Transmission Compatibility G87/21

[Scott Davis]

I've seen some discussion but not related to this specific model of Porsche transmission so I just want to confirm. The G96/01 is obviously compatible with the LS and adapters from KEP but has different bellhousing pattern then G50. Also the fact that the G86/01 from the Boxster is basically the same as the G96/01 has been confirmed several times.

My question is on the G87/21 from the newer S models and slightly better gearing. I would like to confirm there are no issues using the standard G96/01 adapters/clutches/starters etc with the G87.

I think the side shift is on opposite side...any thoughts that could be a problem in the APEX?

I plan to buy first thing tomorrow.

 

[Scott Davis]

A new alternative if anyone wants to consider is the new G81 transmission from the new Cayman and Boxster - also a Gertrag 6 speed. It comes with an internal cooling pump and has the same bellhousing pattern as the G86, G87, G96.01/00 so the adapter plates are already created. As with the G86/7 this box would not be inverted like the G96/01 would be. The difference will be in Clutch fitment with the flywheel - it will likely be different than G86's. GBOX said it shouldn't be a problem but they could likely build a flywheel for $1k (don't quote me on that - it was his off the top of the head estimate).

If anyone is interested and to give you an idea, I found a practically new 3k mile 2014 G81 6 speed for $5k on Ebay -an easy search will find it.They will throw in the clutch and pressure plate for $200 but will likely not handle high torque. New from Porsche @$7k ish. I didn't want to deal with the development of the flywheel but doesn't seem outrageous $$. Gearing should also be looked at.

 

[Justin]

Dumb question:

Where do the half-shafts come out of the Boxster transmissions versus a flipped 911 transmission? Does it make a difference for these cars?

 

[Scott Davis]

Dumb question:

Where do the half-shafts come out of the Boxster transmissions versus a flipped 911 transmission? Does it make a difference for these cars?

My understanding (haven't done it yet), is that with the inverted box the shaft angle is larger (engine allowed to sit lower though). With the Boxster trans the engine sits slightly higher I believe but the shaft angle is a little straighter/lower (not necessarily good on both accounts). Potentially could have frame interference issues here also depending on how things line up since it was not designed with a low sitting trans. Someone with more experience might want to confirm the above.

 

[Tim]

Guys,

Be careful here. The transmission bolt spacing of top two vs. the bottom two is slightly different on a G96/97 Porsche, perhaps the G50 as well (not sure).

Which bolt pattern is supposedly the same? Is it:
A) Cayman/Boxster and G96/97 in their stock OEM mounting?
B) Cayman/Boxster in OEM mount and G96/97 inverted to work in a mid-engined car?

You can get an adapter plate for either I would assume, but just make sure you do your homework on this one...

Tim