Clutch killing me

[tothemax93]

Just happened to me today.
Fluid looks good.
All of a sudden, engine starts to load up, bike trying to move on its own while in 1st, still holding the clutch. Can't move it into neutral.
Held in brakes, engine died under too much load.

Now I have to figure out what the deal is.

Something similar happened to me a few years ago. Bike wanted to creep ahead when the clutch was pulled in. I changed out the slave cylinder. Problem solved.

 

[one2dmax]

that is the opposite problem then he has

 

[D-Max2012]

I did the upgrade to the brake line a couple of weeks ago. I have an upgraded clutch line, not installed yet.. Could the stock clutch line just expand suddenly, not allowing the clutch to engage fully? There are no leaks that I can see. Since I have to do the clutch line anyway, I'll bleed the system when I tackle that project. I hope the weekend is not too hot, or raining.

 

[D-Max2012]

I read something last night, in the Clymer manual about the clutch.
I did not know this was even possible, especially when there are no leaks detected.

In a nut-shell, it stated, Clutch feels fine when bike is cool. After warming up, with clutch depressed and in 1st gear, bike starts to advance and clutch starts to feel spongy.
This is exactly what happened to me.

It says that air got into the system, and to bleed the system.

I don't know how air can be introduced into the system if it is sealed up..

Anyway, I plan to change out the clutch line this weekend to an upgraded SS braided line.

I have to run a small test before I start. Just to see if I can tighten the bleed fitting at all.

If it can be tightened, even a little bit, maybe heat expansion allowed the threads, to let air in a micro amount of air.

That's the only thing "I can think of", that might cause this symptom.

 

[sufidancer]

Hi D-Max,

Does the clutch go back to feeling fine once the bike cools back down?

Or does it stay spongy?

If the fitting is leaking when hot, maybe you can use a small bit of teflon tape on the threads?

 

[D-Max2012]

Yes, it feels like normal after the bike cools.

I'll test the fitting when I go to change out the line this weekend..

I guess the best way would be to let the bike warm up, then see if the fitting can be torqued at all.

 

[sufidancer]

I'd be uber careful about torquing the fitting when hot you would'nt want to snap that sucker.

I googled "clutch gets spongy when hot" and got lots of articles so it is apparently a common issue in hydraulic clutches. Some articles point to the fluid being suspect.
And by flushing and adding new fluid with a higher boiling point can cure this.

I'd go with the cheapest solution and change the systems fluid, flush and bleed.
But you probably already did this. Good luck you'll get it.

 

[one2dmax]

Over filled will cause brake loss when warm as well.

 

[D-Max2012]

Over filled will cause brake loss when warm as well.

Really?
Wow.. there's more to this hydraulic system than meets the eye..
When doing my brakes, I added more fluid to the clutch also.

 

[one2dmax]

As the fluid expands under heat if it's overfilled it simply starts putting pressure back into the system. That in turn causes the fluid to heat up more creating more expansion and so on. This can really go bad fast on a brake system while the clutch takes longer to do it. No more then 1/2 of the window in my opinion.

 

[D-Max2012]

No more then 1/2 of the window in my opinion.

Good to know..
I had it at 1/2 when everything was working correctly.

Now it's like 90% full and I'm having issues..
When I do this clutch (hopefully this weekend), I will bring them both down to where I had it before..

Thanks for the insight..

 

[train460]

Well it seems to work. I DID mityvac all the fluid from the system a couple times thru and it all seems to be good now altho I didn't ride it around the block but it seems to work as it's supposed to. learn something new every day. I guess that the shaft going from the slave side to the other must have been out abit. OH and be carful on the plate bolts. they will break rather easy, I know.
thanks for the thoughts, I made it a whole lot harder than it should have been.

 

[blaxmax]

Well it seems to work. I DID mityvac all the fluid from the system a couple times thru and it all seems to be good now altho I didn't ride it around the block but it seems to work as it's supposed to. learn something new every day. I guess that the shaft going from the slave side to the other must have been out abit. OH and be carful on the plate bolts. they will break rather easy, I know.
thanks for the thoughts, I made it a whole lot harder than it should have been.

They only torque to 5.8 pds.
Glad you got it- I have a mityvac that I've had for 20 years now. It's paid itself off as the 2nd person 10 times over.

 

[D-Max2012]

Hey Train,
Was your clutch doing this??
https://www.youtube.com/watch?v=PyHb-nDbLVM
https://www.youtube.com/watch?v=dOQjXuaTeN0&feature=youtu.be

 

[train460]

Hey Train,
Was your clutch doing this??
https://www.youtube.com/watch?v=PyHb-nDbLVM
https://www.youtube.com/watch?v=dOQjXuaTeN0&feature=youtu.be

Nope. The clutch handle felt great. kinda weird. I have changed out maybe 2 or 3 clutches in the past and never had an issue like the one I had. Rode the bike around the block and seems ok.
Michael