Installing brake residual valve?

[TP]

I put after market power master cylinder and brake pedal on the firewall of my 59 buick. The car stops but the pedal is at the bottom. I have gone through all the steps I think to install the unit correctly. Bled lines[many times},bench bled m/c,new steel and rubber lines,new brake wheel kits,new brakes and turned hubs. It has 16# vaccum. The car originally had a tredle vac power unit on it. My question is ,I am going to install a 10# residual valve in the line of the back brakes.I have also correctly adjusted the shoes. drove awhile and re-adjusted. What am I missing. The pedal stops too low. I even replaced the new 7" vaccum booster thinking it was bad. The m/c is for a drum /drum car supposedly.? Do I put the res.valve up high by the m/c or lower on the frame near the rear? I have been jacking with this for months. Help. Thanks TP

[The Wizard!]

If your master has no residual valves in it you need to put them in lines for any and all drum brakes, it really doesn't matter to much where they are located as long as you have them. Without them you have low to no pedal and they often pull one way or another. You won't believe the diff. they will make.

[swade41]

With the pedal/master combo on the firewall it shouldn't need rpv's. Maybe your drums are turned to much and the shoes are having trouble expanding to them.

[thirty7slammed]

TP, is you mc mounted on firewall, if so I don't think a residual valve will help, They are mostly used when your master cyl. is mounted on frame under car lower than the wheel cyls. they are just a check valve to keep fluid from bleeding back to mc. You might check bore size of new mc, that could make a difference. Call ECI and ask for Ralph, he can definately help.

[TP]

Originally Posted by lBB41

With the pedal/master combo on the firewall it shouldn't need rpv's. Maybe your drums are turned to much and the shoes are having trouble expanding to them.

nope, thats not it. Calibrated them and they're good. I went by the recommendation in the book. Tighten drums until they lock up brakes and back-off I think it said 6 clicks. I am thinking residual valve will do the trick. I'll know by tomorrow night for sure. The master cylinder was supposed to have had them in it. Maybe it's bad. Anyone else have a guess of something I haven't tried?

[TP]

Originally Posted by thirty7slammed

TP, is you mc mounted on firewall, if so I don't think a residual valve will help, They are mostly used when your master cyl. is mounted on frame under car lower than the wheel cyls. they are just a check valve to keep fluid from bleeding back to mc. You might check bore size of new mc, that could make a difference. Call ECI and ask for Ralph, he can definately help.

Yes it is on the firewall. I know in theory it shouldn't need it but it was cheap. I can't remember bore size but it was ordered for the buick. What bore size should it be? Got a number on this ECI? Bore shouldn't affect pedal height I wouldn't think. I'm willing to try anything. I have tryed everything I can think of. If I change the m/c thats on it for one that came on a 69 chevy full size drum/drum with power that should be close wouldn't you think?

[thirty7slammed]

TP here you go.

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http://www.ecihotrodbrakes.com/index.html

[budd]

to adjust your shoes you need to jack up the wheel, give it a spin, you should hear the shoes draging on the drums just a little, a healthy one handed spin should see the wheel make one full turn then stop, if not then adjust it up a little, get in and step on the peddle to center the shoes in the drums, get out and give it another spin, keep doing this on all 4 wheels.

[mikes51]

First, I assume you car stopped okay before, and you haven't changed the brake cylinders (size) at the wheels.

Then the bore of your new power master cylinder should be the same or very close to the bore of your original master cylinder. Can you measure the old one and compare? I'm thinking your new m/c bore is smaller. so to push as much as fluid as your old bigger bore you have to move more fluid, to do that, you have to move the pedal further.

I just re read your post and noticed the tred vac, I don't know how that would effect my above statements. Did those tread vacs have a like their own "master cylinder bore"?

[TP]

Mike, they were basically a power brake system with a master cylinder with a single reservoir[spelling]. They are very expensive to rebuild. It was under the floor and had about the same size bore. I ordered this for the buick expecting it to be the right size. How do you know what size is right? I have a new[rebuilt] m/c for a 69 full size chevy drum/drum that I will try. They are about the same size and weight. The cae does stop but the "oh shit" factor kicks in. This car is for my son and I'm afraid he will panic. Keep the suggestions coming. I will try them all. The car did not run when I got it. So I just assume it stopped. All brake parts are new. If someone figures this out the beers on me at the roundup. Dirty 32 called and suggested I lengthen my rod between the pedal and booster. Right now it has about 1/4 " play in it. I'm going to mark it and then make it longer and try.

[thirty7slammed]

TP,been trying to post this image for about an hour now, Im not to computer savy. Anyway, this is what all the jibberish is in my last post about residual valves.


Good luck and call Ralph.

[mikes51]

Originally Posted by TP

The cae does stop but the "oh shit" factor kicks in. Dirty 32 called and suggested I lengthen my rod between the pedal and booster. Right now it has about 1/4 " play in it. I'm going to mark it and then make it longer and try.

That longer rod is a good idea. If the car does stop okay, then the problem is indeed psychological like you say. Psychological meaning we like to have have an inch or two between the pedal and the floor. That longer rod would move the pedal up away from the floor.

[TP]

37 I went to their site. None of the information is about drum/drum. I'll give ralph a call if all that has been mentioned doesn't work. Mike, I agree, maybe what Danny is saying is right. I hope it fixes it because he doesn't drink beer! Thanks TP

[groove]

You will need to install the residual valves in both lines, as your new MC does not likely have them installed. The valves hold line pressure that would otherwise be forced back into the MC because of the wheel spring hardware pulling the shoes back against the wheel cylinder. I have just gone through the same thing with my Merc after upgrading the MC from a single res to a dual. Let us know how it works out.

[Wyle E Coyote]

Your pedal ratio could be wrong also. If you have too much it will take a lot of travel and feel very soft. Most power brakes only need around 5:1 while manual is more like 7:1. Measure the full length of the pedal then measure the length from the top to the rod mount and divide the divide the pedal by the rod measurement. As an example, if you have a 10" pedal and your rod is 2" from the top then you have 5:1.

The rod length may be a problem but be sure you aren't presssing in on the booster when the pedal is at rest. Also check the length of the rod coming out of the booster to the master. It should just barely contact the piston in the MC. If it presses in the master even the slightest bit you won't get a good bleed on the system.

To check the bore on the MC just measure the piston from the back of the MC. Post that info if you can find it out and that may help too.

Residual valves aren't needed for the type of install you have, the info above about that is correct about needing them if the MC is lower then the caliper or drum.

[billwillard]

VALVE WILL NOT HELP Is the peddle hard when only pushed once or dose it kreep to the floor if you hold it down?

[DICK SPADARO]

Without explaining just what parts you purchased new that resulted in a different pedal experience makes trouble shooting difficult. Since you do have brakes but extensive pedal travel its more likely the problem one of these areas. If you have 1/4" free play in your pedal to master cylinder push rod you have way to much free travel. If your new pedal assembly pushes from the pedal to actuate the master cylinder via a clevis or heim adjuster you should re adjust the pushrod length.To get the free play necessary to prevent constant pedal pressure you should remove the bolt holding on the connecting clevis, pull the pedal to the up position desired. With the push rod inserted into the master cylinder and just touching the piston, adjust the push rod clevis so that the bolt hole opening in the clevis exposes 1/2 opening of the mounting bolt hole in the pedal arm on the master cylinder side.. Replace the clevis bolt and check the pedal to master cylinder free play, should be just a little 1/8" or so. Now just static brake check the distance the new pedal adjustment travels to the floor. If this is the same as before you have have not purchased a master cylinder with the same displacement as the old one as posted Mike 51 suggests. It is important to match the old displacement bore with the same displacement bore on the new master cylinder.

[67Imp.Wagon]

TP, check with Flt Blk on those issues. I believe he went through somthing similar with his and I think it ended up being that they gave him the wrong unit but ca;nt remember all the specifics. But you should shoot him a message and talk to him.

[TP]

Phil, was it on the truck or baker? the truck was mounted under the frame I believe. I'll contact him. I just got in from work and I am going to take Dicks sparados advice and start there. it's basically what Dirty 32 told me to try. We'll see in a few minutes. TP

[TP]

Ok, I spent the evening working on my brakes. Better but I'm still not satisfied. I lengthed the rod about a half inch and it's better. I tried several other things that didn't work. found that a manal brake bore size for 59 buick is 1" but i can't find the bore size for the power. it is uasually bigger. I drive a f-350 deisel truck everyday. I guess I am judging the 59 against the truck. It just doesn't feel right. I haven't driven a car in years. I may be expecting too much. I think next I'll change master cylinders. What would someone suggest? Bore size? application?Thanks for the help. TP