Shifter continually coming loose on the shaft. Is there a trick to it?

[Kenneth S (222)]

Hi Guys,
I have been battling with the shifters on the two bikes I am racing at the moment, the 84 CR250 and the 89 CR250. I continue to have the issue of the shifters getting sloppy on the shaft. Each time I prepare the bikes, I tighten the bolts just that little bit more to within an inch of stripping the thread, but by the time I get the bikes home after a race day they are dancing around again. On the 89 I bought an OEM shifter from Honda for $100 and while it was a nice snug fit when I fitted it, within a few race meetings it is doing the same. I know fitting a steel shifter will help but I would prefer not to have to go that way. Is there a fix for this I don't know about?
Cheers,
Kenneth

[OverTheHill]

You won't like my fix on my 'rat bike' 360 yam but here goes anyway. If all else fails because the splines on the shaft have tapered off on the outer half past the locating groove for the pinch bolt i've drilled straight in [not crossways but straight in] as the lever pinches up. You end up with half the hole in the shaft & half in the lever. Drill in the depth of the lever plus a fraction, which about equals the depth of the shaft spline before the splines end, then tap it to 6mm thread & screw an allen head bolt in which are real high tensile. I dare say you're talking an ally gear lever & i'm talking steel so the drill might wander of to the ally side. Fit a steel lever & do 'that' maybe. That'll start the ball rolling but realy a new shaft & lever are the final cure. One more back yard mechanic thought--won't be a safe enough amount of shaft but thinking drill straight in dead center & tap it to maybe 5mm allen bolt & a bog washer to stop creeping outwards. in the gear lever i use a high tensile 6mm bolt with a spring washer under the head which allows [reluctantly] a slight bend as it's finaly tightened. Mainly talking my old stuffed steel levers as having been slotted wider they pinch up on an angle & end up bending the bolt a little [or trying too]. Found some 6mm bolts with number 10 strength on the head out of my honda car motor, strong 'as'. Anyway--carry on. long essay about not much. Cheers.

[80-85 husky]

sounds like the alloy threads are stretching or the bolt is loosening. I have assumed you are loctiting the bolt.

also check the shifter isn't closing on it self and not clamping the shaft tightly, you may have to take a thin slice out of the inside of the shifter to allow it to clamp tighter on the shaft.

you could also drill the threaded section out and put a longer allen bolt and a nylock nut on the outside with locktite on, that will fix it.

these arnt pretty fixes, but have solved those issues for me

[fireyglen]

The first thing that comes to mind is try loctight on the shaft.the other old cure was to put the lever in a vice and run a hacksaw through the split opening to increase the gap to give you more adjustment when tightening up.

[Andrew L]

Leave the thread in the lever , put a longer bolt in and tighten it up until the lever is as it should be , then use a nylock nut as a locking nut on the protruding thread of the new bolt , has worked for me before and your lever isn't modified either.

[shelpi]

every time this has happened to me I found that putting it in the vice clamp it shut run a hacksaw through it worked every time

[evo550]

Sounds to me like your shaft spline is cactus. Replace the shaft AND gear lever with new.......or weld it

[Kenneth S (222)]

Thanks guys, that gives me a few good ideas to try out

[pokey]

i wouldnt go to the extremes of above just yet. remove it and clean it and the splines spotless. run a wire brush over the splines to remove all the gunk that will be in them . then a small tap with a hammer on the lever to close it up just a little so its a damn tight fit on the shaft. A few "gentle taps will have it seated. do the bolt up and thats all you need do unless the shaft is worn . incidentally they only wear if they are loose and grime gets in 

[GMC]

As others have said, check the gap in the shifter to make sure its not closed up before it's tight on the shaft.
I also run a longer bolt with a nut as backup but also use a high tensile bolt as a normal mild steel bolt can stretch.
If adding a nut onto the back of the thread make sure it has a flat spot to sit on to.

[shelpi]

i wouldnt go to the extremes of above just yet. remove it and clean it and the splines spotless. run a wire brush over the splines to remove all the gunk that will be in them . then a small tap with a hammer on the lever to close it up just a little so its a damn tight fit on the shaft. A few "gentle taps will have it seated. do the bolt up and thats all you need do unless the shaft is worn . incidentally they only wear if they are loose and grime gets in 

of coarse the hack saw treatment is only for good splines on both and is clean and you can see that its touching then it works well, if everything is fluct then replace everything, oh yer replace the bolt Ive seen them stretch before (you would think they would just snap)

[evo550]

If you have to crank the fcuk out of bolt on a new gear lever the shaft is rooted.
The depressions in the spline on the shaft should mirror the profile of the ridges on the spline on the gear lever. On a 30 year old shaft the depression on the spline widens due to back and forth motion of shifting up and down, so even with a new lever and a huge spanner to tighten the shit out of it there will still be side to side movement as the ridge on the spline on the lever rocks back and forth between the depressions on the shaft....

[Lozza]

I'm surprised nobody has suggested the bleedin obvious and to weld the gear lever onto the shaft 

[evo550]

Sounds to me like your shaft spline is cactus. Replace the shaft AND gear lever with new.......or weld it

I did   .......only because I've done it myself in the past.

[pecrazy]

Welding it on would be a last resort, personally hate buying bikes then realising it has welded splines.