915 Trans Advice

[72targa]

I've always imagined setting up a 915 with "airport gears". I also love the hunt for parts. So, if I was to rebuild my 915 in my '72 S, what would be the gear part numbers I would look for? Would I need to look for anything else?

[pu911rsr]

Peter,
Take a look at Carquip's web site, they have a online gear calculator. I don't think Porsche ever used the "airport" term in reference to 915's. There are the 901 gearing set ups (airport, nurburing etc.) so you can compare. The 7:31 boxes are pretty short already but gears are available to make the ratio spacing much tighter, makes a huge difference in feel of car but not so great on highway.
Phil

[Flunder]

For the 901 trans, the Airfield Circuit Ratios used the 6:32 rear axle and are:

I. 14:37
II. 18:32
III. 22:29
IV. 26:26
V. 28:23

[72targa]

Excellent info! Thanks all!!

[Flunder]

First set up is my 915 with 7:31 but have not got it in the car yet; second is 901 airfield; third set up is 915 with 7:31 for '73 RS

---TC-------------A/F--------RS
1st - 14 ; 37 (A/F - 14 ; 37) 11:35
2nd - 20 ; 32 (A/F - 18 ; 32) 18:33
3rd - 22 ; 29 (A/F - 22 ; 29) 23:29
4th - 26 ; 26 (A/F - 26 ; 26) 27:25
5th - 28 ; 24 (A/F - 28 ; 23) 29:21