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Bad Clutch Slip..with New Plates!


mspenz
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It's an 06' 290 and it had a lot of clutch chatter and some noticeable slip in the top 2 gears.

I replaced the clutch bearings and bushes and also put on a new basket (Splat Shop) as the original clutch was jerky, I decided to replace all the plates using a set supplied by Ebay seller 'offroadmotouk' and fitted new springs supplied by Splat Shop.

The majority of the noise has now gone and the engine has that nice tight sounding whine but the clutch slip in 4th & 5th is ridiculous! When I looked at the old plates they didn't seem too bad but I should have measured both old and new before trying them...something I'll do this weekend.

I bought the plates back in August and have only used the bike in the garden 3 times so today was the first chance to get out properly, if the plates are rubbish then it's going to be too late to return them I'd imagine, or am I missing something and could something else be causing this? I personally now think that the new plates could be the problem, anyone else tried a set of plates from these guys before?

 

I've not been on here for a while as I don't get the opportunity to use the bike much unfortunately due to a lack of places to go  :(

 

Mike.

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As said above check there is enough freeplay in your lever for the master cylinder piston to uncover the reservoir hole. If there isn't enough freeplay the system acts like a closed system and when the fluid heats it can expand and hold the plates just slightly apart. Check to make sure the throwout bearing isn't shimmed. I don't know if this is a Sherco thing but some other bikes use shims. You have a new basket so grooved slots are not a problem. Make sure you are not using an oil with additives like PTFE or molybdenum/tungsten disulfide. Only gearbox oil rated for wet clutches.

I don't think the Beta clutch fix will help much with your slipping problem since it sounds too severe for just tab roughness.

Despite what many people think trials clutches don't wear out unless you are doing a lot of full throttle splatters. Most plonkers happily get on with 10 year old plates. Likewise modern springs are made of much better materials these days and it's unlikely your springs are the culprit.

Good luck finding the problem and make sure to let us know what you discover. We're all learning.

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offroadmotouk are a dealers in Northumberland, I bought my bike from them and I've bought a few parts from them including clutch plates. The plates are great in my evo, sorted the drag out when the usual fix didn't work. Their service has also been good so it's probably worth contacting them to see if they can help.

Edited by totty79
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Thank's guys, some good info here to get on with but it'll have to wait until Sunday now as I've other stuff to attend to.

I'll check out that master cylinder free play first (an easy one) but nothing has really changed from before as I didn't change the clutch fluid or adjust the lever...is there a specific amount of slack to set?

 

The clutch springs are new and supplied by Splat Shop, they were also noticeably longer than the old originals so that's good.

 

I contacted John from offroadmotouk and he couldn't be more helpful, he hasn't had any other issues with the plates he has already sold so he has asked me to measure the new set and get back to him, there may be a manufacturing anomaly but that would have probably shown up on other sets.

I did find a note from Splat Shop with the approximate actual thickness of a new set...friction plate will be @ 2.7mm and the pressure plate @ 1.5mm. When I measure my old plates they are exactly that size, although pretty glazed looking :huh: 

 

What do you mean by the throw out bearing being shimmed Dan? 

 

I'm using Putoline 75w light gear oil and have done since getting the bike about 1 year ago.

 

That clutch free play has me thinking now, I've previously changed the fluid but haven't adjusted any play and there's always been a bit of slip under throttle in the last 2 gears but why would it be worse with a new set of plates?

 

Mike.

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New plates I would expect to be slightly thicker,so would put more pressure on the springs and in theory should slip less.Id take it apart and check I hadn't done something wrong and go from there.Id ensure that the master cylinder piston was returning fully and that there's free play between the clutch lever and master cylinder

Edited by huski
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New plates I would expect to be slightly thicker,so would put more pressure on the springs and in theory should slip less.Id take it apart and check I hadn't done something wrong and go from there.Id ensure that the master cylinder piston was returning fully and that there's free play between the clutch lever and master cylinder

 

The new plates probably won't be any thicker than my originals, the dimensions quoted by Splat Shop correspond to my original plates exactly (2.7mm & 1.5mm from new) although they are very glazed and I just replaced everything in the order that came out.

The new set should be of the same dimensions but without the glazing!

 

Maybe it's not the plates after all so maybe it's something else causing the problem, saying that, the new set are much worse than the originals.

I'll take them out again over the weekend and check the thickness first before doing too much.

Edited by mspenz
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Do you have the top friction plate rotated into the shallow notch as the factory recommends?

I don't know what effect not doing this would have

I seem to remember there being marks on the hub & pressure plate that had to be inline as well

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Hi Mike,

 

Try using Putoline Nano Trans GP - http://www.splatshop.co.uk/putoline-nano-trans-gp.html

 

When the clutches are worn, it makes a huge difference, you can freshly swap the oil with Putoline Light Gear Oil, and it will slip, change again with Nano Trans and it will work perfectly.

 

Also see the following info below that Chris has done to help people out:

 

The clutch fibre plates are 2.73mm when new
The steel plates are 1.53mm new
The clutch pressure plate is 5.30mm from where the friction plate makes contact to the outer edge.
The clutch hub is 3.00mm from where the friction plate makes contact to the machined outer edge, the hub can also get quite grooved where the steel plates sit causing problems with clutch slipping and sticking.
The basket is also prone to getting grooves where the friction plates sit, again causing problems with clutch slipping and sticking.
Clutch springs can loose their springiness, the free length of the spring from new should be 45mm, if they get below 44mm they will cause slippage in high gears under high load.
If the spring have shrunk replace the springs http://www.splatshop.co.uk/sherco-clutch-springs.html or we do some washers to put extra tension on the springshttp://www.splatshop.co.uk/shim-washer-14x20x1-din-988.html

We have found the main reason for the clutch to drag (other than mucky oil) to be the friction face's on the hub and the pressure plate been out of square, so if you have the equipment it might be worth clocking up the friction face and the clamping face to ensure they are parallel
to each other, if not you can give the friction faces a quick clean up on the lathe assuming there is enough material left. With these faces being made of aluminium they usually wear more than the friction plates.

Also I assume you have changed the oil recently, if not I'd recommend changing it. I personally change my gear oil every couple of months so it probably gets changed about every 8 times I ride the bike, this helps keep the clutch working well.

The oil type makes quite a noticeable difference to the response of the Clutch, Putoline Nano Trans GP is the best oil we've tried in the Sherco, especially with the clutch, it's pretty good with the gear shifting too and it seams to work for a long time before it needs changing.http://www.splatshop.co.uk/putoline-nano-trans-gp.html

Ipone's Box Xtrem is also pretty good and not quite as pricey
http://www.splatshop.co.uk/ipone-box-x-trem-1ltr.html

See the picture below for the washer that might be missing that causes very bad clutch slippage (highlighted in red) http://www.splatshop.co.uk/sherco-washer-a82035.html
This washer behind the clutch hub should also be 1mm thick

 

The clutch thrust bearing is 2mm thick
The washer for the above bearing is 1mm thick

 

Cheers,

Tim

post-13064-0-84026700-1480084379_thumb.gif

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Do you have the top friction plate rotated into the shallow notch as the factory recommends?

I don't know what effect not doing this would have

I seem to remember there being marks on the hub and pressure plate that had to be inline as well

 

Don't know anything about this but I'll have a look.

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