15 replies to this topic

[toddyboy]

I've had my 04 niner for a year now. Its been a good un and me and the missus been all round Northern Europe on it. However, I Just tightened the rear chain up today and noticed about two inches of slack in the transmission. By that I mean if I put the bike on the centre stand and select a gear then rock the rear wheel back and forth there's approx 2 inches of slack before it locks up. When I start the engine and run the bike on the centre stand at tickover in any gear it snatches like mad and makes an awful graunching noise as it does so. That's too much slack in the drive train if you ask me. Anyone got any ideas what is causing that?

[Studley Ramrod]

My guess is there's extra slack in the drivechain with the bike on the centrestand and it's this slack that's being taken up when you rock the wheel.

 

Or, possibly worn chain, sprox and/or cushdrive rubbers ?

 

I guess you could check for play on the front sprocket/transmission after slipping the chain off.

[JBX]

You should check the chain slack in riding condition aka both wheels on the ground and some weight on the saddle.

 

When you lift the rear wheel it create a kind of resonance wave because of the rotational inertia of the wheel.

This is no good for the transmission.

[toddyboy]

The play is definitely in the region of the front sprocket. The rear one has no play in it. The problem with the 900 is that after you take the plastic casing off to get a look at the front sprocket there's some kind of other casing/mechanism covering it. My previous 850 Mk 11 didn't have that. Feels to me like the excess play is inside the gearbox. Could be a worn chain and sprockets as well but to have that much free play before the chain takes up the drive seems a bit excessive. Could it be something to do with the clutch maybe? It makes a squealing noise every now and then when pulling away in the morning.

[TYREDNGRUMPEE]

I only experience a regular rhythmic graunching noise on mine when it has been overtightened.

The noise is generated by the front sprocket rocking on the output shaft.

"Tightened means something completely different where TDMs are concerned"

 

All the usual suspects, overtightened, worn components, tight spots, misalignment.

Or you haven't got a problem in the first place.

I know when my setup is too tight when sat on the bike and coasting to a stop.

The graunching is most apparent then.

The centre stand is no real test IMO.

50-60mm and judge only once ridden.

Edited by TYREDNGRUMPEE, 30 March 2015 - 06:56 pm.

[ric]

'The centre stand is no real test IMO.

50-60mm and judge only once ridden.'

 

+1

[leehenty]

Motorcycle gearboxes always have play due to how they work. The gears are locked by dogs usually three to five. There must be play or the gearbox would be difficult to use. The play you describe seems normal to me. All twin cylinder bikes will snatch if run off load on stand. The power of an engine is not smooth. It is a series of bangs, this is what the cush drive seeks to damp out.
There is always backlash in a gearbox as the gears in a bike are usually spur gears not helical. Then the gears are driven by splines which must have play to allow them to slide along the shafts.
Some race bikes have helical gears but then you have side thrusts to contend with. In the TDM the gears are good old spur type. Cheap and easy to make strong by forging them machining the teeth.

Edited by leehenty, 31 March 2015 - 01:08 pm.

[Catteeclan]

Lee's spot on as usual.

 

It's normal so stop fussing and ride the bloody thing.

[TYREDNGRUMPEE]

Lee's spot on as usual.

 

It's normal so stop fussing and ride the bloody thing.

 

+1

 

My question is,

How do you get to tour around a swathe of northern europe and then start freaking out over some natural gearbox play that has been there since day one?

Must be the smell of Summer approaching. 

[Catteeclan]

I guess it could be un-nerving if you haven't noticed it before.

[toddyboy]

There's definitely more free play in the transmission than when I first bought it. Put it in first gear with the engine off and rock the bike back and forth and there's at least 2 inches of free travel. Seems too much to me and it's bloody annoying when cruising at say 70mph. It causes the bike to snatch

[TYREDNGRUMPEE]

If this were serious and you had 2 inches of "free travel" at the rear sprocket your bike would be rocking back and forth 6 inches.

So I'm guessing this is not the case and it's your bike that is rocking back and forth 2 inches.

So where's the problem?

Allowing for chain slack there is none.

This is good.

Conclusion - It's not the transmission "free play" that's causing your bike to snatch.,

Edited by TYREDNGRUMPEE, 29 April 2015 - 01:33 pm.

[Riggers]

I've got a centre stand fitted Toddyboy and I've just been to my bike and checked this out. With the bike on the centre stand, chain correctly adjusted, and first gear engaged there is exactly 2cm of movement in one direction on the bottom run of the chain (or approx 3/4 inch). 

 

I'm on my own at the moment so can't check it out for you off the stand.

 

Hope this helps.

[TYREDNGRUMPEE]

Perhaps you should take a look at the cush drive rubbers on your rear wheel and the damping springs in the rear of your clutch basket at the other end of the system.

[toddyboy]

I've got a centre stand fitted Toddyboy and I've just been to my bike and checked this out. With the bike on the centre stand, chain correctly adjusted, and first gear engaged there is exactly 2cm of movement in one direction on the bottom run of the chain (or approx 3/4 inch). 

 

I'm on my own at the moment so can't check it out for you off the stand.

 

Hope this helps.

That sounds normal. Mine has two full inches of free play before it engages back or forth. Def not the sprocket or the chain. The free play is inside the engine