Time for new clutch?

[George inMinneapolis]

Time for some off-season wrenching I believe.

While riding down the highway in 5th gear going into the wind, my speedometer and tach fluctuates up to 10 mph or 1000 rpm. I don't hear any change in speed, nor do I feel any change in speed. Just the tach and speedo are swaying. At 60 mph, this does not occur. It does not happen while driving in town.

So is this signs of time to replace the clutch?

The clutch adjustment at the rear of the transmission is adjusted all the way and there is no more adjustment left.

There is 45,000 on the clutch.

A fall tech day at my house may be in order.

George

[Deleted User 72]

Whenever my clutch was slipping it was easy to tell. At about 60mph I could whack the throttle open and the tach would outrace the speedo. Does yours do that?

[Motorhead]

when you replaced your clutch how many parts did you replace, or what process did you choose

[Kurt in S.A.]

If the clutch slips, wouldn't the tach increase but the speedo remain the same? The tach is reflecting engine speed while the speedo is reflecting rear wheel (or tranny output) speed. 45K seems kind of light on miles for a clutch. I just changed mine after 100K...the clutch disk had much more life in it. But, I just changed everything from the flywheel back...I don't want to have to be in there for another 30 years.

Kurt in S.A.

[Jean]

45K miles seems rather "young" for a clutch replacement.
You didn't say what bike this is and your profile doesn't say, either. Kurt is right, I replaced my clutch about 3 years ago and it had MANY, MANY miles on it, and wasn't slipping although the disk was only 3mm thick. (The pressure plate was a bit doggy tho.) I replaced ALL the parts.
How many miles on the original clutch? How old? Did you replace the finger spring?
Did you have the Pressure plate ground and if so, how much? A new clutch should not require your cable adjustment to be all used-up this early.
We are just FULL of questions....

[Major Softie]

If the clutch slips, wouldn't the tach increase but the speedo remain the same? The tach is reflecting engine speed while the speedo is reflecting rear wheel (or tranny output) speed.
Kurt in S.A.

Yes yes yes.

If the tach needle swung while the speedometer remained steady, that would be a sign of clutch problems (or tranny input splines). These symptoms are not.

Since the two instruments are swinging together, and the tach is driven from the engine while the speedometer is driven from the tranny, George's symptoms are one of two things: Some electrical/magnetic interference that is affecting both instruments, or rear wheel splines slipping - in which case it would be rather amazing that he got home.

Since George claims that he hears no change in engine speed when this happens, I cannot see how it can possibly be anything but an instrument problem.

[Jean]

He did not say which way the fluctuations occurred. So if the tach is increasing by 1000 rpm and the speedo is "loosing" 10mph, there may be some slipping happening. On the other hand, none of the other questions got answered...yet.
If the rear splines were "slipping" I think he'd hear something! Something like rocks in a blender.

[George inMinneapolis]

Thanks for the replies. I got the bike,r80/7, with 70k on it. Papers said clutch changed at 50k. At 70 mph both tach and speedo can swing back and forth noticeably. My instrument cluster brace is taller than stock, perhaps meant for a faring. The cluster does bounce quite a bit while riding. Yet, the symptoms occur around 70 mph. Still, my clutch adjustment is used up. Hmmmmm?

[Duane Ausherman]

You have two clutch adjustments. If you are out of range at the top end, then fix it at the bottom.

I too go with an instrument problem. Were it the clutch, the engine would race and the bike would stay at the same speed, or drop speed.

Do you ride really hard? Average riding won't wear out a good clutch at 45 k miles.

It isn't splines, as you would be walking home. It would also be making some horrible noises.

[Ken in Oklahoma]

On every motorcycle that I've ever owned with a slipping clutch invariably had the same symptoms. The problem appears first only in the higher gears. The engine speed increases and you feel less or little acceleration. I never needed the instruments to tell me I have a problem. My ears and butt dyno were sensitive enough.

George, were your symptoms progressive, meaning at first you weren't sure if there was slippage or not, then it became more pronounced?

Secondly, you said that the adjustment was at it's limit at the rear of the transmission. Were you out of adjustment at the clutch lever also? For you to be totally out of adjustment I would expect both adjustments to be at their limits.

At 45K miles you clutch could very well be worn. Both my '77 R100S and '77 R100/7 developed clutch slippage at around 60K miles. The /7 had had its speedometer replaced, so it's hard to tell for sure how many miles were on its clutch.

But aside from the question of whether your clutch might be slipping or not slipping, I'm concerned about the lack of adjustment at the rear of the transmission. By out of adjustment do you mean you're out of the adjuster's thread length, or something bottoms out, or something else?

I think of the adjuster at the transmission being a "coarse" adjustment and the adjuster at the clutch lever as being the fine adjustment" Do you think of them as the same way?

In any event, if you are sure you are out of adjustment at the transmission, then there is a problem of some sort happening. It's not supposed to be that way. And that something happening is likely to have to do with the clutch push rod or pressure plate. If your clutch throwout (release) bearing at the rear of the transmission were bad that could cause the push rod to rotate against the pressure plate and wear excessively, perhaps so much that you are out of adjustment.

In any event I think that means pulling the transmission and having a look around. At 45K miles you're probably not so far away from a clutch job anyhow.

My thoughts.



Ken