964 G64/G50 to Early Case - Flywheel and Clutch

[scootermcrad]

Well, sometimes big ideas require big solutions and I've officially hit a wall.

The broad overview is, I'm looking for a flywheel and clutch solution that will bridge the gap between an early 911 mag case with a 6-bolt crank (2.2L to 2.5L hi-comp twin plug build) and a G64 from a 1990 964. G50 from a 964 would be similar. Yes, I know this is unusual.

Here's what I know. The transmission bolts up and an off the shelf pilot bearing pressed into the crank is just about perfect to support the input shaft with basically no modifications that I can see. So the major problem is the abundance of space now created in the gearbox bell housing. The dual mass flywheel from the later 964 is much thicker than the early 6-bolt flywheel and obviously the mounting pattern is completely different on the later flywheel. Clutch/flywheel diameter does not seem to be an issue (yet).

Initial rough dimensional thinking suggests that spacing a standard 6-bolt flywheel out from the crank flange enough to where the clutch can actually be actuated, and then repositioning the starter ring gear might get me there, but I need to take more measurements. And a spacer like that would be a heck of a machined part to mate and balance. A CAD study is next on my list. I'll need to get some flywheel and clutch dimensions to pull that off, but I'll cross that bridge when I come to it.

For the sake of discussion, let's not get caught up in electronics or what it's going in. I've got a solution for all of these things (requires a lot of work). Let's just focus on the mechanical part of this.

Has anyone tried this adaptation? Seen it done? Anything? I've talked to Patrick Motorsports and they don't have a solution for me. I've reached out to Kennedy Engineering, but haven't heard back from them yet. So I'm pounding the pavement, so to speak, to understand a potential solution for this. Obviously any 3.0L and up motor will offer a solution for me, but I'm not ready to give up quite yet. I have to believe that SOMEONE has tried this at some point, successfully or unsuccessfully.

Thanks for any help! I know it's an out there idea, but it doesn't mean there isn't a solution.

[mepstein]

I would circle back to Kennedy. They do those kind of things all the time. I've never come across another company that does such a wide variety of adaptors and special orders at a consumer level. Did you call them or just email.

[scootermcrad]

Originally Posted by mepstein

I would circle back to Kennedy. They do those kind of things all the time. I've never come across another company that does such a wide variety of adaptors and special orders at a consumer level. Did you call them or just email.

I just found out about them and inquired via email. I will give them a call on Monday, unless they happen to be open tomorrow. Thank you! I was a little bit surprised to hear that PMS didn’t have a solution or even a recommendation. But, this is a pretty unique pairing, so maybe I shouldn’t be. I really don’t have an expectation of anyone having this ready to go in a box on the shelf, that’s for sure. Fingers crossed!
Thanks again!

[john walker's workshop]

I know Kennedy used to, maybe still does, weld a 6 bolt 911 flywheel center into a vw bug/bus flywheel to adapt a 911 to a bug/bus trans. So possibly they could weld a 6 bolt center to a late G50 style flywheel so you could use the stock G50 clutch assembly. You're good at fab, so maybe you could do it at home.

[scootermcrad]

Originally Posted by john walker's workshop

I know Kennedy used to, maybe still does, weld a 6 bolt 911 flywheel center into a vw bug/bus flywheel to adapt a 911 to a bug/bus trans. So possibly they could weld a 6 bolt center to a late G50 style flywheel so you could use the stock G50 clutch assembly.

That’s good to know! Thanks for the heads up!!

[scootermcrad]

Kennedy did get back to me with more questions. They didn’t tell me “no”, and I provided more info. I’m going to try and get them on the phone to talk through the adaptation.

[scootermcrad]

Ok. It seems Kennedy also has nothing for me. So, I’m going to take a step back and take some real measurements and put all this in CAD so I can really see what these two look like together.

Further thinking, almost seems like a few small modifications to an existing single mass or lightened 964 G50 or G64 flywheel to accept a small crankshaft flange adapter, would do the trick. Need to look at the thru hole in the flywheel and compare the bolt circles of the two bolt patterns. Measurements tell me an off the shelf pilot bearing/bushing can sit right in the 6-bolt crank flange and accept the nose of the input shaft from the G64.

Looks like I’m on an island, here. I’m a little surprised.