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Discussion Starter #1
My '10 1050ST has developed a "clunk" when the clutch engages, audible and which I feel through the foot pegs. It's been a clunky bike since I bought it in March. Front used to click on braking, and replacing the discs fixed that (the buttons on the old ones were very loose, with lots of lateral movement). I've checked torque on the engine mounts, and compared free play in the swing arm with my '07 which doesn't clunk. Free play seems the same. My mechanic says the cush drive is good. I'm hoping to have some time this weekend to get the seat off and access rear suspension bolts upper and lower. Any thoughts as to what it might be? I haven't enjoyed reading about sheared drive pins in another thread...
 

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Discussion Starter #3
Does it do it going from neutral to first or all gears?
It's not the actual gear change - I'm used to the agricultural nature of the gearbox :) Imagine pulling up at lights in gear, clutch in. Lights change, release clutch, clunk as start to move forward.
 

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Discussion Starter #7
Thanks Steve - I hadn't seen that; I'll have a look. On my way home today I confirmed it's to do with roll on rather than clutch. Rolled on, clunk, rolled off before a corner, no clutch, roll on, clunk. I've had a look at the counter shaft sprocket, and it was up to torque. I've a spare, but couldn't see the point in swapping.
 

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Discussion Starter #9
Loose front sprocket?


Fred
Checked and torqued, but I'll get the bike up this weekend and start again. I'll have a good look at the chain links, as Steve suggested, and make sure none are binding. The problem is I've never been able to replicate it on the centre stand, so I'll try with the rear axle stand and sit on the bike to load suspension up.
 

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Be worth checking the cush drive. In fact if you pull it down to check may as well throw in a new set of rubbers while you have it in pieces.

One more thing, you say it's always been a clunky bike, any chance it could actually be off-idle snatch? You know that slight hesitation before the engine responds to your fractional throttle input that afflicts so many Triumphs. It hesitates for a micro second then chimes in and exaggerates every bit of backlash in the drive train resulting in a 'clunk'.
 

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Discussion Starter #11
One more thing, you say it's always been a clunky bike, any chance it could actually be off-idle snatch? You know that slight hesitation before the engine responds to your fractional throttle input that afflicts so many Triumphs. It hesitates for a micro second then chimes in and exaggerates every bit of backlash in the drive train resulting in a 'clunk'.
I was wondering - it's running a modified B69 tune, with timing advance. I might try the TOR tune and see what it feels like. If it smooths the pick-up it might help.
 

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If the sound just started it could be a loose nut on the clutch hub,and or the drive sprocket. Tight chain or loose one will also create a clunk upon clutch release.
 

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Discussion Starter #13
As always, thanks to all who've bent their collective minds to the issue. Just to clarify:
a) the noise and feel is like when you flick a footpeg up and it clicks back down again (that's what I thought I was doing at first)
b) it happens on a gentle roll on the throttle, whether the clutch is being used or not
c) engine, wheel and counter-shaft are all torqued to spec
d) I think (very subjectively) I can feel it more through the left footpeg than the right, but it's hard to tell
e) it's not associated with changing gears

When I work it out I'll let you all know!
 

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When you sit on bike with motor off and roll the bike forward and backward do you hear the noise? Have you tried retorquing the wheel nut and even slightly over torqueing it to see if the noise disappears? Depending on how often the rear wheel has been off and on, the Belleville washer can become compressed slightly to the point where the normal torque can leave the wheel sufficiently loose to cause movement against the drive pins. Dead easy to check and move on if not the culprit.
 

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As an earlier post mentioned: cush drive. In the absence of other obvious problems this seems to me to be the most likely culprit.
My 07 Speed Triple has the typical range of clunks and clacks as the chain drags across the chain guide and through the sprocket teeth, but those noises are evident when pushing the bike around with the engine off. What it seems like I'm reading sounds more like slack getting taken up under initial power.
 

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Used o get exactly what you describe on my 2010 GT. I had been in the habit of plenty of copperslip in places it probably shouldn't be. tried all sorts, front sprocket nut re-torqued, chain varying tension, 46mm sprocket nut. Finally after a good wash with brake cleaner where wheel fits and wheel face and fixing washers behind wheel nut it stopped. Also 2 or 3 turns of insulating tape,(shrink tube would have done) on one of the five wheel driving dowels to take up any free play in the wheel drive on axle. No more clunk. Give it a try. Not costing anything. Pat
 

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Discussion Starter #19
Also 2 or 3 turns of insulating tape,(shrink tube would have done) on one of the five wheel driving dowels to take up any free play in the wheel drive on axle. No more clunk. Give it a try. Not costing anything. Pat
Pat, if you're ever in Melbourne look me up and I'll buy you a cold beer. Compared the two Sprints side by side, in gear. On the problematic one I could rotate the wheel on the hub, with a small but perceptible, and audible, click. On the other one, no movement, no click. Wheel off, heatshrink on the pins, wheel on and torqued to spec (146Nm), and a ride around the local streets to get fuel and... no click/clunk. As it used to do it every time I rode out of the garage and rolled off/on the throttle, I think you may have solved my problem.

:applause :bow :ride
 
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