Improved shifting for side shifters, bolt on? Maybe., Experimenting tonight. Options

[Dr Evil]

I have had this though for a long time to try and remove as much slop as I can in the shifting system. The tail shifter is a bit trickier, but not impossible. I have a side shifter in my new 914 and so, while I build up a transmission for it to drive to Hershey this weekend (this will be the raffle transmission, BTW. Trial by fire!), I decided to see how simple it would be to remove some of the slop.

First, see how much of a gap there is between the shift selector comb and the rod.

This is a huge amount so any bit that can be removed should be an improvement.

Step one was to add material to the sides of the comb faces (Yes, Scotty, I welded). Then, I hand filed the faces and re-formed them to a specific profile. The metal that was added was hardened and a real bitch to file. I figured it was worth it.

The end result was a much tighter fit.


There are a few parameters that I will not go into that need to be respected to get this to work, but the preliminary results were nice on the bench. With the material added and profiled on the faces, the stick throw fore and aft to select gears decreases significantly. There is still refinement that needs to be done on the profile, but so far the preliminary results are encouraging.

Next, I will build a jig so I can directly observe and adjust my profile. And I will also be able to see where I can add material to take up the slack that one feels when they are in gear and can wiggle the stick back and forth.

Once I get this prototype done and tested, I can do this treatment to any side shift console on an exchange basis and it will be a quick bolt on improvement (I hope).
(IMG:style_emoticons/default/happy11.gif)

[Dr Evil]

Interesting. I wonder if that set up would benefit from my treatment. Having never driven a Ferrari, I am gonna have to rely on your description (IMG:style_emoticons/default/wink.gif)

My goal is to satisfy my need to tinker with possibly offering a fairly inexpensive solution for sloppy, stick-in-bucket, shifting.

Eric, you mention an interesting contrast that I can address. The direct rod 911 will never be all that great. The problem is in the box itself. I may mess with this in the future, but the best I can conceive of for an easy fix would only offer tighter fore and aft with retaining the sloppy side to side when in gear (no gated feel at all).

However, I am planning on trying another experiment once I move the lab. An interesting fact about the 914 shifters is how they evolved. The original tail shift had a ball in cup in the center tunnel. This made for a nice fulcrum right at the stick that could effect precise rotation of the tunnel shift rod. Not a bad design, actually. The problem lies in the end and inside the box. There is so much inherent slop once the rod gets connected to the box that it shifts like crap even when in good repair. The shifter mechanism is almost identical to the 911, but with one extra spot for even more slop. I will mess with this in the future, but have low expectations.

Fast forward to 1973 and the introduction of the side shifter. The part at the box was very good and I can easily address the short comings at this point. There is one contact point inside the box rather than 4 sloppy, non-bushed ones. The irony is that they changed the coupler at the stick shift to a clevis. Basically the revers of the tails shift; now good in back, meh in front. The reason I say that clevis is not all that great/precise is that to enact rotation of the internal shift rod the clevis moves the whole inner shift rod side to side. No pivot near the place of action. Now the pivot has been moved a few feet away at the firewall bushing. Inherent slop again.

I have been thinking of a way to put the pivot point close to the stick again. I could just make a rod that adapts the old style shifter to the new style tunnel rod and shift assembly, but then you would have a reversed pattern with left movement actually being toward 4-5 and visa versa. Been too busy to really do much thinking on this. On the original early cars the rotation of the shaft was reversed at the firewall via use of the pivot bolt/coupler to the external rod that hooks to the transmission. Not likely interested in back dating that much just to mess with the shifting. At that point I see no value and do not project any improvement over what is already out there.

So far, the little change I have made, plus a short shift kit, is a pretty cheap and easy solution with a big improvement for those who cant/dont want to shell out the $$ for one of the other systems. I would love to be able to do a head to head with people evaluating all the systems. I would just want to see where my improvement would fit in. So far, I have only driven cars with short shift, renn, and stock.

I am thinking that, as mentioned in a previous post, Renn + this little improvement may = shifting nirvana. (IMG:style_emoticons/default/wink.gif) Interestingly enough, my enhancement could be done to Chris's kit and might add further improvement. This is hypothesis, though. Chris is amply qualified to modify the shifter comb as I have done as he is a professional welder (IMG:style_emoticons/default/wink.gif)