I dont know any of this. So far my swapping has been a little more on the mild side with stock 2nd. I do have a 5 speed 912 tranny to tear down and photograph before figureing out what I want to do with it. It ought to prove educational for many. Then there is the sporto that I need ot pick up, and the 923, 915 and 930. Gonna be busy with the camera this holiday season

Okay, where can I get one of these "taller" 5th gears for my v8 teener. My wife tells me to drive my Toyota Tundra instead of the 914 to "save" on gas.

I really need to figure out how to get a sporto bug tranny into my 914.

that was an autostick...

why not use a sportomatic from a 911?

but why????

4 gears vs 5... most likely less overdrive....

sporto 911 = 901-ish tranny?

Installing an I gear on the mainshaft isn't really that difficult (for an experienced fabricator, lol). I did it for my race box last year.
1) grind the F gear down, don't let the shaft get hot.
2) turn the shaft to the correct dia for the new gear
3) I built up 4 splines onto the mainshaft so the gear welds would not take all the load.
4) carefully weld the gear in the correct position - don't let it get too hot!

Now I need a C or D first gear.

Ya, simple for Chris the welding magician Some day I may have the set up to mess with such things, but not now.

For H gears I have heard that Otto's in Venice,CA can source them for you. Also you may try GPR (call them), or Raby may have one.

What the heck did you use to turn it down? I tried machining one of these shafts with a carbide tool and it ate it. I assume this would be easier to do with an A mainshaft, since there's a lot less gear to take off. How hot is too hot?

The only part of the shaft that is real hard is the outer skin. That's typical of parts that need good wear properties combined with strength and toughness. After grinding off the gear teeth with a belt grinder the interior cuts pretty easy.
Too hot is when the metal starts to turn color. Anything beyond a light straw color is the end of whatever heat treat properties were done at the factory.

Two questions please:

1: Would someone please give me the formula for figuring out final drive ratio vs. tire diameter.

2: Could someone post an exploded view of the 901 - one from a manual is fine, but actual pics would go even further.






Jonathan

If you search the links in my sig you can find some good pics of the tranny. Also try the links in the thread, and onthe pelican site.

Doing the trany thing is cool but what about putting a real engine that redlines at 10K?

High rpm engines are great for peak horsepower but generally suck at making torque.

Part Pricer has lots of diagrams.

Skip

FYI

http://www.carquip.com/parts/911/trans/gea...gears/index.asp