XT gearbox shaft worn

[trophydave]

I have just found out that the gearbox output shaft on my XT350 is worn allowing the sprocket to move about by a small amount.Now I really do not want to completely strip the engine to replace the shaft,so what are my options?There is some space behind the sprocket and I have a spare which I thought about turning down then attaching to the rear of another sprocket to spread the load over a greater area on the shaft(did that make sense?).I have had it suggested that I weld the sprocket to the shaft,but it would need to be in exactly the right place and be to able to remove it again in the future.Any other suggestions?

[Steve H]

I presume you mean the sprocket is cutting into the shaft splines allow it to rotate more than it should. It depends on how bad it is, Ive seen shafts were at least half the spline was cut into. The only way I know of fixing it is to change the shaft. If it were me I would just carry on riding the bike but keep an eye on it.

[guest27]

Hi there
I have had a bike with a sproket welded to the shaft - DT250, full fresco etc - and it was OK until you needed to change the sprocket... (The threads had sheared BTW) - I would try to avoid doing it unless you really have to.

R

[peterj]

When I was buying a new sprocket for my SRX a little while ago, I couldn't get an SRX one off the shelf. Instead I was offered two choices of compatable XT parts. One, like the SRX, had extra thickness (depth?) at the splines, whilst the other didn't. If your 350 has the thin one, perhaps an SRX type would help?

[ken]

Do you have room to get two or even three good sprockets and machine the teeth from one and weld together so as to share the load on the splines.

Ken

[trophydave]

Trawling the internet reveals that a JT 575 sprocket as fitted to an SRX600 or XT600 Tenere should fit(my XT350 has a 520 chain conversion to further confuse things)This has a shoulder on the back and is a couple of mm thicker.I was hoping for a bit more so grinding up a spare sprocket may be the answer.I shall get the cover off again over the weekend and get the measuring stick out to see just how much 'good' shaft is available.

[peterj]

Just had another thought. The sprocket on my old Rickman Honda CB750 was shifted from it's original position in order to line up the chain. Instead of the normal retainer, the shaft was trimmed short and an M8 hole drilled and tapped down the centre of the shaft. A retainer plate was bolted to the sprocket, and also bolted firmly to the end of the shaft (if that makes any sort of sense).

You may be able to do something similar? This would at least take all the wobble out of it.

[trophydave]

Success,for now at least.I took my spare worn sprocket and ground the teeth off.This went onto the shaft followed by the good sprocket then the locking plate.Bolted them all together and they sit nicely on the shaft.I took the bike for it's maiden voyage and all appears well.I suspect the gearing to be a bit out as it will only pull 75mph at 6000rpm in top,but for plonking about the lanes on it seems fine.