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Thread: Another Take on Solid Shift Linkage

  1. #1
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    Another Take on Solid Shift Linkage

    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.
    Last edited by Ajzride; 11-18-2019 at 12:10 AM.

  2. #2
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    Made some really good progress yesterday, although it is moving slow.

    First I got the shifter apart (required me to destroy the push-nut, hope I can find another one in the right size) and had the shaft pressed out, rotated 180, and pressed back in by my local machine shop.

    Next I determined how to fabricate my actual linkage. I'm going to use the 1/2" EMT tubing that I have due to it's weight and strength. I found that you can stuff a piece of 5/8 steel rod down inside the tube if you put just a slight bevel on one end of the steel rod to help get it started, and then just flip it over and hammer the rod into the concrete. After I hammered the rod in, I tacked it a few times with the TIG to make sure it never comes out.

    After I figured out how it would go together, I cut 8 pieces of 5/8 steel rod into 1" lengths, and drilled a 17/64 hole which I can tap to accept the 5/16-24 rod ends I ordered from McCaster-Carr. I then fit 4 of them into one end of each of my four linkage pieces and tacked them in place. The other 4 pieces are still sitting on the bench because I will have to trim my 4 linkage pieces to fit after I get the rod ends installed and can make sure I get them setup to have maximum adjustment in both directions.

    Inserts.jpg

    LInkage End.jpg


    Making those 8 pieces of steel and tacking 4 of them in place took me almost 6 hours. That's the price of not having the appropriate tools for the job. To get nice straight square cuts of the steel rod I tried a cut-off wheel, bladerunner saw, dremel, side grinder, and reciprocating saw. The best results came from the reciprocating saw (which surprised me, I thought the bladerunner would work best, but the blade had too much deflection). As you can imagine, a reciprocating saw doesn't make very square cuts on round rods. I had to square up the rods with a belt sander. Then I was able to drill them on the drill press, but it's not the best drill press, and the bit has some deflection in it, so even though I was on a drill press with a vice, I still didn't get exact center and exactly straight every time. It will be more than adequate for using with 30 degree rod ends, but still kind of ugly, and if I had a lifetime collection of nice metal working tools, probably could have been done in an hour or two.

    I was also able to find the supplies for building the jackshaft. They will be made out of 1/2" steel rod with bronze bushings that i was able to pick up at the local ACE.

    Last night I was really ashamed of my 3D CAD skills as exhibited in my first concept drawing, so I for practice I started working out my current system, from the firewall back.

    IMG_0474.jpg

  3. #3
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    UPS showed up with some presents that arrived a few days early:

    Rod End.jpg

    With that I was able to move forwards with hooking pipe up to the shifter. First I had to modify the shifter to accept a tube, since it just had a ball on the end. I added a tab, but then it wouldn't fit through the hole into the plastic base, so I had to go back and smooth it out and add some curvature to get it to just sneak inside. It's not the idea shape for geometry, but it fits through the hole in the base.

    Shifter.jpg

    I also had to hack away huge sections of the plastic base, since it just had small tunnels for cable shifters to go through and now I wanted big swinging pipes. Even with so much plastic removed, it still feels very solid and doesn't flex at all.

    Now I have a geometry issue to resolve. I have it working, but I'm not sure I have the best solution, see video for explanation and please provide some advice on how to resolve. My current thoughts are to leave it like it is or run a smaller piece of linkage through the frame to allow for more movement.


  4. #4
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    I’ve got to rethink some things. I built the jack shaft today and it also has up and down movement due to its circular motion, and it causes more binding. I’ve either got to get rid of the circular motion or create more clearance.

  5. #5

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    Stick with it (pun intended)... I didn't build mine overnight. Got lots of ideas in my steel and aluminum parts scrap boxes. Four or five iterations are run of the mill and part of the fun.
    Art Quillen

  6. #6
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    Quote Originally Posted by aquillen View Post
    Stick with it (pun intended)... I didn't build mine overnight. Got lots of ideas in my steel and aluminum parts scrap boxes. Four or five iterations are run of the mill and part of the fun.
    Woke up at early this morning with ideas running through my head. If I use a bell crank instead of a jackshaft that would introduce side to side movement instead of up and down. Still movement that affects clearance, but now I have one end going up and down and the other side side, instead of both going up and down. This should allow me to split the clearance needed on two axis instead of 1, giving me more room to work.

  7. #7
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    A thought to consider.
    https://www.youtube.com/watch?v=Bz4a...oZiCk&index=62
    Ignore the blue shaft. Imagine the pivot point of the pink arm is your shifter ball joint. The yellow shaft is your fore/aft shaft. The slot in the pink arm converts the angular motion of the pivoting shifter to linear motion.

    You'll still need to account for the left/right motion needed in the fore/aft shaft when you move the shifter laterally. Perhaps a hoop-type constraint back at the vee where the underseat Xes intersect.

  8. #8
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    Quote Originally Posted by fletch View Post
    A thought to consider.
    https://www.youtube.com/watch?v=Bz4a...oZiCk&index=62
    Ignore the blue shaft. Imagine the pivot point of the pink arm is your shifter ball joint. The yellow shaft is your fore/aft shaft. The slot in the pink arm converts the angular motion of the pivoting shifter to linear motion.

    You'll still need to account for the left/right motion needed in the fore/aft shaft when you move the shifter laterally. Perhaps a hoop-type constraint back at the vee where the underseat Xes intersect.

    Thanks Fletch, I had the idea of slotted fitment at some point last night and it got lost in the jumble. This video is a nice job and gives me some good ideas to work off of.

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    I think I finally have something that is workable. It's proof of concept and ugly at the moment, but it shifts nicely and I can get it cleaned up.

    I did try a slotted attachment on the shifter like Fletch suggested, but it wasn't really moving much in the slot, and I began to think that maybe that wasn't my biggest problem. I finally realized that the bulk of my problem was coming in because the linkage was trying to go over the 1" square tube that makes up the seat attachment points, and then into the frame rail at the same height, and there wasn't enough length for the angle to work. So I filled one of the tubes up with sand and bent it on the vice into a z-bar with a 1.5" offset, and things magically freed up.

    At the moment I've eliminated the jackshaft in the engine bay and just have the two half connected solidly with a pice of 1" square tubing. I'm not sure if I'll put the jackshaft back, or come up with some cleaner solid linkage. Now that I repositioned the linkage in the engine bay from inside the the engine mount to right beside the oil pan, I only have about 2" of offset between the inside and outside shafts.

    My dad offered to help me out with this and bend up some 1/2" stainless tube at work to replace of the EMT I've been using. This will help relieve the binding even more because 1/2" stainless is 0.5 OD, while my EMT is 0.5" ID, I'll pick up 0.22" of clearance by swapping from EMT to stainless. The only downside is I'll have to wait until Christmas to pick it up from him. After Thanksgiving I'll try to get the passengers side bell crank worked out and then I'll move on to making a mount for my rear calipers while I wait on the stainless tubing from Dad.

    Offset Liknage.jpg

    Firewall LIknage.jpg

    Drivers Side Bellcrank.jpg


  10. #10
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    I can now successfully shift through 5 forward gears and reverse.

    I made two changes today:

    1) I added piece of 1" tube under the back two mounts for the shifter. It has previously been bolted directly to the floor pan, and it was flexing a bunch while shifting.
    2) I swapped from a 1-piece unit attached to the shift shaft on the transmission to a two piece, one for each side.

    I probably could have made a solid piece work for accepting input from both sides, but it took a lot of adjustment out having to make sure that both sides could twist and flex enough to handle the other. So now I have one ear that sticks off and picks up drivers side bell crank and another for the passenger side.

    Here is the shifter with the extra brace welded in:

    Shifter Brace.jpg

    Picture of both tubes routed to the firewall

    Twin Linkage.jpg

    Drver's side bell crank, I will replace the piece of one-inch square tube with a hex shaft coupler, on order already from McMcaster-Carr.

    Drivers Side Bellcrank.jpg

    Passenger's side bell crank. I'm going to replace the ACE hardware turnbuckle with a some heim-joint rod ends and a tapped piece of stainless tube, also on order already from McMcaster-Carr.

    Passengers Side Bellcrank.jpg

    And here is the actual attachment to the shifter shaft. I started with the FFR piece and hammered it flat, then fabricated a bar that bolted to it and picked up both bell cranks. Later I split the bar in half, so the one picking up the drivers side bell crank didn't have to rotate with the passengers side. Once I split the bar in half, I had to weld on the passengers side ear because there wasn't enough room for two bolts to prevent rotation. I have to clean this up big time on the belt sander and getting it looking nice.

    Rear Bellcrank.jpg

    Once all the new pieces are in and I"m sure I won't be making any more changes, all the steel pieces will get powder coated.

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  12. #11
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    Nice work. It's always interesting seeing the solutions people come up with. I took a very unique approach to shifting in the 818, almost finished with it and will post once its done.
    818R Build date 10/31/15

  13. #12
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    I don't suppose you figured out how to make it work hydraulically did you? I couldn't figure out a push-pull mechanism so I would only need two cylinders instead of 4.

  14. #13

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    I did build a complete set of master/slave cylinders using hydraulics. All industry type seal components, etc. Stiction problems were the main issue, followed by needing to go with larger lines than my initial plan - needed more fluid flow rate even though I made very small cylinders. Each cylinder was a dual (push & pull) design. I tabled all this after about 3 months of actual build time, which was preceeded by a couple years on and off researching and designing. My thinking now is get in the car and then (maybe) revisit the hydraulics later since it is still something I'd really like to get working.

    They worked great in regard to no slop and pretty much 100% motion tracking - as they should. But they would stick after sitting and took extra effort to break that "stiction" problem - very unpleasant feel overcoming that motion in the shift lever. They also just wouldn't move fast as it was taking too long to move fluid. I was using the brake lines similar to on the car. The ports on my cylinders were on 1/8" drilled holes. Definitely need larger ports and larger lines

    I also tested about 20 different fluids, most were hydraulic spec, but some others as well. Trying to beat the stiction problem mostly. None were a magic bullet.

    A "powered" system with an accumulator, etc., would take away the feel.

    As a side note, also have a complete design for electric servo based, with force feedback. Never really gave up that one yet either. Too many projects...
    Art Quillen

  15. #14
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    If you go electric servo, might as well turn it into paddle shift and eliminate the stick all together.

  16. #15
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    Are you planning to install a tunnel to cover your linkage? I saw a Spyker once at a car show, which had a fully exposed shift linkage which somewhat bisected the passenger compartment. Polished aluminum I believe. It was definitely a focal point of the interior. Interesting that you are working from both sides of the transmission.
    FYI, I designed and installed a full push/pull rod system, using a jackshaft just behind the rear bulkhead for my 818 coupe around 3 years ago. 1 grease fitting lubes the entire jackshaft assy. It’s all been done already.

  17. #16
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    Lance

    Your setup is why this thread is titled "another" take on solid shift linkage. I looked very hard at what you did and I could have mostly copied your setup (except going lower to avoid the Boyd gas tank), but I simply lack the tools necessary to machine a jackshaft with inner and outer linkages with zerk fittings etc. A cheap drill press is the closest thing I have to a precision tool at the moment, I have to be able to build everything with hand tools. While I do invest in new tools, this years big item was the welder, so it will be next year before I consider a lathe, or bandsaw, or mill. The lack of tools to machine a nice inner/outer jackshaft is what led me to go down both sides of the transmission, made the linkage much easier to fabricate.

    I will have a center console, but I would like to expose some aspects of the shifter and linkage, if I can find a way to make it look really good. The biggest impediment to that at the moment is the hacked up plastic Toyata shifter. If I can talk a buddy with access to a CNC at work into making me a sweet looking shifter, I will definitely find a way to do something exposed, a la Pagani Huayra. Otherwise, I'll have to be selective about what I show off.


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    Okay, I wasn’t sure if you were aware of the preceding efforts. I just didn’t want to see you re-engineer something that had already been pretty well fleshed out. Good luck with your design. You definitely have a unique approach to an old problem. IMO, this is a problem for all mid engine cars. The GTM could use some brain power in this area too unless using an automatic trans.

  19. #18
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    I think the issue is made worse in the 818 because of space constraints. In a GTM/SLC/GT-40 there is a lot more room to get linkage or cables in with less intense bends and have a nice feel.

  20. #19
    Senior Member Bob_n_Cincy's Avatar
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    Quote Originally Posted by Ajzride View Post
    I think the issue is made worse in the 818 because of space constraints. In a GTM/SLC/GT-40 there is a lot more room to get linkage or cables in with less intense bends and have a nice feel.
    AJZ,
    I look closely at rod shifting at first. But was to tight getting under my oil pan and exhaust. I ended up with cables coming out the back of an MR2 shifter and going around the left side of the engine. I did go with a side shifter mechanism. the video below is my first version. I changed to the shaft going into the transmission where the neutral switch was.
    Bob

    818S #22 Candy Blue Frame, Front Gas Tank, 2.5L Turbo, Rear radiator, Shortened Transmission, Wookiee Compatible, Console mounted MR2 Shifter, Custom ECU panel, AWIC soon
    My Son Michael's Turbo ICE Build X22 http://thefactoryfiveforum.com/showt...rts-818S-Build
    My Electric Supercar Build X21 (on hold until winter) http://thefactoryfiveforum.com/showt...e-Build-Thread

  21. #20
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    A quick and dirty concept

    CA78FC85-E90E-409C-A574-EE784F05B125.jpeg

  22. #21
    Senior Member Bob_n_Cincy's Avatar
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    Quote Originally Posted by Ajzride View Post
    In my humble opinion, it will be very difficult to make a gated shifter work. Especially if you are using rod shifter to an engine on rubber motor mounts. I originally had OEM mounts but then switched to the group N-type to limited motor movement. The video below shows motor movement with OEM mounts.

    Last edited by Bob_n_Cincy; 12-02-2019 at 06:16 PM.
    818S #22 Candy Blue Frame, Front Gas Tank, 2.5L Turbo, Rear radiator, Shortened Transmission, Wookiee Compatible, Console mounted MR2 Shifter, Custom ECU panel, AWIC soon
    My Son Michael's Turbo ICE Build X22 http://thefactoryfiveforum.com/showt...rts-818S-Build
    My Electric Supercar Build X21 (on hold until winter) http://thefactoryfiveforum.com/showt...e-Build-Thread

  23. #22
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    Holy cow, I’m wondering if I have enough firewall clearance. Thanks for the info.

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