Brakes sticking a lil do I have right prop. valve and adj. on brake rod?

[michael bustamante]

Originally Posted by cdowns

that appears to b a distribution block from a drum system not a proportiong valve setup for a disc/drum system the residual valves will cause the discs to drag

it looks like a disc drum set up prop valve to me, but I dont see the little bleed valve you push in to bleed the system. I dont mean to correct you cdowns but I just swapped to disc earler this month and that was one of my issues as well, this is not from a drum drum setup.
I say double check the calipers, theyre cheap to replace if theyre sticking and also makes sure the caliper pin bushings are not binding the bolt. also make sure you properly bench bleed the mater cyl.
looking at the pic again you CAN see the plunger thing, its the same shade as the exhaust manifold and hard to see but it is there!, Now I say re-bleed the whole system and do a search on how to bleed using that plunger in the prop valve as I havent learned how yet

[oldblue1968chevy]

Ok, I didnt 'bench bleed' my MC.

So this is or isnt the right MC? Thanks!

[DKN]

The MC is for front disc brakes, you can tell because the front reservoir is larger than the rear the factory did this because disc brake calipers require more brake fluid to compensate for pad wear.

The prop valve is correct. You can see the rubber boot that covers the meetering valve on the front of the prop valve. The factory only used meetering valves with front disc brakes.

It is plumbed correct. The rear brake line is a 9/16" thread that will not fit into the front brake ports.

Danny Nix
CPP

[oldblue1968chevy]

So the MC or prop. valve is NOT the problem?

So I just guess I need to check my caliper bushing bolt things?...

This is quite confusing.

[oldblue1968chevy]

"Had the same problem. Checked and changed everything. It turned out to be the pucks in the caliper need to be removed and cleaned. I ended up flushing the system. I thought it was the rod and portioning valve. But it was a easy fix. Drain and flush system and rebuild calipers."

Just realized I made 2 of the same threads...this one is the logner one.

^That is a post I just got...May try flushing everything and checking the caliper bolt bushings tomorow. I need to get this fixed its important lol Ive went thru 2 sets of rotors/brakes already!

[michael bustamante]

I picked up rebuilt caliper from autozone fro 12 bucks each!! work great

[oldblue1968chevy]

they are rebuilt calipers,,? thats why its all confusing lol i duno where to go next minus pulling the wheels an checking the caliper bolt bushings...

everyone was saying i had wrong prop. valve now its the right one and they still hang...ugh

[michael bustamante]

try pushing in the caliper pistons with a c clamp, if they wont budge, then theyre bad, if they do move you have a different problem, also while theyre off make sure those bushings are good and set in right. how does the pedal feel? and yes you do have a 71 72 prop valve there, thats not the problem. unless it needs to be bled as well

[oldblue1968chevy]

Ok, ive been lazy and havent played with the brakes, just 'fun' stuff, lol.

Pedel feels good, it just feels like the brakes hangin' and i get alot of brake dust on my wheels, ALOT.

[oldblue1968chevy]

Ok,

I just took the wheel off, then the caliper its clearly sticking. I could hardly move the front tire (spinning it while on a jackstand). I had to beat the caliper off with a hammer.

It does indeed have bushings in it for the caliper bolts. They do seem a LITTLE loose, I dont think thats the problem though. Im about to round up a C clamp and see if I can get the calipers to compress. But they are fairly new 6 months maybe.

I may try bleeding the system or something Idk what to do really guys. I hope I can get this fixed, its making my front whees look like crap (always dirty, excessively dirty) and crappy mpgs probably (have to work it harder for it to get going, and always a AGRHHHHHHHHHH at a slow roll)

thanks heres a few pics of the drivers side I didnt take pass. side off

[oldblue1968chevy]

OK, I separated booster/MC to see if it could've possibly been the adj. its not, separated it still does the same thing.( with the truck jacked up i should be able to spin the wheels pretty freely, correct?

so its something in the fluid part of the syestem, im giong to post some more pics of the MC

[DKN]

Did you open a bleed screw on the caliper and see if the wheel could be turned more easily?

Danny Nix
CPP

[oldblue1968chevy]

nope, lol

its my dd and i didnt feel like doing that

I would guess it would if i woulda cracked teh bleeder, whats that mean (partwise)

[DKN]

If the caliper piston moved freely after the bleeder was opened that would suggest a problem between the caliper and the master cylinder. Somtimes the proportioning valve sticks, somtimes the hose or hard line become blocked in a way that holds pressure. If the caliper piston was still stuck after the bleed screw was opened then the problem is likley within the caliper. If the piston seal was in contact with engine oil it could swell and not allow to piston to move freely. If the seals were used with silicone, synthetic, or DOT5 brake fluid the rubber will swell slightly, and could cause the piston to feel stuck.

Danny Nix
CPP

[oldblue1968chevy]

Now i could have the wrong brake fluid in it,i can look and see what ive been using.

They havent had contact with motor oil the soft lines are almost all new (braided). All the front lines are new, 1 part of the rear is not (part that runs down frame).

I'll get back to you with whether or not they stick after the bleeder is cracked.

They even squeak every so oftengoing down the road. Very high pitch lol.

thanks alot danny! i do appreciate the help you guys are the best source of info!

[oldblue1968chevy]

Can these things go bad? Should I try flushing it while its out?

Heres a pic before I clean it up and paint it...

I wish I could figure this crap out, its the only part of the front brakes that isnt new

[72lb4x4]

Have you checked to see if the front or rear brakes are dragging? The pads (front) normally touch the rotors but the shoes don't.

Sorry if I missed this in an earlier post...

[oldblue1968chevy]

I KNOW the fronts are...I'll check the rears but im pretty sure its just the front

also, I notcied it while driving the other day, if I hit my brakes hard I come to a tire squealing scary stop....LOL

^not good

[DKN]

Originally Posted by oldblue1968chevy

Can these things go bad? Should I try flushing it while its out?

Heres a pic before I clean it up and paint it...

I wish I could figure this crap out, its the only part of the front brakes that isnt new

Yes these can go bad. You can disassemble it and check for damadged O-rings or seals. If you find bad seals you will need to replace the valve. CPP has them for $49.00 or $69.00 for an adjustible version.

Danny Nix
CPP

[oldblue1968chevy]

if they went bad, could it cause the fluid to not come back to MC?

[DKN]

Originally Posted by oldblue1968chevy

if they went bad, could it cause the fluid to not come back to MC?

Its possible. It depends what part of it went bad.

Danny Nix
CPP

[oldblue1968chevy]

Ok, Im going to try to use and and i think I may be on to something, Im pending an order thru ccp for one of these new..

My prop valve/mc lines were tiny with adaptors on both ends, If the lines were to small that would cause fluid to take along time to come back?...Its not supposed to have adaptors from the factory? So I blew it out compressed air and am going to get correct lines and see what happens

[raycow]

Originally Posted by oldblue1968chevy

My prop valve/mc lines were tiny with adaptors on both ends, If the lines were to small that would cause fluid to take along time to come back?...Its not supposed to have adaptors from the factory? So I blew it out compressed air and am going to get correct lines and see what happens

If you get OEM lines, they will be the same size tubing as you have now and just the nuts will be larger. GM designed them this way so that really determined idiots couldn't screw them into the wrong holes. Aftermarket universal lines have the small nuts and are used with adapters to fit the different size ports.

Ray

[oldblue1968chevy]

Well I got some and they fit the holes more correctly, But they will be a pita to bend right and I cant find my bender right now, im about to go swimming

But could too small of tubing cause fluid to return slowly and brakes to hang?

[raycow]

Originally Posted by oldblue1968chevy

But could too small of tubing cause fluid to return slowly and brakes to hang?

No, you can't get tubing that's too small if you use the pre-flared lines. The smallest I have seen used on factory systems is 3/16" and that is more than large enough for the amount of flow involved. Now if the tubing were to be flattened or kinked because of mechanical damage, then you might have problems.

Ray