Waste Not, Want Not

In Part 51 of the Beck TD saga, I told about the start of a big experiment: rebuilding a locked-up, rusty M41 overdrive transmission. That is progressing pretty well, but I took an interesting side trip the past couple of days. In the last post, I didn't mention that in addition to the rust and bad bearings, the M41 transmission had taken a hard hit at some point - so hard that the "remote shifter" had broken in two! In the photo below, the top part shows the remote shifter currently in Beck TD, and the lower part the pieces of the broken shifter tail from the M41. The hit was so hard that the heavy shaft inside was bent as well, and the top of the shifter plate was bowed.

When I first got Beck, it actually had what I called a "tractor shifter" from an earlier Volvo:

Way back in Part 13, I detailed the work to adapt the remote shifter to Beck's body. Prior owner Mark had disclosed when I bought Beck that the tractor shifter had serious problems. In Part 13, I showed this photo of what I discovered: the shift plate had broken in two at some point. It had been repaired by welding, and later the weld warped to the point that the plate was binding on the two mounting pins.

At the time of that post, I didn't know enough to understand that there was another problem. There should be a big spring in the hole at the top of the shifter plate, stretching over to the edge of the cover. That spring is what makes the shifter feel like a shifter!

Pondering the ruined remote shifter from the M41, I wondered if I could resurrect the tractor shifter with salvaged parts. The shifter plates were identical. In the composite photo below, I circled the welds top and bottom. It's hard to see, but there is a definite warp there.

Those parts were easy to swap, and I went to install the spring. That was the second surprise - it would immediately pop back out. The hole in the cover was worn so badly, the spring wouldn't stay seated. Well, having come this far, I wasn't about to give up. Troy Nace and I disassembled the tractor shifter so I could fit it in the vise on my milling machine. Then I drilled 1/8" to erase the worn hole.

I installed a 1/8" brass pin, "welding" it in place with high strength Loctite:

After the Loctite cured a bit, I used a 3/16" end mill to level the pin with the cover:

I measured the wire size of the spring, and got 0.0665". I chose the next drill size up - a #50 drill bit at 0.0700". I drilled 0.250" deep for the spring pin. It fit perfectly - success!

The tractor shifter has a badly modified shift lever, so it's not really appropriate for use in a car. However, I'm very happy to have it for use as my "shop shifter." When the point comes when I can test the rebuilt M41 overdrive trans in the test fixture described in Part 49, I'll have a shifter to use while testing. In addition, the remaining cover from the M41 trans will be useful in determining if I got the switch tabs installed in the right place as described in Part 51. Good stuff!

UPDATE: look at the photo above again. I'm missing two very important things, and it rendered this post not as good as I thought. I took it out of the Beck TD chain, but left it for completeness. The first thing missing is a big piston that provides the reverse lockout feature. The second thing is that this plate is so old, it doesn't include the cast-in "bosses" to provide room for threads for the overdrive switch. Still an engaging project, but it turned out not to be a useful one!