964 G64 Transaxles - Ins and Outs

scootermcrad · 02-27-2023, 07:54 AM

Hey everyone!

I'm trying to educate myself on early first gen G64 transaxles. I didn't see a lot of discussions on here, outside of converting to C2 configurations for RWD. Not much info on stock configurations, gearing, LSD, etc. I'm interested in the early 964 models, G64.00 type, and if there's anything specific to be on the lookout for when purchasing one. Are their failure points that are typical? Standard service items that are guaranteed right out of the box? LSD upgrades, if not stock? Anyone go through one themselves?

I'll be in the market soon, and I just don't want to fly blind and pickup something that's been sitting in the back of a Ford Pinto wagon for 21 years as a "ran fine when I pulled it", only to find out that every one of these had prefamulated amulite issues and the noble trunions always jammed up with the panametric fam, if left to sit too long.

Thanks for any help! 915 transaxles are about my knowledge limit, and even that is pretty sad. So any pointers or recommendations would be helpful.

Dan J · 02-27-2023, 08:18 AM

They're pretty robust The LSD is variable, controlled by the ECU
Eventually they'll need synchro etc standard G50 stuff
Need a number of special tools to work on them

Tyson Schmidt · 02-27-2023, 08:54 AM

They use small 100mm output flanges. I would ditch the ABD differential and use an LSD with 108mm drive flanges
Other issue is lack of aftermarket gears. They’re different than G50 gears. Not a problem if your keeping them stock.

scootermcrad · 09:18 AM

Quote:

Originally Posted by Dan J

They're pretty robust The LSD is variable, controlled by the ECU
Eventually they'll need synchro etc standard G50 stuff
Need a number of special tools to work on them

Good info and good to know! Thanks!

scootermcrad · 02-27-2023, 09:31 AM

Quote:

Originally Posted by Tyson Schmidt

They use small 100mm output flanges.
Other issue is lack of aftermarket gears. They’re different than G50 gears. Not a problem if your keeping them stock.

100mm flanges. Ok! That's good info! What did a standard G50 use? Not familiar with them.

I would be keeping it stock, but I was curious if the G64.0x was only offered with one gearing option from the factory. I didn't see anything else listed, number-wise, that would suggest it was offered in any other gearing configs. I think the only "improvements" I would consider making might be anything to help with control or robustness at the time of rebuild.

Quote:

Originally Posted by Tyson Schmidt

I would ditch the ABD differential and use an LSD with 108mm drive flanges

Did you mean AWD? If not, what is ABD? Sorry, not familiar with that. Thanks!

Matt Monson · 02-27-2023, 09:34 AM

Read this thread. You’ll find it very informative and useful.

https://forums.pelicanparts.com/porsche-911-technical-forum/1132550-c4-awd-drivelines.html

winders · 02-27-2023, 09:37 AM

Quote:

Originally Posted by Matt Monson

Read this thread. You’ll find it very informative and useful.

https://forums.pelicanparts.com/porsche-911-technical-forum/1132550-c4-awd-drivelines.html

You do realize that scootermcrad started that thread too....

Matt Monson · 02-27-2023, 09:41 AM

Quote:

Originally Posted by winders

You do realize that scootermcrad started that thread too....

Nope. Didn’t even look. Though it leaves me wondering why he didn’t just bump it…

wallra · 02-27-2023, 11:08 AM

https://rennlist.com/forums/964-forum/1322309-g64-gearbox-overhaul.html

scootermcrad · 11:17 AM

Quote:

Originally Posted by winders

You do realize that scootermcrad started that thread too....

Yep! That's me!

That was the fact finding thread that led me to starting this, and what will lead to a build thread that will ultimately lead me to needing therapy.

Quote:

Originally Posted by Matt Monson

Nope. Didn’t even look. Though it leaves me wondering why he didn’t just bump it…

I didn't bump it because it was all over the place with a ton of information about the C4 AWD components and systems as a whole. That extremely helpful thread helped me make some pretty serious commitments, which have brought me full circle to asking specifics about the G64.00 in particular, since it is a very different transmission from the rest.

Hope I'm not being too repetitive. Just wanted to get pretty specific. Probably going to be a short thread.

scootermcrad · 02-27-2023, 11:17 AM

Quote:

Originally Posted by wallra

https://rennlist.com/forums/964-forum/1322309-g64-gearbox-overhaul.html

OH OH! Thank you! I appreciate that!

Matt Monson · 02-27-2023, 11:18 AM

Quote:

Originally Posted by scootermcrad

I didn't bump it because it was all over the place with a ton of information about the C4 AWD components and systems as a whole. That extremely helpful thread helped me make some pretty serious commitments, which have brought me full circle to asking specifics about the G64.00 in particular, since it is a very different transmission from the rest.

Hope I'm not being too repetitive. Just wanted to get pretty specific. Probably going to be a short thread.

Not trying to be critical, though you may find people repeating details from that thread because they didn't see it the first time.

There's very little you can do to modify or upgrade a g64.00 for performance. While the synchros are G50 based, most everything else about it is unique to it. There's no special ratio gears or final drives available. What you get is what you get.

scootermcrad · 01:34 PM

Quote:

Originally Posted by Matt Monson

Not trying to be critical, though you may find people repeating details from that thread because they didn't see it the first time.

There's very little you can do to modify or upgrade a g64.00 for performance. While the synchros are G50 based, most everything else about it is unique to it. There's no special ratio gears or final drives available. What you get is what you get.

All good, Matt! Your help has been appreciated in the previous thread, as well. Yourself and all the others that contributed to my education in that thread was really what solidified my plans, and the direction to go with this earlier 964 version of the gearbox over the later 993 trans. I totally understand the constructive criticism. Just didn't want to drag everyone through multiple pages of un-related information to get to the heart of the questions, which are: what am I looking for, and what should I look out for when looking?

The good news is, I think the questions have been pretty well answered already. All the G64.00 transaxles seem to all be basically the same. I'm totally good with that. In fact, NOT doing a bunch of upgrades sorta makes me happy, in this particular situation. I can turn my focus (and budget) to other parts of the project.

Although... you just made me think of a couple other questions. Shifters and instrumentation. I'm assuming any aftermarket shifter that works for the G50 will work, (WEVO, etc.). I'll deal with instrumentation later, though.

EDIT: Looks like the shifter kits are very different. I guess that makes sense. Not much available. Looking like the Sleepwalkers kit might be the best bet.

porschyard · 02-27-2023, 04:18 PM

Quote:

Originally Posted by Tyson Schmidt

They use small 100mm output flanges. I would ditch the ABD differential and use an LSD with 108mm drive flanges
Other issue is lack of aftermarket gears. They’re different than G50 gears. Not a problem if your keeping them stock.

I know what you are trying to describe when you say ABD but that’s not a correct description on a G64, ABD is on the C2 993 series cars and when equipped with that option it applies a rear brake on one side or the other during wheel spin but IIRC it is only at low speeds say up to 40mph.
As far as installing a LSD in a G64 I think it can be done but again IIRC takes a lot of mods.

scootermcrad · 02-28-2023, 03:38 AM

Quote:

Originally Posted by porschyard

I know what you are trying to describe when you say ABD but that’s not a correct description on a G64, ABD is on the C2 993 series cars and when equipped with that option it applies a rear brake on one side or the other during wheel spin but IIRC it is only at low speeds say up to 40mph.
As far as installing a LSD in a G64 I think it can be done but again IIRC takes a lot of mods.

I hadn't heard that ABD term, and a G00Gle search didn't bring me any results. Thanks.

Yeah, most likely, I won't be opting for any major modifications beyond stock spec. I read through a couple rebuild/refresh threads and found that these G64 transmissions seem to hold secrets about their condition, specifically the AWD clutch packs, until you open them up. So it is probably best that I would consider any purchase to be of "core value" unless it has known history before removal. Looks like a rebuild, even if attempting myself, could get expensive pretty fast, if there is any major issues. I hope I'm wrong about that finding, though. Either way, I think for my purposes, stock configuration will be fine and I would make sure it's complimented with a nice flywheel and clutch assembly, and a nice shift kit.