Disc Brake Help

[Rickb1b]

OK guy's I installed a chevy disc brake kit from one of the vendors. Now for some reason the brakes are dragging excessively. Looks like the disc brakes are not retracting slightly after I let off the brakes. Anyone got any idea how to trouble shoot and fix this. For what it's worth the lines are plumbed from the master cylinder, to proportioning valve, to the H-block, to the discs and rear drums.

Thanks Rick

 

[shamu]

Ditch the H block and plumb it like a factory ford disc brake set up. If you need pics I will send them to you.

 

[Rickb1b]

Pics would be great. When initially plumbing this, my question was; how do you run the line to the right disc. This is why I retained the H-block and the lines from the H-block to the brakes.

Guess I'll just pull the H-block and run lines to the spliter on the differential.

Make sense?

 

[miikee73]

There is a ball and spring in the master cylinder port,the line going to the front brake that is behind a brass cone shapped thing with a small hole in it. Put a screw into the hole in the end and pull it straight out.remove the ball and spring and replace the brass cone.

 

[Pa PITT]

Yes like Mikee73 said .. back in the day I sold a little tool .. which was a really good screw . You screwed it into the cone and pulled that cone out . It was really tough to pull some times . Use something like a seal or dent puller to knock it out.
.. That the valve & spring out of it and then replace the cone..
.......
... I was going to say ditch the proportion valve and keep the H valve . That the way mine is set up.

 

[broncnaz]

While you dont need the H block you dont have to remove it it doesnt do anything. As for plumbing the prop valve well one of the front ports needs to be plugged you only use one and the rest of the front brake plumbing is just like stock one line to the axle and it splits there.
Aside from removing the residual valve from the MC if it has one. Did you double check the caliper to knuckle clearance? if the clearance is to small the calipers will get hung up and cause dragging issues. Also check to make sure the pedal is not putting pressure on the MC you could have a pedal to MC linkage lenght issue.

 

[Rickb1b]

Thanks guys. Funny thing. I went out and took the wheel off, compressed the pads back a little and things started working OK again.

However, in case they start acting up again, is the spring and ball you speak of located behind the cone shaped brass, which is the seat for the double flare steel line.

 

[Rickb1b]

Broncaz, All good points, I will check them tomorrow. And yes I did cap off the second front port on the proportioning valve.

 

[miikee73]

Thanks guys. Funny thing. I went out and took the wheel off, compressed the pads back a little and things started working OK again.

However, in case they start acting up again, is the spring and ball you speak of located behind the cone shaped brass, which is the seat for the double flare steel line.

Yes it is ,when you pull off the brake line at the MC it is the seat for the line. Mine came out easy.I clamped vise grips on the screw. The rotor clearance is also very important.Good luck,the mod is worth the trouble.

 

[Rickb1b]

OK, just an update. Problem is still not fixed. Checked the master cylinder and there are no check ball-valves in there. I decided to take the proportioning valve out. Still had the problem; put the valve back in. Then inspected all the lines. I found the front two steel brake lines flattened a little, so I replaced them. Still have the dragging brakes.

So at this point, every component in the entire brakes system is new, except the two brake hoses to the differential. I have new ones on order. If that doesn't fix it I'll be officially stumped. BTW, the brake rod length is perfect. Thought it might be adjusted too long, but it isn't.

The only other thing I can think of, is the calipers not pulling back. But I think this is highly unlikely, since they are both new, and the odds of two new ones being bad seems low.

 

[shamu]

My guess bad MC.
Now correct me if I am wrong but the front disc line is the one closest to the fire wall.

 

[Rickb1b]

I kind of thought it might be a bad master cylinder too. So I called the vendor to see which one I have. It has both reservoirs the same size, they use this one so you can hook the front discs to either master reservoir. Therefor I tried hooking the front discs to one then the other, didn't change anything. I suppose it's possible I have a bad master cylinder, but it would have to have both valves inside of it bad.

 

[shamu]

I kind of thought it might be a bad master cylinder too. So I called the vendor to see which one I have. It has both reservoirs the same size, they use this one so you can hook the front discs to either master reservoir. Therefor I tried hooking the front discs to one then the other, didn't change anything. I suppose it's possible I have a bad master cylinder, but it would have to have both valves inside of it bad.

Keep trying and good luck brother.

 

[Ghost Pony]

You sure your calipers aren't striking the knuckle? If they are hitting the knuckle they will not float properly on the disc and will drag. My knuckle had to be ground down slightly so they didn't strike the calipers.

 

[Rustytruck]

Jack up your front end. rotate wheel do they drag?
now apply the brakes hard let off and then rotate the tire does it still drag or or drag harder?
if you have manual brakes unhook the master cylinder from brake peddle and rotate the tire does it still drag?
if you have power brakes loosen the connection at the master cylinder.
If the wheel is still dragging loosen the brake bleeder screw and rotate tire did the brakes release.
this will sort out wether its hydraulic or mechanical.
if releasing the brake rod or loosening the master cylinder sloves it then its a mechanical issue and the mastercylinder and pushrod lengths need to be resolved.
if loosening the bleeder resolves the issue its a hydraulic problem usually tied to the mastercylinder mounting.
if both sides have the same problem check your mastercylinger mounting and knuckle clearence.
if its only one side and the bleeder screw loosening doesn't relieve the pressure I would check for a stuck piston.
in clearencing the knuckle it needs to be clearenced more than just not touching since as the pad wears the caliper gets closer to the knuckle.
This all assumes you actually get all the air out of the system.
As for the master cylinder the mounting for disc brakes must not have a residual valve and for a mastercylinder to have no residual valve in either ports means it was made for front and rear disc brakes thats OK if you have both but if you have drum brakes in the rear then you have the wrong mastercylinder or you need to add a residual valve on the line going to the rear drums. If you have a true proportion valve that is not adjustable it needs to be the proper one for Disc, Disc or a different one for Disc, drum systems.

 

[rekoj71]

another question is how much dragging (i.e. how many fingers to push the tire around). Is it just touching once in a while and you can hear it. I think my other cars do that a little too. Or another possibility, I did a brake job once that after putting new disks and new pads on, the whole assembly was tight enough (no extra tolerance) that the pads were already retracted against the caliper frame as far as they could go. I had to fight to get the loaded caliper over the disk and it had drag untill I drove it for a day to wear them in a bit. I didn't do fast driving cause I was affraid that if it built up too much heat I might warp a rotor. It was the same on both sides too. Just an idea.

 

[Ranchtruck]

OK, just an update. Problem is still not fixed. Checked the master cylinder and there are no check ball-valves in there.

Did you pull the seats out of the master cylinder ports? The residual pressure check valve lives behind the seat, I call it a duckbill valve because that's what it looks like.

Have someone step on the brakes while you look at the master cylinder reservoir with the lid off. There should be an upwelling/squirt in the reservoirs as the pedal is first applied. This is the pistons moving past the compensating ports. If there isn't, the pistons are pushed too far into the cylinder when the pedal is released.

Stand hard on the brakes, then get out and crack one of the bleeder screws open. If you get a squirt and the brakes stop dragging, you have some check valve still in the system.

 

[Dan73Grabber]

OK, just an update. Problem is still not fixed. Checked the master cylinder and there are no check ball-valves in there. I decided to take the proportioning valve out. Still had the problem; put the valve back in. Then inspected all the lines. I found the front two steel brake lines flattened a little, so I replaced them. Still have the dragging brakes.

So at this point, every component in the entire brakes system is new, except the two brake hoses to the differential. I have new ones on order. If that doesn't fix it I'll be officially stumped. BTW, the brake rod length is perfect. Thought it might be adjusted too long, but it isn't.

The only other thing I can think of, is the calipers not pulling back. But I think this is highly unlikely, since they are both new, and the odds of two new ones being bad seems low.

Check your shims and caliper alignment. I just installed same items from Tom's and have had no dragging issues. Good luck Bronco dude!

 

[u10072]

Forget all the diagnostic stuff- did you grind the calipers or not? If you can't see an 1/8" of daylight between the caliper and the knuckle after installed and pressure on the calipers--- you need to grind some more. You can chase all kinds of stuff but if the clearances aren't there, all the advice in the world is usless.

 

[Rickb1b]

Ok this is for the archives. I'm pretty sure I have figured out my problem. I changed the front center brake hose and the problem seems to have gone away. The brakes feel normal now.

Now this is for all the experts out there to help shed some light on this. I have always been told the way to tell if a brake hose is bad, is the brake pedal will feel spongy. In my case the brake pedal got more firm. After driving and using it, it kind of felt like when you are pumping up the pedal prior to bleeding them. However, if I let it sit overnight the pedal feel would be normal at first and then after a couple of uses, they got firm again. It basically felt like a really firm pedal that wasn't releasing all the way and based on how hot the hubs were getting, I'm pretty sure it wasn't.

OBTW, yes I did grind the calipers. There is well over 1/8in clearance.