Brake Help

[007]

What would cause my front disc calipers to BOTH begin to drag after having been removed and reinstalled and rebled? What have I missed or done wrong?

 

[Tinman22]

Why did you do this r&r and bleeding of said calipers? Sunday boredom? No really did you replace the rotors or pads or guide pins? Was it a caliper rebuild? I once changed wheel bearing grease and in the process twisted both brake hoses while placing the calipers on the springs thus separating the inner liner causing a tear in both hoses which acted like a valve not letting the fluid to return to the master cyl.

 

[hdgapeach]

Wish there was one answer to the question. Here's a list of possibilities:

Master cylinder or brake booster push rod too long
Sticking caliper pistons
Caliper alignment to mounting surface and rotor
Warped rotors
Seized wheel bearings (easy to verify by spinning the hub when caliper is off)
Collapsed or kinked flex hose
Master cylinder too full of brake fluid
Sticking metering valve (proportioning valve)

Don't know what all brake system maintenance you did so the list kinda covers a little of everything.

 

[Tinman22]

I changed pads once with relatively new rotors that were slightly warped caused a skipping drag,overheating the calipers and causing them to seize.

 

[007]

Thanks for the info...

I took them off so that I could replace ring/pinion. They were never disconnected from the lines, just unbolted and hung out of the way. Really frustrating that BOTH are doing this and about to the exact same degree.

 

[Tinman22]

Battling the unknown is the worst. Are the hoses in good shape and relativly new? Did anything change out back in the brake system?

 

[007]

No. No other changes whatsoever. Lines are quite new. I have replaced the master cylinder and vacuum booster for other reasons. They were rusted and leaking. But that has made no change to this issue.


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[Tinman22]

Not trying to ask stupid questions it just comes natural but your certain its caliper drag? Does everything spin with them off ?

 

[007]

I'm certain because of the heat, the smell and the ridiculous brake dust on the rims. After the gear swap I drove it home just over 4 miles and I had dust all over the rims.

 

[jpeck71]

Sand and re-grease the sliding surfaces of the calipers maybe? Don't know.

 

[Torxhead]

I am thinking that they are hanging up somewhere, like at the pins or in the cylinders, repair or replace.

 

[IOPort51]

When I put a booster on my brakes I found that for some reason there was not as much resistance in the MC and it allowed the peddle to stick just enough to allow the disks to drag. See if the peddle is not coming all the way up and /or if lifting the peddle frees things up. I was dragging the top of the peddle on the wire plug on the steering column ever so slightly, just enough to keep it from fully disengaging.

This is reaching pretty hard but it may be worth a look see.

 

[hdgapeach]

While they are tight (dragging / seized, whatever), jack the front up and loosen a bleeder screw to release the pressure (if there is any). Then see if you can spin it freely by hand. If the system is maintaining pressure with your foot off the brake, you may have a line, proportioning valve, master cylinder or push rod length issue (or a combination of more than one).

If that doesn't determine the problem, take a wheel off and try to press the piston back into the caliper. If you can't compress the piston with only reasonable pressure, it may be seized and in need of a rebuild / replacement.

I noticed you stated you let the calipers "hang" until you re-installed them. Did you use something to hang them with or let them swing on the flex hose? The hose can be damaged by letting the calipers dangle without something to keep slack in it.

I'm still wondering if the push rod is a little too deep into the back of the master cylinder.

I know all the suggestions are all over the place, and sorry 'bout that. Start at one end and work your way to the other. You'll eventually get it straightened out.

 

[007]

One problem I have is that with my QuadraTrac I can never just spin a wheel like I'd like to. I don't believe it has anything to do with the rod as the problem did not happen BEFORE the gear swap, and it did after and continues to do it after the new master cylinder and booster.

They didn't hang, they were balanced around where the axle and springs bolt together. I never let them hang by the brake line.

What I wonder is if those triangular shims or pins that hold the caliper to the bracket around the rotor are what has them bound up? Is there a caliper I can use that does not require these? I freakin' hate them. Looks like in 82 they started using "normal" calipers and not the Ford style caliper.

The TSM says it's bellcrank pivot pins - what are those?