G50-50 install. in a pre 1989 & 930 differences

[Stophos]

Can anybody tell me what is involved in fitting a 1989 G50-50 in an earlier 911/930. Also when purchasing a 930 tub is there any significant differences in the 77-88 models.
Thanks for any help and insight.

[dean]

I have never done or seen a G50-50 install. I have heard and seen pics and they are longer than a G50. It depends on what car you are installing the G50-50 in. There is a difference in the 78 on 930's. The rear end section is longer moving the motor rearward. I have installed a G50 into an SC and it was a fair amount of work. But well worth it. I would do it again.

So you might have to cut the torsion tubes and go coilovers and reshape the lower seat area depending on the year car.

[Stophos]

I understand that the torque tube would need to be cut although I not sure of the details. I think you can still use torsion bars but they must be shorter ones from non-wide bodied cars. I do have a coil over setup so this is not a factor for me. I am trying to figure wether it would be better to use and earlier model ( less $$) and what year might be better suited) or if I should just hold out for an 89 and avoid the butchering and expense? I would look for a later model tub but I have been told that my coil-over suspension parts wil not fit.

[tiorio]

Darn fine question. The G50-50 is a G50 with internal modification as I understand it. This would mean that the 89 turbo will be significantly different than an earlier tub. From the 911 turbo factory workshop manual:

"A new five-speed transmission has been installed in the 911 Turbo worldwide from Model 89 onward. This gearbox corresponds to the G50/00 Carrera gearbox with regards to construction and repair...[with different gears and reinforcing]....Refer to the Carrera workshop manual for maintenance information."

Based on that it looks like the tub is where the majority of the modifications happened. You're looking at the same process as putting a standard G50 into an earlier tub. 89 also has the hydraulic clutch and associated gear which an earlier tub would not.

Probably not what you wanted to hear...

[Dennis Kalma]

Can't comment directly on your desired change over, but I am in the process of fitting a six speed G50 to an '89, so some of the changes are relevant.

The G50 is longer, I think similar in length to the 930 transmission that used the longer bellhousing and rubber centred clutch. I gather from my research that the bell housing was lengthed around 28 mm, which Porsche compensated for by moving the engine rearward about 30 mm. I have been unable to find out conclusively whether the rear crossmember (by the tail lights) is different, I think it is, but in any event the Turbo engine support bolts are further back and tuck in very close to the sheet metal at the rear of the car.

G50 Carrera's ended up fitting the transmission by collapsing the centre section of the torsion tube and correcting for its reduction in stiffness with some huge honking sheet metal supports that tie into the rear seat area. The torsion bars could no longer meet in the middle of the torsion tube due to the collapsed bit, so Porsche just stuck them out further into the rear fender well, which in turn nessitated different outer fenders to clear the trailing arm removal.

In my case, I figure that the torsion tube collapsed bit gained about 30 mm in length, plus the ability to move the engine rearward (up to 30 mm with modified engine mounts), plus removing the lengthened bell housing (machining the 28 mm off) ought to get me the room for the 63 mm or so that the six speed is longer than the five speed G50.

In your case, you may want to check where your rear motor mounts are, you may actually have enough room for a G50 without modifying your torsion tube. If not, you have several choices. One is to have the housing machined down (people like Patrick Motorsports do that), second is to install the collapsed torsion tube a la the post '87 911's and third, move to coil overs.

There are some pics showing the G50 (shortened) against the 915 and 901 transmissions, but I can't find the thread....search should get you to it....

Hope this helps...

Dennis

[alfizzo]

Stophos,

call bobby hart at california motorsports. he does most of the shorting on the g50. i lost his phone #. does any one have bobby's #?