Bandit 1200 clutch slave cylinder piston Seal keeps blowing

[kamahasanyi]

Hi. The bike is 2006 Bandit 1200 (SK6). The piston seal on the clutch reserve cylinder keeps blow. I changed the clutch. Started it up, heard a clunk from the left hand side, and then saw brake fluid leaking

I rebuilt the cylinder and put in braided clutch hose. Go to bleed the clutch, just as the lever gets hard and I can start with the bleed, bang the seal goes again.

Anybody have a clue what's going on?

I am a bit stumped. Two main candidates: either the slave unit itself is at fault and needs to be replaced or there is something wrong with the right side pushrod (the left looks okay). I think it may be the latter. My working theory is that if the pushrod doesn't move, then the piston can't and the pressure behind the piston blows the seal. If so, clutch will have to come out again: the right side pushrod is way deep in there.

I guess there is the third option of the clutch master cylinder having an issue but really doubt it.

Please help. Thanks

Edited March 6, 2017 by kamahasanyi

[suzook12]

Or is it coming too far out?

 

[kamahasanyi]

Thanks suzook12. Possibly. rebuilt the slave cylinder with a mechanic friend, with the idea that is going to far out, as you suggest and which makes sense. Put it back on the bike. Engaged the clutch to start it, which it did. Pulled the clutch lever, felt a bit of resistance, and then bang again.

Will pull the clutch and see what is going on there.

Edited March 7, 2017 by kamahasanyi

[suzook12]

When you say you changed the clutch, was it like for like or have you done the coil spring conversion? If the latter, did you put a ball bearing in between the rod halves?  If the same, missing something like the pusher bearing and/or thrust washer could be enough to let the slave piston out too far. If you've changed one or both the rods, did you check the lengths?

[kamahasanyi]

I replaced the clutch plates, at 100k the bike needed it, so like for like. I opened it up yesterday and reinstalled the clutch, it didn't look right. I suspect that the gear generator hadn't matched up with the other gears or that a washer was in wrong (as you suggest), causing the pushrod to travel too far. After work, am gonna put some oil in, bleed the clutch system (again) and see what happens. Will be very happy if my stuffing up the clutch first time was the problem.

Thanks.

[kamahasanyi]

Hey. In the end, it was me. I installed the clutch wrong. The gear exchange wasn't mating so the pushrod travelled too far, blowing the clutch slave piston seal. Thanks suzook12

[Fazz711]

Glad you sorted it out 

[suzook12]

Least ya got it now

[canamant]

Take a good long look at the gears on the back of the clutch now.  If they didn't engage properly and you torqued up the clutch centre nut, then there will have been a big lateral load on the gear.  It might be warped now.  Seen pictures of the alt drive gear broken into several pieces on the old site.

 

[colinworth79]

Normally if you put the clutch back without meshing the gears they snap off a couple of teeth . I always like to put the basket back in then try to move the alternator and oil pump gear and make sure you can detect the back lash in the gears so you know its meshed . I did the same thing once many years ago in a rush , had the buy new gears and have the exhaust and sump off to find the remains .

[suzook12]

1 hour ago, colinworth79 said:

Normally if you put the clutch back without meshing the gears they snap off a couple of teeth . I always like to put the basket back in then try to move the alternator and oil pump gear and make sure you can detect the back lash in the gears so you know its meshed . I did the same thing once many years ago in a rush , had the buy new gears and have the exhaust and sump off to find the remains .

Bin there too lol, bar far and away easiest method is to pull the alternator then refit it after the clutch, only one gear to worry about at a time then

[kamahasanyi]

7 hours ago, canamant said:

Take a good long look at the gears on the back of the clutch now.  If they didn't engage properly and you torqued up the clutch centre nut, then there will have been a big lateral load on the gear.  It might be warped now.  Seen pictures of the alt drive gear broken into several pieces on the old site.

 

Hi. Bike seems to be working all fine. Here is what the back of the clutch looked like.

[canamant]

It's the big gear on the back of the clutch basket I was on about,  The small one engages with the oil pump but the big one engages with the alternator and sometimes it goes "tooth to tooth".  That's the one that can be damaged.  Had it happen to me but luckily I spotted it as the primary gear seemed to be slightly out of line so I didn't tighten up the clutch centre nut.  ALso had a problem when I built an engine from parts.  The alternator drive gear and the gear on the back of the clutch are paired and there are two different pairs depending on model.  I fitted an alternator with the small gear on a clutch with the small gear.  It rattled like mad for about 5 seconds until I realised what had happened.