Clutch woes(?)

[Riceburner]

Took my Rockster out for a shake-down on Sunday morning, and all was good..... until I slowly realised that the gear changes were a bit rougher than usual.

Upshifts without the clutch are fine - but all shifts using the clutch were 'sticky' - the gears didn't want to engage smoothly.

After a few of these I surmised that the clutch wasn't fully disengaging, and realised that the bite point on the lever was further back than it should be, and the lever felt somewhat spongey.

So - first step will be to change the fluid, and 'hope' that it's just that: old fluid (I haven't changed it, and I've had the bike 4 years now... no idea when it was last done).
Need to get the Stahlbus bleeder from Motorworks....

There didn't seem to be anything dribbling down the back of the slave cylinder - but if the push-rod seal has only just gone - there won't be anything 'yet'.

I'm seriously hoping it's 'not' a blown push-rod seal, I've done a clutch before, and it's a relatively simple job - but not one I'd relish.


Has anyone had similar symptoms and it was just the fluid??


hey ho... there's always something to do!

 

[Ian J Hartley]

Check the colour of the fluid at the master cylinder.

If it’s black it will point to a failing clutch slave cylinder.

 

[Riceburner]

Check the colour of the fluid at the master cylinder.

If it’s black it will point to a failing clutch slave cylinder.

Will do.

 

[Steptoe]

A leaking pushrod seal ( gearbox input shaft out put end seal) will have no effect on the clutch biting point or clutch operation. If it is that seal leaking the symptoms are a slipping clutch.

 

[Riceburner]

A leaking pushrod seal ( gearbox input shaft out put end seal) will have no effect on the clutch biting point or clutch operation. If it is that seal leaking the symptoms are a slipping clutch.

That's oddly reassuring to read.


I suppose the worrying side though it... what would have an affect on the biting point (or rather - the feel of the biting point on the lever), if not the fluid?

 

[squibb34]

Having been there several times, admittedly not with a Rockster, it seems likely to be a failing slave cylinder.

Fresh fluid & a bleed might deliver some joy, but it's often short lived in my experience.

Good luck finding a fix.

 

[MikeO]

Try pumping the lever and see if that improves the clutch action. When my slave cylinder went bad in France (thankfully just short of getting to the Tunnel on the way back), it worked and helped to get me home...

 

[Riceburner]

Checked the fluid last night....


eeuuuwwww

Pulled the vast majority of that shite out with a syringe, and tried to dry the reservoir out as much as possible, then pumped a good amount of fresh fluid through (there was already a bleed nipple on the slave, hooray!), until it was flowing clean from the far end. Closed up the bleed nipple and gently pulled the lever to expel any excess air, and I could feel the clutch spring release exactly the way it should.

Pinged the lever a few times to draw any excess bubble or old fluid up the pipe work but very little came out and everything seemed good.

Going to take the bike out tonight to confirm all is good.


Hopefully that's all it was - ancient fluid.

 

[Ian J Hartley]

Checked the fluid last night....


eeuuuwwww

Pulled the vast majority of that shite out with a syringe, and tried to dry the reservoir out as much as possible, then pumped a good amount of fresh fluid through (there was already a bleed nipple on the slave, hooray!), until it was flowing clean from the far end. Closed up the bleed nipple and gently pulled the lever to expel any excess air, and I could feel the clutch spring release exactly the way it should.

Pinged the lever a few times to draw any excess bubble or old fluid up the pipe work but very little came out and everything seemed good.

Going to take the bike out tonight to confirm all is good.


Hopefully that's all it was - ancient fluid.

Ancient fluid my arse!

You didn’t say what colour the fluid was, which is important, also If there were metal particles in it is another key indicator.

When the small thrust bearing in the end of the slave cylinder piston starts to fail, the piston starts to spin in the cylinder, causing excess wear and turns the fluid black with small aluminium particles.

From what I can see, you need a new clutch slave cylinder.

Make sure you don’t go far on your test ride.

 

[Riceburner]

Ancient fluid my arse!

You didn’t say what colour the fluid was, which is important, also If there were metal particles in it is another key indicator.

When the small thrust bearing in the end of the slave cylinder piston starts to fail, the piston starts to spin in the cylinder, causing excess wear and turns the fluid black with small aluminium particles.

From what I can see, you need a new clutch slave cylinder.

Make sure you don’t go far on your test ride.

Hmm - you may well be right.

 

[Steptoe]

When the small thrust bearing in the end of the slave cylinder piston starts to fail, the piston starts to spin in the cylinder, causing excess wear and turns the fluid black with small aluminium particles.

Not only black. I've had bikes in with clutch fluid that resembles liquid mercury

 

[Riceburner]

Bits on their way... It makes perfect sense to swap out the slave.

 

[Riceburner]

Well - this is turning into a bit more of a job than I thought....

Firstly: both of the small lower bolts holding the RHS footpeg plate have stripped the thread in the gearbox casing. Easy fix, but I needed to order up a helicoil kit (arrived today from Tracy Tools).

Secondly: reassembled the rest of the bike last night and started it up...... and it's hunting and sputtering... odd. I DID pull the main throttle cable around trying to get at the rear-frame stub bolts, but didn't think I'd done anything much. Had a good check over (it wasn't the cable ends popped out of the throttle body... I know all about that): realised that the main throttle cable wasn't behaving at all correctly, then spotted that both short cables to the throttle bodies were frayed to hell! I've a nasty feeling that the main throttle cable may also be damaged, so stripped off the tank again and got as far as getting the cables all unhooked, but couldn't for the life of me pull the cable junction box out. I think it's 'rusted' in place so will have to strip out the battery box etc to get to it.

hey ho - it's a 20 year old bike, so these things are to be expected.

Last time I did this, I'm sure I bought a complete kit of all 4 cables from Motorworks, but I can't find that entry in their new website so will have to ring them instead.

 

[Steptoe]

Well - this is turning into a bit more of a job than I thought....

Firstly: both of the small lower bolts holding the RHS footpeg plate have stripped the thread in the gearbox casing. Easy fix, but I needed to order up a helicoil kit (arrived today from Tracy Tools).

Secondly: reassembled the rest of the bike last night and started it up...... and it's hunting and sputtering... odd. I DID pull the main throttle cable around trying to get at the rear-frame stub bolts, but didn't think I'd done anything much. Had a good check over (it wasn't the cable ends popped out of the throttle body... I know all about that): realised that the main throttle cable wasn't behaving at all correctly, then spotted that both short cables to the throttle bodies were frayed to hell! I've a nasty feeling that the main throttle cable may also be damaged, so stripped off the tank again and got as far as getting the cables all unhooked, but couldn't for the life of me pull the cable junction box out. I think it's 'rusted' in place so will have to strip out the battery box etc to get to it.

hey ho - it's a 20 year old bike, so these things are to be expected.

Last time I did this, I'm sure I bought a complete kit of all 4 cables from Motorworks, but I can't find that entry in their new website so will have to ring them instead.

You only needed to remove the rear wheel, shock, and exhaust silencer to replace the slave cylinder.. Undo the top nut on the L/H fork leg, push down the stanchion and loop the clutch line this side of the leg, that way it gives you plenty of slack to pull off the slave cylinder and then undo the clutch lines. and yes, you can remove the slave unit inbetween the airbox and the gearbox mounting tube, i've done it countless times.

 

[Riceburner]

You only needed to remove the rear wheel, shock, and exhaust silencer to replace the slave cylinder.. Undo the top nut on the L/H fork leg, push down the stanchion and loop the clutch line this side of the leg, that way it gives you plenty of slack to pull off the slave cylinder and then undo the clutch lines. and yes, you can remove the slave unit inbetween the airbox and the gearbox mounting tube, i've done it countless times.

That's all done now, although it would have been a lot easier with a bike-ramp, it's the grovelling around on the floor I object to these days.

If I hadn't loosened off the rear-subframe I wouldn't have found the stripped threads in the gearbox casing. I'd rather know about those.

 

[Two wheels good]

To remove Bowden/cable box there's a clip you depress and with your other pair of hands give it a gentle whack from the other side.
AFAIR clip is on RHS.
New cables will be a joy. There's a modified mounting kit at the twist grip that you'll have to get too.

 

[Riceburner]

To remove Bowden/cable box there's a clip you depress and with your other pair of hands give it a gentle whack from the other side.
AFAIR clip is on RHS.
New cables will be a joy. There's a modified mounting kit at the twist grip that you'll have to get too.

Where's the clip in relation to the battery mount plate? Is it something you access from above? or from the side? It's not mentioned in the workshop manual..... (if it was, I'd have found it by now!)

I saw the modified cable run on the Motorworks site, not sure I'll bother tbh, it's worked fine so far.

 

[Steptoe]

Where's the clip in relation to the battery mount plate? Is it something you access from above? or from the side? It's not mentioned in the workshop manual..... (if it was, I'd have found it by now!)

I saw the modified cable run on the Motorworks site, not sure I'll bother tbh, it's worked fine so far.

It’s a small flat metal tab which is underneath the junction box, the section of tab you need to press down on protrudes on the r/h side and helps keep the junction box in place. Push down with a finger and with other hand grab the cables and yank the junction box out .. the oil breather pipe needs to be pushed out of the way, and the l/h throttle cabl needs to be disconnected from the throttle body,

 

[Riceburner]

It’s a small flat metal tab which is underneath the junction box, the section of tab you need to press down on protrudes on the r/h side and helps keep the junction box in place. Push down with a finger and with other hand grab the cables and yank the junction box out .. the oil breather pipe needs to be pushed out of the way, and the l/h throttle cabl needs to be disconnected from the throttle body,

Thanks Steptoe, good description. I'll take a look at it tonight if I get time.

 

[Two wheels good]

"Tab" that's a better description.
I have an image from a manual but can't insert it.