Saw this on another forum. An interesting fix on the C1 gearbox. Starts about 10 boxes down.

Great fix if you've got a CNC lathe or similar gear turning device...

How about just making a new selector drum that moves the selector over a bit further, or make the gears thicker so the dogs engage a bit more??

MMMM very interesting, I haven't got any problems so far.I think the engine itself is bulletproof, it's the gearbox, but with this conversion it seems that the engine would be the same as an E model...

I would be worried about machining the gears tho'.

SO would I...

Arnt the gears macined and then case hardended.....Harder than a hard thing!

I did (almost the same thing) last year on a Suzuki gearbox (450LTR quad). Same problem to start with. Insufficient engagement of the dogs, strangely enough on 3rd gear as well. On the Suzuki there is a central boss which bears against the circlip. All we did was to turn off 2mm from the boss and add a 2mm thick washer on the other side. If anything it was more difficult to sort as the 450 LTR is a vertical split motor. The other related problem we had on this motor was the flat plate on the selector shaft prevented full selector movement. We just ground a bit more material out and it worked fine. The gearbox didn't last forever but that's not a surprise when you look at quad riders and the size of their boots
Edited to add: Machining was not a problem. Done in and old parallel lathe, dry (no suds). I believe that the gears are probably induction hardened, hence the bit we machined was soft(ish).

[Edited on 21/2/08 by MikeCapon]

hi try this page might help you out

www.ksrc-au.com/html/fixing_a_zx9r_gearbox.html

paul

[Edited on 21/2/08 by ch1ll1]

Good one that Ch1ll1 seems a lot easier that one. I've only got the gearbox left to go wrong now so I can't wait to do that now

can in handy when i did mine !

Unlucky mate. Out of interest did the rebuild go well and did you use an E model box like in the guide?