902/14 + VW Engine in a 911SC!? (915 coarse output flange?)

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BACKSTORY

I know what your thinking....WTF! why would you! lol, ok let me share the back story first....so ive disappeared from the forum for 3 or so years =( but i'm on my front foot again, and i've since bought a 1979 911SC coupe (3.0 180 Bhp) which was last driven on the road in 2007! Great project which I am really enjoying working on =P

It has occurred to me with the car having sat for so long, not only does the engine, fuel and oil system need a full strip down, but so does all of the "running gear" and of course the electrics, trim, etc. Don't even get me started on the body!

So I have decided as I happen to have a 912/14 (1969 LWB 4 speed box with push clutch, and VW T2 camper engine (with mounting bar holes) both lying around, and as funds are currently tight, hey why not fit them!....get the beast driving, get bank some smiles per gallon, and keep project morale up =)

THEN come back to either plenty of welding and/or (of course) the 911 engine and fuel system at a later date, all of which are going to take alot of my time.

THE GEARBOXES

Ok I have both the gearboxes side by side and have started looking at them I have a

902/14 (Manual 4 speed) Coarse output flange for 108mm CV's part number 90133220915/21, output flange face to output face approx 265mm

915/61 (Manual 5 speed), Fine output flanges for 100mm CV's, output flange face to output face approx 245mm

I have two sets of driveshafts, the ones from the SC (495mm with 25 splines, 100mm CV's (32mm), and some from a 1969 (495mm, with 28 splines, 108mm CV's (40mm).

AXLE/CV/OUTPUT OPTIONS

I think my output flanges are fairly long, and this may be a problem? They are 110mm end to end (total length), and approx 76mm for the shaft itself (end of coarse spline to inside of cup face). This makes the cup about 34mm in length. The 915 cups looks to be roughly 29mm, which would be good to reduce the "total flange gearbox width" so i dont have to shorten the driveshafts...?

A) Fit 1975.5 to 1979 "coarse" 915 output flanges. I believe these are shorter in cup length? (same shaft?) and will fit the 902/14? The ones i have seen look a little stubby, so i can only hope they are long enough.

B) Use 914 output flanges, again i believe these are shorter in cup lentgh? with the same shaft?...but i think they have 94mm CV type joint diameter

B1) in which case I would need to find some 94mm CV joints, which are 25 spline and 32mm? Do they make 'em?

C) Leave the 902 flanges on...which are 108, and fit a Grand Jeep Cherokee back prop shaft CV (looks to be 108mm, 25 spline and 35mm), the only issue is my driveshafts are probally too long as the 902 flanges already stick out more output face to output face than the 915....so I would need to shorten the driveshaft or etc.

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If it works I think (A) would be the easiest(?) keeping most of the SC axle in place?....I understand they may be hard to find. Actually that is ok, as I have plenty to do, either dealing with some rust or working on the running gear!

PICTURES OF FLANGES

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[darrin]

why not start by trying to get the 911's existing engine (and transmission) running -- unless you KNOW it was put away broken? Lots of folks have had good luck firing up engines that sat longer than yours. For good/bad, these are the heart of the 911 experience. Next, if engine no good as-is, check out https://www.kennedyeng.com/engine-adapters and see whether they can provide you with a kit to match your VW engine to the 915 tranny?

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Hi Darrin,

Indeed it is in the back of my mind. I have had a 911 engine which sat before for 16 years which went on to be a good engine.

I suppose with mine, the fuel system is already junk, and i figure if it has a good crank, then stripping it and at the very least a full re-seal with checking everything is the best way to keep things that way (i.e not pumping any old debris around a "potentially" good engine.

I may of course go that way, but i figure if i could get the car "running" quick using a VW engine, then that would allow me a nice year or so to really work through the 911 engine.

I guess we will see how we go, i think the axle will be harder than it looks....so it may just end up being all SC afterall, and that aint so bad lol =P

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I took some measurements which may help...

17 teeth coarse spline

A) 74mm

B) 61mm

C) 45mm

D) 35mm

E) 109mm

Of the above B, C and D are the most important, E and A can be different from mine. All dimensions approx, I just did a quick measure.

Hopefully someone will know!?