Shifter puzzle

[yelcab1]

I have a 1971 chassis, with a 964 3.6L engine, and a 915 gearbox, Wevo shifter and an all metal non-OEM coupler. I am able to get all five forward gear but cannot get reverse. If I mess with it and get reverse, I cannot get 5th gear.

What in hell is going on?

In previous cars of this genre, I can remove the taper pin from coupler to gearbox shift rod and wiggle the whole shifter-rod-coupler out to disengage the car from the gearbox. This combination does not do that. I have to remove the entire shifter housing and pull the rod forward in order to disengage the rod from the gearbox. That seems really odd to me.

[Walt Fricke]

I've never heard that the 964 engine was longer than its predecessors, thus somehow meaning the transmission would have to be more forward if the rear engine mount location wasn't different.

Someone else will have to answer the question of whether the '71 long shift tube for the 911 transmission is longer than those for the 915. Is the aftermarket coupler somehow longer? Can you loosen the forward side clamp and slide the coupler forward? Or is this a weld-on coupler?

I assume you had the gear box in 1, 3, or 5 when attempting to separate the coupler from the tranny shift rod?

Since 5th and reverse are selected in the same basic way, governed by adequate rotation of the main shift shaft so its 5/R finger firmly engages the shallow relief/slot in the 5/R shaft, it would seem that if one works, the other will, and vice versa.

[yelcab1]

I managed to get all the gears to engage. But the gearbox shift rod is definitely sticking in too far so that the coupler does not just slide off. Or the coupler is too long, or something. I had to modify the coupler to make it shift into 2/4/R gears.

[yelcab1]

Between modifying the Wevo coupler, and cutting the shift tube, I moved the engagement point a total of 6mm to make the gearbox engage the even gears. So, the combo (964 engine, 915 gearbox, and 71 chassis) is about 6mm longer than the stock combo (2.2T, 901 gearbox).

OK, that's info for the next guy.

[rumlyne]

did you happen to check to see if the "all metal non-OEM coupler" is the
same length as a stock one?

[Trackrash]

Yes the shift rod is indeed longer on the 901/911 transmission compared to the 915's . Actually it is about 15mm longer, I have read. I had to shorten mine when I went to a 915 in my '71. You can actually see that the sift rod sticks out of the 915 trans noticeably further than on the 901. Not sure why Porsche did that as it makes it noticeably harder to R&R the motor and trans.

[yelcab1]

ah, confirmed ...