Swm Clutch

[woody]

Question for any of you SWM owners whose bikes have a nice light clutch action - How do you set up the clutch spring tension?

Are the pressure plate bolts tightened right up to the end of their travel and left like that or are they then backed off so many turns. Bike in question is a Jumbo which has the lightener under the tank connected up but the clutch action on the lever is very heavy - the pressure plate bolts are screwed all the way in so I'm wondering if they should be backed off a little but as I have no manual or set up info I've no idea. I can experiment obviously but if someone knows how they should be set it would make life easier than trial and error. Although it is a Jumbo I gather the clutch is the same as the disc valve models.

If I can at least set the pressure plate pressure correctly it may also cure the other clutch problem which is the snatching, graunching, juddering action that is worse than a TLR and which, along with the heavy action, is making use of the clutch impossible.

Any help appreciated thankyou and then I can go and try it out in the next Miller round

[malcra]

Just a couple of thoughts following our brief chat Sunday;

1. my 280cc bikes have only 4 clutch springs in place out of the 6 and one of the bikes only had 3 at one stage, but slipped a bit on the road in 4th and 5th. The Jumbo has all 6 springs in place.

2. the clutch plate bolts are nipped up all the way on the 320's and the Jumbo.

3. the adjuster inside the clutch cover needs to be spot on, with the cable adjustment slack, it needs to be touching the clutch pin.

4. On the Jumbo and post-80 320's the swivelling plate inside the clutch cover that applies the force to push the clutch pin runs on (3?) small ball bearings (the earlier Red/White 320's don't have them), but have been found to be missing on a couple of the bikes. The earlier 320 Guanaco clutch action is more notchy and no-where near as smooth as the later bikes

5. After rain (like Sunday), the clutch cables seem to fill up with water and need regular doses of WD-40. I've also changed the cable runs a couple of times to get the smoothest route.

None of the Hungerstone SWM's (ie mine and Gav's) have the same clutch symptoms as your Jumbo, and the only time it did was on my first trial with the Jumbo and I hadn't set the adjustment (3 above) correctly. It juddered and would slip/grip in all the wrong places.

[jumbostu]

Hi Woody

Check your cable condition and routing ( take em off and clean em with a solvent spray and force wd 40 down em ( the recommended way to clean a cable was to use hot soapy water!!!) Brand new cables are obviously the best way to go. Dismantle and clean / grease the lever mounting pivot under tank and drill a hole further down the arm to re locate the pin - not so low as to distrot cable run (this will increase its leverage effect) the jumbo needs all it springs in place or will slip like mad. I use and change regularly standard ATF fluid (16 quid a gallon = 4 quid a change) 1200cc of it from memory and my clutch works as well as can be expected from a Rotax motor - consistent in use and a reasonably light useable action. Saying all that tho I bought a Jumbo from Martin with the under tank lever missing and a cable straight from bars to clutch and it is a good bit lighter in operation than my original Shcreiber Jumbo setup!!!! Failing that I fitted a hebo hydraulic conversion to my 320 with good easy success tho 120 quid and not original looking at all.

Cheers

jumbostu

[martinm]

Hi Woody

Have to agree with all the suggestions Malc and Stu have mentioned so far, here are 3 other things worth checking.

1. If you have the clutch apart, check the condition of the alloy part of your cluch basket. The inside of the "teeth" tend to get notched out by the plates and give a jerky feel to the clutch. File them back smooth, or if they have gone too deep a replacement basket might be on the cards.

2. The steel clutch actuating arm on the inside of the case runs on 3 ball bearings.....as described by Malc earlier. The Jumbo's had three different versions during their production, the early version was the same as the 320 with a circular actuator running on 3 small (3mm diameter) ball bearings, the later versions used a 3 pointed star affair with larger 5mm ball bearings. If you bike is running the earlier set up, check out the underside of the actuator plate, the ball bearings create ruts in the surface which interupts the clutch action.

3. Try extending the clutch actuating arm by welding a 10mm section in the middle.....was a popular mod back in the 80's on the 320's that SWM eventually marketed as a "works extra".

Hope this helps

Martin

[twinshockdude]

martin is spot on as usual,my 280 has the extended arm and is as light as my majesty clutch.

correct adjustment is vital to avoid drag or slip.

[woody]

Thanks for all the suggestions. I've tried most already but haven't looked to see if the condition of the actuator where the ball bearings are is ok, so I'll check that. Haven't yet tried extending the arm either as I was hoping not to have to do that.

Cables and routing are all ok and the lightener arm under the tank is free in its movement. I've also tried a single cable (new) from a 280 but the problem was still there. The actual pull/release action on the cable is smooth enough but it is just too heavy. That's one problem.

The other is the mechanical graunching/thrashing noise when engaging the clutch together with the eratic take up. If I ride in 3rd gear slowly with the clutch just around the biting point it's almost as though something somewhere is going in and out of mesh as the drive take up drifts in and out. Sounds and feels horrible. Gearbox is definitely ok as there are no problems at all when the clutch is disengaged, so clutch is definitely the cause of it.

Condition of the basket and centre hub all looked good where the plates slide but I'll check them again and make sure and also check again that the adjustment is correct on the actuator. Plates are all new.

My other suspicsion is that the clutch gear assembly is worn where it sits on the 2 roller bearings and is rocking/wobbling on the shaft because there are marks on the kickstart gear that sits behind the clutch which indicates that the basket is catching it. The mark isn't constant all around the gear, there are several marks, equidistant around the gear indicating that the basket may be rocking/oscillating to cause that. I wondered if this is what was making the hideous graunching noise when the clutch is used. So I fitted a shim behind the existing spacer that sits behind the clutch hub and this seemed to improve things as it stopped some of the rocking on the shaft as well as moving the basket away from the gear.

I've now bought 2 new roller bearings and a sleeve, so I'll fit those, try it with the shim and re-check everything suggested above and see what happens.

If I'm not riding it at the Rhayader Miller round Malc, don't ask how I got on, because it will be at the back of the garage with a pick-axe handle sticking out of it....

[martinm]

Right then Woody.

Have a look at the attached image, and check the following

1. Have you got both the spacers (1) either side of the clutch bearing as shown

2. The washer (9) has the castleations on the inside, is it on the shaft correctly

3. Clutch nut (10) should have a recess on the inside so it will tighten down over the start of the splines on the shaft.

4. The gear (18) can be installed the wrong way round, make sure the domed centre section is pointing outwards.

If all else fails I will send you up another clutch basket and primary gear to try, in case the gear drive on yours is damaged somehow.

Let me know

Cheers

Martin

Edited May 30, 2007 by MartinM

[woody]

Thanks for this Martin.

Both spacers (1) are fitted. I've never noticed that the lock washer (9) should specifically fit one way round so I'll check that too, although it seems to be located ok on the splines. Clutch nut is definitely on the correct way and locates ok. Also wasn't aware that the gear could be installed the wrong way around. I've never removed it but the clutch has definitely been off before I got the bike so I'll check that too.

I'll have another go at it on Sunday and let you know. Maybe the pick-axe won't be needed just yet...

[malcra]

Woody,

it took me 3 attempts to get the gears assembly back together correctly when I rebuilt the engine and I also managed to get the gear (18) in the wrong way round on the final build (though not being able to kick it over was a bit of a clue). Hopefully its just the order of assembly thats the problem and see you next weekend in Rhayader.

(btw still haven't worked out what that frame is exactly)

[jbswm]

something you might want to check is the clutch plates themselfs,280 plates are thinner than jumbo plates.maybe over time someone installed the wrong ones...

[martinm]

something you might want to check is the clutch plates themselfs,280 plates are thinner than jumbo plates.maybe over time someone installed the wrong ones...

Not according to the parts book Jonny. The part numbers for the friction and steel plates are the same on both the 280 and 350 motors...have just checked the book.

Martin

[woody]

Had a look at the clutch tonight - plans to do it yesterday fell apart due to a 30 year reunion with a lot of old work buddies on Saturday night which went on until about 4am. Sunday apparently, passed me by - 30 years ago I'd have just gone straight from the party to a trial....

Checked the basket first and smoothed off all the fingers where the plates have caused ridges - had my glasses on this time so could see the ridges I couldn't see last time I looked when I wasn't wearing them - another reminder of a passing 30 years. They weren't too bad as it happens but baby's bum smooth now. The splines on the clutch hub are fine so the plates have a nice smooth action in the basket.

Next checked the gear (18 in the diagram) as this wasn't a tight fit on the shaft and the bush appears worn. Swapped it for the one out of the spare motor (which I am now convinced is from a bombadier) and this is a much better fit although still a tiny bit of wear in it. So now the clutch basket with its new bearings/sleeve and the gear both have a lot less 'rock' when sitting on the shafts. They've definitely been catching one another before.

The clutch actuator is fine, no wear and smooth in action. Haven't had time to extend it yet. Adjusted it per the manual with cable disconnected. Clutch is all assembled as it should be.

Moved the secondary cable down a notch on the lightener arm and lowered the mounting point for the outer to keep it in line. Made sure the pivot was free and greased on the arm and everything is free in movement.

Tried it around the garden and the action is now lighter and about how I thought it would be although it needs to be lighter still to make it comfortable to use on a regular basis - which may be the case as it is not an easy bike to ride just on the throttle with no clutch due to it being a bit lumpy and quick off the throttle.. Carb tweak, timing and a flywheel weight may sort that though. The drive take up felt better but it still isn't right. There is still some juddering on take up in 2nd and above and the bite point catches me out as it isn't consistently in the same place. If I ride in 3rd gear again, as before, slowly with the clutch just around the biting point there is still some grating going on but it is not as violent as before but it still hasn't got smooth take up in 3rd, needed for example if going from nothing out of a turnn up a big climb. If I kill the engine though and dip the clutch with the bike in gear it disengages perfectly and I can move the bike backwards and forwards as though it is in neutral (try doing that on a modern bike....) so there is no problem at all with the plates disengaging. Perhaps it's now down to oil, so tomorrow I'll try some ATF in it and see what happens. At the moment it's Silkolene light which there is nothing wrong with but maybe this clutch just doesn't like it.

Thanks for the help and advice, I think whatever happens now it will be in a useable state so I'll give it a try on Sunday at the Miller round. I'ts a bit more modern than I'd like to ride in the Miller rounds really but I've got to try it somewhere so Rhayader will do. Just got the shocks to sort now...

[woody]

Had another attempt to cure the clutch woes after using ATF didn't make a jot of difference.

This time I thought I may as well extend the arm on the actuator too as the pull on the lever is still too much for constant use. The actuator on this bike is the circular type as described above. The 'ramps' on the back of the actuator which run on the ball bearings look ok with no grooves or anything that would cause irregular movement. However, I did notice that where the arm extends out of the actuator housing it rubs on the side of the housing for the length of its travel, the section that it rubs against being 'ramped' also to presumably help move the actuator out of the housing when the clutch is applied. This appears to be by design but I can't see why it is needed as the 'ramps' on the back of the actuator are enough to do that. Moving the actuator by hand, you can see where the arm is rubbing against the section of the housing and it is rough in action. I imagine that this is what is causing the erratic take up of the clutch as the arm may be sticking along its travel, particularly when doing the ride in 3rd slowly whilst slipping the clutch test.

Although I can't see why it is designed like this I resisted the temptation to grind off the offending piece and took the clutch case off the spare motor to compare. This one has the star shaped actuator and the arm is free in movement, there is no ridge in the casing for it to rub against. I fitted this case and it is immediately obvious that the action is lighter (but still not enough....) and more importantly smoother. Tried the bike and it has improved things definitely, but the clutch itself still has a snatchiness about it and take up in 3rd is nowhere near as precise as it needs to be. 2nd is acceptable at best. Still, at least it is better than it was so I think on the original case, I will grind off that section where the arm is sticking and see how it feels then with the extended arm. May also try the complete set of plates out of the other motor too, just out of curiosity. At least I should be able to use it on Sunday now.

Edited June 8, 2007 by Woody

[trickymicky]

I had a new SWM 240- blue frame model. Clutch was heavy, but the importers did some sort of modification kit, which i bought. Cant remember exactly what it was but i think plates were involved, and i seem to remember it had the desired effect. Also, if its not been mentioned before, for those using Domino levers, there are different types. On some the hole where the cable barrel fits is nearer the pivot, giving a lighter clutch action (providing it still clears ok)

[mattylad]

I had trouble with my Jumbo nclutch.

Check if the arm under the tank fouls when you pull it on. Mine touched against the main frame tube.

I needed to flex mine away from the main frame before it cleared and pulled freely.

Cheers,

Matt