Residual Check Valves

[LDO]

Ok, 57 3100 with the CPP complete front disk brake kit. Booster & MC are mounted in original location under cab.

I have the red 10lbs check valve on the rear drums, 2lb blue check valve on the fonts. I know the check valves are used when the MC is lower than the calipers and mine looks like the MC is slightly above them just from 'eyeballing' it.

Came back from my test drive yesterday and smelled hot brakes and they were smoking a little. It also felt as if the truck had to overcome the dragging brakes when starting from a stop.

When I pump up the brakes, my front disks lock up and stay locked up until I tap the brake pedal and then it releases pressure. Haven't checked the rear drums yet.

Is this a normal operation for these check valves?
Do I need these in the system?
Anyone run a similar setup as mine without them?

Thanks for the help!

[_Ogre]

i don't think the residual check valves are your problem.
many of us have had the same problem of disk brakes dragging on new mc installs.
mine was caused by new cab mounts depressing the brake pedal ever so slightly.
most are caused by the rod length into the mc, check to see if it is adjustable and shorten it a bit.
my mc was depressed less than 1/8'', it doesn't take much to make them drag.
not sure what is causing your lockup on the front disks, fix one problem at a time to see if the issue still exists.

[LDO]

Follow up!

My 2lbs pressure valve was installed backwards. YES, I am a doo-fus!

But that wasn't the end of my problems. You are correct, the pushrod needed adjustment.

All good now.

[LDO]

Well, now that I've got the valve installed correctly, I've been driving the truck a little and I'm not too happy with the front brakes. After sitting at a red light for a bit, it feels like there is a line loc or something where I have to tap the brake pedal in order for it to release.

Any advice on what I should try?

Any negatives on removing the 2lb valve to see how it feels?

[_Ogre]

when you mentioned that in your first post, i was hoping you were mistaken.
maybe a problem with a caliper locking up, try to repeat it with the wheels in the air and see if it's one sided.
make sure your pedal isn't hanging in the floor.
removing the valve may require more pedal travel, but if you suspect the valve, by all means remove it to test.

[LDO]

Ogre,
thanks for the advice. Gonna get to work on it this morning and I'll post up what I find. I do know it's both front wheels because the last time I had the truck up on jacks, I verified they were both locking when I hit the brakes. I hope I get this resolved.

[mr48chev]

What master cylinder did you use? a lot of the drum/drum master cylinders have built in residual valves behind the brass seat for the fitting on the brake line. When guys started switching to disks they would have to pull the brass seat out an take out the little valve and spring and put the seat back in.

I't's a bit of misinformation when it is mentioned that the residual valves are needed only for the vehicles with frame mounted master cylinders. They are also used with firewall master cylinders but quite often builders use the residual/combination valve that comes with the master cylinder off the donor vehicle with those installations and some kits come with the combination valve.

[LDO]

I bought the entire front disk kit from CPP that comes with the MC and the prop/ valve as well as the press. valves for the front and rear.

[Old Crow]

I hate to drag up an old thread, but the OP in this one mentions adding residual valves to both the front discs and rear drums.
We're using a kit we got from CPP with the booster and master mounted under the floor, but ours didn't come with the valves. I've been looking at instruction sheets on different manufacturers sites trying to determine whether or not there should be valves on both ends of the system, but none I've found really say one way or the other.
This truck's a long way from on the road, so the trial and error method is not available to me right now.
Does anyone know for sure if both ends of the system should have valves?

[crossfire84]

Not sure if this will help.

[dwcsr]

Valves are used only when the master is below the wheel cylinder and if the master has the valve in it its always for the drum never for the disk. You should not have to add valves with the master in the stock location and ride height.

Your bolts are on the way

[wolffcub]

Originally Posted by Old Crow

I hate to drag up an old thread, but the OP in this one mentions adding residual valves to both the front discs and rear drums.
We're using a kit we got from CPP with the booster and master mounted under the floor, but ours didn't come with the valves. I've been looking at instruction sheets on different manufacturers sites trying to determine whether or not there should be valves on both ends of the system, but none I've found really say one way or the other.
This truck's a long way from on the road, so the trial and error method is not available to me right now.
Does anyone know for sure if both ends of the system should have valves?

Im running disk/disk using no residue valves. No issues no matter what angle i park at or steep the grade. Im even lowered 3" from stock but the wheel calipers are still just below the MC level. All the info i ever got was that the are only required when your MC is actually below the calipers or cylinders.

[Old Crow]

Ride height on this '54 is going to be about 3" lower than stock, maybe just a smidge more. Eyeing it as it sits on the lift, the calipers are just about even with the m/c with no weight on the suspension.

I've also got a '58 truck in here that the owner put a front disc kit on(no idea who's kit). No valves in that one, either and no matter how tight we adjust the back brakes, the pedal is still really low. Pushrod length is good, and the pedal is firm, but only a couple of inches off the floor.
I was thinking of trying a set of valves in that one too, but it's at stock height, so that might be a waste of effort.

[OrrieG]

Originally Posted by Old Crow

I've also got a '58 truck in here that the owner put a front disc kit on(no idea who's kit). No valves in that one, either and no matter how tight we adjust the back brakes, the pedal is still really low. Pushrod length is good, and the pedal is firm, but only a couple of inches off the floor.
I was thinking of trying a set of valves in that one too, but it's at stock height, so that might be a waste of effort.

Sounds like the length of the rod from bottom pedal lever arm to booster or MC is too short, longer rod will move pedal further off of the floor. If you are using the stock brake light switch on the fire wall it needs to come up higher to engage the switch lever.

[LDO]

Well, I removed both valves from my brake system and everything is working great for about a year now. No drag and no other issues.

[Old Crow]

On the '58, pedal height at rest is pretty much at the stock height. Travel is, like I said almost to the floor. It's got a hydraulic brake light switch, so that's not an issue.
I suppose I could try lengthening the outside rod a bit. I've already checked the booster push rod length, and it's OK.

LDO, how come you removed the valves? Couldn't get it to quit hanging up otherwise? I was wondering if it was a big deal to have those valves in the system if they weren't really needed?

[LDO]

yes the brakes would lock at a red light. I would have to dbl tap the brake pedal and then the truck would start moving forward. Didn't care for that so I removed them and now all is fine.

[yoshi]

I'm having problems with too much pedal travel on my 49. Disc/disc with new mc under floor. Email chat with Brothers says I've gotta try bleeding them again.

[wolffcub]

you still using a stock linkage set? I used a booster kit that keps the stock clutch and brake pedals and main shaft. I actually cut my brake pedal so it lower to the floor because mine would never come close to hitting the floor and felt awkward lifting my leg so high for it.

I went thru all the same issues. First off the pedal went all the way down after doing nothing but bleeding. Found it the rod in the master cylinder was too short. Adjusted it so it was longer and then had the issue with the brakes holding at a light. Found out the rod was too long. Took a bunch of fiddeling with but it now works perfect. I took all my valves out when trying to find out why they were locking at the lights turns out i never needed them anyways.

I found that using a vac bleeder was better then pumping the pedal as you can just take your time and not need someone else to help.

[Old Crow]

Well, I spent yesterday on the '54 truck, making sure the booster pushrod is right and finishing up bending the lines. O'Reilly's finally showed up with the unions I needed about 3:30, and when I checked the mail, the banjo blocks I needed were there, so I guess Monday I'll finish up the '54 and start adding fluid.

The '58 is in storage right this moment because they finally decided to fix the roof in our other shop building that was damaged last winter in an ice storm. Idiots gave me zero notice to find a place to store 5 half-completed cars plus the parts I had stacked in the work area. Then they stood around for 2 hours while the guys and I pushed cars and moved parts.
Once I get it back, first thing I'll do is verify the booster pushrod length, then maybe add a bit of length to the rod from the pedal to the booster.

On bleeding, I usually use a big syringe I got at the Co-op to force fluid back through the lines from the wheel cylinders/calipers into the master cyl. Most of the time, after I've done that from all 4 corners of the vehicle, a quick round of normal bleeding, and the brakes are good to go. If I end up using the check valves, I'll have to use a more conventional method, I suppose.