Another Take on Solid Shift Linkage

[Ajzride]

I've thought about starting this thread about 4 times over the last two weeks, but every time I'm about to get started, I get another idea to think over. Back when I first got the car I hooked up the FFR shifter and the supplied cables, and tested it out to see how I liked it.


At the very top I want to put two disclaimers,

I understand that when setup properly there is nothing wrong with cable shift mechanisms, my reasons for going to linkage have to do with my desired path being too close to the exhaust to cables without risk of melting them

I have no idea what I'm doing so please let me know if I'm about to royally screw something up or make a decision I will regret.

When I put the transmission i first and then the shifter floated back to neutral (with the trans still in gear), I knew things would be rough. I also couldn't shift from 2nd to third, because I kept blowing past neutral back into first. After that I ordered a MR2 shifter and have been planning to use it with a zero decibel bell crank. However once I got to looking at how everyone routed their cables with the MR2 shifter, I realized that I wouldn't be happy with having cables inside the vehicle, I just can't make a tight enough radius with them to keep the linkage tucked away like I want. Once I realized that, I started looking at what others had done to eliminate cables. I really thought I was going to go the route of Art and use linkage inside the cabin and then convert over to cables once I got outside the cabin. Many thanks to Art for posting very specific details on his linkage. Although I'm going a slightly different path from Art, his design plans have really inspired me to where I am now. The reason I've decided to go a slightly different route than Art is because I don't really have enough room on the outside of my fuel tank to send the linkage out of. At this point Im really wishing I had pulled a Bob and put my fuel tank up front because then I would have tons more room for shift linkage and wiring on the rear firewall, plus a better weight distribution, but I've already got tons of parts that I've bought and won't be using, and the Boyd's tank would be a really expensive thing to add to that list (plus I would have to re-plumb my fuel system).

What i ultimately decided to do was go under the fuel tank and put my jackshaft against the rear firewall on the outside. To accomplish this I either had to go under the car, or raise the fuel tank up. I think going under the car and having my shift linkage as the lowest thing on the vehicle would be a recipe for disaster, one decent speed bump and I might be stuck in whatever gear I was in when I hit it. When I looked at raising up the fuel tank, lifting is a 1"n was very easy to do, but lifting it 2-2.5" was gong to start to eat into my ECU space, as well as impact seating position. I decided to stick with a 1" lift and that meant sending my linkage through the frame. The frame at that point is 1.5" square tube, and it's part of a 3 piece triangulated section on the rear wall. Based on how it is setup, I probably would have been fine just drilling some holes in it, but I decided to insert 1" square tubing through it and weld it in to minimize the impact to the structural support.

Passthrough from Inside.jpg

Passthrough from outside.jpg


Once i had decided to put the jackshaft in the engine bay I got to looking at routing. The shortest path with the least amount of interference is actually to go right up under the engine mounts (there is a nice little hole that you could right through), but this gets really close to the exhaust, and would probably cook any cables that I were to have there. That is when I decided to go solid linkage all the way. And when I started looking at how it could route, I decided I could really simply both my bell-crank and my jackshaft if I routed it down both sides of the transmission, with one set of linkage on the passengers side to rotate the arm to select 1/2-3/4-5/R and another set of linkage on the drivers side to push the arm in and out to select 1/3/5-N-2/4/R.

This presented another complication. Based on how the Arm on the back of the transmission is placed way at the drivers side, I really wanted the rotational linkage on the passenger side and the in and out linkage on the drivers side, but the MR2 shifter has the connections reversed. Since I needed to flip the front-back action anyone (since I was running down the opposite side), I knew I could put a pivot point inside the tunnel that would provide the flip and also move the linkage to the other side, I was just worried about space, so I did a 3D model to make sure it would all fit, and while it is tight, it does fit:

MR2 Shifter 3D Cad.jpg

The next thing I did was put my shifter back together, because I had disassembled it to powder coat it.

Shifter Exploded.jpg

Next I put it in the car along with my seat to determine where I wanted it to be located front to back, and that is when I realized that the base for the shifter was so huge it was going to get in the way of my linkage and really eat into the space I needed for mechanisms. I thought about order a zero-decibel kit, but it's an awfully nice (and expensive) piece to have hidden away under a console, so I fabricated one out of 3/16 flat bar.

Shifter Plate.jpg

Next I fabricated up the mechanism to flip the rotational linkage and move it from the drivers side to the passenger side:

MR2 Crossover.jpg

It worked beautifully, but it just looked really complicated, and even more crowded than my 3D model had shown it would be, so I started to worry. This is where I put up for the night and tried to sleep on it, except I couldn't sleep on it and got insomnia thinking about it. I eventually decided that I didn't like the MR2 shifter for two reasons

A) The required crossover to flip the rotational linkage from drivers to passenger side
B) The linkage hooks up on top rather than on bottom, Which means my console will have to be much taller to hid it, and leave less room for cupholders.

I decided I needed to find a shifter that exited out the bottom, and also had the rotational linkage on the passengers side. It turns out Art has fabricated exactly what I need, and all I needed to do is copy is work.... except I'm about 1/100 the machinist Art is, and i would spend more on tools needed to make his shifter than it would cost me to sub it out to a machine shop. So while I may eventually pay someone to make me a shifter, I decided to try and make do with what I have for now. The stock FFR shifter has bottom exit attachment points, however the linkage on the drivers side, but it also has front exit cables. If I turn it around, I will have rear exit cables and the linkage on the passenger side, that seems pretty good to me. So I decided to see how I could make that work. By turning the shifter around, the levers now move backwards from what you need, that works out just fine for me on the drivers side because I wanted to use a inversion bell-crank anyway because it should give me better leverage on the in and out motion, the passenger side though, was going to be backwards for me because I was no longer using a pivot point on the inside to move the cable from top to bottom. I could always put a small pivot point inside the console just to flip it, without really moving it up or down, but I'm not sure how much tension that would add to the system. I'm going to try and do my inversion at the jack-shaft. I've sketched up both linkages for visualization to make sure I'm not getting something backwards.

DRIVERS SIDE
Drivers Side Linkage.jpg

PASSENGERS SIDE
Passenger Side Linkage.jpg

I also tabbed up a mounting spot for the shifter, it will be mounted 1" off the bottom of the floor, this works really well with my seat eight, and gives me a good angle on my linkage:

FFR Fliped-Top.jpg

FFR Flipped-Side.jpg

And that is where I am at now. I need to figure out how to get the FFR shifter apart so I can have the shaft pressed out and flipped 180 degrees so that it is angled a little better, but the truth is it would probably be find just like it is since I have it set so low and far back.


What I will work on next is determining how to fabricate my linkage and jack-shaft. I have some 1/2" EMT that I would like to use as linkage, as it is light and strong, but I'm not positive on how I can attach heim joints to it. I'm thinking about pressing in some 1/2" rod and tapping the rod, but I'm open to other ideas on linkage material or how to attach the heim joints. I also have to think about the jack-shafts. Making them will be pretty easy since I won't have an inner and an outer like Art, just an inner, but I need bearings. I have some Delrin but I'm not sure it will hold up that close to the exhaust, I may need to find some brass.