1986_IROC-Z

I tried fixing my front calipers which were sticking (simultaneously) by replacing calipers, pads, rubber hoses, flushing and bleeding the system. All new stuff.

With everything back together, the front wheels will still not turn freely. Lots of drag. The bearings are fine (calipers off, rotors spin free) and I do know what normal drag feels like, this is much, much more.

I haven't road tested the car, figuring my original issue is still persistent and didn't want to grill/smoke a brand new set of brakes. But then I got to thinking. Not a brake expert here.

1. Am I assuming incorrectly? Do the brakes actually need to be bedded / used with some real force on the road before the pads seat and (maybe) free up the calipers?

2. While mounting one of the calipers, I knocked one of the new pads loose, and it fell into my catch pan, with a bunch of brake fluid, friction surface down! Is it toast? I employed the 5-second rule, fished it out, wiped it off. Do I need to replace it?

Jorlain

iTrader: (4)

1. Not much help here, but I'd make sure the piston is fully compressed and go from there.

2. Spray the pads\rotor with liberal amount of brake cleaner and wipe thoroughly.

dahuntin

Had the car sat long before you noticed that the brakes were sticking? If so the bore of your calipers is probably rusted from water in the fluid. Happened to my car when I was trying to get it running after sitting for 3 years. I replaced the calipers and flushed the fluid and then everything was mint.

dmwracing42

iTrader: (3)

Two questions for you. Did the calipers slide right over the rotors or did you have to force them on? And do the caliper pistons appear to be all the way in or are they extended some?


In theory a brand new caliper should be fully retracted, and there should be enough clearance for the caliper, with pads installed, to slip easily over the rotor. If they did not slide on easily, something isn't the right size, simple as that. Alternatively, if for some reason your calipers are extended at all, that's your issue. Driving the car will force it back some if this is the case, because the runout on the rotor will force the pads to back off until you apply the brakes again.


In reference to the brake fluid thing, I'd say you probably want a new pad. Brake fluid isn't good for the brake pad material and it can degrade it. I've hosed pads off with brake clean that got drops of fluid on them, but to dunk it may be extreme. Someone else may have different advice but that's my two cents.

1986_IROC-Z

Replaced both front calipers, rubber brake hoses, flushed a bunch of new fluid through, bled all 4 corners starting with the farthest wheel (right rear) and worked my way nearest to the master cyl.

1. Calipers with new pads slid right on the existing rotors. No issues with mounting. But this was before the system was bled/ no pressure in the system.

2. I have to imagine the pistons are slightly pushing out now, but can't tell with everything put back together. All I know is with fluid full, brakes bled, and before a road test, the calipers are not allowing the rotors up front to rotate with the proper amount of (light) drag. They're real tight, just like before, and I'm worried I'm going to end up cooking a brand new set of brakes.

dmwracing42

iTrader: (3)

That's interesting. It sounds like something is keeping the system pressurized after you release the pedal. Because pads generally have less friction before they seat, at least in my experience. I suppose it could be worth a short ride to see what happens. Like around the block just to see. If it gets better then you have an answer. If not then you have to start looking at the rest of the hydraulics. You won't kill a set of pads in a mile drive.

Ron U.S.M.C.

......

1986_IROC-Z

I put everything back together and went for a spin. Came home and everything was HOT. Jacked up the front and the wheels were hard to turn again.

New development...I separated the master cylinder from the booster just for the hell of it.

There appears to be an old--and maybe persistent--fluid leak at the back of the master cylinder. This would explain the paint damage below the booster, from before I bought the car.

Second... separating the master from the brake booster relieved all binding of the front calipers. The front wheels spin freely/ normal caliper drag with the units separated.

WTF? I now know the master is a reman unit (stamped on fluid reservoir) and my booster appears to be original/OE (matches the exact pic in the service manual) and it's general condition would also suggest it is OE. So I wouldn't suspect the push rod or anything else has been changed out, lengthened, adjusted (it's one piece, I think?).

I'm so damn tired of this project...I bought a brand new master cyl to see if that helps stuff. The booster is still good, no fluid in the vacuum hose.

sofakingdom

iTrader: (1)

If fluid has leaked out the back of the MC, the booster is farkled. Don't kid yourself otherwise. Brake fluid DESTROYS its diaphragm. Only a TINY amount deteriorates it; long-term exposure like you clearly describe ruins it completely.

Replace your booster. Take that MC back and trade it in for the MC/booster set. Unless of course, you just REALLY ENJOY working on your brakes. Because you WILL be again, real soon.

1986_IROC-Z

Received loud and clear

Removing the old brake master in prep for the new parts arriving today, I pulled this out of the brake booster. It's apparently been sufficing as the pushrod.

Can anyone tell me if this is stock?

I have a hunch, 95% sure it's not, and it would explain 99% of my problems.
(For those looking at this thread 10 years down the road, it's a picture of what looks like a hacked off stud from a cylinder head inserted where the booster pushrod should be)


).

sofakingdom

iTrader: (1)

Yup, looks like those are threads on it (helical) as opposed to "grooves" or whatever....




Humans.



Doesn't look stock to me.

One of those - the right thing, most likely - will come in your new booster/MC set. Although, if Stimpy had made it the right length in the first place, it would have probably worked just fine.