If your M/C is below your calipers (like the illy above shows it) you need residual valves. If you don't put em in fluid will drain from the calipers and wheel cylinders. New system are always a bear to bleed. I bet ultimately there is air still trapped in the system somewhere. On a new system I had, I couldn't bleed the brakes for the life of me. I changed, M/C's, bleeders in the calipers, changed the pedal. What eventually fixed it was tapping the calipers with a rubber mallet while bleeding it to coax some stubborn bubbles out. JMHO Joe
I could be wrong but I never heard of a Drum/Drum setup that used a proportioning valve. As I understand the original post it's going to be a Drum/Drum setup.
A factory m/c for a drum/drum set-up is the ones that normally have the built in RPV's. The factory RPV's are installed under the tube seat (the tapered part that the brake line seals against) - to see if there's a RPV in there you can VERY CAREFULLY take a tooth pick or paper clip and insert it - if you feel resistance - you are feeling the "rubber flap" of the RPV. Another (safer) method is to shine a light into the fitting - if you DON'T see light in the inside of the master it is likely being blocked by the RPV. I also suppose you could just blow into it - there will be more restriction over all and it will be extremely difficult in one direction versus the other - but make sure no one see's you so this - you don't want to start any rumors. You can deny it later. Keep in mind the factory normally did not use a proportioning valve with a drum/drum setup - but they had the resources to size each component for the application. In a hot rod - you might have to resort to an adjustable proportioning valve if you want to optimize your system.
The determining factor on whether or not you need a proportioning valve is real world testing. The delicate brake balance the factory built into braking systems is more times than not lost when we hot rodders mix and match components. Simply adding taller rear tires to an otherwise properly working factory drum/drum (or disc/drum for that matter) can be enough to get your rear brakes locking up prematurely. Test it and know for certain it works as needed - this way when a emergency situation arises - you can put yourself in the best possible chance for a good outcome.
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