Shifter: Check my math please...
 

Ok....gearheads and mathematicians. I could use a little help. Here it is.

I'm wondering besides the feel of the B&M short shifter what does it really add in respect to speed. From their claims it can reduce travel by 40% ...so i say 35% cause everyone lies about thier products. Here is the question.

In feet per second (fps) how much faster would you be to say 0-60 mph or more importantly 0-100 mph. I figured the average 0-60 time in a 2000 'S' was about 5.9 sec. and 0-100 at 13.6 seconds.

100mph= 147 fps roughly

So, in a 'S' I will have 4 shifts on my way to 100. I thought about .25 second per shift was fair.

Does that sound right? So, that is .75 second in shifting time.

I guessed at the speeds during shift times and the equivalent fps.

With my math I came up with... racing against an identical me in an identical S the B&M equipped car would would win by about 34 feet or about 2 car lengths. What about 0-60 maybe a car length?

Does that sound right? :dance: Thank you in advance. r*f

I'm not sure the speed of the stick is the bottleneck to quicker shifts. Activating the clutch also takes some time.

http://www.renntech.org/forums/index.php?showtopic=766

http://forum.boxa.net/index.php?showtopic=4709

Thanks CG and TP.

CG: You're right about the clutch taking time. So that leads me to another question.

BEfore a short shifter install is the bottleneck the clutch time or the shifter?

Example: Does it say... take .5 seconds to activate the clutch and "power" shift it into gear before the clutch is completely out. Yet, it only take .25 seconds to actually shift the stick. If this is so the short shifter is a waste of money.

This seem about right. Feet are slower than hands and individual reaction times are what matter.


-OR-

With a short shift install does it take the same .5 seconds to clutch but I was wrong on the shifting time.

Example: Regardless, it really takes about .5 seconds to clutch. The shifting time is really .75 seconds and with the new shifter can be lowered to .45 seconds and now one can perfectly shift within the clutching "window".

Does this make sense?



Toolpants: I read the articles and the second one was interesting. It stated the throw was basically identical from 1st to 2nd and the change was -58% from 3rd to 4th? What about 2nd to 3rd? Identical? Is B&M saving you 58% on one shift and maybe 5% on the others?

So, in 3 shifts it saves 68% total divided by 3 for a total savings of 23% overall. THis is making my brain hurt..I'm gonna go for a spin. Thanks again

On the C4S I measured, the shift throw from 1st to 2nd is the same as the throw from 3rd to 4th. David in the UK said the 1-2 throw is the same as the 2-3 throw on a Boxster S as well.

The 1-2 throw on the C4S was reduced by 36.85%, as was the 2-3 throw.

David did the same thing I did but on a Boxster S. I was not there to see how he measured and I did not check his math, but he came up with a 58.3% reduction. I am very suprised by this figure and will have to double check it.

Anyway, any type of shift lever will let you shift only as fast as the syncros will let you.

Thanks for the input guys.

I checked his math and it was a 38%ish reduction in throw. So, i'm guessing one could improve a 0-100mph run by about 25-50 feet due to the synchro issue. That's substantial for $300.



If anyone has done timed 1/4 mile or 0-100 mph runs with and without a short shift please post your results.