The Perfect Clutch

[vandy010]

Howdy folks,
just throwing up a diagram here and in this case it's a TY175 Yammie.
the problem i'm having is that its very hard to "slip" the clutch smooothly as it seems to engage with a real jerky motion. not ideal for trials.
motor has new bearings/seals, clutch basket has had the wear marks from the plates all smoothed out and i'm using good old Valvoline XLD which i've been using for years with no problems in all my bikes.
i'm wondering if the plates are a bit "gummed up" from previous years so am considering sanding them on a flat surface with 400 grit paper and will also check clutch arm (it 15 in the diagram) for any wear.
the cable is well oiled and works fine.
so i guess the question is,
what kind of things are you blokes doing to your clutches to create the "perfect clutch"?

[TT5 Matt]

yeah sand the glaze from the steels and fibre plates,make sure both types of plates are paralle,measure free length of clutch springs to see there all the same length and check the pivit cam for unusal wear

[David Lahey]

Yes agree with having the steel plates nice and rough and a nice flat cam surface. New friction plates also improve the engagement action. I put off getting new friction plates in one of my TY175s for many years until the clutch clip in top gear became too annoying. With new friction plates it got its grip back and engagement became much nicer too.
Also check that the arm is at 90 degrees to the cable as the clutch disengages. This minimises the sliding friction between the pushrod and the cam surface

[Mike52]

The obvious question is , and I rekon you have already checked this , are there any grooves in the clutch basket fingers?
Don,t get pissed at me Vandy but some people don,t know that those bumps can effect clutch operation 

  I read your post and missed the bit where you had already done this Duh    

[vandy010]

The obvious question is , and I rekon you have already checked this , are there any grooves in the clutch basket fingers?
Don,t get pissed at me Vandy but some people don,t know that those bumps can effect clutch operation 

it's all good Mike
thats what i meant in my first post.
so yes,
i've already addressed that issue as i've encountered that problem before.
i do remember spending a bit of time on the clutch set~up when i put the motor back together and was pretty happy with the cable to arm position and after talking with fellow riders at the weekends trials and riding a few other bikes we mostly seemed agreed on the scuffing up of the plates being the hopefull solution.
always interested to hear what guys are doing.
thing is, i won't get to work on this bike for a while as i'm busy getting others ready for the tittles.
thanks for the info and feedback guys, keep it coming.

[smed]

Try using proper 2t gear oil or at least ATF,they are a lighter weight oil & will fling off the plates easier,

XLD probably works better on an mx bike than a trials bike because of the higher revs that the clutch is pulling

I had a young guy bring me his late model Yam YZF250 complaining that the clutch would not disengage properly(ie drag),I took the bike for a spin & sure enough when you pulled in the clutch the bike would keep on going full steam ahead,even dragging the rear brake would not make it break loose.
I quizzed the owner on what type of oil & how much he put in as he had recently serviced it & that's when the problem started happening,He had used the correct oil & the correct amount as per the owners manual, So I thought I would have a look at the plates,I drained the oil out of the motor & out of the oil tank(dry sump innit),when i saw the amount of oil in the tray i knew i had found the problem,like about twice the correct amount,the owner had drained the sump & not the oil tank & then refilled with the correct amount stated in the book if you done it properly & drained both,the result was the clutch swimming in oil,not able to fling it off making it drag,refilled with the right amount & brand new again  

[matcho mick]

why are we suggesting "roughing the plates up",Vandys trying to get it to slip,not fugging grip!!,
here we go!,this will have most of you doing clutch encounters of the closeup kind 
jap steels are STAMPED out,not lazer/water jet cut etc,they have this really nice rounded edge on one side ,the other bloody sharp!,if you put the sharp edge inward,you get a lovely release,but fugging awful take up,always put the round err sharp edge out,(thus relying on lever ratio for lift,overcoming sharp edge,spring pressure for smoother return)
thus endeth the lesson kiddies  ,

[crossedup2]

Mick

I can't see the ball bearing in your diagram that makes things smooth. I had heaps of trouble with a clutch years ago on an IT175 after a rebuild. Poor adjustment, grabbed, slipped and had a totally shit day racing. Got home and found the ball bearing in the bottom of the wash tub. Should the push rod (14) and the diaphram push rod (9) have a bearing in there or is the end of the push rod rounded like a bearing?

Whole thing worked perfectly when bearing was put back in..

Peter B

[vandy010]

I'm hearing ya Pete,
the YZ125C/X are very similar and have a ball bearing but the TY doesn't.
from memory when i rebuilt the motor there was no ball bearing as per the diagram and when i tried to fit one in, the pressure plate had a gap to the plates.
so out with the ball bearing and back to how you see things in the diagram.
adjustment is fine, it's just a real jerky/sticky action when releasing the clutch.

Matcho Mick,
the idea that came up in conversation was that there may be some "gummed" up stuff from it's previous life/oil, before me. so the theory being to lightly sand it off with 400 grit bringing the plates back to a fresh surface.
all the plates have plenty of meat on them and measure within spec which from memory is around 2.7mm~3mm for the fibre plates.

[Billet YZ]

When you have cleaned up the clutch basket fingers i`m assuming this might have been done with a file only, if some of the fingers needed more taken off them to clean up than some of the others your clutch plates will only be making contact on some of the fingers and not equally.

This might be causing the clutch to be grabing and not releasing smoothly. Peter.

[Frank M]

I've got the same thing on a brand new TTR125. The clutch releases in mm steps and my son nearly goes mad stalling the motor of his beginner bike.

The fault was the cable. When testing it seperate it works fine and smooth, under the force of the clutch its sticks.

After oiling the cable with PTFE-oil (Teflon) and simply using it over a few weeks, the clutch now works as a real fine "one finger clutch" and releases stepless.

[Lozza]

Add 20HP.....................................................................

[vandy010]

Add 20HP.....................................................................

TY410

[GMC]

One other thing that comes to mind is that some fibre plates have small round recess’s / dimples in them that can act as suction caps and hold the plates together.
If your plates have these dimples then try running a light hacksaw cut through each dimple to break the seal.