Huge brake drag after rear rebuild - how to solve?

[phaetn]

Looking for some advice.

Just had left rear caliper replaced with a rebuilt unit along with new rear rotors and pads on both sides because I ignored a rubbing sound for too long. (Denial is a powerful force!) Turns out the rotor rubbing against the pads -- and then the metal to metal against the caliper -- ended up being the only thing keeping my axle and wheel assembly on the car because the $5 circlip at the bearing had popped. Eeek!

It was fixed at a local mechanic -- not a Fiat specialist, but competent. Now, a couple of days later, I noticed that the rear hubs are getting hot and that the car doesn't roll quite as easily as it should. Jacked up each corner individually and discovered that the rear wheels are hard to rotate by hand, especially the right, and even the fronts have some minor rubbing. This wasn't the case previous to the rebuild: The car had been easy to push by hand, but it's not so now. The mechanic did bleed the rear brakes and top up fluid.

I suspect too much hydraulic pressure, or something else amiss. I will bring back the car on Monday. What should he look for? Given that he's not a Fiat specialist, could he gave missed something and didn't account for the compensator? Could it be the installation of the pads? Does he just need to dial back the "acorn nut"? I don't know exactly where this is, but I hae seen it referenced and assume it's at the booster or master cylinder...

With many thanks,
phaetn

[azruss]

First, did he screw the rear calipers back in. were the sliders lubricated. did he adjust the e-brake too tight. With new pads and rotors, the rear brakes have very close tolerances and require the caliper adjust to be backed off as far as possible.

[coise]

Also , after you screw in the piston make sure the line (on the piston ) are in the upward position otherwise it won´t work properly. Ask me how I know

[Dougieb]

Also, you might check the flex lines to the rear brakes.
If both rear brakes are dragging it could be this.
When they get old, they can swell up i side and not release pressure from the rear calipers.
I have seen this so bad that it would keep the brakes locked up.
There are three hoses to the rear: one at each caliper and one in the center rear underneath.
One way to check this is to jack up the car (best to support with the axle to not engage the rear brake compensator).
Confirm that a rotor is still dragging, and then crack open the bleeder valve briefly and then close it again.
If this lets off enough pressure to make the rotor spin freely, then you have a hose problem.
If you do this carefully, you should not have to rebleed the brakes.

My rear brake compensator was frozen, as I imagine many are.
But I do not think that would cause brakes to stick.

Good luck.
Let us know how it turns out.

Dougieb

[phaetn]

Thanks for the replies everyone. I'll bring it to the mech first thing Monday morning and mentions this.

Is there any way to bypass the compensator if that proves to be an issue?

Update
I did have a minor stroke of insight this morning, and remembered that when I tested yesterday by jacking up each corner of the car that the engine had been off and maybe pressure had built up in the system (i.e. pedal was hard and not like when in running condition). It stands to reason that it needs the vacuum of the engine running for the booster and associated systems to work properly.

So I started the car and even jacked the back when running and it's definitely a bit better -- I could turn the rear wheels more easily and the left (replaced by rebuilt caliper) was definitely better than the right. I could push it back and forth in the garage now, whereas I couldn't yesterday. Something is still amiss, though. The hubs were definitely much too hot yesterday and I could feel resistance at times -- it wouldn't always roll on a slight incline (especially backwards) when I was expecting it to when out and driving. There were times when pedal stop seemed higher than at other times.

Update 2
Took it for a short 10 minute drive. Sometimes it sticks (and I can feel it make the car come to a stop) and other times there's next to no rolling resistance. Pedal play changes, too. The right rear definitely is much hotter than the left, but they're both clearly dragging at times.

Thanks again and cheers,
phaetn

[RoyBatty]

Are you absolutely sure that the axles are not sliding out?
I once incorrectly installed one of the rear axle bearing retainers and in doing so oversized the retainer such that it did not stay locked on the axle. This allowed the axle to slide out as you have already experienced and the only thing keeping it on the car is the caliper assembly.

[Exit98]

Keeping it simple. Could it be you need to re-adjust your emergency brake?

The adjustment is directly under the cabin in the center of the car. Loosen it up and see if it helps. Couldn't hurt to try.

[RoyBatty]

The OP titled this thread with the words "rear rebuild".
Is he referring to the rear brakes or the rear axle assy?
Did he have the rear axle bearings replaced by someone not very familiar with the bearing retaining ring type setup?

[phaetn]

Thanks for the replies.

I really dont get the sense that it is the handbrake. It is largely ineffectual, and at two to three clicks of pull doesn't do anything. At the full pull range (5 clicks?) there starts to be minimal force applied.

New bearing and circlip were installed on rear left, along with rebuilt caliper. New rotors and pads for both sides, along with all new associated springs and clips. Rear brakes bled and brake fluid topped up. Differential oil drained and replaced with fresh 80W/90 gear oil (i.e. EP). Given that the mech identified the problem (which was that the axle was walking out and only held on by the rotor against the caliper) and that I ordered a new bearing and circlip (plus spares) I would have to conclude that he was well aware of the problem and fixed it appropriately. At my request, he didn't replace the right rear caliper, though I do have another rebuilt one of those on hand, too.

I think the dragging has to do with hydraulic pressure. Sometime the pedal is higher, and there is dragging, other times the pedal goes lower and the wheels seem to spin more freely. I wonder if something is binding or fluid not flowing properly.

I will bring in it and ask him to check it out. In my province all mechs have to give a 90 day warranty for their work so hopefully I won't have to pay any more $$.

Cheers and thanks again,
Phaetn

[RoyBatty]

I have heard in the past, that the soft brake lines can degrade from the inside out and act to block flow which can prevent release of the pressure when you let off the pedal.
Aha!
I just read a few previous posts and Dougieb has already informed you of this possibility.
Have you investigated this yet?

[phaetn]

Well, it's a satisfactory ending, if not a satisfactory diagnosis.

I ended up brining it in Wed. and by then everything seemed fine, with nothing touched/altered. Not sure if there was just something in the fluid, or if a pad wasn't seated right or what, but now there's no more rubbing, the car rolls fine without resistance and stops well, and the pedal feel is back to the way it used to be. Maybe tolerances are really tight and it just had to get worked in...

The mech put it on the hoist and double checked it and couldn't find anything wrong. <shrug>

I guess I'll have to wait and see if it rears its ugly head again later.

[4uall]

Glad to hear it all worked out

[ylbill]

Well, it's a satisfactory ending, if not a satisfactory diagnosis.

I ended up brining it in Wed. and by then everything seemed fine, with nothing touched/altered. Not sure if there was just something in the fluid, or if a pad wasn't seated right or what, but now there's no more rubbing, the car rolls fine without resistance and stops well, and the pedal feel is back to the way it used to be. Maybe tolerances are really tight and it just had to get worked in...

The mech put it on the hoist and double checked it and couldn't find anything wrong. <shrug>

I guess I'll have to wait and see if it rears its ugly head again later.

I pm'd you explaining that I had a very similar problem with my brakes. Was wondering what the outcome was and saw your updated post. My brakes were dragging bad after putting excess pressure when needing to come to a quick stop. After that the brakes starting dragging pretty bad. I just went out to back the car in the garage after a few days of sitting and there wasn't any drag. It rolled freely. I'm thinking its the hoses as was suggested earlier. They drag when heavy pressure is applied and seems like they back off as it sits for a while. Any thoughts on this? Thanks

[phaetn]

In my case there had been a loud "thunk" after a day or so of driving after the brake job, after which it *really* dragged and I pulled over as I could actually feel the resistance. After mashing the brake a few times it seemed to get better and I could get underway again, though it then had that light rubbing -- I couldn't really notice it when driving all the time, except that when coming to a stop I could feel there was just a bit more rolling resistance than usual, and the hub was getting hot.

All gone now. I dunno why. It's one of these situations that's probably hard to diagnose by the mech unless it's actually happening at the moment.