70'T 901 or 915 tranny which one?

The question that I have is this I have a 915 from a 75 or 76 that I am going to replace my sporto with. I am starting to see the problems that are coming in the next few monnth's (axle's,shifter,speedo...). What will make this 2.2 motor run better a 901 or a 915, in terms of gearing. Should I get rid of this 915 and just find a 901 or am I better off to just bite the bullet and finish the project with this 901. Also If I upgrade the motor down the road to a 2.7 will I then have problems with the 901.

thanks for the help

I'd go with the 901. It will handle a 2.7 and is slicker to shift in 1st and 2nd gears. It's also lighter. You can probably trade someone for a 901 easily.

------------------
Tyson Schmidt
72 911 Cabriolet
92 C-2 Cabriolet

Are you the guy in Akron w/ the yellow car? You were going to get some info on the sporto and call me back?? That was like 6 months ago??? What the F? Just Kidding. Scan the posts for info on the conversion. Bob Thayer was going to do it last I talked to him, not sure if he ever did it. Sorry to see you leaving the infamous sportomatic ranks.

Joe Hahn '68 911L Targa w/sporto.

Hello

The 2,2 have a special 2,2 only clutch setup. If you go 915 you have to do some slight hamering abouve the cone and change the Shifter/clutchcable. As you have a sporto so you have to do this anyway.

I would opt for a 2,0 trany as you still can use the driveshafts. 901 can only bear limitet tourque and a 2,7 is the limit. But i would not use a 2,2 2R/3R case to make more than a 2350 cc out of it. Your crank will thank.

Donīt trash the sporto as some parts are very usefull for others. Plug the oil line with bearing ball and use a shrink end to make it bullet proof. Donīt forget to move the temperaturesensor.

Grüsse

I am in the middle of converting a 1971 911T Sportomatic to a 915 5 speed. At this time, I do not have a garage in which to work on my car (I tore down my garage to make way for a new garage this Spring). That is why I sent the car to Johnson Motorsports (a very reputable garage near Minneapolis/St Paul) to do the conversion for me. Bob Johnson recommended a newer 915 transmission with an aluminum case. He said that the aluminum cases are a little heavier than the magnesium case 915's, but they are more durable.

I decided against a 901 transmission because of the strange gear shift pattern. On the 901, Reverse is towards the front where 1st is on most other 5 speeds. I did not want to embarass myself by grinding the reverse gears while looking for 1st in the wrong place.

Bob Johnson knows enough about these cars (he prepares and races 911's) to know that he needed to order and install a differential from an older 915 transmission so the transmission flanges would match my half-shaft flanges (otherwise you end up changing out the half shafts and maybe the swing arms too - where do you stop?). He also knows how to install an electronic speedometer to match the electronic pickup in the newer 915 transmission and to re-route the brake lines to avoid crushing them when he lifts the larger 915 into place.

Bob Johnson hopes to finish my car within the next week and I may learn more before this is all done. It is good to work with someone I can trust.

------------------
Bob Thayer
1971 911T
rthayer@hdrinc.com

The 901 will be a simpler conversion, lighter, and require less modification; but you need to be happy with the shift pattern and the associated "feel" of the 901 box

I like the 901 over the 915 but a G50 with Borg-Warner syns is nice to! In the end it's a matter of taste and of course which one you can get in good condition; worn synchros are worn synchros and suck in any box ;D

Hello

The early shift patern is great for track use but iky in the city.

Also there is no problem to hit the reverse ( OK, if you donīt care anything....) and people donīt try to engage the 1st gear while driving ( And forcing the synchro to wear ). If you look around you will find some other cars witch also had this shift pattern ( 924 Turbo, 928, Mercedes 190 E 2,3 16 V , BMW M 1/3/5. Maserati, Ferrari ).

Well I asume those cars need a sophisticatet driver.

A 915 trany on a 125 HP engine ? I think Porsche must apologize to all those racers who have 250+ HP and have a high risk on failing tranys.

The 915 is very usefull on a heavy car with lots of tourque or for people who use to trailer something.

Anyhow if you decide later to put in a bigger engine you have done it.

Grüsse

will a 901 from a 68-69 car fit and how hard to install.

Also what do you mean about the 2.2 needing the clutch parts from only a 2.2, please elaborate

thanks

The 901 trans is used in the 914s and handles my hot rodded 3.0/6 very well. As a matter of fact the 901 is also used on the v8 conversions. They lock out first gear. That is the only weak link....

I used to do two gear burn outs with my 250 hp 3.0 and a limitted slip differential....it handled it very well.

I doubt a 2.2 is going to push a 901 trans anywhere near it's limits....