short shift extention?

[long board]

Does anyone make a lever extention for a short shift? I installed a W short shift kit and it's great, but the shifter lever is just a little too far away for my preference. I suppose I could have an extention custom made, but I was hoping to buy one already made. I didn't see one from our host.

[911pcars]

Yes, the WM SS lever is shorter. That allows WM to claim a shorter shift distance as compared to the factory SS kit. Too short IMO, and this contributes to a notchier feel some say.

But if you install an extension to make your lever longer and easier to reach, this will increase the distance the lever moves from gear to gear, partially offsetting the effect the WM kit provides. This harks back to the seesaw and fulcrum math problems we had in high school.

If a long-enough extension is added, then there may be no benefit at all from the WM kit. One downside is that the shorter gear-to-gear, at-the-gearbox motion remains. Because of this, "normal" shift motion and rate of lever movement may prematurely shorten the life of the synchros as compared to using the factory lever in the first place. Does this make sense?

Sherwood
http://members.rennlist.org/911pcars

[long board]

Yes, I think it makes sense. I was hoping for just a 2" extention. That would improve the overall driving position. I guess no one makes anything?

[CHILI]

Is it too far away in all gears, or just 1xt, 3rd and 5th? If it's the latter, you can just adjust the throw at the coupler. It will of course make 2nd and 4th further back too. I noticed I needed to do that once I installed my ss kit because my shoulders were coming out of the seat when I was shifting into 3rd and especially 5th.

[Oh Haha]

Check out my post from earlier today, "pics for Nick H."
I made an extension that brought the shifter closer to me. Iused the stock shifter guts, though. I t will take a little imagination but I like the way works now. YMMV.
Wayne

[911pcars]

Longboard,
I've posted this pic before to compare different lever lengths. You can use these dimensions to compare where you are now with what you'll have with a 2" lever extension. I know of no product that will do this other than an extra tall shift knob. You can could also permanently weld on an extension piece once you decide.

A = factory stock, X = ~42mm, lever lgth (assuming factory shift knob) = ~292mm
B = Factory SS, X = ~54mm, lever lgth. = 280mm
C = WM SS, X = ~59mm, lever lgth. = 248mm

Sherwood



Note: dimensions from PCA UpFixin article, Vol. 8, page 57

[long board]

Great stuff guys. Thanks!! Oh, and happy new year

[911pcars]

I worked out the pertinent calcs: Please correct me if I made a mistake:

Factory shifter (A):
a -------------------------------------------b-----c
where a-b = 292mm, b-c=42mm, Ratio = 6.95:1

Factory SS (B):
a----------------------------------------b----------c
where a-b = 280mm, b-c = 54mm, Ratio = 5.18:1

WM SS (C):
a-------------------------------b--------------c
where a-b = 248mm, b-c = 59mm, Ratio = 4.20:1

If the gearbox requires 1" (25mm) total travel from gear to gear (the "c" end), then the ratio amounts are the same as the distance lever end (a) must travel.

In the above cases:
Assuming the end of the levers (c) only move 1" from gear to gear, the upper end (a) of the shift levers then move these distances from gear to gear:
Factory lever, A moves almost 7" from gear to gear
Factory SS lever B moves about 5" (about 25% reduction)
WM SS lever C moves only 4" (about 39% reduction)

If we add a 2" extension (approx. 50mm) to the WM lever (C), then the equation becomes:
a------------------------------------------b--------------c
where ab = 292mm (248 + 50) / 59mm, ratio = 5.05:1 (compares with B)

In other words, with a 2" extension, the upper end of the WM lever moves about the same distance as the Factory SS lever. However, since the fulcrum points are different, the rate of gear change affects the speed of the lower end (c). Given the same rate of shift lever motion, the WM lever will move the shift mechanism faster and thus (theoretically) cause more wear to the synchros. OTOH, the lever will be closer to you (good) and the shift feel may be more like the Factory SS (also good).

Hope this helps somebody,
Sherwood