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Discussion Starter · #1 ·
A friend just completed a very interesting mod to shorten the forward/back shist throw. Though I haven't had time to check the mod myself, it sounds so good that I just had to post it.:clap:

He moved the ball-joint on the gearbox inwards by 15mm by mounting a new ball. This effectively reduces the throw by 30%! Only disadvantages I have seen is the increase in force needed to shift (common to all short-throw shifters) and the possible bendind force on the shift cable. In any case a mod worth looking at. :crazyeyes

For those eager for more mods he has also shortened the shift stick by 20-30mm, a more complex mod involving disassembly of the shift lever. I'm also not so fond of the increased distance between steering wheel and shifter through this second mod, so I won't follow him on this. :shrug:
 

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Hi tbd,

thanx for posting this pic! Interesting and simple mod!
But: don´t you produce a rated break point of this arm without any reinforcing?? hmmm.....
First I´m waiting for my new gearchange cables and then.....

greetings from the Ruhr area!
Martin
 

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Discussion Starter · #3 ·
In principle it could be a break point, but then the remaining material seems thicker and more solid than the shift cable and the ball-joint itself. So, I don't think it would be a problem.
 

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This is actually a very common way of creating a shorter shift throw see the following:

NEUSPEED Short Shift Kit

Basically, by shortening the joint position distance you essentially shorten the throw. WIth that said, the correct way to do this is to manufacturer a new cable shift control arm vs. altering the existing. The biggest reason as someone has already alluded to, is the stress level on the added ball joint (not sure if it's welded or drilled in) will eventually cause it to fail.

If anyone has CAD software and can provide a blueprint for a manufacturer, this would probably be relatively inexpensive to produce. I certainly would be in if anyone were to take this project on. Heck, I'm surprised no tuner/after market company has taken this on yet. It's one of the easiest things to make with not a lot of R&D involved. If you google short shift kit for any mass produced manual transmission sports car, you'll always find anywhere from a couple to as many as half a dozen choices.
 

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Discussion Starter · #8 ·
Today Martin and I took the opportunity to complete the mod on my car. The effect is amazing:nanner:

Effectively the fore/aft stroke of the shifter is reduced by 30%, making gear changes considerably quicker. We also replaced the rubber bushing for the cross shift cable with a stainless steel part. Together both changes make an incredible improvement in resolving what has to be the Evora's greatest downside.

The change is not too complicated. First remove the air box. Remove the shift cable and very carefully drill a 6mm hole 15mm inwards from the original support. A shorter distance would allow a longer throw, but I would not go further inward than the said 15mm. Install the 6mm ball joint (we used a stainless steel part) and connect the cable to the other side. The cross shift joint is a one-to-one replacement. Then reinstall the airbox., reonnect all hoses and plugs and enjoy:coolnana:

Do be carefull about one thing: making sure nothing falls down into the engine bay. We had one hose clamp fall down and it took us longer to take of the undertray to get it back tnah the whole mod. TADTS

First pictur eis the mod in progress, the second shows the stainless steel joint for the cross cable.
 

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How big is the part that needs to be modded?

Can you show me which part it is on the diagram?



Is it 15?


On a side note I have a complete shift cable assembly that is new and available for RnD to get a part manufactured to fit if it will help...
 

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Discussion Starter · #10 ·
You need to drill a 6mm hole in part #15 as you rightly guessed. No need to disassemble the gearbox, access is from above and outside the box.
 

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Wouldn't it be more ideal that someone machined a new part for this location that was shorter? This sounds great but I am concerned about the loads on that "thinner" section of metal over time.
 

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Yes, not only is a hole being drilling in a thin section but this 30% reduced shifting motion is creating 30% higher loads in this ball joint. Guys, you are building in a acccident waiting to happen. Hopefully just a mis shift into neutral or stuck in gear where you can coast to the side of the road/track, BUT also possible fro it to break mid-shift with gear not fully engaged and maybe a jamb???
 

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Wouldn't it be more ideal that someone machined a new part for this location that was shorter? This sounds great but I am concerned about the loads on that "thinner" section of metal over time.
This concept is basically what the LETSLA did for the Elise/Exige a bit more elegantly.
 

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Discussion Starter · #14 · (Edited)
I was equally concerned about the forces and potential failure. So we did some measurements and calculations.

Of course, the there is a 30% increase in force at the back end. But, the forces required at this end are very low, and you can change gears here with your small finger. The weak end turns up to be at the front end where the cable connects to the shifter, and where you have exactly the same ball joint and a rather poor weld holding things together. Actual movement at this end now matches the movement of the shortened lever on the gearbox. You also have the full friction of the cable to overcome, and which is at least 50%. Additionally the weakening hole takes considerably less than 50% of the material, which is also about 3.5mm thick.

The whole shift assembly is a poorly designed unit where Lotus took the stock Toystore gearbox and connected it to their individual shift cables. The original Toystore design was quite different from with completely different geometry.

Of course a machined part would be nicer, but if you look at the part in the drawing it gets complicated as it is a single welded piece.
 

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I could be VERY interested in a properly machined part if removal of the stock part isn't a nightmare waiting to happen.
 

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Then instead of removing the old part - why not fabricate a simple arm that attaches to the original location and has a NEW mounting point as opposed to drilling etc?

Seems like it would be easier to do, just as reliable as OEM, and a HELL of a lot cheaper on materials and install time...
 

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Discussion Starter · #17 ·
Then instead of removing the old part - why not fabricate a simple arm that attaches to the original location and has a NEW mounting point as opposed to drilling etc?

Seems like it would be easier to do, just as reliable as OEM, and a HELL of a lot cheaper on materials and install time...
The original arm is welded to the shaft that you see as part of item #15. It won't be easy to find a way to eplace it stand-alone.

What you could do is manufacture a sleeve to put over the existing arm that includes the post for the cable ball joint. But, this will get very complex, as it affects the geometry in evvery direction, will be hard to fit tightly and need to be of much harder material.

BTW: I did check both with my dealer and with Daniel of KomoTec before making the modification. Neither had any concerns regarding weakening the bracket or structure. Only difference was that KomoTec would have had to charge 2-3 hours of labour to make the mod, which essentially just involves drilling a mounting hole - it was Daniel who suggested to do it myself.
 

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What you could do is manufacture a sleeve to put over the existing arm that includes the post for the cable ball joint. But, this will get very complex, as it affects the geometry in evvery direction, will be hard to fit tightly and need to be of much harder material.
This is what I was thinking might work. It could easily be made of aluminum and just bound to the piece below. This can't be that difficult...
 

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Discussion Starter · #20 ·
It is still working great, can't even remember how the shifter was before. Seems so natural.

I also checked the installation a few days ago, everytihing remains tight and solid.

So, a good mod, no issues, just fun! :clap:
 
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