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Registered
Join Date: Sep 2002
Location: Bend, Oregon
Posts: 1,167
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901 Gear Ratio
I just acquired a '67 911 that has had the original 901 transmission modified from a 5-speed to a 4-speed. The car was being built at one time for hill-climbing and A-X and the idea was that it would be benficial to eliminate the stock first gear because it was on the same spindle as reverse and had a tendency to break under heavy load (the car has a 2.7 with Webers and has dyno'ed at 220 HP).
So the current pattern is a conventional "H" with the old 1rst gear dogleg eliminated and the new four gears spanning a range similar to the old five gears. I don't have the records and I'm wondering if anyone has any idea of the ratios they might have used? A friend of mine who has driven the car who owns a Speedster with airport gears says it feels similar to those. Thanks, John Audette http://www.audettecollection.com Last edited by jaudette3; 05-25-2006 at 09:02 AM.. |
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05-24-2006, 06:26 PM
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Registered
Join Date: Dec 2003
Location: Arapahoe County, Colorado, USA
Posts: 9,032
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John,
If it has standard 4-speed gears for that year the transmission would be a 902/0. It has the following gears: 1st A 11:34 cut on the main shaft as 2nd in a 5-speed. 2nd H 39:32 interchangeable with 3rd gear in a 5-speed 3rd Q 24:27 interchangeable with 4th or 5th in a 5-speed 4th X 28:24 interchangeable with 4th or 5th in a 5-speed. It would have a 7:31 ring & pinion gear set, same as 5-speed. Of course one of the beauties of a Porsche transmission is you can interchange gears almost to your heart’s content. It could have anything. The easy way is to partially dissemble it and look. For a street 911 it would be more desirable to have a 5-speed stock geared AFMSX. Regardless of type gearbox, you shouldn’t do burn-out jackrabbit starts. Well, is you put a 930 trans in your car …. Here is a 902/0  © Dr. Ing. h.c. F. Porsche A.G. Best, Grady |
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05-24-2006, 07:14 PM
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Registered
Join Date: Sep 2002
Location: Bend, Oregon
Posts: 1,167
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Grady -- thanks for the informative reply.
- John Audette |
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05-25-2006, 09:03 AM
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Alter Ego Racing
Join Date: May 2002
Location: Florida
Posts: 5,553
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John,
If you give me the tire size and RPM's and speeds on different gears I should be able to tell what you have in there. Drop me a line with the info.
__________________
International GT Champion; Porsche GT3 Cup Trophy Champion; Klub Sport Challenge Champion; Rolex Vintage Endurance Series Champion; PCA Club Racing Champion; National Vintage Racing Champion |
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05-25-2006, 10:08 AM
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Alter Ego Racing
Join Date: May 2002
Location: Florida
Posts: 5,553
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John,
If you give me the tire size and RPM's and speeds on different gears I should be able to tell what you have in there. Drop me a line with the info.
__________________
International GT Champion; Porsche GT3 Cup Trophy Champion; Klub Sport Challenge Champion; Rolex Vintage Endurance Series Champion; PCA Club Racing Champion; National Vintage Racing Champion |
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05-25-2006, 10:08 AM
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Registered
Join Date: Jan 2003
Location: Woodland Hills, CA
Posts: 1,342
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Hey, Grady -- You wouldn't happen to have the complete 901 gear chart including the ZD gear...
__________________
Sandy 1969 911E 1970 240Z |
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05-25-2006, 05:12 PM
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Registered
Join Date: Dec 2003
Location: Arapahoe County, Colorado, USA
Posts: 9,032
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Sandy,
Yes, e-mail me your address and I’ll mail you a copy. This is my Rennenhaus gear chart. It works great for track use. It is 11x17"  Best, Grady gradyclay@hotmail.com |
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05-25-2006, 06:37 PM
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Registered
Join Date: Jan 2003
Location: Woodland Hills, CA
Posts: 1,342
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Grady --
THANKS! Email just sent. 
__________________
Sandy 1969 911E 1970 240Z |
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05-25-2006, 08:05 PM
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Registered
Join Date: Jan 2000
Location: Waukesha, WI USA
Posts: 702
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chart
HI Grady,
If it's not too much trouble could you e-mail me a copy? Thanks Jeff |
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06-23-2006, 04:14 AM
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