Clutch slipping

[obelix]

I was about 500 miles on my holiday trip when I noticed clutch slipping when accelerating suddenly.

It makes the usual 2000 - 3000 rpm jump up when you turn the gas hard. So far so good.

I turned around and drove all the 500 miles back home again. The phenomen was there every time I accelerated from a gas station so I had to do it easy. Luckily I could chose a route on highways so no stopping except for gas. Arrived at home I tore the clutch open and found ... nothing.

All the clutch plates are fine. Thickness varies between 3,10 and 3,15mm, book says inferior limit is 2,8 so they are ok. Only very small black deposits.

All the friction plates look fine. Clutch plates were nicely wet, no shuddering or erratic operation. No probs when disengaging/engaging the clutch.

No sign of burning or discoloration associated to slipping.

The clutch spring on the outside looks ok and had tension, the bolts were tight.

All the parts seem never to have been apart before.

The weather was dry, the bike only lightly loaded. No rear tire slipping.

I have absolutely no clue what happens. :blink: The last thing I did was to change the clutch line to a longer stainless steel line as I mounted a different grab bar. I did another bleeding now but no bubles there. I changed to DOT 5.1 from 4.0 but the 5.1 is said to be completely mixable with 4.0 (the 5.0 is completely different and can not be mixed). The new line is routed cooler, behind a heat shield so I discard the hot fluid possibility.

The bike has only 12000 miles and the previous owner was also a careful driver, 60 yo and professional heavy truck mechanic. It's a GenI of 2004. I don't ride the clutch either, my Honda is still on the first clutch at 60000 miles.

Anyone any suggestions? I will stilll try to clean the clutch plates and soak them in a different oil. AFAIK the last oil change was done only 800 miles ago by a well known dealer, I got 3 liters of oil as spare and it seems it's the correct type. I hate to give this to a dealer as they are probably also clueless and have me pay for the time they wonder what happens. :angry:

 

[kolonial72]

Does this happen regardless of speed/RPM? Or does the phenomenon only occur at low speed?

Get yourself a helper. Have them slowly operate the hand clutch lever while you check the mechanism for smooth operation. If you detect a sticky spot, you may try lubricating the cable. Actually, maybe just lube the thing right off and see if there is a difference. I think you're due. Not sure if there is anything else you could clean or lubricate while you're at it.

Does the shift mechanism work properly? Try checking it for smooth operation. I doubt it would be your culprit, though. If it's not quite smooth, consider removing and cleaning it. Quote from Radman: "Remove the entire assembly (part of the left footpeg plate) disassemble, clean, and grease. The difference will amaze you. Ditto rear brake lever/pivot assembly."

Hopefully someone else with more experience will chime in here. If none of the above works, I would start thinking about that clutch spring. Maybe it has tension, but perhaps not quite enough. Darn thing shouldn't be fatigued this early in life.

 

[Silent]

Did you recently change your oil to an "energy conserving" oil? If so, that can cause the problems you're describing.

 

[ionbeam]

Indeed, look at the engine oil from your last change. (No additives added by you or the person that changed your oil, right?)

There is no 'cable' to lubricate in your hydraulic clutch system. Air in the clutch lines or a problem with the clutch master cylinder would prevent the clutch from fully disengaging -- meaning that you clutch would still be partly ENGAGED, the opposite of your problem. If the brake fluid in your clutch system were to cause any problems, it would result in failure to disengage.

It sounds like you have eliminated all the big, common issues that could cause clutch slipping. If you can find nothing else, flush the old engine oil out and put in oil that you know has no additives, is not 'energy conserving' and change the filter too. If the problem still remains you may want to pull the clutch slave cylinder, remove the clutch rod and verify that it isn't bent. I don't recall ever hearing about a bent clutch rod on the FJR.

I'm betting on the engine oil.

 

[charismaticmegafauna]

I was about 500 miles on my holiday trip when I noticed clutch slipping when accelerating suddenly.It makes the usual 2000 - 3000 rpm jump up when you turn the gas hard. So far so good.

What are you describing here (in detail)?

Clutch slipping is usually first noticed when accelerating hard in the highest gear (top, 5th, gear) -- greatest load.

All other things being equal...., one of the first rules of troubleshooting is to return to the area where you last worked.

 

[ionbeam]

I was about 500 miles on my holiday trip when I noticed clutch slipping when accelerating suddenly.It makes the usual 2000 - 3000 rpm jump up when you turn the gas hard. So far so good.

What are you describing here (in detail)?

Clutch slipping is usually first noticed when accelerating hard in the highest gear (top, 5th, gear) -- greatest load.

All other things being equal...., one of the first rules of troubleshooting is to return to the area where you last worked.

Umm, it wouldn't be caused by the rear tire slipping would it?

+1, Gunney to what CMS says about *worn* clutch slipping normally happening in taller gears. In this case I think that worn clutch plates have been eliminated.

 

[obelix]

Your suggestions are all welcome. I just checked the slave cylinder for smooth operation over the full trust lenght and it was fine.

Actuation rod bent might be an idea but in this case again I believe it would not fully DISENGAGE as it's shorter. Though no sign of anything abnormal happening here, even the drop of lithium grease on the small ball still present.

I noticed the slipping first when accelerating relatively hard in 4th at about 40-50mph when the rpms jumped up. This could be easily repeated. Then I noticed it again maybe in 2nd or 3rd when accelerating. Later I noticed it in any gear when putting a high torque to it. Tire slipping? Rather not. When this happens in 4th I'd have made a royal slide off the road.

All I can do is clean out the previous oil with brake cleaner on the disks, then soak them in regular oil. Maybe even replace the clutch spring. But if anyone has another suggestion just tell me.

The last area where I worked was the clutch line replacement but I really can't see anything causing this. And I checked the operation of the slave, just in case.

 

[kaitsdad]

Indeed, look at the engine oil from your last change. (No additives added by you or the person that changed your oil, right?)
There is no 'cable' to lubricate in your hydraulic clutch system. Air in the clutch lines or a problem with the clutch master cylinder would prevent the clutch from fully disengaging -- meaning that you clutch would still be partly ENGAGED, the opposite of your problem. If the brake fluid in your clutch system were to cause any problems, it would result in failure to disengage.

It sounds like you have eliminated all the big, common issues that could cause clutch slipping. If you can find nothing else, flush the old engine oil out and put in oil that you know has no additives, is not 'energy conserving' and change the filter too. If the problem still remains you may want to pull the clutch slave cylinder, remove the clutch rod and verify that it isn't bent. I don't recall ever hearing about a bent clutch rod on the FJR.

I'm betting on the engine oil.

+1.

changing your engine oil would be the first thing I would do.

 

[johnny80s]

Indeed, look at the engine oil from your last change. (No additives added by you or the person that changed your oil, right?)
There is no 'cable' to lubricate in your hydraulic clutch system. Air in the clutch lines or a problem with the clutch master cylinder would prevent the clutch from fully disengaging -- meaning that you clutch would still be partly ENGAGED, the opposite of your problem. If the brake fluid in your clutch system were to cause any problems, it would result in failure to disengage.

It sounds like you have eliminated all the big, common issues that could cause clutch slipping. If you can find nothing else, flush the old engine oil out and put in oil that you know has no additives, is not 'energy conserving' and change the filter too. If the problem still remains you may want to pull the clutch slave cylinder, remove the clutch rod and verify that it isn't bent. I don't recall ever hearing about a bent clutch rod on the FJR.

I'm betting on the engine oil.

+1.

changing your engine oil would be the first thing I would do.

+2

 

[kolonial72]

There is no 'cable' to lubricate in your hydraulic clutch system.

Oops, I'm a retard. That's right, no cable. I think I had a flashback. Might explain the colored lights that are following my fingers as I type.

 

[ionbeam]

If all else fails and only gonzo ideas remain, here is a gonzo idea. I've seen people install new lines using Teflon tape and had the tape extend past the internal threads. This allows the fluid to flow in one direction but the tape flopped over the opening at a junction and blocked fluid flow going in the other direction. Old brake/clutch lines can separate internally causing the same situation as the Teflon tape.

 

[obelix]

If all else fails and only gonzo ideas remain, here is a gonzo idea. I've seen people install new lines using Teflon tape and had the tape extend past the internal threads. This allows the fluid to flow in one direction but the tape flopped over the opening at a junction and blocked fluid flow going in the other direction. Old brake/clutch lines can separate internally causing the same situation as the Teflon tape.

Thanks Ionbeam. I had a similar idea but couldn't find anything. The clutch line is new but who knows...maybe it's worth a shot. Will cost me 50$ for a new ss line but if everything else fails....

First thing tomorrow will be getting new seals and put a different oil in.

 

[C&C]

You never mentioned what type of oil was used for the oil change. You said the person who changed it said, 'proper' by a well known dealer but if that person was from a Harley dealership or another that doesn't need to be concerned with a wet clutch that may be the problem. You said the oil was changed 800 miles ago; was that about when your condition began?

 

[obelix]

In fact I own this bike only for 700 miles or so. I never noticed clutch slippage before though it MIGHT have been present.

The oil and the new clutch line are my only points I can think of. I suppose the oil was correct as I got 3 liters spare with the bike and, being made by ELF, state in large letters no friction modifier included and suitable for wet clutches.

Harleys are very rare here compared to the japanese manufacturers and BMW so I don't think a pro in bike repair could make such a mistake.

 

[lnewlf]

Oil first-My clutch seemed to like Rotella synthetic-seemed to make it release easier but that would not held your problem..but anytime I had a slipping clutch on anything after futzing around with all possible solutions a set of new fibers and a diaphragm [spring ,that is] fixed the problem. Barnett parts are the mutz nutz but OEM Mamaha stuff will run less than a C-note.. Your fibers could be glazed or the spring could be fatigued..

 

[obelix]

I just finished the work. I disassembled the clutch, gave everything a thorough cleaning with brake cleaner (agressive stuff, take care). Then I put the friction disks overnight in an oil bath with good quality motorcycle oil. Reassembled everything, changed out the rest of the oil in the engine, filled up and made a test ride.

My first impression is the problem's gone. Took her in 5th from 50 to 120 mph without a sign of slipping or hesitating.

My guess is that the son of the previous owner (where the bike was standing the last year) topped the oil up with some super-slippery synthetic for cars. This made probably up for the problem. I have to go on a longer test ride and heat her up for some hours to see if it really is gone but I hope so.

My thanks to everybody who tried to help.

 

[johnny80s]

Good news. I will keep my fingers crossed.

 

[S76]

Glad to hear you are making progress, but be advised it may take an oil change or two to get it all out.

 

[Silent]

Sounds like friction modifiers have struck again. Glad to hear your on the right track to fixing the problem for good B)