Watty82

Really appreciate all the info Peter. I'll dremel the notches into the end of the primary shaft. The bearing that the primary shaft slots into doesn't seem to have a circlip holding it in place, I thought it was supposed to have one. I'm very interested in doing the gearbox plate idler gear mod with a Delrin bushing, although I'll get the bike back together and see how it rides first. Both the cam follower return spring and selector shaft position spring seem in good condition, so I'll try to fine tune the eccentric adjuster. I haven't had a trials bike in over 20 years so I'm really exited about getting out on this beast. I've been riding enduro but the trails in Finland are really technical so I think a trials bike would be way more suitable. So I'll be restoring the Ossa ready for Spring. Thanks again, Matt.

Thanks for that Peter. I finally got the gearbox out using an expansion bolt and slide hammer. It didn't take that much force in the end, just alternating hits between the output shaft and clutch shaft. Luckily the gears all seem OK except some slight wear on the idler gear. The selector drum notch for neutral seems really wore, maybe this is the reason for dropping into gear. I was thinking of machining the notch a little more to help keep in neutral. The two bearings inside the engine casing seem a bit gritty so might replace them and install a clutch fixer rod at the same time. Are they pretty standard bearings? I will probably also drill an oil hole in the gearbox plate to help oil draining. Both the output shaft and clutch shaft seem a bit loose (side to side movement), is this normal? because it seems like a big job to replace those bearings. Is there any other mods that I should do whilst the gearbox is out? Thanks for all the help, Matt.

That's a good idea, I'll give it a try if I can't find the right sized expansion bolt. Maybe the shaft has been loctited in place, I'll report back when or if I eventually remove the gearbox.

Cheers for all the input, thanks for the link but I've already been through it several times and I haven't missed anything. I'll try to find a suitable expansion bolt from work tomorrow to fit in the clutch shaft. Then make some kind of slide hammer from it which will hopefully work to dislodge it.

Thanks for the replies. I wish there was supposed to be 6 nuts. The only circlip on the countershaft was to remove the sprocket. When I tap the countershaft with a rubber mallet it seems like the countershaft moves and isn't the problem. It seems more like the clutch shaft is stuck, almost like it has a fixer nut although it definitely doesn't. Could it be that the clutch shaft has some how stuck to the bearing in the crank casing. So when I hit the countershaft it twist the gearbox. Somebody must have experienced this problem before.

Yes definitely no fixer rod, I can see straight though to the breather. I'm wondering if the clutch shaft could be somehow stuck in the bearing. I might try a large expansion bolt in the clutch shaft so I can pull from there.

Hi, I recently bought a 2011 tr280i. The bike looks in good condition but seems to shift into gear by itself while the engine is running. So I'm trying to pull the gearbox out to inspect. I got the five bolts out and have it in gear but it just doesn't seem to move with a tap on the output shaft. It seems like the clutch shaft is jammed somehow. It doesn't have a clutch fixer nut because it's 2011 so I really need some advice of how to remove it. Cheers.