Quote:
Originally Posted by 911pcars
Review Tyson's post #4.
The shift lever attempts to transfer accurate shift actuation in the gearbox. However, the distance between gearbox and shifter is an expanse of sheet metal that has less than ideal rigidity. This means a lever sliding into a fixed "slot" in the shift housing won't necessarily result in a direct 1:1 relationship with what you want to happen at the end of the 4 foot shift tube, especially if the vehicle is under torsional twist as when cornering/turning.
Sherwood
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Yes the lever is fixed in the gate slot but there is still a bit of play in all the bushings and joints that should leave room for the twist in the car body and engine mounts during driving. The fixed lever position have to be in the center of that play, leaving the transmission input shift rod under no tension except for when changing gear. That of course makes the entire setup very dependent of the condition of those bushings. More play means less throw to a point when gears won't engage.
Lets do some rough calculations.
If the normal un-gated lever can be moved freely from 9 to 10 degrees (or 5mm of knob movement) towards the drivers side when in first gear. The total play is one degree and the gate slot should hold it at 9,5. With the movement ratio from lever to shift tube being something like 1:3 that gives the body and engine mounts +- 1,5 degrees of allowed twist. That is over 20mm of deflexion for each meter of width.
I (or anyone) could easily set up an experiment to measure the twist in the car. Just remove the top plate and rubber. Select a gear. Pull the lever gently to one side with a rubber band to take out the play. Drive and observe the movement of the knob.