More Clutch Woes

23-05-2020, 06:18 PM

I'm having a bit of an issue with getting the clutch working on my old 2000 M600 which has been sitting for quite a while.

The original slave cylinder was seized solid, so I bought a secondhand replacement complete with master, lever and pipe from a 620. Fitted it and then had a lot of issues trying to bleed it, but have managed to finally get that done. The lever is now nice and firm when operated.

However the clutch still doesn't work.

There are potentially two issues that might be causing the problem.

1) the "depth" of the slave cylinder seems to be about 2-3mm more than the length of the pushrod sticking out. I've read that there was a change in spec at some point and that a extension piece can be needed, but I think they are 10mm, which would be way too big.

2) The throw of the slave cylinder is around 1mm when the lever is pulled. Does this sound about right? It is very little movement.

slob · 23-05-2020, 06:36 PM

1. the depth is a bit variable, it may be 2-3mm more now but hydraulic systems self adjust to some degree (like pumping your brake pads onto the disc after the pistons have been pushed back into the caliper). I you remove the reservoir cover on the master cylinder, how far canyou push the piston back into the slave? 7-8mm? Then a 10mm spacer would fit. Keep an eye on the reservoir, you might need to remove some fluid!

2. ~1mm sounds right, from looking at the top plate on a dry clutch with an open cover.

Luddite · 23-05-2020, 06:44 PM

The 600 and 620 push rod part nos. are different, which suggests they may be different lengths. The slaves have different numbers too so you may need a 620 rod to match your slave, (or a spacer).

slob · 23-05-2020, 07:00 PM

I might have a spacer from an Oberon slave lying about, I'll take a look in the garage tomorrow if you like.

23-05-2020, 07:54 PM

Quote:

Originally Posted by slob

1. the depth is a bit variable, it may be 2-3mm more now but hydraulic systems self adjust to some degree (like pumping your brake pads onto the disc after the pistons have been pushed back into the caliper). I you remove the reservoir cover on the master cylinder, how far canyou push the piston back into the slave? 7-8mm? Then a 10mm spacer would fit. Keep an eye on the reservoir, you might need to remove some fluid!

2. ~1mm sounds right, from looking at the top plate on a dry clutch with an open cover.

Currently can't push the piston back at all. I tried doing it with an Allen key and muscle power but will try making a G clamp to put a bit more force on it tomorrow.

slob · 23-05-2020, 08:09 PM

that sounds like it’s either all the way back or buggered. Since you have movement, it doesn’t sound like it’s seized. Make sure you remove the cap and watch the fluid level, otherwise you could blow the seals with the g-clamp!
You ‘re positive you can’t pump it out 2-3mm further with the lever?

23-05-2020, 09:54 PM

I went out and pushed it back with a gclamp, made a 10mm spacer and bolted it on. To bolt it on I had to release the pressure through the bleed nipple to get the three bolts on the slave to tighten up.
Feels great at the lever but doesn't release the clutch - if I put it in gear I can't turn the back wheel with the clutch in or out ��

Luddite · 23-05-2020, 10:35 PM

Quote:

Originally Posted by boyse7en

I went out and pushed it back with a gclamp, made a 10mm spacer and bolted it on. To bolt it on I had to release the pressure through the bleed nipple to get the three bolts on the slave to tighten up.
Feels great at the lever but doesn't release the clutch - if I put it in gear I can't turn the back wheel with the clutch in or out ��

Jamminbmx fitted an Oberon slave to his 600 with the 10mm spacer and it transpired that the 600 runs a 305mm pushrod rather than 325 or 335mm so you definitely need the spacer. http://www.ukmonster.co.uk/monster/s...ad.php?t=58147

Perhaps it's still not fully bled and has air in the system. Remove the slave and try immobilising the piston with your g-clamp then operate the clutch lever; if you can squeeze the lever despite the piston being locked, then that would point to air in the system.

jerry · 24-05-2020, 11:41 AM

It is possible to put the clutch back together but the lifting back plate may not be fully slotted onto the drum itself which means they can be 2mm lift in the drum and it wont work ..seen this a few times on clutch re assembly ,, when fitting first 2 of the 6 springs pull the lifting plate towards you to make sure its bedded in the drum slots

slob · 24-05-2020, 12:08 PM

I don't think the clutch has been apart Jerry, just the original slave failed.

23-05-2020, 06:18 PM	#1
boyse7en Guest Posts: n/a	More Clutch Woes I'm having a bit of an issue with getting the clutch working on my old 2000 M600 which has been sitting for quite a while. The original slave cylinder was seized solid, so I bought a secondhand replacement complete with master, lever and pipe from a 620. Fitted it and then had a lot of issues trying to bleed it, but have managed to finally get that done. The lever is now nice and firm when operated. However the clutch still doesn't work. There are potentially two issues that might be causing the problem. 1) the "depth" of the slave cylinder seems to be about 2-3mm more than the length of the pushrod sticking out. I've read that there was a change in spec at some point and that a extension piece can be needed, but I think they are 10mm, which would be way too big. 2) The throw of the slave cylinder is around 1mm when the lever is pulled. Does this sound about right? It is very little movement.

23-05-2020, 06:36 PM	#2
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,736	1. the depth is a bit variable, it may be 2-3mm more now but hydraulic systems self adjust to some degree (like pumping your brake pads onto the disc after the pistons have been pushed back into the caliper). I you remove the reservoir cover on the master cylinder, how far canyou push the piston back into the slave? 7-8mm? Then a 10mm spacer would fit. Keep an eye on the reservoir, you might need to remove some fluid! 2. ~1mm sounds right, from looking at the top plate on a dry clutch with an open cover. Last edited by slob; 23-05-2020 at 06:39 PM..

24-05-2020, 11:41 AM	#9
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,903	It is possible to put the clutch back together but the lifting back plate may not be fully slotted onto the drum itself which means they can be 2mm lift in the drum and it wont work ..seen this a few times on clutch re assembly ,, when fitting first 2 of the 6 springs pull the lifting plate towards you to make sure its bedded in the drum slots __________________ MONSTERMAN

23-05-2020, 06:44 PM	#3
Luddite Registered User Join Date: Aug 2011 Location: Southampton Bike: M1100evo Posts: 2,465	The 600 and 620 push rod part nos. are different, which suggests they may be different lengths. The slaves have different numbers too so you may need a 620 rod to match your slave, (or a spacer).

23-05-2020, 07:00 PM	#4
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,736	I might have a spacer from an Oberon slave lying about, I'll take a look in the garage tomorrow if you like.

23-05-2020, 08:09 PM	#6
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,736	that sounds like it’s either all the way back or buggered. Since you have movement, it doesn’t sound like it’s seized. Make sure you remove the cap and watch the fluid level, otherwise you could blow the seals with the g-clamp! You ‘re positive you can’t pump it out 2-3mm further with the lever?

23-05-2020, 09:54 PM	#7
boyse7en Guest Posts: n/a	I went out and pushed it back with a gclamp, made a 10mm spacer and bolted it on. To bolt it on I had to release the pressure through the bleed nipple to get the three bolts on the slave to tighten up. Feels great at the lever but doesn't release the clutch - if I put it in gear I can't turn the back wheel with the clutch in or out ��

24-05-2020, 12:08 PM	#10
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,736	I don't think the clutch has been apart Jerry, just the original slave failed.