Front Disc Brakes sticking a little - why and how do I fix it?

[Orange]

So I replaced my booster, master cylinder, prop. valve, and lines running to the unions this weekend.

Did a complete bleed until I got clean fluid only through all the lines (from the RR, LR, RF, LF, and brakes stop fine. No light on the dash, everything is really pretty good.

Only thing is the fronts stick a little. They aren't just plain grabbing, but they do hold. I jacked up the front, and the wheels won't make a complete full revolution without stopping. The rears are fine.

When I started to bleed, I was going to use a vacuum and pull the air out, so I had to start with the LF, and it wasn't going to well, so I went to the old fashioned way (someone pumping, someone opening/closing the bleeder).

Well, when we got to the front, it wasn't bleeding good still, actually not all. So after pushing in the pin on the prop. valve and still not getting anything, we figured out the master cylinder had air locked. So we re-bled it (bent lines over into the bowl from the port). It had been bench bled already. Then the fronts bled fine and everything was great. Except the sticking pads.

So, that's where I am at. What's to troubleshoot.

DLB

[Bus Ted Knuckle]

Did you replace the rubber lines? If not then it could be collapsed on the inside, and acting like a one way check valve, letting fluid in, but not out.

It does not sound like a bleeding problem to me. It must be in the caliper or line.

[cdowns]

did you remove the calipers and clean and lightly lube the surfaces track that the caliper goes in and out on

with no pedal applied the rear shoes retract for no contact of the brake surface and drums/ and the front discs donot retract there is always a slight contact with the pad and disc// as long as the caliper has freedom of movement and the track is not rusted and causing binding you're good to go and will stop just fine

[70c10]

Just curious, did you mess with the spindle nut at all???. If you were repacking the bearings and overtightened the nut, it will cause a heavy drag when spinning by hand.

[Orange]

I didn't go past the unions.
So no spindle nut, and no caliper adjustments or lubing.

I am not sure why didn't notice it before though if it were the lines. Perhaps with the prop valve being bad it wasn't holding pressure on it? Thus, letting them bleed back anyhow, even if the rubber lines were bad?

DLB

[jhow66]

There is a differance in disc-drum and drum-drum masters. The drum-drum one have a check valve in the master cly. where the lines screw in to hold about two lbs.of pressure so the brakes shoes will not retract all the way. If you have this kind of master it will not let the disc cly retract enough.

[Orange]

This is exactly what I used.
http://cgi.ebay.com/ebaymotors/1955-...38487254QQrdZ1

(You have to do some rod modifying to do it, but it is clean and moves the booster in a ways).

DLB

[hgs_notes]

Does it pull to one side? If so, it just may be a caliper sticking. It will probably need replacing. If its even on both sides while stopping, I don't know.

[Orange]

Not pulling. It didn't have this problem with the old system - but the old system also had a bad booster, bad prop valve (I think) and a leaky master.

DLB

[jhow66]

Open a bleeder and see if wheel frees up.

[Orange]

Thanks - I'll try that this evening.

DLB

[6869704X4]

Originally Posted by Orange

(You have to do some rod modifying to do it,

This caught my attention. If the rod is too tight it might not be releasing all the way.
How old are the hoses? They could both be bad.

[grayw0lf]

Disc brakes??? What are those?

[Orange]

Originally Posted by 6869704X4

This caught my attention. If the rod is too tight it might not be releasing all the way.
How old are the hoses? They could both be bad.

That was my first thought too.
Here's the way I set the rod up - I bolted up the booster - fed it thru the firewall, and then connected that to the brake pedal in a strait line without any tension on it. My adjustment can only go in (toward booster), not out (away), because it is already all the way out. So, it is literally as far away as possible. I made the pieces to connect it - instead of using the pieces that were there. I went the hard way around to make sure it was right.

The hoses have been on the truck since I have had it (10+ years) so they could be stock for all I know.

DLB

[6869704X4]

We're thinking along the same lines. Something that would affect both front calipers.
Brainstorming here but is there anything that could prevent the rod/linkage from coming all the way back? Hitting the firewall or bracket?
Isn't there a rod between the booster and MC? Is it adjustable?
Maybe your new booster/MC combo had enough new power to kill both front hoses at the same time?
Wouldnt hurt to get some new ones, maybe some shiny steel braided ones, since you dont know how old they are.
jhow66 is right. If your hoses are collapsed you can crack the bleeders while they are still stuck. If they release that is a sign pressure is being held there.
Again, I'm just thinking out loud so if I'm repeating stuff just put me on ignore, I'm used to it.

[Orange]

LOL - Not hurting my feelings a bit.
I am open to anything.

I actually spent the evening cleaning the garage. I will do the same tomorrow, and probably Sat. morn. So maybe by Sat. evening I'll get around to getting something accomplished.

The rod isn't sticking - I actually did pull on the pedal to make sure when I first encountered the problem. And the rod between the Booster/MC had no pre-load on it, so I don't know how I could back it down really. To take it forward would be simple, but I can't come back with it so easily since I am all the way back with the setup already.

I will start simple with what you guys have tossed at me, and if anyone else has any ideas, throw them at me. I will post back. I am procrastinating because of that long drive to work I have (about 3 miles).

DLB

[cmacky]

Orange, Check to see if there is a kink in the metal lines going to front brakes.

cmacky

[69TowRig]

Originally Posted by jhow66

There is a differance in disc-drum and drum-drum masters. The drum-drum one have a check valve in the master cly. where the lines screw in to hold about two lbs.of pressure so the brakes shoes will not retract all the way. If you have this kind of master it will not let the disc cly retract enough.

That was my first thought too, that he had a drum/drum with the residual pressure valves.

[Orange]

Macky - if that's it, then it's from the union over, and I did it when I put them on (which I really don't think happened, because I pretty much just screwed the new ones on). But if that's the case - then you are going to come over and take the old ones off and put the new ones on for me.

No res. valves in the system. Just the combo/prop valve - and the (what's supposed to be) disc/drum master.

DLB

[neonlarry]

I looked at the ad on ebray and they said drum\drum also so there may be residual pressure. One quick way to tell, I think you said you could feel the drag with the wheel jacked up? If so crack the bleeder valve and see if the drag is still there. If not then you have some pressure someplace.

[cmacky]

Orange, If you still need some help, I will be around Sunday afternoon. I've got to work and go help my brother Saturday.

cmacky