I haven't had the opportunity to dismantle my front end... yet. I was under the impression that...

1. The torsion bar spline fits the leading edge of the control arm
2. The 914 torsion bar spline is smaller diameter than the 911 one

So the 911 arm is not identical to the 914. I see in PET that the part number for the 914-6 control arms match the 911.

I'm posting it because a reliable 914 source locally has told me that they are interchangable (911 / 914-4) but I didn't believe so.

Thanks to anyone who can clear this up.

The only difference between a 914/4 control arm and a 911 control arm are the splines for the torsion bars. The 914/6 uses the 911 control arm, so it has the 911 torsion bars.

Other than that one item, they are interchangeable. I have 914/4 control arms on my car with 911 struts and a 911 aluminum cross member. No problems getting anything to fit.

cheap way to increase front torsion bar from 17mm to 18.8mm

My brain must not be functioning well this morning.
So the simple answer is - a 911 torsion bar will fit right in a 914/4 control arm?
Yes, or No?
Thanks!!!

No ... they are splined differently.

911 arm requires the 911 torsion bar

914 arm requires the 914 torsion bar

The 911 assembly will fit the 914, but you have to have the complete 911 arm (arm, closing caps, torsion bars, adjustors )

The answer is no.

Not sure if this is splitting hairs, but the 914-6 tortion bar isn't the same as the 911. Yes it has the same size splines, but it has a lower torsion strength to acount for the lower 914-6 weight.

Thanks everyone. for ringing in to.

Looks like my local 914 guru's got it wrong.

One last variant, I'm not sure any of us would see it, but apparently some 914-6 GT cars had torsion bars with different diameter splines at either end of the torsion bar. Not sure what the point was, maybe it was to save weight.

The a-arms are interchangeable as long as you change the whole arm, including the torsion bars.

I have a complete 911 frontend, including 911 a-arms and 911 torsion bars.
It all bolts directly into the 914.

If i'm reading your post correctly, that's what your "914 source" told you, in which case he was right.

For racing purposes, the torsion bars would have a higher rate to control suspension movement / body roll when highly loaded as in a corner. Control of body roll is critical to maintaining the maximum tire patch on the road (minimize camber changes).

And Andy, I read it as they wanted to stuff 911 torsion bars in a 914/4 control arm or visa versa.

I didn't read it that way at all.

Well, English is not my first language, this must have been lost in translation.

It was under the context of replacing a bent 911 arm. So no they aren't the same.

I've got a 911 front end now to go into my teen, but one strut and contol arm didn't survive.

Clay,
Did you have to modify the access cover to fit aluminum cross member? I've read that 914 cover plate won't fit with 84-89 911 aluminum cross member.
Also, are the late (84-89) 911 control arms made of aluminum as well?
Thanks,
Mike

I have never seen an aluminum control arm on a 911. the 964 and 993 have them, but the suspension is much different and won't interchange with the earlier 911 and 914. The tray I used is from a 911 with the aluminum cross member and not the 914 one. IIRC it fit fine with no mods.