MTFCA Forum

The shiftlock assembly on my TT will not keep the Ruckstell in underdrive. When driving in Ruckstell underdrive the Ruckstell slips into neutral. When I removed the shiftlock assembly I found that the piece with the chisel edge that is supposed to be on one side or the other of the yoke is backed out and pushed into the piece it is supposed to be on one side or the other of. (Sorry, I don't know the correct terminology for all these parts) If you look at the pictures I think you can see the problem.

I hit the chisel edge piece with a screwdriver and it popped to one side of the piece it is supposed to be on one side of, its correct position. I re-installed it and did a test drive shifting back and forth from underdrive to drive. After about ten shifts it crossed up again.

Is this reparable?

Sounds like either the ring or plunger or both are excessively worn, and/or the plunger spring is too weak.

Contact Chaffin's Garage for good replacements.

Thanks, I sent them the pictures and asked if they had the parts.

They replied to my email quickly, they need more pictures, I hope I sent them what they need. The plunger and where it engages look sharp to me, so probably the spring is weak?

I agree, your plunger and notch ring parts look pretty good to me, but the folks at Chaffin's have much more experience in such things.

The notch ring has a groove worn in the center of it. That looks to be what is kicking the plunger diagonally.

Does not look like wear to me, looks like a piece is broke out but could still be the problem. I would suggest maybe cleaning up the edge, but I am sure the piece is hardened so don't think a file will touch it much. How are the pins it rotates on and holes they fit into?

I think Stan Howe has a really good thread in one of the older forums on rebuilding the Ruxtell shiftlock assembly with pics. I used it as a guide for working on my TT. I do know that if the screwed in plug isn’t in far enough it won’t stay engaged and if too far will not let you shift it. -Matt

It rotates freely, and there is no slop in the pins. Here are more pictures of the edge in question. It looks like some wear to me, but not a chip broken out.

This is an older shift lock and does not have the "screwed in plug".

I searched for Stan's old thread, but couldn't find it. In any case, if I remembered correctly, Stan's thread was for the newer, long-nose shift lock, not the simpler, short version you (and I) have.

If Chaffin's suggests replacing the pivot ring, I would do it and see if it fixes your problem. The pins that hold the ring to the shift lever were only a light press fit on my unit.

The wear mark on the ring has what appears to be about the same angle as the plunger when it was cocked diagonally in your first few photos. It looks like the wear mark is probably also about as wide as the side-to-side play that the ring has in the yoke. This groove may be a symptom and not the cause of the problem but the presence of it is what eventually kicks the plunger on an angle when shifting.