Transmission life and short shifters?

[rdane]

I keep hearing and reading that a short shifter is really hard on the tranny. Can anyone please explain the problems of additional transmission wear after of adding a factory short shifter?

[moazam]

Wayne says:

"Let me repost (from 101 Porsche):

Ironically, many people install a short shift kit onto a poorly shifting transmission, and then magically proclaim it 'cured.' In fact, in most cases, they didn't fix anything with the transmission - the short shift kit is simply 'muscling' the transmisison into gear using more force and more leverage. The bottomline? Only install a short shift kit into your car if your transmission doesn't have any shifting problems.

-Wayne"

Same thread, John Walker states:

".....the longer link below the pivot point moves the shift sleeve faster than it was designed, so that tends to prematurely wear shift items, and the shorter link above the pivot increases the effort required to do the shifting."

(Wayne's Tranny article)

................................

In another thread Jack Olsen says:

"A short-shift kit is going to shorten the life of your syncros. It will not improve your shifting, only shorten the throw distance -- unless you do the peripheral upgrades (bushings, linkage, adjustment, Swepco) at the same time."

Chuck Moreland says:

"Short shift kits don't really solve any shift problems. They do make the shift lever heavier.

IMHO they only make sense for people who have trouble reaching the 5th gear (short arms) or if the shifter is hitting your aftermarket seat.

Otherwise, they do nothing except increase the effort. That extra inch of throw isn't what slows down shifts."

Last two quotes are from:
Best short shift kit

[AES]

Correct me if i'm wrong, but from long ago science lessons I vaguely remember that if a simple machine input moves a shorter distance then the output sees a smaller force which moves thru a longer distance in this case limited by the trans hardware.

[tkrefeld]

Should be okay with a shorty. but it does NOT mean you slam into gears hard and/or fast. You still have to finesse is like a 915 w/ regular shifter, or yes, the gearbox will wear faster.

[wevoid]

I posted this recently as part of an answer about a 915 locking in 2 gears,

"If you are using a Short Shift kit of any kind?, remember it is called a Short Shift, not a quick shift. Effectively a Short Shift is a “slow shift” allowing you to achieve the same travel distance and speed inside the transmission by moving your hand more slowly and for a lesser distance on the shift lever……"

Regards

Hayden

[rdane]

"A short-shift kit is going to shorten the life of your syncros"

Specifically I want to know the back ground to this comment. I know a short shifter adds to the amount of force needed to change gears. That is a simple leverage problem. You loose leverage going to a shorter stick and throw. But I miss the additional wear on the syncros.

Is this the sum of support for those comments?

"the longer link below the pivot point moves the shift sleeve faster than it was designed"

[911pcars]

Because the pivot point changes with a short shifter, there is a little less shifting leverage. However, the distance the lever travels is shorter. With a factory short shifter, the distance from gear-to-gear is reduced by approx. 25%. One component of this is the shorter distance to shift OUT of gear. There is no extra wear involved as a result of this. The other component is shifting INTO the next gear. Again, the distance is shorter, but an area of potential wear. Rushing the 915 gearbox into gear, even with the stock shifter, places undue strain on not-too-efficient factory synchronizers. With a short shifter, the same patience is required to not rush the synchros. However, not everyone has the same patience threshold.

BTW, whenever downshifting, I encourage double-clutching in order to permit faster downshifts and to reduce wear on the synchros. IMHO, there is no downside using a factory short shifter if one also uses the proper double-clutching technique (which by itself has its own very lengthy thread).

Sherwood

[speeder]

There are no great mysteries to solve here, you could have a shifter w/ half the throw of the short shifter and not damage your syncros as long as you do not attempt to "beat the synchros" in the race to engage a gear.

Short shifter, long shifter, factory "in between shifter", (yes, there is such a thing), you can ruin your trans w/ any of them if you try to move the lever faster than the syncro wants to engage. Obviously, the shorter the throw the easier it is for a bad driver to do this, same hand speed=faster shifting speed at trans.

Whichever throw you have, just don't try to shift faster than the lever wants to move and you will be fine. If this degree of 'touch' escapes anyone, stay away from 915s, (and all Italian cars!), or be prepared to bend over and spread wallet on a regular basis.

[Bill Verburg]

Originally posted by speeder
There are no great mysteries to solve here, you could have a shifter w/ half the throw of the short shifter and not damage your syncros as long as you do not attempt to "beat the synchros" in the race to engage a gear.

Short shifter, long shifter, factory "in between shifter", (yes, there is such a thing), you can ruin your trans w/ any of them if you try to move the lever faster than the syncro wants to engage. Obviously, the shorter the throw the easier it is for a bad driver to do this, same hand speed=faster shifting speed at trans.

Whichever throw you have, just don't try to shift faster than the lever wants to move and you will be fine. If this degree of 'touch' escapes anyone, stay away from 915s, (and all Italian cars!), or be prepared to bend over and spread wallet on a regular basis.

Exactamundo!