I am reposting this out of my build thread. Someone suggested that I put this up there for those not following that project. Some of you could benefit from these.
Let's talk about shifting. I am running a 911/01 transmission mated to a 915 shifter that has had the guts rearranged. Basically, I flipped everything around so the R lockout was left-forward rather than right-rearward. I think added a Seine Gate shift and all was good. Except, when it wasn't and I kept nicking R on the 1-2 shift.
I tried everything and the reality was, the center of the gate shift was more precise than the rest of the linkage all the way down the line. The shift coupler already had the bronze bushings installed. That is not the culprit. The only place in the shifter assembly was the shift rod support.
in my opinion the shift rod support bushing is a weak spot in the system. Improvements are available for the shifter assembly and universal joint couplers are available. The two combined can nearly take all the play out of a 911 shifter. Except for the one weak spot right in the middle. So I fixed it.
I have been throwing this idea around for several years and finally put the effort to fix it. I made a new shift rod bushing. It is 30mm long, fits tight, made of modern, self-lubricating material and, fits in the stock location.
Here is a comparison of the new shift rod bushing compared to the stock bushing.
You can easily see the width. The external OD has a flange that mates to the forward edge of the stock bushing support bracket.
my new bushing is a press-fit into the bracket. The rear is secured with a circlip mating with a groove in the external surface.
What many don't realize is that the stock bushing has a radius along the inner surface and that minimizes the contact on the rod. There is a lot more play in the shift rod than most people realize. Once the new bushing is installed there is almost zero play. Just enough clearance to allow it so slide freely (front to rear and rotational) but without any of the off-axis play that plagues the stock bushing.
Here is a comparison of play between a new stock bushing (before) and an updated bushing.
After install there is a noticeable improvement in shifting quality. No more missed gear nicks. I am calling this the ultimate shift rod bushing.
An, while you are at the machine shop, might as well make some extras. I don't see myself replacing one anytime in the next 10 years or so. These are available if anyone sees the need. There are already a few supporting shift rods in the wild.
