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General Category => General Discussion => Topic started by: pressureangle on March 03, 2017, 07:41:57 PM

Title: Clutch drags hot...?
Post by: pressureangle on March 03, 2017, 07:41:57 PM
Sooo.... searched the forum and didn't find answers... unexpected.

Everything in my '85 LM 1000 is either new or fine shape. The flywheel splines are great, the hub is brand new, the center disc is flat (was on install, anyway) and friction plates are new.
The clutch is perfect when cold/cool/warm, but when hot it drags, and the hotter it gets the worse it is. I don't mean while holding it at a light, I mean after extended idling in traffic-engine heat alone is enough to make it drag, and add a little stop-n-go and it's bad. The only thing I can think of that may matter is I added the hydraulic kit from MG Cycle. I have adjustable Brembo masters, so there's plenty of throw.

When cold, the plates rattle happily in their Italian dry-clutch chat. I bled and re-routed the hydraulic line, which seemed to help but I haven't had it quite as hot as when it got bad.

Any takers? Tell me the center disc hasn't warped. Engagement is smooth and clean, even when hot-except that it doesn't disengage fully.
Title: Re: Clutch drags hot...?
Post by: jacksonracingcomau on March 03, 2017, 08:06:41 PM
Easy to tell if hydraulic or clutch problem but you have to get it hot enough to not work.

If it's fixed it's probably rerouting the hose away from hot pipe or engine that worked

The arm on back of gearbox where cable used to attach is the key
Measure the throw you're getting on it cold and hot, if fluid is boiling it won't throw as much. See is you can operate clutch with tyre lever on arm.

I had this on sons MX bike with hydraulic clutch and often had to change fluid between races, you're bleeding it seeming to fix it sounds similar.
Me, I like cables

If it's not hydraulic problem, dive in, someone's going to mention Surflex plates, hated by most
Title: Re: Clutch drags hot...?
Post by: guzzisteve on March 03, 2017, 08:30:17 PM
Is the arm at 75mm from the flat on the back cover? As in a full stroke to disengage?
Title: Re: Clutch drags hot...?
Post by: charlie b on March 03, 2017, 08:38:30 PM
Mine did that.  To the point that I'd readjust the clutch cable after it warmed up.  Never figured out what the cause was.  I think it was due to overheating it badly one day when I was in a traffic jam (user error).
Title: Re: Clutch drags hot...?
Post by: 80CX100 on March 03, 2017, 09:38:08 PM
My '80 CX100 has shown similar symptoms, for all my rides in the country or a normal ride downtown,,,, the clutch works fine,,, no problems at all,,, but 3 yrs ago, on an unusually hot day in October I was in downtown Ottawa stuck in rush hour,,, it seemed like there were constuction crews doing road work at every intersection. Both the bike and I got very hot,,, it seemed like once the bike and clutch got to a certain temperature, the clutch started to drag a little and got progressively worse to the point that I could barely slip it into gear from neutral.

I later spoke with a mechanic about it,,, he was of the opinion that big old dry clutches don't like to get real hot and can misbehave when they do,,, that was apparently why wet clutches were developed?,,, fwiw Idk.

I stopped taking that bike downtown, just riding around the burbs or the countryside and It's been fine,,, might not be perfect,,, but it works for me, fwiw ymmv.

Kelly

Title: Re: Clutch drags hot...?
Post by: jacksonracingcomau on March 03, 2017, 09:52:09 PM

I later spoke with a mechanic about it,,, he was of the opinion that big old dry clutches don't like to get real hot and can misbehave when they do,,, that was apparently why wet clutches were developed?,,, fwiw Idk.


Kelly

Wonder if he's seen a car clutch ? They seem to deal with stop start traffic
OOPs forgot, you lot don't have cars with clutches
Dry clutches work well , wet clutches actually very early in the piece, probably more to do with lubricating primary chains than anything else. Modern times, it's more likely noise that's the issue.

I've had plenty of dramas with hot wet clutches too (some of them huge fun)
Title: Re: Clutch drags hot...?
Post by: pressureangle on March 04, 2017, 07:36:44 AM
Hmph.

No clear answer. At least it's not uncommon.
Back when I rode it to work, with the stock cable and clutch I don't recall this happening, but if it did it was never so bad and I rode it daily in 90*+ weather and rush hour stop-n-go traffic.
Title: Re: Clutch drags hot...?
Post by: acogoff on March 04, 2017, 11:26:40 AM
     I have the same situation with my T3. Do not drive in a congested area very often but when I do I have got into the habit of reaching over and turning the adjuster about 3 clicks to get more pull on the arm. Lose most of the free play though so turn it back again when the traffic situation changes. I'm pretty sure it is my intermediate plate either broken or warped, but I have been just living with it for the last 5 years/25000 miles and it gets no worse and clutch still functions. I see no need to tear into it unless it gets worse.
Update** October 2017 Had transmission off and the only problem I could find were worn hub spline(2mm hub) and the 2mm clutch plates that had 25K miles on them were worn to match. Replaced all with 4mm clutch hub and discs and so far no more problem.
Title: Re: Clutch drags hot...?
Post by: jacksonracingcomau on March 04, 2017, 04:50:54 PM
Hmph.

No clear answer. At least it's not uncommon.
Back when I rode it to work, with the stock cable and clutch I don't recall this happening, but if it did it was never so bad and I rode it daily in 90*+ weather and rush hour stop-n-go traffic.

Robert's your mother's brother, you've answered your own question
Put the cable back on, what exactly was the problem you  were trying to fix with the hydraulic one ?
Title: Re: Clutch drags hot...?
Post by: pressureangle on March 04, 2017, 07:04:25 PM
Robert's your mother's brother, you've answered your own question
Put the cable back on, what exactly was the problem you  were trying to fix with the hydraulic one ?

Nothing. It's jewelry. I had to get rid of the brake master, and wanted the levers to match. So I found a set of used Brembos off of a wrecked Sport.

<shrug> we'll see if it gets better or worse with time.
Title: Re: Clutch drags hot...?
Post by: groundhog105 on March 04, 2017, 09:40:53 PM
I have the exact same issue and I have a cable activated clutch.  I too would like a fix.   Brand new clutch and assorted parts. 
Title: Re: Clutch drags hot...?
Post by: jacksonracingcomau on March 05, 2017, 04:15:04 AM
Nothing. It's jewelry. I had to get rid of the brake master, and wanted the levers to match. So I found a set of used Brembos off of a wrecked Sport.

<shrug> we'll see if it gets better or worse with time.

Time heals all wounds, except those achieved for perceived artistic value, if form is preferable to function, how can anyone help you ?

I really hope it gets better, but snow in the Sahara much more likely

Others with worn out or replaced by amateurs clutches, use search, Surflex might be keyword, then try splines, very different to OP's issue.

If it worked well, bling made it diabolical......... ................... rocket science ?
Title: Re: Clutch drags hot...?
Post by: flangeman_70 on March 05, 2017, 09:18:17 AM
Hi,

I have a PBR hydraulic clutch on my Centauro and a Magura on the SPIII.
The Magura needed bleeding just this Friday after displaying your same issue. What causes this? Air! Where does it come from?  Either the air was never fully eliminated or as the fluid is hygroscopic and ages it attracts water vapour, as this both heats and is constantly being pumped through tiny orifices it cavitates and the gas is expelled creating bubbles. The air accumulates in the slave cylinder which is much warmer than the rest of the system and the air expands creating a larger volume to be compressed before the fluid can move the slave piston.
TIP When the dragging starts and you get a chance, reach down and push the clutch arm towards the back of the bike. This expels the air from the slave and it instantly cools returning the clutch to a near normal operation. If this works, bleed your system :thumb: :bike-037:

Adam
Title: Re: Clutch drags hot...?
Post by: charlie b on March 05, 2017, 12:09:37 PM
Wonder if he's seen a car clutch ? They seem to deal with stop start traffic
OOPs forgot, you lot don't have cars with clutches
Dry clutches work well , wet clutches actually very early in the piece, probably more to do with lubricating primary chains than anything else. Modern times, it's more likely noise that's the issue.

I've had plenty of dramas with hot wet clutches too (some of them huge fun)


Dry clutches do work well.  But...the clearances on a multiplate motorcycle clutches are much smaller than most car and truck engines.  Look at how little the clutch pushrod moves and divide that up by the 4 spaces between the flywheel, pressure plate, intermediate plate and two clutch plates.

I was also guilty of having too much free play in the clutch lever.  I was used to wet clutches and adjusted the same.  The Goose liked very little free play, ie, just enough so there is no pressure on the clutch pushrod when released.  For me that meant less than 1/2" of free movement of the end of the clutch lever.
Title: Re: Clutch drags hot...?
Post by: swooshdave on October 11, 2017, 04:48:09 PM
I have the exact same issue and I have a cable activated clutch.  I too would like a fix.   Brand new clutch and assorted parts.

It seems more that a few people have this problem, perhaps not with new parts but just with the clutch not behaving well when hot.

Warped plates?

Constantly adjusting the lever isn't a viable option.
Title: Re: Clutch drags hot...?
Post by: wirespokes on October 11, 2017, 11:11:55 PM
Swoosh makes a good point. Also, I seem to recall the hydraulic clutch on my R1100S took some sort of oil rather than brake fluid. Perhaps a change of fluids is called for?
Title: Re: Clutch drags hot...?
Post by: swooshdave on October 12, 2017, 11:38:27 AM
Swoosh makes a good point. Also, I seem to recall the hydraulic clutch on my R1100S took some sort of oil rather than brake fluid. Perhaps a change of fluids is called for?

I'm saying it happens on cable clutches too.
Title: Re: Clutch drags hot...?
Post by: swooshdave on October 12, 2017, 12:55:10 PM
My old California II seems to work perfectly with my normal countryside rides. If I am stuck in traffic with many intersections and traffic lights, the clutch becomes very 'grabby' and does not fully disengage.  :undecided:
The clutch was rebuilt with new parts, and most of the time it is very smooth ... except when hot.  Cable free play adjustment is perfect, as well as the clutch arm position.  I also now avoid riding in town. :bike-037:

Well, that helps...  :rolleyes:
Title: Re: Clutch drags hot...?
Post by: lazlokovacs on April 14, 2021, 01:03:43 PM
reviving an old thread, just got back to london and started up my lemans 1000. I'm having the exact same symptoms as the OP and the others.

I have a cable clutch.

The clutch is only a few years old.

Ain't surflex.

Properly put together.

Arm ain't bindng on anything, cable is good.

F----ING ANNOYING

Somethings not right here.
Title: Re: Clutch drags hot...?
Post by: jacksonracingcomau on April 15, 2021, 01:50:51 AM
reviving an old thread, just got back to london and started up my lemans 1000. I'm having the exact same symptoms as the OP and the others.

I have a cable clutch.

The clutch is only a few years old.

Ain't surflex.

Properly put together.

Arm ain't bindng on anything, cable is good.

F----ING ANNOYING

Somethings not right here.

OP knew what created his, self inflicted wound
Yours needs scientific approach
For a few years (#?)  the new clutch has worked
What has changed?
Unlikely the weather, London never that hot in April AFAIK
So, was the motor ridiculously hot?
If it never happened at height of summer, something has changed or worn out
Could be splines or buckled intermediate plate, once cooked they don’t like going flat again
Could even be friction material having a hissing fit

But much more likely external issue, have you tried operating clutch arm with screwdriver or pry bar when hot?
If you can’t get it free that way, it’s time to go in
Title: Re: Clutch drags hot...?
Post by: Scout63 on April 15, 2021, 09:35:48 PM
My v50 clutch drags hot or cold. I have to pull in the lever and blip the throttle to free it for shifting or stopping.  I’ve taken it apart and everything looks fine.  The only thing left to check is the crank thrust bearing, but that will involve another complete tear down. I can live with it.
Title: Re: Clutch drags hot...?
Post by: lazlokovacs on April 16, 2021, 04:02:53 PM
yeah, it's been a few years, but not many miles... around 5000... free play started moving a bit at the beginning, I thought ok the clutch is bedding in... since then I've not had any regular miles on it, so each time I come back I'm sort of fresh to it, so hard to notice any movement over time...

At such short mileage I refuse to believe that the clutch is donald ducked, will get the thrust bearing out and report back...

Means I'm using my old tiger 500 for getting around London, quite good actually!!

Title: Re: Clutch drags hot...?
Post by: JoeW on April 16, 2021, 04:38:09 PM
Is it a Sure Flex clutch? They all do that, put an SD Tec kit in it.
Title: Re: Clutch drags hot...?
Post by: lazlokovacs on April 16, 2021, 05:42:57 PM
thats the weird part,

It wasnt a surflex...

Title: Re: Clutch drags hot...?
Post by: Chuck in Indiana on April 16, 2021, 06:06:24 PM
I was going to say that, too, Joe.. but he said
Quote
Ain't surflex.