did my clutch engagement point just change?

Been putting some good miles on the GRiSO in the last month and I'm very, very pleased with it...

Out on a 3 hour jaunt through the mountains today and I noticed about halfway through I suddenly had just a smidge more free play at the clutch lever... just a smidge... seems odd, as hydraulic clutches shouldn't move about as I understand it. No other symptoms, bike shifting sweet

Years on Tontis have taught me to be vigilant concerning any changes at the clutch lever..

I'm due to take a long trip in 10 days time so was just wondering if the experts out there think it's worth investigating, or ?

I guess I'd be checking the tightness of the cylinders and looking for any leaks...? Or maybe it's just telling me that it's time to change the fluid? How often do you guys change the fluid?

It's been beautiful dry warm weather here and the bike lives in a heated garage

My first hydraulic clutch motorbike so excuse the naivete of these questions

thank you

Hi Lazlo
You are rigth, the bite point should not change on a hydraulic clutch.
Check that the fluid level is still correct.

Most hydraulic systems benefit from an annual fluid change... few get it,

If the fluid level has not dropped i would look for something mechanical in the lever assembly or possibly the slave or "command" cylinder screws. I hope it is not the latter as they are hard to get at

Change the clutch fluid every 10,000 km. CARC Guzzis are murder on clutch fluid. No idea why.

WRT the friction point changing check the plunger in the barrel on the clutch lever. It is threaded into the barrel and secured with both Loctite and a grub screw but they can come loose. If they do then the point at which the clutch starts to engage will change as the plunger moves in and out of the barrel.

cheers guys

will have a look and change the fluid at a minimum

is the correct procedure as simple as pumping the old fluid from the handlebar reservoir out through the bleed nipple under the seat?

couldn't find this in the workshop manual anywhere....

yes
squeeze lever (hold it it in)
open bleeder
catch fluid
close bleeder
release lever
add new fluid to reservoir as needed
repeat
repeat
repeat until brown fluid is all gone.

easy

if you have a vacuum pump like a mighty vac , it can speed the process up - slightly different technique though

changed the fluid, stuff that was in there wasn't too nasty...

no change, still got more play at the lever than I used to have

I'll check the plunger next

Pete Roper wrote:

Change the clutch fluid every 10,000 km. CARC Guzzis are murder on clutch fluid. No idea why.

WRT the friction point changing check the plunger in the barrel on the clutch lever. It is threaded into the barrel and secured with both Loctite and a grub screw but they can come loose. If they do then the point at which the clutch starts to engage will change as the plunger moves in and out of the barrel.

nailed it

yes, there was no grub screw in evidence!

Beware the wearing master cylinder. Mine did the same thing recently and it turned out to be the master cylinder was beyond redemption.

As Pete says, change your clutch fluid every 10,000 km. This is something I did not do and I paid the price.

I changed both my brake and clutch fluid in November and about 3,000 miles ago (4828km. I checked them a couple of weeks ago. The brake fluid looked new but the clutch fluid was noticeably dirty. Just a testament to what Pete and Tony describe. I plan to do at least the clutch every year. I sucked out the master cylinder this time and replaced with new and didn’t do the entire system.

I used to see my clutch fluid turn from honey-golden to "blecch" in about a week, when I had the see-through sticky-upper reservoirs.



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No that I have these, I don't see nothin'. Ignorance is bliss.



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Just kidding. I change it a couple of times a year.

allright,

plunger screw has started moving again...

so I'll try a higher strength thread locker this time.

can anyone tell me how far in the plunger should be set? far enough in that the clutch disengages obviously, but is it possible to go too far and lose free play?

thanks as ever guys

Lazlo there should be a very small Allen grub screw holding it in place. Check to see if that is missing or damaged. You may have been there already but this is the final piece that locks the plunger into place. Perhaps some Loctite on the grub screw too?

Setting the plunger depth can be a trifle tricky. The thing is you have to have enough free play to allow for any expansion and the piston of the MC has to be able to return to the very end of its travel when the lever is released. If it can't return completely it won't uncover the priming port to the reservoir thus making the hydraulic system 'Closed'. That being the case as the fluid heats up in use and expands it can't return to the reservoir when the lever is released so the only way it can is by pushing the slave piston forward which initially will preload the thrust bearing, which itself isn't a good thing, and eventually it will lift the clutch sufficiently for it to start to slip.

So setting the plunger depth you want to have it with a millimeter or less of travel before you can feel the lever start to lift the piston off its register but it must have that tiny bit of free play. It is quite sensitive. Too little and the clutch will slip in service. Too much and it will drag when the clutch is supposedly engaged.

As Tony points out the plunger should be secured by a grub screw. Make sure that hasn't gone walkabout somewhere on one of your trips.

Thanks Pete,

Grub screw is back in tight, there is loctite on the plunger, I can pull in the clutch in first (engine off) and verify that the clutch is fully disengaged by rocking the bike back and forth, AND I have a smidge and a half of free play before the plunger hits the piston.

It's shifting like a champ with no slipping so I guess I'm good?

My first hydraulic clutch so I'm very green on this one....

Egads, I have never, not even once, changed the clutch fluid on any of my CARC bikes. Surely tragedy awaits.

Steak wrote:

Egads, I have never, not even once, changed the clutch fluid on any of my CARC bikes.  Surely tragedy awaits.

Surely.

Mine died earlier this year after 13.5 years

Steve, I'd do it. It's so simple, costs pennies and the fluid goes to shit really quickly. Nobody knows why!

Yeah, it's always been on the todo list, but just keep kicking the can (or the DOT 4 bottle...)