gearbox/back end woes !!!!

[newbuild100]

This one is a baffler.
93 GS100, 60k.
If I roll along in gear, pull the clutch lever in and deaden the engine, . . something on the gearbox area sounds like a bag of spanners. (I Found this by chance, one wouldnt normally dip the clutch and hit the kill switch).
If I sneck into neutral, no noise at all.
(Ive tried the above on the centre stand,its exactly the same)

To try and suss out the problem, The gearbox has been overhauled (and stripped again to re check). There is nothing wrong with it. (All brgs etc replaced)
Ive had the clutch out, its pretty much perfect.
The flywheel looks fine, no play in there and no oil debris. (Which one assumes eliminates the crank too)
Today,I had one of the slightly suspect ujoints replaced on the drive shaft.

On rebuild, I still have the same problem.


I have replaced the final drive unit, with a spare one. Still no change.


HOWEVER, and this is a good one. If I remove the rear wheel, when on the centre stand, the noise completely stops !!!!!

The only thing i havent swapped is the drive shaft itself. (Shock absorber !!)
(I have a rebuilt spare somewhere).



Clues/ideas anyone ??????????????

 

[BamBam]

Check for play in the Paralever /beval box bearings, IE has the Alen nut on the inside of swinging arm next to the wheel come loose and rubs the wheel.
See this thread
http://www.ukgser.com/forums/showthread.php?t=171843

Post 3, 3rd pic

 

[newbuild100]

Ive tried all that, and its all fine.
Besides which, ive changed the bevel box etc and its still the same.
I think the noise is only there with the wheel in because its accentuating any play/backlash anywhere. ie, the noise is actually there all the time
(im pretty sure ive pinpointed the noise to the gearbox)

There is no noise when the box is in neutral. BUT in gear, wether the clutch is in or not, the noise is wretched. It does it in all gears.


Any more clues would be welcome folks

 

[brassmonkey001]

Loose spoke?

 

[newbuild100]

No mate, sorry.

Re the normal backlash in these gearboxes . . when we turn the input shaft, there is a slight "delay" before the output shaft turns. As this backlash is quite prominent, can i assume its not backlash in the meshing gears but perhaps in the male dogs on one gear moving back and forth in their respective locatiing slots (in its corresponding gear)??????

 

[bumpmuncher]

If I roll along in gear, pull the clutch lever in and deaden the engine, . . something on the gearbox area sounds like a bag of spanners.

noise doesn't change when you kill the engine = engine not making the noise

If I sneck into neutral, no noise at all.

ah ha bevel drive and shaft most likely fine as well as the gearbox output side of things, bearings etc
its most likely to be something on the gearbox input or clutch release, you say the gearbox has been looked at probably not that then .
so is the clutch release rod bent or damaged or the release bearing knackered.
how are the splines on the clutch/ gearbox input shaft.

but then you say

HOWEVER, and this is a good one. If I remove the rear wheel, when on the centre stand, the noise completely stops !!!!!

so feck knows

 

[newbuild100]

Pushrod fine, as is the clutch itself and the release bearing..
The gearbox itself was stripped because of the "normal" output shaft/input bearing failure.
Im begining to think I may have a bent shaft in there somewhere.

The noise is there in ALL gears !!

Me head hurts !!

 

[newbuild100]

Clues anyone please ?????????????

 

[Steptoe]

There is no noise when the box is in neutral. BUT in gear, wether the clutch is in or not, the noise is wretched. It does it in all gears.


Any more clues would be welcome folks

Clues anyone please ?????????????

So if the box is quiet in neutral but noisey in gear that points to the gearbox output shaft. The input and layshaft are both still turning when in neutral, but not the output shaft.

 

[newbuild100]

Mm, that interesting. Thanks.
Out of the "Gears" which move along its own shaft and have "dogs" on them (engaging in its neighbour), and as the box is noisy in every gear, is it possible to diagnose even further which shaft may be bent ??
Im also kinda suspecting one of these three Gears/dogs may be worn (or the corresponding slot) !!!!!!

I know at the end of the day, the box will have to come apart . . .AGAIN.
Im looking for clues beforehand though.
Certainly nothing obvious was seen on the very recent stripdown (admittedly, we werent looking for bent shafts and worn dogs/locating slots though)

 

[bumpmuncher]

The input and layshaft are both still turning when in neutral, but not the output shaft.

is that the case when the bike is rolling along in neutral with the engine off as nb100 describes ???

 

[newbuild100]

Rolling along in neutral, the gearbox is normal, ie quiet !

And yes, can someone confirm that the input AND layshaft are both turning when in neutral ?????

 

[bustupbiker]

Newbuild, if the great one, Sir Steptoe says it, It IS SO...

 

[newbuild100]

Ok thanks.

I did ask because I have been previously informed that ONLY the input shaft moved when in neutral.

Thanks again.

Ps . . me head still hurts !!

 

[bumpmuncher]

Ok thanks.

I did ask because I have been previously informed that ONLY the input shaft moved when in neutral.

Thanks again.

Ps . . me head still hurts !!

if the machine is at standstill with with the engine running. then yes the input shaft will be turning and not the output.

I think possibly steptoe missed that you had deadend/ killed the engine and the machine was rolling along. making everything arseaboutface regarding what is turning when in neutral.

 

[newbuild100]

Another slight clue . . .

If I/we set the bike on its stand, running, with a few revs on and in gear (ie, the back wheel is in the air and spinning), the Gbox sounds like a bag of spanners BUT when we slightly depress the rear brake to scrub slight speed from the gbox/engine speed, the hideous rattle fades.
I now wonder if the rattle is one the "dogged" gears rattling back and forth in uts respective slots, and when we apply the brake, its stopping the to and from movement.

!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[MickDB1]

I am almost sure you aint uiposed to run the engine in gear with the swinging arm dangling as it is probably the best way to wreck you driveshaft
HTHY

 

[newbuild100]

It aint dangling fellow. The bike is fully built up.