Clutch question

[dbeardslee]

As the weather has warmed up here in Ohio I have noticed that my clutch adjustment seems to change as the engine temp goes up. I installed a new clutch about two months ago and it has been working flawlessly up to this point.

I've been riding it a lot lately in rush hour (what a misnomer) traffic which means a fair amount of time sitting at red lights. A couple of times on particularly hot days (for Southern Ohio that means over 90 degrees) it seems like the clutch just barely disengages. Once I get moving and my air cooler starts working the problem goes away.

I suspect it's just the engine getting hotter than normal causing the clutch plates to expand and closing up the tolerances. I don't think it's getting super-hot as it continues to idle and run fine. I have the clutch adjusted properly (cold engine), and the clutch lever has the recommended 1-2 mm of slack in the cable.

At this point I'm thinking I need to remove the slack in the cable to allow a little more travel at the throw-out bearing. Anybody else ever had a similar problem with their clutch?

[olebiker]

Be careful that you don't end up with the clutch slipping just a bit and glazing up the plates. Aircooled engines are more likely to do funny things in high heat while not moving much. Plus the rider can get a bit goofy (hey I am not goofy all the time).

[boyat68]

dbeardslee:

Quote from the manual: "The clutch mechanism adjuster is used to provide proper disengagement. Normally, once the mechanism is properly adjusted, the only adjustment required is maintenance of free play at the clutch handle lever."

Free play adjustment 2~3 mm (0.08~ 0.12 in.)

Also a caution Note:

"Do not operate the clutch lever until clutch mechanism adjustment is complete. This could cause dislocation of the steel balls in the adjuster housing. If the balls are out of position in the housing, the clutch will not disengage. To reposition the steel balls in the housing, remove the right side case cover."


It looks as if you have to check your mechanism adjustment.

[dbeardslee]

It's properly adjusted at the clutch housing. Again, this is an intermittent problem that seems to be related to heat. Just wondering if anyone else has had similar problems.

On glazing, I think this is one of the more misunderstood phenomenon when it comes to drum brakes and, in this case, clutch plates. Glazing is typically a problem in big trucks, and it generally happens on long, steep, downhill grades. The drums will actually heat up to red-hot, but it isn't the drum that glazes - it's the pads. Specifically asbestos pads. The asbestos crystallizes at high heat which causes crystallized material to get in between the pad and the drum. As the friction plates use cork (not sure if they have any asbestos in them or not) I'm not sure they can glaze, and at any rate, the temperatures you would have to reach to glaze asbestos would be excessive for a motor. The motor would probably seize before they glaze. I would be more worried about the clutch getting hot and warping the plates, but I hear what you're saying.

[trbig]

The clutch material is probably not what gets glazed, but the oil being overheated and the carbob molecules forming and sticking to the surface of the pads and steels.... kinda like when you season a cast iron pan. You coat it with oil and then cook the pan in an oven to smoke the oil. It leaves a carbon surface that is nonstick... something you don't want in a clutch.

This may be what is happening to you... starting to carbon up, then the detergents in the oil are cleaning the baked on stuff off after you get back going. I'd change my oil more frequently in these situations if I were you.

Tod

[dbeardslee]

Trbig - thanks for the reply. I think it was just a little too much slack in the cable. I tightened it up a little and it seems to be fine now. I can still feel the adjustment change in it however. When it's cold the clutch engages when the lever is almost all the way out. When it gets hot the clutch engages when the lever is closer to the handlebar. Doesn't slip.

Funny you should mention changing the oil - just did it this afternoon. I change the oil every 2000 miles, and the clutch (both friction plates and steels) only has 1200 miles on it. One thing I did do was switch from 20W50 back to 15W40. Engine seems to like it better and I'm pretty sure a thinner liquid will dissipate heat faster than a thicker liquid. Is that assumption correct?