Homemade Short Shifter

[blkfordsedan]

The math is a very simple ratio, (long arm / short arm) or (length above pivot / length below pivot). If the stick above the ball is 12" and below the ball is 1", then you have a 12:1 ratio and your hand has to travel 12" to make the shift linkage move 1". If you shorten the stick 2" and leave the bottom alone, you have an 10:1 ratio. If you you leave the stick alone (12") you would only have to lengthen the arm below the ball .20" to get the same 10:1 ratio (12"/1.2"). It make absolutely no difference which way you do it, it still reduces the effective distance the knob travels based on the over-all ratio. Obviously, re-working both ends will make the biggest difference. If you shortened the stick to 10" AND lengthened the bottom arm to 1.20", you would end up with an 8.34:1 ratio. That would shorten the knob throw from the original 12" to only 8.34" or almost 30%. It should also be noted that the force required to move the shifter is also increased (by the same factor) as you reduce the ratio.

The beauty of the "adjustable throw" shifters like Pacesetter, where you slide the ball up & down on the stick, is that when you move the ball you are effecting both sides of the ratio arm.

[sketchman]

I guess the math part was too complicated, so here is a diagram.
As I said before, cutting off the top DOES reduce throw, only slightly, you just don't have the mechanical physics of the reducing ratio of the varying lengths.

You also said what I quoted which just isn't true. You don't HAVE to touch the bottom to significantly reduce the throw, and certainly not to "truly reduce" it. You just have to cut more off the top to do the same thing as adding length to the bottom. In the end, hacking the top is easier, cheaper, and faster than adding length to the bottom no matter how much you have to hack to get the results you want, up to the point where you run out of length on top to cut. That's all I'm saying. Different strokes.

[DrMaxwellEdison]

Different strokes for different folks^^^^