Tranny Linkage for TH350

I am using a 1980 GMC Van's column shift steering column. I've cut it down to fit and detailed the install on this webpage Steering Column. I was worried about making the shift linkage from the column to the Turbo 350 tranny. I was using the 76 Camaro linkage as an example and it required a hole drilled in the side of the frame, some spring supports and very strange brackets.

76 Camaro linkage

76 Camaro's tranny linkage - complicated tranny bracket on left, column shifter rod facing down, frame spring assembly on right

I straightened out one of the 54's shift linkage rods and hooked it to the steering column shifter. I had to determine the distance that the shift linkage rod moves from the Park position to the "1" gear position in the PRND21 on the steering column shift indicator. I put the shifter in Park, measured the distance from the floor to the bottom of the rod. I put the shifter in "1" gear which is the other end of the shifter movement range and again measured the distance from the rod to the floor. The distance that I came up with 2.5" of movement at the steering column.

Simple tranny linkage

Simple T350 tranny linkage for 54 Pontiac

rod bracket

Tranny rod bracket

I measured (eyeballed) the angle that the shift linkage at the tranny arcs through and felt it was pretty close to 90 degrees. A little bit of geometry and I figured that I would need a shift arm of about 2.25" in length center to center from the rod to the tranny swivel.

I found some 1"x1/8" flat stock and cut a chunk out. I bent it into a Z shape so that the arm and rod bracket would clear the tranny. The tranny bolt has a rectangular hole for positive positioning of the tranny swivel. The rod end uses a rod bracket that was from the 76 Camaro. The rod bracket locks the rod in place with a mounting bolt. The rod bracket floats in the tranny swivel hole by a spring that allows some movement of the linkage. I installed everything and found out that there wasn't enough movement at the tranny end - the center to center spacing was too short.

brackets

Tranny shift lever - Note rectangular hole for tranny bolt

The angle of the tranny swivel was not very good either. The swivel was pointing almost straight up in the Park position and was aligned vertically with the linkage rod. This was very poor geometry and had the potential of jamming the tranny in the Park position.

lever connected

Tranny shift lever connected

I re-measured everything and came up with 2.75" center to center spacing. Built another tranny swivel with the rectangular hole aligned horizontally with the bracket. Hooked everything up and it worked perfectly. Park was where it was supposed to be, and so was the "1" gear position. The geometry worked fine and the tranny and linkage shifted smoothly with no binding.

All in all, it went very smoothly, was simple to make and a lot easier than I expected. This is something that anyone with marginal skills can do in a couple of hours.

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Copyright July, 2011 Eugene Blanchard