911 Turbo - 4 speed or 5 speed?
 

Hi guys :
I have a question, perhaps some of you can help me.

My understanding was - the ONLY 911 Turbo that comes with a 5 sp gear box was in 1989. No exception. (of course, this is the PRE-964 / Pre 1989 era)

Am I wrong?

Somehow, a friend was telling me that in 87, there were a very few (special 911 turbo) that was made with the 5 speed G50 gear box.

Can anyone confirm that?

Thanks
Carson

Hi Carson,

I think you are correct. IF you are talking about cars direct from the factory.

Those with 5-speeds, such as mine, have been converted afterwards. Thankfully.

RUF also made a 5-speed which they offered before the '89 factory version. Their branding (RUF) is pretty obvious so you could tell if it's one of their babies.

Others will surely weigh in.

Yes the '89 was the only factory 5spd G50 930.
Ruf had their own version based on the 930 4spd with an extra gear added.
Special wishes - who knows. Any of the Carrara based turbos would have likely used the Carrera G50.

My 87 has a 5 speed conversion, not from the factory....

No factory cars to the knowledge of notable Porsche people left the factory with G50, my 87 has an 89 G50/50 in it with custom motorsports gears and a chromoly Paul Guard GT differential, very pricey. Indeed anything is possible with Special Wishes but highly doubtful.

Yep, I happen to be one of the lucky ones too. I came across this '87 930 cab about a year ago, complete with G50, and yes she rocks. Do not know alot with regards to the conversion, but everything looks and works tidy,
John G

Just curious -
To convert a 4 speed turbo to a G50, is it a straight forward move or its much more complicated and require specialist to do a proper job?

If i were to look at a ... say 87 930 with 5sp conversion, do i need to be cautious about the conversion workmanship/craft?
Thanks

My account; In the right rpm's, and well out of the hole, the 930 four speed transmission will perform like a champ.

However unless you know what you are doing and you leave the line like you want to charge with something else (like you think you can get a fair reaction time out of the hole :D ) you couldn't pass a yellow school bus full of children dressed in their Sunday bests for the life of yourself!

You might be better off trying to read the funny papers and stir a Bloody Mary in preparation of boost. SmileWavy

Stout as it is,, God love ya,, search out a G50 or a Ruf transmission,, or live with the heartache, frustration and realization that four gears is all you gonna get! :D

IMHO, money is better spent on converting the 930 transmission from a wide ratio gearbox to a close ratio one. With the torque these monsters develop under boost, keeping the turbo spooled between the wide gear spacing is most desirable.

I need to pull my trans and do 2nd and 3rd,Werk can you suggest any ratio changes,part numbers etc as id like to do this while the trans is out,thanks

Wish I could, but I would recommend contacting a specialist in aftermarket gear sets to help you with the selection. They have much more experience in that area than I do. They also may ask you questions about the R&P ratio you have as well.

I think Pelican member A930Rocket has done gear work on his 930 transmission. He may give you some insight on what he's found.

The 930 tranny comes with 9:38 ring and pinion.

Andial made popular the 8:41 r+pinon.

With everything else stock i.e. the individual gears, my car with 8:41 at 7000 rpms:

1st gear 45 mph stock is 55

2nd gear 78 mph stock 94

3rd gear 115 mph stock 138 mph

4th gear 156 mph stock 189 mph


2nd and 3rd gear are great at 78 and 115 mph, and fourth is really close to perfect except it could use another ten mph on top end, so fourth gear at 165 mph would still be devestating acceleration. I can spin the tires or just about shred them with this second gear and third is UNREAL 60-90mph, fourth is instant launch.

1st gear on my car is too short to be useable, so I would think 52 mph would be about right.

I have bruce anderson's 911 performance book so I can translate any speed into an actual gear number if somebody really needs that info but you are better off getting the book...pages 239 and 240.

You can use either ring and pinion and just pick what speed you want to hit in each gear and there are several ratios available.

I think 52 mph, 84 mph, 124 mph and 166 mph would be perfect for a 350 to 400 horsepower engine. That is a smidge taller than what I have.

Less turbo lag.

For my 356-930 street rod I changed 2nd from the stock 1.304 to 1.737 and 3rd from 0.893 to 1.208. At redline, MPH is now:
1-50
2-70
3-96
4-177
About $500/gear
For the street, the close ratio keeps the engine high in the HP/torque region. Rate of acceleration in both 2nd and 3rd is way cool.
The downside is the drop in torque from 3rd to 4th resulting from the aprox 3050 RPM drop. (Stock drop is approx 2350.) Acceleration wise, it feels like you dropped into overdrive instead of the next gear.
You're trading speed for acceleration. This said, the end of 3rd gear is reached in less than 10-seconds and is also well above the speed needed to irritate any highway patrol officer.
IMO, the gear change/rebuild of the 930 trans is not a DIY project. Have a 930 transmission pro do the job. I didn't have a pro do mine and the engine/transaxle was out 2X in 3X before it was right. Not a rewarding experience.


A supplier of gears (and charts to show one what gear ratio changes will accomplish):
Guard Transmission
PO Box 280
Meadow Vista, CA 95722
888-894-3277
530-878-4499
http://www.guardtransmission.com/
No affiliation.

With the gear info, it might be helpfull to post the rpm at 70 mph.

Yes, that would have been good to provide.
All speeds noted are at 6600 RPM.

At 70MPH, I'm spinning about 3200RPM in 4th gear with the 8:41 R&P, stock gears and 24.8 in. outside diameter tire.

Ditto on 841. It keeps the motor from lagging in 4th gear without getting the Highway patrol interested and keeps the clutch from early replacement. Top speed is way beyond driving on most roads limits and will not top out on most tracks if you are doing that sort of thing. With the stock gears you will never redline even at Road America's long straights no matter if you even have over 1000 HP. With a 841 ring / pinion your problems ( turbo lag, not enough red light jump ) are solved using the stock trans ratios gears unless you are on European unlimited speed roads ( or Bonneville flats type of roads ) with lots more HP to get it to redline.

I have the shorten R/P. Try to get the German ones, the Italian made ones will whine according to my wrench. Get the R/P and be done with it. You don't need no stinking G50/50. It will eat 95% of the cars on the road with a little bit and pieces of bolt-ons if you are interested in that sort of red light drag.