Shifter Arms
 

Hi guys,
I recently picked up a 1997 fxsts (softail springer) and while out on ride I looked down and noticed that the shifter arm was walking its way off the splined shaft. I pulled over, tightened it up and got back on. It wasn't but a few minutes and it was doing it again. I have temporarily wrapped a stainless steel zip tie around it to keep in in place.
Fast forward to yesterday, I got on my 2016 ultra classic and the heel shifter fell off and I noticed that the toe shifter was walking off just like the springer.
The shaft has semi-circlular undercuts that the bolt is supposed to go through. How can these arms be walking off with the bolt still in them? I must be missing something basic!
Thanks in advance for any insight.

ETA add a pic of my zip tie fix on the springer.
https://cimg0.ibsrv.net/gimg/www.hdf...c07b6f7918.jpg

Not sure if I am completely getting it. But my mechanic friend showed me how I had a little wiggle in the arms that go on the splined shaft on my bike. So I bought a new arm. Those are things a self trained hack like me don't notice. But this is a guy who rides old bikes, and keeps them in great shape.

I bet if I look at my other bike, it probably wiggles too.

I can only comment on the 2016 touring OE shift arms. They shouldn't walk laterally unless the pinch bolt is completely removed due to bolt engagement in the shaft's semicircular groove. Are the 2016's arms aftermarket?

Barney, that's my understanding also which makes this even more puzzling.
I bought the bike used, but as far as I know both arms and OEM.

Some aftermarket shiters have the bolt holes just far enough out, or bolts just small enough that the bolt don't sit in the groove. You can try thread locker to keep pinch bolt from backing out or drill and tap a hole for a set screw that will be in the groove (I would thread lock this screw too). I lost both (aftermarket) heel and toe shifter levers on the interstate in Arkansas coming back from Tail of the Dragon last year... fortunately I had stock HD shifter levers in a saddle bag.

If the touring arms are OE, they will have a bar & shield embossed on the inboard side.
https://cimg8.ibsrv.net/gimg/www.hdf...13bbcc000b.jpg

Did you take the bolt fully out? There very well could be a grove worn in to it.

Another possibility is that it has the wrong bolt. Usually a lock bolt is only threaded at the end, not all the way up the shaft. It could also be the wrong size...

I think chopper_man nailed it. When you look closely, the bolt protrudes into the shaft undercut very little, maybe the depth of the thread. After pulling the bolt out I could see where one thread was flattened. This probably allowed the heel shifter to slide off.
My plan is to get a new bolt and try to find a plumbing washer to wrap around the bolt and get more material into the undercut. Don't know if this will work but it's a start.

Thanks to all who have chimed in!

PS: the arm has the Harley logo so it is OEM.

Do you 'bang' the gears when you shift? I have seen guys kick and stomp the hell out of those shift arms.