Transmissions Options for the SIX Options

[dekman]

Apparently I damaged my 901 while at Laguna Seca last week(against the Cayman S). Actually , it was making noises on the drive up. Of course I can repair it...but I'm thinking of future motor upgrade(ie 3.6 or 3.8). So, need the "experts" to imput on my possibilities. Of course a 915 w/ wevo kit... but... what about a G50/1 5sp '88(short bell housing) or G50 6sp('95) or boxter S 6sp or 930 4sp(short bell housing) or ? . Wevo kit only made for the 915 but I suppose a cable system could be used on the rear shift units. What will fit? Current engine is a 3.0L w/ 46 webers(~220-240 hp). Any thoughts or advice appreciated... (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif)

[Aaron Cox]

go wevo'd 915

and pass on the 901 to me (IMG:http://www.914world.com/bbs2/html/emoticons/tongue.gif)

[dekman]

OK Aaron....you'll be first on my list.

[alpha434]

Might as well G50. We'll get you through the install. The 6sp would be nice.

And then someone will have done it, and we can refernce back to it for ever. Take one for the team!

But a 915 should be fine, if you are opposed to working out the problems for a g50.

Mendeola makes really nice trannies for P-cars. Check out the "Mendeola Rex." With paddleshifters. It's the no-cost-too-high-solution.

[John]

If you are really considering the power output of a 3.6 or 3.8, I would find a 930 trans, and figure out a way to mount a cooler on it.

915's are ok, but even with the torque of the 3.2, Porsche changed to the g50 as the 915 was borderline (evidence of this manifests itself with the intermediate bearing problems).

I think that with enough money, one could "build" a 915 strong enough, but I think you would have a bunch of money tied up in it.

Just my $0.02

[alpha434]

915s have the 5th gear sticking out like the 901 has the 1st sticking out. Weak point. It almost makes the 901 more desirable for racing as long as you stay out of first, but 915 was superior since you don't "start" in 5th. G50 has everything enclosed. And the 930 takes care of a lot of problems. But I've never been inside the 930.

But look at the Mendeolas. If you're up against boxsters already...

[Joe Bob]

915s are pretty tuff....mine finally died when a design flaw cracked second gear.....45K miles of me combined with a 3.6 and the inside looked great....surprising as the combination is usually pretty toxic. The box had 82K on it total....

Second gear let loose at the bubble void inside the gear when the shafts started to oval the bearing race at the intermediate plate. I did a sleeve job, used a WEVO bearing retainer and replaced second gear.

When it went BANG I was able to shut down w/o further damage and ONLY replaced second gear.....all the other gears, synchros and stuff looked brand new.

I found another good 915 case and plan on selling it since I don't need it.

[Joe Bob]

901s.....If you have the parts....rebuild it...I used a euro 3.0 behind a 901 with a Quaife LSD.....slammed in some new gears and away I went....lot's of good used 901 parts around.

Unless you are putting out over 300HP....stay with that. The 915 needs a lot of mods to work right in a 914.....same with G-50 and the 9030 trans

G-50....extremely tuff box. Wrench friend of mine says he doesn't know much about htem because he's only seen one bent G-50 in his carrer.

930 trans....basically a G-50 with four speeds....both are pricey in comparrison to a 901 or a 915....

[BigD9146gt]

Someone correct me if I'm wrong, but the G50 trans diff cannot be flipped in the housing. Even though you can flip the whole trans just like you would do with the 930 box, you'd be better off using the 930 box.

The 915 with all the wevo gear is the best choice above the 901 box. A friend of mine was a crew chief for a 935 at Le Mans back in the 70's, and they ran the 915 box... so if a professional driver can manage the 5th/reverse issue, as well as every 911 made since 72, its not as much of an issue "on the track" as most people make it out to be.

The 901 takes 150hp with a beating. Start being considerate around 200hp, and at 220hp, the first and second gears need to be treated like they have a handycap rear-view mirror tag on them. Plus the amount of rubber you have will be another big factor.

With 3.6 or 3.8, 17" rims, I wouldn't even waist my time with anything less than a 915... and probably jump straight to the 930. Because with all that power, your gonna have to show off.

Cheers, Don.

[Mugs914]

You're right Don, to run a G50 mid-engined you've got to flip the whole thing over. Fortunately it isn't too hard to convert, but those things are BIG! You will most likely have trouble getting a G50 into a stock tub, but if you are willing to do a bit of surgery in the rear trunk area it'll go. (IMG:http://www.914world.com/bbs2/html/emoticons/sawzall-smiley.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/welder.gif)

I'm not sure that you'll need that much beef though. I think the 915 would be plenty (The overhung 5th isn't an issue), and the four speed 930 would surely be enough to handle any "moment of weakness" that you may suffer. (IMG:http://www.914world.com/bbs2/html/emoticons/cool.gif)

If you aren't familiar with Patrick Motorsports check 'em out here:

http://www.patrickmotorsports.com/

They convert all of the various gearboxes for 914s as well as a cable shifter system that is absolutely fantastic. Not affiliated with them in any way other than being a very satisfied customer...

BTW, here are a couple of pics of the flipped G50/52 'box in my turbo race car project. It was modified by Patrick to run inverted and with a shortened bellhousing. The G50/52 is a bit longer than other G50s, but not by much. Either way, you can see that it's a pretty tight fit in a 'teener!

[Mugs914]

'Nuther shot...

[Mugs914]

One more, just fer fun...

[slivel]

Maybe it's just me, but it looks like the flipped box will raise the CG quite a bit?

Steve

[Mugs914]

QUOTE (slivel @ Feb 14 2006, 12:02 PM)

Maybe it's just me, but it looks like the flipped box will raise the CG quite a bit? Steve

Well, all things being equal, it would. With the engine in the stock location the major mass of the flipped gearbox would be about three inches higher than an upright 'box.

In this case the engine/gearbox has been lowered by over two inches and moved forward about an inch. The way it's all placed in the chassis, the major mass of the gearbox is a little higher than a 901 in the stock location (an inch, approx.), but the overall C of G is about the same or just a touch lower.

The higher gearbox also allows for better underbody aerodynamics... (IMG:http://www.914world.com/bbs2/html/emoticons/cool.gif)

[dekman]

Thank you all! Appreciate all the great input/photos. Let you know when I deceide. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)