Two Questions About Porsche Transaxles

[Mike Smith]

1) I've seen multiple posts indicating Porsche AWD transaxles (like G96.30, G96.31, G96.50, G97.31, G97.35 & G97.50) must be converted to 2WD (capping the front shaft) before being flipped and run backwards in a mid-engine configuration. What is the reason for this? I know room in the rear may be an issue but I was actually toying with the idea of throwing a v-drive in the rear and sending another shaft to the front wheels for a mid-engine AWD set-up. Is this not doable because it would damage the transaxle somehow?

2) I would like to use an LS7 but am also interested in a PDK transaxle if possible. Is this possible? Is there a computer controller that needs to interface with the engine or can it control the PDK independently regardless of engine? if it is possible, what transaxle model numbers should I be looking for?

Thanks in advance.

 

[Eric A.]

The AWD versions are somewhat longer than the others so unless your car is really long in the rear you won't be able to do what you are suggesting unless you install it in the same way as it was originally in the Porsche.

The PDK cannot be run upside down so you would have to install it as a rear engine drivetrain. I don't know if anyone has designed a controller for them but since Porsche is very tight with information it might not be very easy to do.

 

[Mike Smith]

Thanks Eric.

I am actually building a Lamborghini Murcielago replica. I asked my question on this forum because you all are very technical and seem to know your stuff. Not sure if I would have room for the tranny in that config or not either. I'd have to measure it.

As for the PDK, I figured you wouldn't want to flip an automatic so I am not surprised by your response. Is there a ring gear that can be reversed instead of flipping the tranny. Sorry if that is a dumb question. I don't know much about these units yet.

 

[Mike Simard]

I am actually building a Lamborghini Murcielago replica.

Doesn't that car use a trans going forward with a takeoff going back to a diff tucked next to the back of the engine?

(BTW, how does everyone keep up with all the mikes here?)

 

[Eric A.]

I don't think there is room to flip the ring gear. If the PDK was used in the Cayman you could use that one as that car is already mid-engine. I will have to ask my friend who is a Porsche mechanic.

 

[Lynn Erickson]

2013 Boxster and 2014 Cayman use PDK

 

[Mike Smith]

Doesn't that car use a trans going forward with a takeoff going back to a diff tucked next to the back of the engine?

(BTW, how does everyone keep up with all the mikes here?)

Yes, the OE configuration is longitudinal but I don't think it is realistic to replicate that feature. I just want something fast and mid-engine.

I'll update my Display name to be less generic.

 

[Mike Smith]

2013 Boxster and 2014 Cayman use PDK

Yes, thank you. Would these transmissions hold up to an LS7? I kind of doubt it but I really don't know for sure. LS3 may be a safer way to go.

Thanks again for all the responses. You all have a really great community here of knowledgeable people.

 

[Eric A.]

I checked with my friend who is a Porsche mechanic and racer and he says the PDK is strong but getting the electronics to work will probably be a nightmare. It is linked to the engine and most other systems in the car and will take quite a lot of electronic engineering to develop a controller for it.

 

[Scott]

The only PDK swaps I've heard of included the Porsche engine. although the mechanical's would be easy to fabricate to mate up the electronics will not be a trivial matter to deal with.

There are other dual clutch gearboxes out there but all are electronically controlled so any gearbox you pick will likely have a heap of electronic issues.

 

[Leon]

my 2 cents worth, run a conventional trans forward with a transfer case or "V"drive to the rear diff, you will save yourself a heap of drama and money. There is a heap of full time AWD systems available these days that are a fraction of the cost and complexity of the Porsche stuff you are looking at. Sounds like a great project good luck.
Cheers Leon.

 

[Graeme Stebbing]

Hi Mike are you aware of this build by KEV KEV worked a treat.
Kit c e n t r a l :: Lamborghini Diablo And Other Kit Car Builder's Support Group

 

[marc]

I know you can run the engine reverse rotation from the boating world. would that work?

 

[Eric A.]

It is not a good idea to run the gears in the transmission the reverse of how they were designed. Especially the ring and pinion. Running the gears on the back side puts stress on other parts and the tooth shape is not designed for that.

 

[Leon]

You don't need to run anything in reverse rotation. You just flip the diffs, they still turn and load the teeth in the right direction or you do it through the transfer gears so your drive shaft or shaft's turn the right way, its pretty simple. Cheers Leon.

 

[Scott]

With most gearboxes with helical hears you can't reverse the rotation of the input shaft as there is inadequate thrust surfaces on the opposing side of the gears. I've not seen a porsche/vw/Audi gearbox that allows you to flip the carrier since the old 3 and 4 speed bug transaxles.

 

[Michel]

The 915 porsche 5 speed gear box can have his crownwheel pinion flipped of and accept also
Quaife LSD with some light grinding into the case for blot clearance ( nothing big )
An electric oil pump plus cooler helps a lot in easier gear change after 1 hour running