harleyKmodel

I am guessing that this is the speedometer drive. It does not appear to have any moving parts in it, so I am not sure how it works? Any insights would be appreciated. It's a 1956 KH. I had it out and cleaned it and put it back. Not much to it, just a partially rounded end inside. Like a button.

Thanks

If there is no gear on the end and the hole for the shaft is plugged there might be an issue inside-look deep inside the hole for a gear ? If there is a gear there a butcher must have got to your drive unit for some dumb reason ?

most likely the worm gear was cut off and the hole was plugged to eliminate the threat to the cases from a broken gear check the end of the unit this is a common remedy my '57 is done this way

You mean like this?

Yep like I said plugged look inside the hole to see if there is a gear if not the inner shaft bearing I bet has a reinforcement ring around it blocking off the hole for the drive gear so it was left out.

speedometer drives are the #1 killer of engine cases

Inner bearing housings fail also that is why a lot of them were ringed for added support and when ringed the speedometer gear has to be left out. If there is no gear at the end of that hole that might be what some one did.

How does the drive cause problems? It just rides off first gear. I always figured it blowing out was just collateral damage after the weak bearing boss breaks off because it is only supported on one end. Than the gear set stacks and boom go the cases. If not stock app I always weld a support plate to keep the boss from being able to break off from abuse, or time. Low gear is right there at the bearing boss in trans, waiting to break it off after a hammer drop. Etc. A lot of torque is on that. Early K transmissions were very weak
The gears were updated and grossly improved in steel type and method of production almost every year til 58

Bearing failure definitely would lead to mi alignment of gears and destruction. As would failed gear or shaft...

the worm gear can break off it gets caught between the first gears and separates the shafts breaking the right case