6 speed trans and 993 engine, Inverted 6 speed trans from a 993 Options

[Miguel K R]

Hi,
I am going to fit a 6 speed G50 trans (inverted) from a 993, with a 3.6L varioram engine.
I will have to use a cable shifter (from Patrick Motorsports or CableShift. California Motorsports modifies the trans for a cableshift running from the side but that is excluded for me as I am based in Europe and would have to send the trans to the US to be modified, and back to Europe).

My question is if there is enough length for the long nose of the trans . I know I have to cut the trunk for the inverted trans.
I have seen at the Renn... forum a car which had the bellhousing and shaft shortened at Patrick Motorsports in 2005 but they did not explain if that was necessary, or if as an alternative, the opposite side could have been shortened.
CMS states that shortening the bellhousing is not recommended for G50's later than '89 due to starter compatibility issues. I guess the issue is the elimination of the guide bushing for the starter when the bellhousing is shortened, and that is not an issue for '89 and earlier cars, because High Torque Starters which do not use that bushing are available.
For '90 and later cars I have not been able to find those starters.

Can someone help with information on the application of the 6 speed trans from a 993 ?

I am building a 914-6 GT replica and already started applying the fender flares, and modifying the engine cover with a second grille.

[ClayPerrine]

I researched using a G-50 6 speed, and decided to go with a Cayman 6 speed instead.

Reasons for this:

1. The G-50 will not bolt directly to an air cooled 911 engine upside down. The four bolt pattern for the transmission is asymetrical. You have to weld up the bolt holes and redrill them. And there is not a lot of meat where you have to drill the new holes, so I worry about the structural integrity of the trans case.

2. The G-50 is longer. You can't get a 6 speed between the engine and the rear of the 914. The Boxster/Cayman G-86/21will fit. It doesn't leave much room behind the trans, but it will fit.

3. The cable shift setup on a G-50 is an add on aftermarket item. The Cayman 6 speed was designed for the cable shift.

4. I would have to cut the rear trunk floor to fit the G-50. With the G-86/21 it fits under the unmodified floor.

5. This is the big one.... Cost. A clapped out G-50 fit only for a core to rebuild is going for over 10K right now. A ready to run, low mileage Boxster/Cayman G-86/21 is going for about 4K.

I would recommend you look at a Boxster/Cayman trans for your engine setup.
And the Varioram height issue can be overcome by putting a big dimple in the engine lid.



Coming in January, I will be pulling my engine/trans out to put in the mark II clutch assembly. We are also making adapter plates, starter mounts, and flywheel spacers for the coming kits. Yea, I know.. its taking a long time. Give me a break. I am enjoying driving it. (IMG:style_emoticons/default/driving.gif)

[Miguel K R]

I researched using a G-50 6 speed, and decided to go with a Cayman 6 speed instead.

2. The Boxster/Cayman G-86/21will fit. It doesn't leave much room behind the trans, but it will fit.

3. The Cayman 6 speed was designed for the cable shift.

4. With the G-86/21 it fits under the unmodified floor.

5. This is the big one.... Cost. A clapped out G-50 fit only for a core to rebuild is going for over 10K right now. A ready to run, low mileage Boxster/Cayman G-86/21 is going for about 4K.

I would recommend you look at a Boxster/Cayman trans for your engine setup.

Hi Clay,
Thanks a lot for your help.
I am now convinced to forget my 6 speed G50 (and sell it), and buy a 6 speed Boxster/Cayman trans.
I searched a bit about this and people were mentioning that an adaptor plate was not available, and a there was an issue for fixing the starter.
Were you able to buy an adapter kit, or did you have to design your own, and do you have drawings ?

Thanks in advance for your help

Miguel

[ClayPerrine]

I researched using a G-50 6 speed, and decided to go with a Cayman 6 speed instead.

2. The Boxster/Cayman G-86/21will fit. It doesn't leave much room behind the trans, but it will fit.

3. The Cayman 6 speed was designed for the cable shift.

4. With the G-86/21 it fits under the unmodified floor.

5. This is the big one.... Cost. A clapped out G-50 fit only for a core to rebuild is going for over 10K right now. A ready to run, low mileage Boxster/Cayman G-86/21 is going for about 4K.

I would recommend you look at a Boxster/Cayman trans for your engine setup.

Hi Clay,
Thanks a lot for your help.
I am now convinced to forget my 6 speed G50 (and sell it), and buy a 6 speed Boxster/Cayman trans.
I searched a bit about this and people were mentioning that an adaptor plate was not available, and a there was an issue for fixing the starter.
Were you able to buy an adapter kit, or did you have to design your own, and do you have drawings ?

Thanks in advance for your help

Miguel

Miguel,

I had some help, but we ( @partsguy22 ) and I were able to make the adapter parts. It took months, and we are planning on selling a kit after we make and install the mark II clutch assembly. You can see the whole thing in my build thread. http://www.914world.com/bbs2/index.php?showtopic=279084

It's not easy, but it can be done. And the kit won't be cheap either.

Clay