Distance from engine face to rear of flywheel

[sjc]

This may or may not be the right forum for this question, but I figure someone here either knows the answer in his (or her) sleep, or has a car sitting where they could take the measurement off of it trivially.

I need to know the distance from the engine face to the rear edge of the flywheel (rear meaning the clutch side) for a 9-hole flywheel that fits a 915 transmission.

Why do I need this odd bit of info? I'm converting an '86 911 Targa to electric drive, and it's crucial to maintain this distance when the flywheel is mounted on the tailshaft of the electric motor. I got the car as a glider, without engine or tranny, so I had no opportunity to take the measurement myself. I'm hoping someone here can help me out, and thanks in advance to anyone who can.

[Walt Fricke]

What is the engine face? Do you mean the outer or inner lip where the transmission mates with the engine?

Also, the clutch side of the flywheel has a lip on its edge. Measure to that, or to the clutch disk wear surface?

Not a spec. many are likely to know. Given how things normally work, with splines and adjustability, doesn't matter. Unless you are designing something, like you are. Maybe the guys who run 5 1/2" Tilton clutches know.

[sjc]

1) to the back lip of the flywheel (not the clutch surface)

2) I don't have an engine to directly answer the question. I want the distance from whatever portion of the engine face touches the bell housing of the transmission at the point where the bolt holes match up (see picture).

Thanks for any help you can provide.

[billjam]

I only have details for a 3.6 964 engine, but I wouldn't be surprised if it is similar to earlier models. I think you are looking for the dimension from the gearbox mounting face to the end of the crankshaft where the flywheel mounts, that's X in the drawing below. For a 1992 3.6, this dimension is 9.0mm.
Just to clarify, the yellow part is a section through the crankcase and the grey part is a section through the flywheel.

If X is the dimension you want, I guess the next step is to get someone with a 3.2 to check the measurement on their motor. I am sure someone on here will have one partially dis-assembled.
If you don't have much joy here, post this on the 911 Technical Forum - it's much more active there.
I'll attach a pic so you can get an idea of what the flywheel end of the engine looks like.

Sounds like an interesting project. I'm sure there will be some interest here from some quarters. Just don't let the purists beat up on you!

[sjc]

Originally Posted by billjam

I only have details for a 3.6 964 engine, but I wouldn't be surprised if it is similar to earlier models. I think you are looking for the dimension from the gearbox mounting face to the end of the crankshaft where the flywheel mounts, that's X in the drawing below. For a 1992 3.6, this dimension is 9.0mm.
Just to clarify, the yellow part is a section through the crankcase and the grey part is a section through the flywheel.

Aha! Thanks for the picture. X isn't quite what I want, but it's close. I want the distance from the gearbox mounting face to the back of the flywheel, and I can compute that from what's in the drawing and what you've told me. The drawing shows the distance from the back edge of the flywheel to the flywheel mounting face to be 44 mm, and you've said X is 9 mm, so the distance I want, from the gearbox mounting face to the back of the flywheel, for a 3.6 liter/G50, is 44mm - X = 35mm.

Sounds like an interesting project. I'm sure there will be some interest here from some quarters. Just don't let the purists beat up on you!

No blowback so far. I think perhaps partly because I'm starting with a non-functional car :-)

[Grady Clay]

Last time I was at Gbox in Boulder (several years ago), they had a ‘late’ 911 installing an electric motor and batteries.

Most impressive, the owner had an identical (year, model, color, appointments) normally aspirated 911.

I would love to test drive them – back-to-back.


It would be wonderful to see someone ‘electrify’ a C4 with motors for each wheel.
The controller must be capable of exceeding normal Porsche performance.


Best,
Grady

[fanaudical]

Hi:

I have the 2.7L and the 915 gearbox out of my 75 Targa right now. I'm not sure if this is comparing apples and apples for an 86.

In taking measurements, the distance I get from the mounting face to the lip of the flywheel closest to the throwout bearing is 0.650 inches. The clutch wear surface is recessed another 0.140 inches (so that would be 0.510 inches from the face to the wear surface).

Please keep us posted on the project.

[sjc]

Originally Posted by fanaudical

Hi:
I have the 2.7L and the 915 gearbox out of my 75 Targa right now. I'm not sure if this is comparing apples and apples for an 86.

To further complicate things, the transmission I have is a 915/63 ('80-'83), not a 915/73 (what would have been in the '86). My thinking was that something had to remain the same over the years, but I realize now it might not be the distance to the back lip of the flywheel, but rather (as you pointed out in a PM) to the clutch wear surface.

Thanks much for providing both measurements.

I will keep the forums posted as this progresses; I'll start a build thread over in the regular forums.