I understand that the bars should not be switched from one side to the other (pre-tensioned or something). When I pulled mine the other day they were stamped R and L but the one marked R was on the right side when standing in the front of the car looking back at it and not as oriented from the driver seat like everything else is.

Is this accurate?

So the theory behind this (as far as I can tell) goes: "so the metal gets used to twisting a certain direction and if you reverse this twisting it's more likely to fail." (Reading again i see a "pre tensioned" so my rant below may not have anything to do with this... I suspect it doesn't really matter that much though, I don't really know of any treatment to add hysteresis to the elastic portion of the load curve)

I've heard this a bunch before, and I always try to follow it because hey, why not? When I changed my axles I never knew which way the replacements had been installed and havn't had a problem in several autocrosses and a lot of spirited driving. Also none of my engineering textbooks mention anything even resembling this effect.

I'd put it back the way you found it and not worry too much.

Fairly well documented in the factory manual stating that they are "pretensioned". They should be left and right from the drivers seat.

Bruce Anderson was asked this question a number of years ago, about 911 t-bars specifically. His reply was that the new bars are not directional. When you use the bar on one side of the car, the bar is stressed in one direction. Reversing that stress can lead to early failure.

So the bars should be put back in where they came out of.

--DD

Thanks for the replies - I swear mine came out reversed (R & L). I was being very conscious of this as I had read before I pulled them not to switch sides. My '72 is very unmolested (I have owned it since '78) but anything is possible. It is even possible I had a brain fade.

I will re-installed the "R" bar on the right side as seen from the driver's seat (and the L on the left).

Cheers!

Page from the FM...

Click to view attachment

CAUTION!
Torsion bars are pretensioned during production...

Yep - agreed - I think I even read it in Haynes manual so I was being careful. But I will get them installed properly when the suspension comes back from powder coater.