caliper sticking, even when replaced with reman

[woodrat]

I've got a 1990 Legacy wagon with about 320k on it. Last spring, I started getting a dragging brake on the left rear, and went and bought reman'd calipers, new rotors, pads and park brake shoes all around. Ended up scoring another car a couple of days later, so I shelved the parts and parked the car until a couple of weeks ago.

Put everything on , adjusted and bled everything, and drove it 20 miles, and sure enough, the left rear caliper was dragging the whole way. Came home, and ordered up new soft lines for both sides on the rear, changed them out, same thing. Read up in the manual, and saw that the rear brakes are routed through a proportioning valve. Couldn't find a new one, but I got a clean one off of a lower mileage car at the u pull it. Put that in, bled everything again, still the same problem. Put the brakes on, let off, and three wheels are turning freely, the LR is frozen up tight. You can put a screwdriver in there and pry it loose without a tremendous amount of effort, but as soon as you apply the brakes again, that one stays clamped down tight until you pry it loose. The pin that the caliper slides on is clean and well greased. I would suspect that I got a bad caliper except that it's happening on the same wheel as it did before this reman'd caliper was installed.

I even disconnected the hill holder cable and backed that valve all the way off, just on a long shot, but that also changed nothing. I cannot see any damage to the steel lines anywhere under the car or under the hood, either.

Any ideas? What the heck is going on here?

[woodrat]

hm.. looks like I got some bogus information from the Hayne's manual, after all. It says that this brake system is split diagonally, so that one circuit feeds the LF and RR, and the other circuit feeds the other two. But when I crawled around and followed lines, it looks like the rear of the MC serves the front brakes, which is where the hill holder lives, and the front of the MC, with two lines coming off of it, serves the rears. So, now I'm thinking that I may just need a new MC, after all... I was believing the manual, and trying to figure out how only ONE corner could be freezing up like this.

[Someperson]

do it and see? i was figuring mc but i'm a noob so....

[rallyak]

It might be possible that it was a poor reman and the pistons sticking, but its weird that the same side is dragging. I don't know if I would suspect the mc.

[James614]

I'd be reluctant to replace the MC if it's only symptomatic to one wheel. The re-maned calipers are usually good, but it's not all THAT unlikely that you got a bad one that just happens to be the same wheel. More than likely if you go to the parts store and tell them what it's doing and what you've checked, they replace it no questions. Its worth a shot before you go spending money or other parts.

[woodrat]

I'd be reluctant to replace the MC if it's only symptomatic to one wheel.

the rear wheels each have their own separate line coming from the MC on this car, which is what made me think it could be the problem, and this MC has been on there for a LOOOONG time. So, I figure I should probably replace it anyway, and then I will have a complete new brake job. I bought this caliper months ago, and I'm not sure I could return it now.

[rallyak]

Age or milage shouldn't be a factor that much as long it not leaking fluid, all of mine have the original mc one with over 700,000 miles. It still could be bad but I would be surprised.

[Legacy777]

Haynes is correct and the brake system does have a diagonal split.

Do you have ABS or non-ABS? If ABS, there will be two lines that run to the ABS unit and four lines out. The two rear lines will go through the proportioning valve.

I would wonder if there is corrosion or junk in the lines going to that rear wheel. It could be getting lodged in the line and keeping pressure to that line. I suppose it could be the proportioning valve too...crud in there.

[woodrat]

No ABS. The single line coming off of the rear of the MC goes to the hill holder, which then has two lines coming out of it, each one going to a front wheel. The front of the MC has two lines coming off of it, which go to the proportioning valve, and then two lines leave the proportioning valve, headed to the rears. It doesn't APPEAR to be split diagonally, anyway...

Bad proportioning valve was my first thought, after replacing the soft lines, but changing it didn't do anything. Flushing and flushing and flushing hasn't seemed to help, either, and the flow of fluid out of that corner seems to be ample, and similar to the other side which is working fine. I suppose I COULD have gotten a bad reman'd caliper that just happened to be the same corner as was sticking before, but it just seems like such long odds...

[Legacy777]

Hmmmm, that doesn't sound right about the brake lines. Do they look OEM and not tampered with?

I'm not sure what to tell you at this point....

[woodrat]

yes, they do look all OEM and not messed with. Which wheels are the hill holder SUPPOSED to control?

[Legacy777]

Here is the diagram of how it should be routed.

http://www.main.experiencetherave.com/s ... holder.jpg

Are you 100% positive you're tracing out the lines correctly?

[woodrat]

It's possible I switched a couple as I was following them along... That's a diagram that I did not have in the Haynes manual.

[Legacy777]

I'd suggest double checking just to make sure. That diagram is from the Subaru factory manuals.

[woodrat]

I will, thanks. Even if they are routed like this, as they are supposed to be, the LR wheel still appears to have its own separate port on the MC. Unless the new caliper is no good, I suppose it could still be a MC problem. Either way, don't have many things left that it could be. MC or bad caliper, since the lines appear to be flowing evenly when I bleed. Thanks.

[Legacy777]

I guess the reason I'm suggesting verifying the lines is that one of the devices downstream of the MC may be holding pressure to that wheel, and verifying the routing would just be good to do.

I guess let us know if you find the routing is the same in the diagram or different.

[woodrat]

well, it appears that it IS routed like the diagram you sent, I crossed up a couple of lines while I was tracking them down. Even at that, I did replace the proportioning valve, and that was the only device between the MC and the LR caliper.

And a new master cylinder, as predicted, didn't help, either, so I actually got a bad caliper after all. I wanted to replace the MC, though, so when I take this caliper back, I can tell them that every other component has been replaced already. I bought this caliper quite a while ago, back in March, from a shop 80 miles away, and I want to be able to make the strongest case I can for having them replace it, since I am pretty far past the usual return time.

At least when I'm done, everything will be new, all the way down to the park brake shoes.

[Legacy777]

Yeah....the caliper is the only thing left other than the hard lines.