HELP! Lambretta Gearbox noise

[wack 63]

Sliding dogs catching gears when in neutral?

[dapper]

Also check that end plate studs/bolts aren't catching on the inside of the rear sprocket. Oh, and when you've sorted it post what was the eventual problem

[The Hiwatts]

We have had the gear box in and out a total of 14 times now!!!!

Ok, we changed the hub bearing, we have tried every shim from 2mm to 2.8mm, new phosphor bronze bush, new end plate, bearing, new needle roller bearings,tried various gearboxes, new chain, tightened front sprocket, new clutch, tried old clutch, new springs old springs, I'm close to setting it on fire!!!!!

I don't know what to check now? - it's not the kickstart, ground down shaft or running on teeth!!!

I'm reluctant to spend anymore money on possibly crown wheel or new gearbox if it doesn't cure the gearbox rattle in neutral!!!!!!

Talk about a f**k off!!!

[The Hiwatts]

Just to add, it's got a Brand new top end, bearing seals crank barrel piston, new top chain guide too!!!!

[wack 63]

When you fit each gear individually how much side play do they have on the layshaft? You said you've tried other gearboxes but the noise was still there, did you change layshaft?

[bristolmod]

any ST90 in there?

[The Hiwatts]

Gears are quite tight on layshaft - we have tried various layshafts too!!!
sT90'in gear box too

[Pepot]

If I were so desperate as you are, Id try empting the gear oil,remove the chaincase, and start the scooter by pushing it in second gear. Once started check where the noise come from and if you can see something turning unevenly. Only for a short time. I know it sounds strange starting an engine without gear oil, but thats what I'd do if I was in your case...

[Pepot]

I've just remembered something that happened to me with an indian crown. The hole where the bronze bush goes had been unproperly machined, so it wasn't perfectly perpendicular to the crown. You could see the whole clutch doing strange movements even turning the engine by hand. The clutch is attached to the christmas tree, so it could explain your gear noise and why it stops when you press the cluth.

[tavspeed]

my mates chain snapped and holed the casing near the rear shock mounting,chain jammed between casing and crownwheel,after the welding repair etc,we rebuilt the gearbox etc,
backend sounds like it has a frog in it,which disapeared when clutch is pulled in
,so we stripped and checked ,gearbox turns freely,new crownwheel and bush and spider fitted,noise still there.
after much head scratching we noticed,when turning the rear hub, the spider was rotating eccentrically,and the crownwheel was wobbling slightly as it turned,so we think the gear cluster has got bent slightly,as when the chain jammed it would want to force the clutch and shaft downwards,trying to source a new cluster,so might be worth checking yours.