Topic: Stuck front brake on a 72 K2

[edwardmorris]

So I picked up a 72 CB 750 on craig's list last week and it came with a sack full of things wrong with it, the front brake is probably the most obvious one as it almost gave me a cardy pushing the bike 10 ft to get it into the garage. More history and progress on other issues in the links in my sig if you're interested. I took the front caliper off completely and voila, bike is moving ALMOST freely (grinding rear wheel is still adding resistance). But the brake pad won't budge. The bleeder valve and the line in put look as though they have rusted shut. Didn't force these coz I don't want them to crack or break off. I tried what this guy did https://www.youtube.com/watch?v=l2WW-yoiimI (without his fancy set up, right off the bike) but I had no luck, the damned thing just won't budge. I will post pics soon, any suggestions in the meantime are most appreciated.

[Stev-o]

Have a grease gun? Try this method....

 
http://forums.sohc4.net/index.php?topic=15059.50


Or buy a used caliper......

[ncstatecamp]

M10 1.25 zerk fitting- grease gun worked for me

[mark52]

Same here

[ekpent]

I just recently removed the pad and piston from 2 very solidly stuck calipers on a 550F and 750F. First step was to completely remove from the bike and start some soak penetrating oil around the old brake pad edges. Next step was to put caliper in a vice and carefully with good heat and penetrating oil get the bleeder valve out. Once it breaks loose screw it back in and out as you go to work that oil in. Once bleeder was cleaned I reinstalled on the brake line and bled normally. When it came time to 'force' out the old pad and piston with hydraulic force my buddy put extreme force on the handle while I whacked the old pad with a hammer repeatedly and both eventually broke loose and their innards came forth. Felt good as I went 2 for 2.

[edwardmorris]

I think I'm gonna have to make run to the store and get some fluids to get all the rusted attachments off. Nothing is budging despite practically soaking in the CRC Brake Parts cleaner. If anything I busted the damned brake pad trying to pry it out when I saw the slightest bit of movement (or at least it seemed like it had moved).

[edwardmorris]

Got some PB catalyst and have been soaking both the bleed valve and the brake line ends to get this thing off the bike but neither of them are budging, as if they got welded together. I'm afraid id I try any harder, I'm gonna start stripping off the edges on them and it will end up being completely useless. I'll keep at it for a while. Don't have a grease gun or the attachment. Even if I did, wouldn't be much help if the damned thing won't separate from the bike

[ncstatecamp]

Got some PB catalyst and have been soaking both the bleed valve and the brake line ends to get this thing off the bike but neither of them are budging, as if they got welded together. I'm afraid id I try any harder, I'm gonna start stripping off the edges on them and it will end up being completely useless. I'll keep at it for a while. Don't have a grease gun or the attachment. Even if I did, wouldn't be much help if the damned thing won't separate from the bike

Heat, pb blaster, marvels mystery oil. Your three best friends, also a plastic syringe for using the marvels.

[70CB750]

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

[edwardmorris]

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

Its the line hole and the bleeder that I can't get out.

[78whiteorbs]

http://forums.sohc4.net/index.php?topic=104370.0

18$ well spent!

[scottly]

Got some PB catalyst and have been soaking both the bleed valve and the brake line ends to get this thing off the bike but neither of them are budging, as if they got welded together. I'm afraid id I try any harder, I'm gonna start stripping off the edges on them and it will end up being completely useless. I'll keep at it for a while. Don't have a grease gun or the attachment. Even if I did, wouldn't be much help if the damned thing won't separate from the bike

You need the proper tool to remove the brake line fitting: it's called a flare wrench.

[70CB750]

+1 on flare wrench.

What I have done before on rusted calipers is to hammer socket tight  on the bleeder - when the flare wrench is not enough. With socket on you will either get it out or brake it.
Same for the brake line fitting.

Good luck!

[ekpent]

You can still remove the caliper from the bike at the fitting where the metal pipe joins the rubber hose a little farther up the line.     Then you can get the thing to a bench and get it in a vice where you can start working it with some heat from a propane torch and some oil so its not flopping around.  I have a Snap-On flare wrench and they are nice because the ends are also thicker for a better perch on the nuts.  You need some heat though to break that bond on those two fittings.

[edwardmorris]

You can still remove the caliper from the bike at the fitting where the metal pipe joins the rubber hose a little farther up the line.     Then you can get the thing to a bench and get it in a vice where you can start working it with some heat from a propane torch and some oil so its not flopping around.  I have a Snap-On flare wrench and they are nice because the ends are also thicker for a better perch on the nuts.  You need some heat though to break that bond on those two fittings.

Already tried to take it apart further up the line but even that was no good. Tried a little force and the damn thing started to strip. Tried again this morning after soaking in PB, still the same #$%*. I'm telling you, its like the whole assemble melded into one big pile of crap. I may have to invest in a torch if I keep running out of options....

[70CB750]

You could just get a different caliper, they are not that expensive. 

[ekpent]

Well the next step up is to take the hose off the splitter that is under the bottom triple tree.That is also where the front brake activates. That is a big 14mm and if that one does not come off I would be very surprised. Surprised you could not split it at the metal to rubber junction,it does take 2 wrenches there.

[ekpent]

You could just get a different caliper, they are not that expensive. 

At this point he can't get it off the bike.

[edwardmorris]

Well the next step up is to take the hose off the splitter that is under the bottom triple tree.That is also where the front brake activates. That is a big 14mm and if that one does not come off I would be very surprised. Surprised you could not split it at the metal to rubber junction,it does take 2 wrenches there.

Did try it with two, the smaller nut keeps tending to strip. The bigger one has a better hold. Will try to take it off at the splitter shortly.

[Stev-o]

Are you using the correct size wrench?  (Not an adjustable?)

[edwardmorris]

Yes, 10mm wrench. Just made a tools run and bought a flare wrench set and even with that, its just stripping, no dice. The bolt higher up in the line gave me hell as well but a deep well socket helped break it loose. Finally have it off the bike. Will try and put it on a vice at the in-laws and see if I can get either of them to come loose. Easier to try heat when its off the bike as well, so will give that a shot and post back. Is it fine to leave the line open without any fluid in it (including the master)? All of it drained out once I loosened the midway bolt. If all this fails, time to procure FFJ's famous $18 service.

[RAFster122s]

You are going to need to attack it with heat and basically cook it to get it to yield. Stop trying now and get yourself some MAAP gas and a torch or a propane torch.  Heat the metal around the bleeder and 5-10 minutes of torch work and then cool the bleeder with some PB blaster. Let it return to room temp and hit it with PB a few times as it cools. Then when you can handle it easily you can reheat it another 10 minutes. Let it cool a few minutes hitting it with PB Blaster again and then slip your 10 mm wrench over the line and give it a go with the caliper body clamped in a vice with a couple layers of cardboard to protect the body or some heavy cloth or leather to protect the caliper body from marring.
Just don't push too hard to round it off.

The bleeder I usually get a deep socket and use a 1/4" drive socket so I can't easily break it. Again, put it under load but don't really wail on it...don't want to snap it off.

If after a couple high heat cycles I can't get it and I've not screwed it up, then I break out my last resort. I fire up the grill and get a couple pounds of Gulf Wax (Paraffin wax used for canning vegetables and fruit) in a loaf pan that will fit the caliper body.  You can put a block of something to take up space so your paraffin is going to emmerse the caliper.
Get the paraffin liquid and cook the caliper for about 20 minutes and then let it cool. Before the wax hardens up, you pull out your caliper and let it cool back to room temp. Then try removing your bleeder and hard line again. Odds are you will be rewarded with them coming out.
This trick is an old machinist method and it works very well as the wax is pulled into the spaces between the bleeder or the line and it helps lube it so it can come out.
Sometimes it is better than the torch method but the torch method is safer.
The Paraffin wax is very flammable so, take caution as it can catch fire.  Not to mention water can cause it to splash which can cause burns requiring hospital attention.

Good luck!

[edwardmorris]

HA finally a breakthrough, I was  able to get both the nipple and the line to break loose with heat and PB blaster like ncstatecamp and ekpent suggested. Needed to use a killer hand vice grip while the caliper was on the bench vice to get it to move a hair. All I needed, then it was more PB and unscrewing gradually. Now, I'm gonna go get me a nice dinner and then on to bleeding and popping that pad off of there Thanks for the help so far, and for being patient with me. I hope you guys will help me with the rest of it as well

[70CB750]

Nice!

[edwardmorris]

........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?