Gearbox noise when I let off trottle

[Meath]

I just noticed today there was a bit of a bang out of the gearbox, it happens when I'm driving along and let off the trottle for engine braking. Doesn't happen when I let off the gas and slow down gradually. The "bang" from the gearbox is similar to the noise you get when you're starting off in neutral and click it into first.
Anyone know if it's serious?

 

[bmwrich58]

Possible bad U-joint in the drive line.
Start with this:...
Put on center stand and roll rearwheel back n forth by hand out of gear and see if any notchiness/noise,repeat with bike in gear.

 

[Deleted account 190920001]

its just backlash in the gears. its worse when you slam the throttle because it has to take up all the play quickly where if you role off the throttle slowly its more gentle and doesn't bang. There isnt any big rubber cush drive in these bikes to quieten it down.

 

[Meath]

Possible bad U-joint in the drive line.
Start with this:...
Put on center stand and roll rearwheel back n forth by hand out of gear and see if any notchiness/noise,repeat with bike in gear.

I'll give that a go to see if anything happens

its just backlash in the gears. its worse when you slam the throttle because it has to take up all the play quickly where if you role off the throttle slowly its more gentle and doesn't bang. There isnt any big rubber cush drive in these bikes to quieten it down.

That sounds exactly what's happening.
To be honest when it happened yesterday I was wondering if it was a new sound or not cos the gearbox is clunky anyway. But the girlfriend was on the back and she even mentioned it, so it definitely is a "new" sound.

 

[RickG]

check the swinging arm bearings while you are down there, especialy the drive-side one

 

[smartbear]

noisy banging

I just noticed today there was a bit of a bang out of the gearbox, it happens when I'm driving along and let off the trottle for engine braking. Doesn't happen when I let off the gas and slow down gradually. The "bang" from the gearbox is similar to the noise you get when you're starting off in neutral and click it into first.
Anyone know if it's serious?

mine doesnt "bang" into 1st gear from neutral,it makes a subdued clunk-try changing your gearbox oil to see if it quietens it down any

 

[Meath]

Well, since a day after my last post the bike stopped in the middle of the road! Called the recovery truck, turned out the drive shaft went.