Clutch Problems

[flynavyj]

Hey all, i originally had a similar question attached to my introduction thread here :http://nighthawk-forums.com/index.php/topic,6686.0.html but i know i'll get a little more exposure over here. This is the initial issue.

Clutch would work ok for appx 25-30 minutes, then the clutch wouldn't disengage, you could pump the clutch handle repeatedly and build up enough pressure to get it to disengage so i could make it home, but that was about all. Two days ago i bled the system multiple times, finally got what appeared to be all the air out yesterday, and took the bike for an 1.5 hr ride, w/o any hiccups at all. Clutch engagement/disengagement seemed more correct (at the beginning of the stroke) and everything seemed fine. I got home, turned the bike off for five minutes max, and felt the clutch handle, it had almost no resistance again (like i had air in the lines again). I also noticed a very tiny spot under the bike (smaller than a dime) of some type of fluid (guessing hydraulic, didn't smell like oil). Today, the clutch felt much better again, but i didn't ride it, and based on the small little fluid drop, i was making the assumption that the slave cylinder had a leak. So today, i tore off the slave cylinder, encountered one problem (splitting the spacer, insulator, from the cylinder). The insulator has a small crack in it (either from me attempting to hit it off, or it was broken before, but i vote for the prior. I was able to clean the units, between the cylinder and insulator was tons of gunk, there was also plenty on the spacer side too. The O-Rings didn't look "terrible" no tears, or really misaligned pieces, i am curious to see what the piston cup ring looks like when new, as mine is a tad crunched (not terribly, but a little bit). Here are the photos, let me know what you're thinking, and if anyone knows a good location to get another insulator, or if it can be repaired with some jb weld, RTV, etc, as it looks as thought it shouldn't have any fluid flowing behind it. Am i correct in that thinking? I'm going to pick up a new piston cup seal and oil o-ring from the dealership tomorrow, and hopefully this will solve my "clutch" issues...if not, then i'll be digging into the master cylinder as well...Pics below.

Slave Cylinder Disassembled

Spacer (most of that gunk has since been removed, it was worse than that originally)

Cylinder

Insulator (crack is to the upper left)

Insulator (with crack visible)

Piston

Spring

Spacer Rear

Spacer Oil O-Ring


On the oil o-ring, i noticed that it's pretty flat, which could allow some seepage, but the engine case looked as though there was a "decent" connection made between the slave cylinder and the case. The piston Cup Ring looks a little flat, which makes me think it could potentially allow some fluid to bypass the piston and press towards pushrod, if so, it'd make sense that small pockets of air might be able to get back passed the same hole...If the spot is small enough, that might explain why air keeps getting into the line, and only a small amount of fluid leaks out passed the o-ring. It doesnt explain however why the clutch didn't act up until the bike was stopped, unless the movement kept the bike from heating up significantly, and temperatures actually rose once the bike was stopped back home. Lets bounce some ideas guys/gals, i'm sure we can get this thing solved. Thanks!!!

[coffee_brake]

With heat also comes the fact that the hydraulic lines which are made of rubber are expanding and bulging out when you pull the lever. This means much of your mechanical force applied at the lever is pushing on old rubber squishy lines instead of pushing the cylinder.
Then, if there's a leak, game over. I just had this scenario this week with the line spouting a leak. In your case it looks like the slave cylinder is the one leaking. You are not going to be able to use that clutch with fluid leaking out of it.

I'm wondering if the assembly took a hard hit and that's why it cracked.

Looks like a rebuild of the slave cylinder may be in order, you can see that it won't be hard. But I think you have to replace that spacer?

When you re-assemble, consider using a new stainless line between the master cylinder and the slave cylinder. It vastly improves clutch feel and will eliminate the "old line swell" you're likely experiencing now. You don't have to go buy a high-dollar line make specifically for your NH. All you need to do is measure the appropriate length with a string, making sure there won't be hard bends at the ends, and buy a custom line by length with the correct ends (ebay sites let you choose the length and the ends to match your setup). Should be no more than $40 on Ebay, a little more if you buy a brand-name line.

[flynavyj]

Thanks for the info Coffee brake, and i'm definitely going to look into getting some SS brake and clutch lines as i do this rebuild. Everything comes with time and money i think. I stopped and bought all the seals today, came out to about 30 bucks in rubber (yuck) and installed them all. I didn't take the bike for a test ride, but i'll try to do that tomorrow, and maybe i'll be able to find out if it's still acting up or not. The only part that was a pain was the Oil Seal in picture 2. The rubber that's on the top and visible is a tad deceiving, while it was soft, the rest of the seal was nearly "welded" into the spacer. Making matters worse, it has a metal core, so you can't just push through it and gank it out. Besides that piece, the rest went back together like pie. My piston seal was definately worn in comparison to the new one, i also replaced the oil seal on the top of the piston, and the o-ring in the rear. I installed my original (and broken) insulator, and have noted no leaks from it, which is what i expected since no fluid SHOULD be reaching it. Besides that, used the vacuum bleeder to bleed the line, and was in business a few minutes after assembly, rode it up and down the block, and luckily for me, i didn't screw anything up bad enough for the system to not work...Now to only see if it fixed the problem.

[coffee_brake]

Very cool, and I assume you cleaned and polished the surfaces of the metal so they can have as little friction as possible....I find that a sludge paste of baking soda and a few drops of water is very good for polishing metal and cheap to boot....

[ariwhiteboy]

Very nice, doesn't it feel good to fix something on these old bikes?    Great job with the explanation and the photos too, you should retitle the thread as a how-to so in the future other members will be able to find it easily. 

[flynavyj]

It does feel good, but i'll feel better once i've guaranteed that it's fixed. I rode the bike today, but not for very long, i'm tempted to take it to work tomorrow to see how she's doing, but we'll see if i do or not. I did clean out the cylinder, but i didn't really "polish" it up well, which looking back on it, i wish i had. My biggest fear was getting it marred and having a gap for air to leak in, and fluid to leak out, so i just basically wiped it down, made sure there was no major buildups, and re-assembled it with the new piston seals.

The PO mentioned that oil was leaking out of the alternator. After seeing the paint flaking under the  slave cylinder, i assumed that the cylinder was the source of a dirty hydraulic leak, but after riding today, i did see one drop of oil come down, and one drop resting under the alternator. Pretty sure the oil seal on the alternator shaft is seeping a little bit, so if all is going well, i might get to that in the future...With the very very gradual amount it's leaking, this might be something that i'll take care of further down the line...long as it stays slow, i doubt it'll lead to a premature alternator failure.

[flynavyj]

Well, good news. I rode the bike on a 36 mile round trip today to work and back. And she didn't let me down. More than enough power for solo commuting, and passing at highway speeds. But the best news is that the clutch didn't act up on me on the way there, or on the way back. I'll be keeping an eye on it, but it seems likely that the problem i was having was in slave cylinder, and the rebuild has worked it out. Thanks for the help all.

[coffee_brake]

Yay!   

[flynavyj]

Yeh, that felt good. But i'm currently waiting on a starter rebuild kit (there's always something). Another question, when you put the bike into gear, and pull in the clutch, how much rolling resistence is there? I tested it on my SV, putting the bike into first, and then pulling in the clutch and trying to roll the bike. The bike does roll, but you can notice a very small difference with the bike being in gear. When I tried the same thing on the NH, i noticed that it was noticably more difficult to move, but you could still roll it, just had to really push it to get her going. With the clutch out however, and the bike out of gear, it wasn't going anywhere....So i'm just wondering how "disengaged" the clutch should get, and allow the bike to move. Thanks.