LF calper still sticking!

[Zaffer]

I have a 1982 2000 and the brakes have been getting worse over the past couple of years. In fact, I didn't drive it at all last year due to time and the LF brake grabbing so badly. I figured it was a sticking caliper, especially since it got worse as time went on and I had bled the brakes and rebuilt the front suspension and steering.

I just installed new calipers, rotors, and pads and the LF is still really tight, however I noticed something odd: When I was putting everything back together, the slides were difficult to get back in, primarily the second one (it didn't matter if the second one being installed was the upper or lower). They were also really tight getting out with the original caliper. With just one in, I could move the wheel relatively easily, but not with both installed. It was also doing this before the brakes were bled, so pressure should not have been an issue. I have also replaced the brake lines and master cylinder. It wasn't doing this after the new master cylinder, so don't think it's an adjustment issue, but could be.

I bled the brakes, but no difference. I decided to take it for a test drive and the LF is really grabbing. In fact, the rotor is now blue (after about 3/4 mile of driving). Should I go ahead and get new slides and caliper brackets? Is there something else going on? I got the calipers, rotors, and pads from Auto Ricambi and the parts are correct for my car, so I don't really think it's the new parts, especially since I'm having the same issue as before.

Thanks for any ideas.

[tima01864]

Did you replace the hoses. Are they brittle? I would suspect the hoses. The rubber going to the calipers.

[Zaffer]

Yup, replaced those two years ago with SS lines. I replaced the rear brakes (hoses, calipers, pads, and rotors) two years ago as well. Once everything cooled down, the car rolled fine. Took a quick spin (1/2 mile) and everything was good, so decided to take it for a longer drive and the caliper started to do the same thing after about 3 miles. Got back and sure enough, the LF was definitely hotter than the RF, but also the RR was hot as well. Not sure if it has anything to do with the LF as I believe the brakes are split front and rear, not diagonal?

Is it possible that there are manufacturing discrepancies with the calipers?

[tima01864]

I believe they are on separate circuits. Disproves my theory.

[kilrwail]

Is it possible that when you assembled the caliper, you got the spring on the wrong side of centre? If you did, then the wedges are almost impossible to insert and will jam. Sorry I don't have a diagram or picture to illustrate what I'm talking about.

[DieselSpider]

How well did you clean the rust and scale off the springs, slides and caliper brackets?

After cleaning the rust off did you coat them with a decent quality caliper grease when reassembling them?

[Zaffer]

No grease except the one that gave me trouble, which did help. As for rust, barely any on any of the components. I have the springs between the slides and the caliper carrier, but not sure if that’s right. I attempted to find a picture, but didn’t see anything.

I will disassemble and apply a light coat of grease to everything when I get the chance.

[aj81spider]

Here's a picture of my brakes assembled if it's any help.

[18Fiatsandcounting]

What kind of brake fluid are you using? Any chance that it's not compatible with the rubber seals in your master cylinder and brake calipers, causing the seals to swell and seize?

Here's what I would do. Start with the LF wheel because that seems to be the worst. Jack up the car, and remove the wheel and the two little wedges that hold the caliper in the bracket (but leave the caliper pressing on the pads). At this point, the caliper should move around fairly easily. Then have an assistant press the brakes a few times, very slightly at first and then progressively harder. Each time, you would check that the caliper is somewhat loose against the pads when the brakes are released. See if you can see the point when the caliper starts to lock up, and what your assistant was doing to make that happen (hard stomp on brakes, rapid use of brakes, etc.)

I'm just trying to see if you can recreate the problem without having to turn your rotors blue while driving down the road.

-Bryan

[Zaffer]

AJ81spider, that very well could be my problem! I have the spring between the sliders and bracket, not pushing on the caliper itself like in your picture! The rotor does move freely with the caliper pulled back some (sliders not installed), so if the springs are pushing the caliper towards the rotor and not "away", that may very well do it!

I'll re-do my calipers (all of them) as far as how everything is assembled and get back to everyone (probably won't be for a week or two as I'm pretty busy at the moment).

Thanks!

[Zaffer]

18fiats,

I am using DOT4 brake fluid, which is what I’ve been using since I have owned the car, about 8 years now. I have replaced all components, except for the hard brake lines, so I doubt it’s the fluid, but stranger things have been known to happen.

[18Fiatsandcounting]

I am using DOT4 brake fluid, which is what I’ve been using since I have owned the car, about 8 years now. I have replaced all components, except for the hard brake lines, so I doubt it’s the fluid, but stranger things have been known to happen.

I doubt it's the brake fluid either, but it sounds like you've found a possible cause with the springs as was suggested by others. It's just odd that the brakes would seem OK for a while but then progressively lock up. Kinda like an issue with the master cylinder or stuck caliper pistons or collapsed brake lines, but you replaced all of those.

Anyway, good luck and let us know how it turns out, as I'm sure many of us are curious.

-Bryan

[Zaffer]

I haven’t been able to redo the calipers yet, but one theory I have is that the caliper release enough to not bind completely when cool but enough to cause the pads to contact the rotors and heat them up. I’ll find out next week and post my results.

[18Fiatsandcounting]

I haven’t been able to redo the calipers yet, but one theory I have is that the caliper release enough to not bind completely when cool but enough to cause the pads to contact the rotors and heat them up. I’ll find out next week and post my results.

Could be. Easy to check: Jack up a front wheel, make sure it spins OK, then whale on the brakes a few times and see that the wheel still spins just as easily. Or, even easier if the car is parked on a flat area, see if you can gently roll it by hand a few inches forward and backward, then whale on the brakes and immediately try rolling by hand again.

If the pistons aren't retracting as they should, you'll notice it with the above tests.

-Bryan