Slipping clutch

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Wingjon

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Joined
Dec 14, 2007
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Location
Everett, WA
I just returned from a great ride over part of the North Cascade Hwy. (north of Seattle) That's the good news.

The bad news is that when I attempted to roll on enough throttle to pass a car at 60 mph or so, the clutch slips badly. First time this has happened, but it continued through the ride.

The bike is an '06 FJR with just over 20,000 miles. It has not been ridden hard (since I bought it with 3,000 miles two years ago); no drag race starts and no power shifts. The oil has been changed with reasonable regularity and now has Motul semi-synthetic in it that is ready to be changed. The engagement point on the clutch lever is almost all the way released where it used to be close to the bar.

Is it reasonable to suspect that the clutch is toast with this low mileage? Has anyone else experienced this?

I would appreciate any insight available.

Jon

 
There are several opssibilities;

1. Clutches can slip if you use an oil with friction modifiers - but you said you run an overly expensive, semi-synthetic intended for bikes, so that isn't likely the case.

2. It is possible that you have some debris between the clutch plates, reducing the contact area.

3. You could have a problem with the hydraulic sender or servo that prevents it from retracting.

4. Perhaps you managed to break a clutch spring or have a bad throw bearing.

or, more likely, since you've indicated that the engagement point has gone to the limit;

5. You could be low on fluid or there might be air in the system.

6. You've toasted the plates.

Having said that, clutch plate replacement is not major surgery and assuming you haven't glazed the pressure plates, a full set of friction plates (there are a total of 9 plates) costs less than $70 plus a new gasket.

Could you have worn out the clutch? Absolutely. But if you've been using the clutch gently and have not spent your life in stop-and-go traffic, the clutch should last a long, long time.

 
Last edited by a moderator:
Adding to BramFrank's excellent post...

When is the last time the hydraulic fluid (clutch and brake) was changed?

While that shouldn't cause your symptoms, it would be a great place to start checking the hydraulic systems while looking for other problems.

 
+1 to everything Bramfrank wrote.

As for the mileage, toasting the plates can happen in a day if somebody starts pulling hole shots. (drag starts) A family member toasted the clutch in an earlier bike of mine when it had a lot less miles than yours has.

 
<snip>The bad news is ... the clutch slips badly. First time this has happened, but it continued through the ride.The bike is an '06 FJR with just over 20,000 miles. It has not been ridden hard (since I bought it with 3,000 miles two years ago); no drag race starts and no power shifts.

The engagement point on the clutch lever is almost all the way released where it used to be close to the bar.

Is it reasonable to suspect that the clutch is toast with this low mileage? Has anyone else experienced this?

I would appreciate any insight available.
If the clutch slips (without you doing it) -- yes, that definitely is bad. M/c clutches are, generally, robust -- but, won't tolerate continual slipping (especially at high speed -- high engine/clutch speed).

You may need to consider those unknown miles....?

You may, also, have something coming loose within the clutch itself -- bolt/s loosening? -- may need visual inspection.

I don't think there's a miles = worn-out component. Some never wear-out a clutch while others have 'issues' more-or-less frequently.

Certainly, you'll need this attended to at the earliest possible opportunity. Once the clutch slips at speed, under power, things will get rapidly worse. Doesn't mean all is lost, yet -- someone needs to investigate.

Good luck.

 
Thanks for all the input. I will start digging into the various suggested areas tomorrow. At least it doesn't sound like too big a deal to fix.

 
If I had what you are explaining I would go after the clutch master cylinder. Especially since you said the clutch is grabbing much higher (further out) than it used to. This could be an indication the master cylinder is trapping fluid in the lines.

If you take the cover off, and the fluid is clear enough to see through, (if not you will have to suck it out) there are I believe 1 or 2 tiny holes in the bottom of the resevoir. If the hole(s) gets plugged up, and it only takes a tiny piece of debris, it will not allow the fluid to return to the resevoir, thus trapping it in the lines. This will keep some constant presure on the clutch pressure plate and not allow the clutch pack to be fully engaged by the springs.

Another thing you may try is with the engine off, exercise the clutch lever a few times, then open the bleeder screw on the slave cyclinder and see if you get a tiny squirt of fluid out. If you do then you know you are retaining pressure. Granted it will drool as it is gravity feed but there should be no pressure.

Or just do a regular bleeding proceedure to see if you can flush out any dirt that may be screwing up your master cyinder. The fact that you say the clutch engages different than before should be your clue to this.

These clutches are pretty bullet proof and it takes alot of effort to ruin one. Unless you have been drag racing every other weekend I doubt it is worn.

 
Follow up report.

The problem was the clutch plates were trashed. I've gotten several opinions for this ranging from using full synthetic to mixing oil brands to abuse. Thinking back, I have done lots of low-speed "friction zone" practicing, so maybe that's the problem. I seem to remember that the cop motor school bikes get lots of clutch replacements.

Thanks for all the input.

 
Follow up report.
The problem was the clutch plates were trashed. I've gotten several opinions for this ranging from using full synthetic to mixing oil brands to abuse. Thinking back, I have done lots of low-speed "friction zone" practicing, so maybe that's the problem. I seem to remember that the cop motor school bikes get lots of clutch replacements.

Thanks for all the input.

I am glad you got your bike working, but I don't believe that for a minute. There are too many bikes out there with way more miles, running various synthetic oils and no problems. But your up and running again so that's good.

 
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