[Grady Clay]

Terry,

Your ’69 901 should have the “reinforced” input shaft. It has a larger thread to hold 1st gear on. Don’t let the term “reinforced” fool you; it is just as weak as the other “non-reinforced’ input shaft.

I auto-Xed my ’68 911 with 901 AFMSX, AEKQV, CAJPU, and more. You can take a 4-speed A shaft or 901/911/914 F or GA shaft and weld onto it any 904 second or 901 second-third. You can use others but it adds stress to the pinion and input shaft bearings.


Here are two good choices:

Find a spare 901 4-speed. It has a A first gear in the normal 2nd position. Install really short other gears (2-3-4).

Install a 915 with a taller 1st and shorter other gears. A 915 is much stronger and better for auto-X.


I assume you have a 225 mm clutch. You want to have it as slightly expendable so you can abuse slip it under power. You want everything strong enough so you can dump it in a lower gear and cause drastic over-steer into a sharp corner.

With your driving and heal-toe skills, you can just use your stock 901 if you are careful.

Please give me some feedback. What is the type number of your 901? What gears does it have? Is it aluminum case or magnesium? Does it have an open differential or LSD?

Best,
Grady