Contour Enthusiasts Group Archives Forums Modifications Transaxle Shift tower mod (56K slow)

Well, since it is obvious that shift tower bolts will still continue to shear and possibly make a mess of the transmission I decided to make it safer and while I was at it I eliminated some play in the shifter.

I made a wire safety for the shift tower bolt so if it does shear it won't drop down into the trans and blow the diff out the side of the case....should I be that unlucky. I used good steel wire for this safety, a piece of mig welding wire is what I used. I drilled the bolt head across the top with a 1/16" bit. Then I looped the wire through, twisted it up and then looped the ends around the shaft above the bolt head. If the head shears off then the bolt will hang in relatively the same place. Took about 5 minutes to slowly drill through the bolt head using oil and slow drill speed. Don't worry, the metal was not that hard and in the case of the bolt it was soft inside the head. Probably why they shear so easy!

I also did a little work on the plastic bushings on the shifter pins in the top of the towers. They ride in the actuators and as they wear down can permit a significant amount of shifter slop 'play' as they do. I mic'd both of them and measured the slot that they fit into and one was more worn than the other of course. I cleaned them well and took some JB Weld epoxy and coated a thin layer on the sides of the plastic thust bushing, the sides where it makes contact with the metal slots.
After it cured (next day) I used a fine sand paper on a flat surface and started sanding down the two sides of the bushing until the thickness approached that of the slot that the bushing rides into. It only took 5 minutes so this is not a hard modification and I think it will be well worth it. I mic'd them again and as soon as the new thickness was around the width of the slot I switched to a fine sandpaper (600 grit from 220). I then sanded until it fit into the slot smoothly but with no play.
When that was complete I greased them both up and popped them back on the balls of the pivots in the slots.
Be carefull not to mix the two up as the slots may not be the same thickness and the plastic bushings will have correspondingly different thicknesses as well. It was in my case anyway. Ok, with that back together and some grease there was almost no movement in the shift tower actuation levers.

THere was a little slop in the pin connection on the outside where the cable end plugged onto it. This is the lever with the big weight on it. I unbolted that and checked out the pin. It is supposed to be press fit in there but mine has some decent slop on it from the years and would have a little bit of left to right deflection as well as spin in its bore. I placed an old socket on the floor then set the lever on the socket so that the pin fit in the socket and I had clear access to the back side of the pin where it was pressed into the lever. Then I took a ball peen hammer and treated it like a rivet, mushrooming the back of the pin a bit with multiple small blows until it was tight again.

These mods took out all the play in the shift tower and it feels extremely tight and precise now. Like New as they say.

Here are some pictures:
Safety wire


pivot bushings

very nice, i will be doing these things when i build my trans.

one question...is it not possible to replace the bolt that comonly shears with one of a higher grade?

Yes you can get better bolts. I'd recommend at least a hardness of 10.9 or better. If you have the money have a machine shop mill one out of quality steel or maybe even a threaded stud and a self locking nut to go on it. There are some very high grade bolts/studs available like the kind they use on cylinder heads.

have you got spect on the bolt warmonger??

overall length, diameter, tpi??

No. I didn't remove it, I only secured it.
I think it is a 8.9 hardness bolt...it is stamped on the head. It really appears to be a standard bolt, probably 8mm diameter by 1.5mm thread but that is a guess based on the head size.

M7x1.0, grade 10,9 actually.

Well, I don't know about the bolt in your shift tower, but there is no way mine was 10.9 harness. I punched a hole through it with a 1/16" bit very easily. Thanks for posting what you found in yours.