gasgas4life Posted January 12, 2010 Report Share Posted January 12, 2010 (edited) A few weeks ago my chain jumped off the sprocket at high revs, the bike stopped immediately and also damaged the 3rd gear within the gearbox. We split the engine and found that 3rd gear (gear pinion 3EME. Part no. = MO59) had two teath broken off! we ordered the new gear and fitted it but we discovered that once the gearbox was put back together we were unable to select 3rd gear. It would go through 1st, neutral and 2nd fine but would get stuck half way trying to get into 3rd. Stripped gearbox again but couldn't find anything wrong! Scratched our heads a few times and percivered by taking 3rd gear out completely and just having 1st and 2nd! I have now been running with only 1st and 2nd for a couple of weeks mainly to compete in important trials late in december! Have now stripped the engine once again to find the reason of this problem. After looking at it again we narrowed it down to the 'free pinion gear' part no. = MO58 having rotated on its bronze bush that sits on the shaft. this has made it impossible for the other gear below to interlock with it. After we noticed this we rotated the 'free pinion gear' (MO58)that was very tight on the bush (MO67) so that it locks into this adjacent gear. Once we done this it went up and down the gearbox normally! Since we done this the gear has moved again so 3rd cannot be selected anymore. The gear (MO59) that was originaly broken in the gearbox locks into the gear on the bush (MO58) so where they met at contact it would have dislodged or damaged the bush? We were just wondering whether this gear (MO58) is surpose to be free wheeling on this bush or fixed in the right position for the other gear to lock into it? Hope it makes sense and thanks for your replies! EDIT: Forgot to attach link to the sherco parts book! - http://www.sherco.com/spare_parts/2009/200...ok_trial-2T.pdf I think its something like page 14. This problem is concerning gears 8 and 9, basically gear 12 isn't interlocking with gear 8. Edited January 13, 2010 by gasgas4life Quote Link to comment Share on other sites More sharing options...
tony27 Posted January 13, 2010 Report Share Posted January 13, 2010 Can't quite remember how that piece goes but seeing as it has a circlip either side holding it in position it possibly is meant to rotate on the bush. The diagram in the parts book supports that theory as well, the other shaft has a sliding gear(M059) that lines up with this one From memory the reason for the circlips etc is to allow the next pinion(M060) to be fitted to the shaft My guess would be that the bush has picked up in the pinion, get it out & look to see if it's been loctited in or whether it has a scuffed/ripped area Other thing to ask is are you 100% sure that a shift fork is not bent & everything is assembled correctly, I managed to put a washer(M071) on the wrong side of a bearing which took up some clearance allowing the box to try selecting a gear when lent to the left in neutral If you're not absolutely sure on how things should be I'd suggest contacting chris at splatshop as he was a great help for me Hope this helps out Quote Link to comment Share on other sites More sharing options...
gasgas4life Posted January 13, 2010 Author Report Share Posted January 13, 2010 We did think that it was surpose to rotate but wasn't totally sure. We have assembled it all to how the manual descrides it and have also taken it down to our local dealer for them to look at and they were fine with it too. We have ordered new gear, shaft and bush so when it arrives we can see whether it free wheels or not. Quote Link to comment Share on other sites More sharing options...
trialsnutterman Posted January 13, 2010 Report Share Posted January 13, 2010 Yes it should spin freely, the gear is in constant mesh with gear number 9 on the diagram so unless you where in 3rd gear it would be spinning relative to the output shaft so with it being tight it is going cause problems. Are you sure you got the broken teeth out of the gear box maybe one is jammed in the selector drum. Quote Link to comment Share on other sites More sharing options...
gasgas4life Posted January 13, 2010 Author Report Share Posted January 13, 2010 Yes we found both teeth lieing in the bottom, they had been snapped clean off so wasn't any small lose bits about. Still cleaned it all out with oil though! Thanks you for input guys! Quote Link to comment Share on other sites More sharing options...
copemech Posted January 14, 2010 Report Share Posted January 14, 2010 (edited) Without having one in front of me, I am daft! Yet fact is in these things you got your sliders and your spinners. Each must operate freely. Add the fixed gears. If this thing took such a shock it broke a gear, the opposing gear(s) may be damaged as well, all is suspect including the shaft which could be distorted or bent from the major bind-up. Everything should rotate freely. As this incident was not caused by a crash(cram) situation, I doubt the forks or drum would be damaged. Sounds as thou you are on the right track. Which is the culprit? not sure? Personally, I cannot ever recall any reports of this happening, althouh not impossible, you do indeed seem to be the lucky one! The only positive thing about this situation is the fact that in such a case, the motors doo indeed seem to come apart much easier. Been there and don that! Keep us posted and cheers on you, Edited January 15, 2010 by copemech Quote Link to comment Share on other sites More sharing options...
gasgas4life Posted January 16, 2010 Author Report Share Posted January 16, 2010 Wahoo! All sorted now! Went up and down the gears fine when i tested it today. You were all right - that gear was surpose to spin because the new gear span on the bush fine. It must have taken a big knock to move that bush but luckily the shaft was in good condition. Could have been worse i surpose! Thanks again for your input, helped alot Quote Link to comment Share on other sites More sharing options...
copemech Posted January 17, 2010 Report Share Posted January 17, 2010 Wahoo! All sorted now! Went up and down the gears fine when i tested it today.You were all right - that gear was surpose to spin because the new gear span on the bush fine. It must have taken a big knock to move that bush but luckily the shaft was in good condition. Could have been worse i surpose! Thanks again for your input, helped alot Good on you as you have it fixed now! Glad to get the report as this is a unusual situation. Thank you as well for your input! Good job man! Quote Link to comment Share on other sites More sharing options...
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