Rear brake line

[Acooljt]

OK, some of you may remember my topic a while back about my rear brake rubbing, BADLY. If I put the bike on the stand and spun it, I wouldn't even get a 1/4 of a turn. Well you guys said that a rear brake "return" line is probably blocked. Well where exactly is this line? Cause I don't think it exists. The only lines I see are from the master cylinder to the pump(or whatever you wanna call it) and another line from there to the caliper. What exactly is it that I'm suppose to clean?

[humhead]

Sounds like your rear caliper isn't releasing. It could be clogged or your master cylinder could be clogged. Have you bled the rear brake ? If not, try that first.
If that doesn't work, you'll have to clean & rebuild the M/C & caliper. While you're at it take a good look at your rear brake line. If it's original, It's time to replace it.

Terry

[Acooljt]

Alright, so I just drained the entire rear brake system, mastery cylinder and all. I pumped the brakes with all of the lines disconnected and then pumped them with the lines connected but with the bleed screws open to get out all brake fluid.

Then, IT'S STILL RUBBING!!! Yeah, there can be no pressure since all the brake fluid is gone! So I pull the caliper off, and voila! The rubbing sound is gone! When I spin it, it gives me about a half turn(180 degrees). Is that about right?

So then I put the caliper back on but without the pads in this time and it rubs no more. So I look down and the right piston is much closer to the rotor than the left piston is. Oh yeah, and the pad that was on the right side was wore down to the metal.

So I'm wondering if that right piston is frozen? Is there a fix for this or do I need a new caliper? Or have I totally diagnosed this wrong and it's something else?

[Clone]

I've never repaired the bikes caliper, but usually you can get the bore honed at a shop and then replace the piston with a new one.

[Jethro]

I would get a new set of seals for the caliper and rebuild it.

[Acooljt]

Does my diagnosis sound correct to you guys?

[humhead]

You're on the right track. Your rear caliper needs a rebuild. I'd also check your rear rotor for grooves/warping. Try http://www.z1enterprises.com/default.aspx
For the rebuild kits you'll need.

[Acooljt]

The odd thing is, the kid that sold it to me said he rebuilt the rear caliper. Now I'm aware he could have been deceiving me, but why would you point something like that out if you know the thing is faulty?

Also, my rotor is groovy-city but have you seen the price for a new one!?! My ass will hurt for weeks.

[fatkid89704]

dont buy a new rotor just go on ebay and find one way cheaper.

[Pearson]

Does my diagnosis sound correct to you guys?

Like Jethro said, time for a rebuild. I just finished mine...but tell us what bike/year you're working on?

My pistons were frozen but I was able to blow them out with compressed air. Clean the piston with a soft scrunge in one direction only around the piston. Inside the caliper I went to a 0000 steel wool, again only in 1 direction, around the surface. Keep everything very clean. I rinsed my calipers in water before blowing them out and drying with a lint free cloth.

I'm seeing rebuild kits on ebay all the time so pick some up. Remember, just because the PO rebuilt the caliper doesn't mean he did a good job. Take your time, lay out a super clean environment and replace all gaskets, boots, o-rings and seals. It's not the cheapest thing to do but it's not hard either and brakes are no place to skimp. Also, pick up special brake grease at the counter of your local autoparts store for $1.

Keep at it, ask questions here.

[Clone]

Somebody who knows better should be able to tell you, but you could get the rotor turned to smooth it out, but then I would worry about the service thickness

[chef1366]

Can you physically push the piston back in?

[Acooljt]

First of all, it's a 79 GS850.

Yeah, I also thought about turning the rotor but wasn't sure if that was an option or what, no one mentioned it.

Also, I have not tried to push it back in with my finger.