stub axel interchange?

[lonewolf]

Hi guys.
question:
is the 6 bolt stub axel attached to the 915 tranny on a 80sc interchangeable with the earlier 4bolt from a 72 915.

can you put a 6 bolt stub axel on a 72-915 tranny?
reason is i have a tranny from my 72 parts car thats in ex cond and wondering if i should sell or keep as a spare for my 80sc

i know about the speedo differences

thanks to all.

[Fishcop]

Short answer?

Sort of

You can do it by changing either the gearbox output flanges or the stub axles at the wheels. You may encounter spline issues with the g/b flanges especially with a limited slip diff - it's better to change the stub axles (very easy).

And before you ask - no you can't put a four-bolt CV on one end of a drive shaft and a six-bolt on the other end

Given that you could use the parts off your current box, then yes I'd hang on to it as a spare.

[lonewolf]

ok thanks
you know what i,m talking about . some people call them different things so i used stub axel as sort of a more general term (not to insult anyone here. i know there are a lot of brains here)
i would rather change output flanges. then i can sell stub axels with control arms. and the big 4 bolt axels.
to me having both trannys side by side , exchanging the output flanges if possible seems easier. 1 bolt.
it,s the internal splines in the tranny i,m wondering about.
thanks for you answer.

[Walt Fricke]

I'd worry (well, worry is a bit strong) about output flange splines too. Somewhere along the way Porsche changed the 915 output flange splines. Early ones had larger (fewer) splines. Later ones have finer splines. When Quaife's were new they only made a small spline version. Guys with earlier transmissions (like me with a '77) had to buy fine spline output flanges in order to use the Qauife at that time.

My guess - you can't swap them. But if you wanted a 6 bolt CV for your earlier transmission you could find a coarse spline 6 bolt output shaft.

Walt

[lonewolf]

do you know what year had course spline 6 bolts cv, or what year did they go from course to fine?

[Walt Fricke]

I don't.

But '78 is as good a guess as any, since that is the year the bolt that holds the flange in changed per my small parts manual (which doesn't call out the flanges separately).

A guy simply needs to know there is a difference, and then pull the flange and look to see what he has. With all the parts and assembly interchangeability Porsches have, and given the age of things, you can never be really sure what you have until you look.

Walt

[Early_S_Man]

Unless the '72 has been changed to a '76 or later LSD or open diff. ... the fine spline output flange won't fit the coarse splined stock diffs fitted in 1972.

[lonewolf]

walt
you mentioned a 6 bolt course spline output flange
have you seen these?
do you know what year had them?

[Early_S_Man]

I believe the late'75 models had coarse-splined 6-bolt flanges.

[Walt Fricke]

My Euro '77 (rolled out of the factory in the summer of '76) had the coarse splines and 6 8mm bolts. Or so I believe, because I had to round up a pair of fine splined output flanges when I put a Quaife in it.

But, Lone Wolf, you simply can't put all your faith in what was supposed to be the case in what year. You need to look at what you have to know what is compatible with it.

For a tranny not in a car this is simple - one bolt holds it in. If it wasn't late and so cold in my unheated garage, I might even go pull a flange off my spare tranny, which is the original from my car, to confirm my memory.

Walt

[lonewolf]

i understand completely walt.