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Discussion Starter · #1 ·
Someone made a suggestion I move this discussion to a new thread so here it is.

I know I have always disliked the long throw shift on my GTL. I ride several different bikes and every time I get back on my GTL it is like learning to shift all over again. Not to mention I have always felt like the long throw adds to the "clunky" feel, and sound, of this gear box. I measured the throw of the GTL at the toe peg (70mm) and several other bikes and found most have a significantly shorter throw than the GTL (35mm on the short end and 60mm on the high end). Granted my sampling was rather small. So, I worked up a method to shorten the throw on the shift.

I have been studying this for some time come up with a simple way to shorten the shift throw. The simple solution would be to shorten the lever on the ratchet shaft at the top of the gear box, or move the link further out on the foot lever. Problem is, either solution would have the link interfering with other components. What I came up with is a bell crank that I mounted on a pivot that is in place of one of the smaller case bolts. Worked out the leverages and geometry while still managing to steer clear of interference. The result is a throw of roughly 37.5mm so just a bit more than half.

What really surprised me was just how much difference this made in how this bike shifts. 1st to 2nd can be done with just a simple "flick". Down shifts are fun again! Neutral is harder to "feel" but not as bad as other bikes I have had.

Some others have expressed an interest in purchasing a kit and I can make some of these up since I own a machine shop. I am thinking somewhere between 100 and 150 bucks depending on how many are interested. This is a simple DIY install with some basic hand tools. I am still working on a version for the GT since the foot lever is different and therefore the geometry will need to be worked out. The set up I have working on my GTL would result in an impossibly short throw on the GT. If anyone local that has a GT in interested I could set them up if they were willing to be a "guinea pig"...

Anyone interested... Thoughts...

Here are some pics of the prototype setup I have on my bike.
 

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Even though I too have a machine shop I would be willing to purchase a kit from you instead of taking the time to make my own. Count me in.
 

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Interested!
 

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I thought I had sent you a message here, but I think what you've done is ingenious, and I too want to know how to get one of your kits!

Count me in!!

TJ
 

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Texas Thorn
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Interested as well.
 

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Discussion Starter · #10 ·
Thanks to everyone for the feedback.

I have plans to work up a more production ready version in the next couple of days. Spent some time over the weekend verifying a bunch of measurements that I had done with a tape measure initially so I could update my CAD model (see pics). I will also be doing a version for the GT that I will do my best to test on my GTL. Still hoping for someone local (Denver area) with a GT that is interested so I can verify the results...

From the sound of things I am going to plan on 1 or 2 dozen kits to start with and if I can get these worked in without disrupting my shop schedule too much should be ready in the next couple of weeks.

I will keep everyone posted.
 

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Discussion Starter · #14 ·
Why does the rod need to be straight? Couldn't you get the same effect by moving the pin on the shift lever closer to the toes, then bending the rod around the oil filter?


Just askin !
Actually I did consider that option. One would have to put the attachment point on the foot lever right at the toe peg to accomplish much. And there really isn't any room to attach anything (ball socket or tie rod end) between the foot lever and the oil filter. Best case scenario if one accomplished that, the result would be a shorter throw but not as much as this set up. Then there is the interference with the glove box to consider... Not to mention that would have to be one really crazy crooked link that would have to be really substantial so it wouldn't bend like a spring.

Also, the bell crank has another advantage in that the ratio of toe movement to the movement of the lever on the ratchet shaft is non linear on up shift. Due to the changing force vectors as the bell crank rotates the initial movement off center is faster, roughly 2:1, but as the bell crank rotates the ratio drops back to almost 1:1 near the end of travel (not quite, since we don't want it to over center). On down shift it is nearly 2:1 all the way which makes for really smooth down shifts.
 

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Very slick! I'm interested.
 

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I can't believe I found something else to buy for my bike! I too am very interested!
 
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I will send a note to a friend with a GT who lives in Longmont and see if he is interested in being a tester.
I live in Loveland if you need any help.
 

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I'm interested as well. Wasn't unhappy with stock feel of shifting but it sounds like a nice improvement.
 

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Short shifter

I would be glad to participate in your 'kickstarter campaign' for your design. Looks like it makes sense and by the explanation of the ratios would make for a very easy shift!
Thanks!!
 
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