Rennshift install / 901 spring pressure, Are the springs pressing on bits in the tranny? Options

[smdubovsky]

I installed the Rennshift last night. Nice piece of kit to be sure. It spring loads the 4/5 plane just like the factory shifter spring loads the R/1 plane. My question is, what are the springs pushing against in the tranny?

The stock 915 (in a 911) uses a little tab on the 5/R side to keep the springs from pressing the shift linkage against stuff in the tranny. Here is a pic from Seine systems (he makes a 915 kit that also springs load 1/2 and adds the tabs to both sides).



You can see the little tabs and the hook on the shift lever that relieves the spring pressure when your anywhere other than the center plane (3/4 in a 915, 2/3 on our 901s). The reasoning is that you can spend alot of time in 5th gear in a 911 and its putting pressure on the linkage & couplings. The stock 914's stock shifter doesnt have it, but you'd never spend alot of time in 1/R either.

What is the spring loading in the 4/5 plane doing to the tranny? Are the 901 shift fork internals that much different from a 915 (doesn't look like it in the pics I've seen)?

Just looking to keep the tranny healthy,
SMD

[Dr Evil]

Hey man,
The shift forks inside the 901 are held in place by springs and balls that rest in groves on the rods. I will try to get some pics for you. The rods are actuated by a comb looking apendage that sits atop the shift console shaft. If one were to put pressure on the shifter it is likely that it would be in the left/right plane of the car which is equal to the in and out of the shift comb on the console rod. This would not effect anything negatively. Putting too much pressure fore and aft on the shifter would make the internal gear selector rings push harder on the synchro teeth and synchro band (not too big of a deal) but would also cause the shift fork to constantly put pressure on teh groove of the synchro sleeve causeing premature ware of both parts, friction, and lots of metal fragments over time.

So, in short, side to side pressure is no big deal in a 901, fore and aft can be.

1/R is spring loaded only to keep one form hitting R accidentally.

As far as I know, Wevo does not make a 901 unit because the Renn shift is already out there and a perfectly fine unit.