Topic: Stuck front brake on a 72 K2

[Stev-o]

Victory!

[Black 750K8]

........with the caliper body clamped in a vice with a couple layers of cardboard to protect the body...........

I'm glad I had the common sense to do that before I read your post

I rinsed things out and they are back on the bike now, except I can't get it to bleed correctly. I'm probably doing this wrong, but here goes. Put the line back on, bleeder slightly loose and watched the fluid drip for a second, tightened the bleeder. Added fluid to the master, then slowly opened the bleeder and had someone squeeze the lever gradually. Fluid came gushing out the bleeder, and as the lever was let go, bubbles popped out. Did that a few times but that's all that is happening. The lever is too lose now and there is no resistance at all. And there is ALWAYS bubbles, no matter how many times I try, what's missing?

OK you are not going about this correctly at all
Never let go of the leaver until the bleeder is closed.

Leave the bleeder closed then pump it a couple of times and keep pressure on the leaver and crack the bleeder just a little the leaver that someone is squeezing will go down hold it down and closed the bleeder. Keep doing this until you see no more bubbles never let the reservoir go empty.

[ekpent]

Quick bleeding technique. Close bleeder at caliper. Have a friend, wife etc pump the master brake handle. After pumping for a bit then leave the handle pulled in and you crack the bleeder open. Shut the bleeder and tell the friend to release the master handle and pump again. Keep repeating while watching the fluid in your reservoir, you will have to add some along the way. Put a hose over the end of the bleeder to direct the outflow when it finally hits. You will feel when you are starting to get them bled.
  Did you put in some PB Blaster around the edges of the old stuck brake pad yet. Spray some around the edge and get thing soaking in some good stuff. When you get to trying to force that old pad and piston out it will probably take some force on the handle and some taps or hits with a hammer help to break it loose in conjunction.   HAVE FUN   

[Black 750K8]

http://forums.sohc4.net/index.php?topic=259.msg207521#msg207521

Here is a good post from TT
Thanks TT

PS You need to read the FAQ a little one most all you need to know is there or in the Tips & Tricks

[lucky]

Nothing beats the grease gun. Plug the line hole, stick the gunto bleader and pump. It will come out without much effort.

It is a law of physics: You cannot compress a fluid,(grease) so something will give.

[70CB750]

here is the grease you want to get for the brake pad:

http://www.ebay.com/itm/DOW-CORNING-Laboratory-High-Vacuum-Grease-976V-Stopcock-/280617417916?pt=LH_DefaultDomain_0&hash=item415619fcbc

[edwardmorris]

here is the grease you want to get for the brake pad:

http://www.ebay.com/itm/DOW-CORNING-Laboratory-High-Vacuum-Grease-976V-Stopcock-/280617417916?pt=LH_DefaultDomain_0&hash=item415619fcbc

Thanks, but I won't be needing it epkent is 2-2 on this one so far. Read the instruction on how to bleed properly (thank you black 750 k8), took several breaks and let all the bubbles out, last of them came out this morning and I actually felt some resistance! In this excitement, I took a day off to finish the job. Once the bleeding was done, had my wife help me with the putting pressure on the break while I hammared away gently in a circular pattern around the edge till that bad boy broke loose. ANYONE ELSE TRYING THIS, USE EYE PROTECTION IF YOU HAVE THE CALIPER PRETTY MUCH SOAKED IN PB BLASTER. That stuff burst outta there like crazy, few poundings later, the pad started to move and it was awesome watching it pop right out. Filled up the master and kept at it till the piston popped out with a crapload of black gunk. I'll post pics in a bit here. Trying to clean out as much of it as I can and hopefully will put it back together today. Again, thanks to all for your help and great advice. My hammer in now renamed to, Epkent's Hammer (Thor is retired :p)

[70CB750]

The shop manual points out several places on the brake pad, where you are supposed to spread a layer of lubricant. 

The posted link is the best lubricant you can use for that purpose - to make sure your brake is not stuck again after a year or so.

[edwardmorris]

The shop manual points out several places on the brake pad, where you are supposed to spread a layer of lubricant. 

The posted link is the best lubricant you can use for that purpose - to make sure your brake is not stuck again after a year or so.

oops! Should have followed the link first, thought it was a grease gun.

[ekpent]

Carefully remove the rubber seal that you see in the caliper and remove all the white residue in that groove. Scrape a little and more will appear. Clean it well before putting the seal back in and your piston will thank you. How is that piston anyways,pretty smooth or a little pitting ?

[edwardmorris]

Carefully remove the rubber seal that you see in the caliper and remove all the white residue in that groove. Scrape a little and more will appear. Clean it well before putting the seal back in and your piston will thank you. How is that piston anyways,pretty smooth or a little pitting ?

You have me worried now. I took pix every step of the way and there is no sign of a seal, unless its hidden in plain site. Piston is mostly alright, very slight pitting. Need to make a run for some caliper grease, trying to put it back together so I don't have to leave the line open to the elements. Or am I worrying needlessly here?

[Patrick]

The seal is in the wall of the caliper. It is what keeps the brake fluid from gushing out around the piston every time you squeeze the brake. Get it out gently with a pick or small screwdriver. If you are careful you can probably clean it and reuse it.

Patrick

[ekpent]

Patrick described it well and the line can be open for awhile no big deal,wrap the end up to catch a drip if need be.The seal will look like a black band going around inside the caliper. Take your time and clean that seal area,its one of the reasons for a sticky piston.

[edwardmorris]

Found it! I did my best to clean it, what do you guys think? Haven't put it back together yet, lemme know if I should clean it more. Also, any other suggestions for reassembly?

[edwardmorris]

And after

[ncstatecamp]

Heads up, you should never handle break fluid with your bare hands. Being that it's water soluble, your skin can soak it up and then obviously not good for the kidneys.

[edwardmorris]

Thanks for the tip! Used to wearing gloves all the time from the old TRD days. Brake put back together for the time being, will order fresh pads and the grease suggested above from ebay when I start the rebuild. Now, moving on to getting that rear wheel to co-operate and get this thing on the road!

[edwardmorris]

DRAAAAAAAAATS! Bled the brake last night, bubbles kept coming, took a break and went back this morning, only to find out that brake fluid is leaking at the bleeder valvle, the brake line at the caliper AND at the midway point by the headlight! Pretty much everywhere I touched it. What is causing this? I tightened everything pretty good, but I don't know if I needed to torque it to a specific setting....ideas?

[flybox1]

you are introducing more bubbles if you release the lever with the bleeder OPEN.
put a section of hose on your bleeder, and loop it down into cup, or loop it up and secure it to your bars...
open bleeder
squeeze lever slowly
close bleeder
release lever
repeat...
recheck MC level and top off when needed.  dont let it get too low.
watch for the fluid to push into the hose, and continue to repeat this until it pushes all the bubbles out.
turn your bars to the left to get the MC nice and high.

[edwardmorris]

No, I'm doing the bleeding right as you described it, its just that everytime there is any resistance in the lever, fluid is leaking from those three places...

[Patrick]

Did you replace the copper crush washers on each of those connections? Those are not regular washer. They get smashed to fill in the gaps and you should always replace them every time you remove a line. They are a common size, unlike the bleeder valve, which can be a pain to source locally for less than dealer price.

[70CB750]

You can just anneal copper washers to make them soft again.

[edwardmorris]

Did you replace the copper crush washers on each of those connections? Those are not regular washer. They get smashed to fill in the gaps and you should always replace them every time you remove a line. They are a common size, unlike the bleeder valve, which can be a pain to source locally for less than dealer price.

Yes everything that came off, went back after cleaning. Found this diagram here, you're talking about part 13 right?
http://forums.sohc4.net/index.php?topic=117472.0

[Patrick]

Yeah, those are the washers. Did you replace them or just reuse them? You need to torque down the banjo bolts holding the brake lines real securely. I'm thinking maybe about 14 pounds of torque. Maybe somebody who has the spec readily available will post. Leaking around the bleeder screw would be more troubling to me. Do not over toque that screw or you are liable to twist it off the next time you try to loosen it. Snug, with just a little oomph (maybe 7 lb torque) should suffice. If it is still leaking through the screw at that torque ou should replace it.

Patrick

[edwardmorris]

Yeah, those are the washers. Did you replace them or just reuse them? You need to torque down the banjo bolts holding the brake lines real securely. I'm thinking maybe about 14 pounds of torque. Maybe somebody who has the spec readily available will post. Leaking around the bleeder screw would be more troubling to me. Do not over toque that screw or you are liable to twist it off the next time you try to loosen it. Snug, with just a little oomph (maybe 7 lb torque) should suffice. If it is still leaking through the screw at that torque ou should replace it.

Patrick

I reused them because they were in pretty good shape, no scratches, bends or warping. I'll admit I was a bit cautious when tightening, I didn't push it all that much. I will go through the manual and see if I can find the exact torque settings and redo them. For the bleeder, too, didn't tighten too much because of the same fear. However, the most baffling one is the leak at the line that ends at the caliper. I know I tightened it pretty securely, and its not the threads that its leaking from, its actually coming up from the inner diameter if I explained that correctly.