Clutching at Straws.

Camel, Sahara, Kanguro, Coguaro
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Clutching at Straws.

Post by harrymuffin »

If your plates are rusty then you are not using it enough. Ever tied getting the clutch to free on an inline transmission car not used for some time? It's an engine (or gearbox) out jobbie to free the friction plate stuck to the flywheel.Regarding ball bearings, and pushrod lengths, I have only found one Morini that came my way with a ball bearing and removed it. Providing the assembly of rods plus the larger input dowel is sticking out of the gearbox and contacting the lever, then it is just a matter of adjusting the fulcrum lock screw to give the correct clearance between lever and crankcase, which will give you the correct displacement of the spring plate, cannot remember clearance without looking it up. The rods should not wear, as they effectively run in oil or mist from the gearbox and hardened, plus they only load up together when the clutch is operated. I know the penchant today is to sit at the traffic lights for 5 minutes or longer with first engaged whether car or motorcycle, so perhaps education is needed if they should be turning blue or start to drag owing to heat build up.
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72degrees
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Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Clutching at Straws.

Post by 72degrees »

harrymuffin wrote:If your plates are rusty then you are not using it enough.
Well as the 'racer' only gets used about 10 days of the year, that might well be a factor. To be fair, the 375 doesn't get used an awful lot, but has had a sweet clutch since I last did the seals and shimmed it years ago. Now I think about it, the first time the hill climb engine was used in anger it had the plate stack (and cup spring assist washers) from that and it was fine, so I think I'll probably borrow them off that for Manor Farm and Wiscombe in September.

I don't have any drag, but I do have to search for neutral sometimes as I come to the start line. Then, once the green light shows, it's case of visor down, clutch in, snick in to first, blip, blip, blip, launch.
Butch
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Joined: 15 Oct 2016 16:47
Location: Essex
Location: Mid Essex

Re: Clutching at Straws.

Post by Butch »

So Saturday I got the bike back up on the table. Pulled the clutch again and withdrew the actuator rods to check against the new ones I now have from NLM. Yes it really does have four parts – the mushroom ended bit, two similar length thin rods, and the short fatter rod that the actuator arm presses on on the RH side of the engine. As people have commented – there is no ball in this arrangement, I’d just requested NLM send me one so as to keep my options open. But they all looked just fine. Comparing, the new thin rods were probably about a mil (.040) longer each. Putting it back together with the new stuff now backed the arm out so far I couldn’t get the case back on over it. Swapping one of the thin rods for an old one I could now get the case on, but I hadn’t got enough slack in the cable. So I reverted to the original stuff. Might try and butcher a cable some time.

I’d bought a new cable, the second one I’ve fitted, and the action was a lot nicer – what had I done to the last replacement? I tried the clutch with just 3 of the 5 springs fitted, but that led to an uneven lift. So tried it with all five but the nuts backed off three turns. I always have the nuts backed off around an eight turn anyway. Am I likely to have any problems running like this?

A test ride showed no improvement. So I stripped the whole lot down again and checked the shims. I had three in there giving about .030. Swapped some around and went with about .050 (all imperial). I understand that this is supposed to make the clutch more on/off switch like but a test ride suggested this was OK. And maybe it is slightly better. At a standstill, if I drag the clutch then pull it back in sharpish whilst working the pedal I can sometimes get neutral. I’m probably going to try putting around another .015/.020 in there, but that can wait for another time. It will be some weeks before I get back to this.

Bike was back on the station run this morning, and the clutch is at least a whole lot easier and smoother at the lever.
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72degrees
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Re: Clutching at Straws.

Post by 72degrees »

I always back the spring nuts off a tad and haven't had a broken stud for years (more likely caused by over-tightening when they then they seize up and break on attempting removal probably). As my experience suggests, 'loose' shimming isn't the only reason for a binary clutch. In your case I might be tempted to try making up one custom actuator rod that is significantly longer out of silver steel with heat treated ends and see if that helps. Riding the 375 on Saturday for the first time after mainly using the ER6 made me realise that I rely a lot on the neutral light on machines that have one. Even that needs a delicate foot occasionally. I suspect that I suffer neutral finding performance anxiety when I don't have an idiot light to reassure me. Quite often I tentatively ease the clutch lever back to find I found neutral OK after all.
'It must be a .....'
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Joined: 12 Sep 2010 12:25

Re: Clutching at Straws.

Post by 'It must be a .....' »

' Putting it back together with the new stuff now backed the arm out so far I couldn’t get the case back on over it.'
Hi, is the adjustment of the operating arm is wrong? It should be about 15mm from the crankcase edge.
And a rare opportunity to use an 11mm spanner!

Good luck
Butch
Posts: 94
Joined: 15 Oct 2016 16:47
Location: Essex
Location: Mid Essex

Re: Clutching at Straws.

Post by Butch »

Somewhere back down my diatribe of whinging posts you’ll see that I ended up butchering two cups on my initial clutch strip down because the nuts just wouldn’t undo and the studs turned, and then having to replace/peen two new studs in. Hence I’ve been leaving a little slack ever since, and so I figure that the difference between an eighth turn and three isn’t so very much.

My plates were covered in oil on that first strip, and I was in there because the clutch was dragging, not slipping. All plates since replaced for new – along with the oil seals.

I did some spannering waaaaaay back for a guy who raced a Thruxton Bonneville. He used to leave his plain plates outside all winter to pick up some goodly corrosion for better grip.

And thanks for the latest input. On neutral lights, I would say that mine is the biggest liar I have experienced on a bike. It illuminates;

. When in neutral
. When I’ve failed to engage neutral from first
. When I’ve failed to engage neutral from second

Point on adjusting the clutch arm duly noted. If I accept that the adjuster forms part of the rod length then by fitting longer rods and reducing the adjuster I end up with the same result. My understanding is that the lever angle is what would make a difference to the actual actuation. I think that I can get a bit more length in there, though I’m not sure this will help – the lever angle looks quite healthy to me as it is; and that will take some fooling with the std cable to accommodate.

Anyhoos. It will be some weeks now before I get back to this one. I’d have to say from my experience this weekend that maybe the shimming isn’t so precise a science, so it will be interesting to see how throwing a bit more in the stack will work.
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72degrees
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Re: Clutching at Straws.

Post by 72degrees »

I'd much rather have no neutral switch rather than one that lies.

Thinking out loud. How about swapping one of the thick friction plates for another thin (or significantly worn) one to give a bit more space when separated? Might slip then I suppose but it might be an interesting experiment. Then I've known clutches on other machines (wet clutch ones) that managed to slip and drag at the same time.
Butch
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Joined: 15 Oct 2016 16:47
Location: Essex
Location: Mid Essex

Re: Clutching at Straws.

Post by Butch »

Yeah – I’ve got plenty of spare bits now. I have fooled with the stack make up before. I swapped out the dished plate for a flat one and added a thicker friction plate to make up the space. Made no difference to the dragging problem, but did make it a harder pull on the lever – which it would if you think about it. Armed with some different length rods, and if I tweak one of my cables the permutations now must be pretty much endless.

I think maybe I’m on track with just adding more and more shims now though. Maybe.

It has to be said that with the new cable and latest build the action at the lever is at least quite pleasant. I’ll probably be hearing the nuts scraping in the casing soon as they continue to unwind.
Butch
Posts: 94
Joined: 15 Oct 2016 16:47
Location: Essex
Location: Mid Essex

Re: Clutching at Straws.

Post by Butch »

Had the bike up on the table again on Saturday for another go at the shimming. Points to that;

. Last time in there I'd backed off each of the 5 clutch nuts by three turns. They were still all at that setting i.e. they'd not wound in or out in service since then. I'd not noticed any slip during use with this setup.

. I started off with approx 35 thou of shim in there. Last time I increased that to about 45 thou. This time I increased it to maybe 55 thou total.

. I reassembled with the nuts all wound out three turns again. This coupled with my second new cable (I think there must have been a fault with the first one) gives a fairly gentle and smooth pull.

. On the road it is not perfect but I'm thinking is the best that I can get it. In gear at a stand still I have to allow the lever out a little to drag more fully, after which pulling it back in along with a well timed 'nudge' at the pedal will fairly reliably get neutral; from either first or second.

. I've seen all of the notes on correct shimming, but my experiences suggests this is really not that exact a science. I'm definitely running with slack in there now and I'm not experiencing any sudden clutch action that might be suggested for that set up. I do think that for sure I needed more shim as I now have.

So I'm happy with this set up finally. Not perfect, as noted, but perfectly livable. Thanks to everyone for their input on this one. Case closed.
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