Torsion bars

[Gfhug]

The torsion bars are handed, marked LH and RH, yet they look identical.
Is there something in their manufacture that makes them work only on one side of the car?

What would happen if they were fitted to the wrong side? (No, not even I plan to do that)

Thanks in advance for enlightening me

Geoff

[andrewh]

interesting spin on the issue. I had assumed it was to identify then for refitting after they had been used and taken on a set. I doubt that they are handed from new but you never know.

[Jaglex]

they seem to have different part numbers.
But is this only to get it with the correct mark "left" or "right" on it?

[Hugo]

As far as I know they start off the same, but acquire a 'set' after use, so they don't like being loaded the wrong way thereafter. That doesn't explain the different part numbers though, unless there is some subtle difference in the alignment of the front splines with the rear splines?

[288gto]

For what it's worth, 911 torsion bars are handed Left and Right. It was my understanding that they were pre stressed at the factory to improve the available elastic deflection of the torsion bar. If this was the case with Jaguar ones that would account for the different part numbers.

Having said that, as with everything I post on here,I might be completely wrong.

Simon

[Simon P]

Well that certainly puts on new twist on things.....

[andrewh]

on further reflection, I would think they are prestressed. If it was a matter of identifying them for stripping and rebuilt I would expect the manual to instruct you to make sure you fit the correct one back in the right place. interesting to find out.

[Gfhug]

Thanks all (even Simon P ) for your thoughts. Pre-stressing seems to be the reason, I wonder if the new, upgraded ones SNGB sell are pre-stressed too?
The manual certainly doesn't seem to have any comments about fitting to the correct side and the torsion bar brackets at the rear of the bars are the same part, so no differences there to the bars.
All rather, technically, interesting.

Geoff

[PeterCrespin]

Pre-stressing seems to be the reason, I wonder if the new, upgraded ones SNGB sell are pre-stressed too?

'Scragging' is part of spring making. There have been some good threads on J-L by a spring maker IIRC, or at least a metallurgist. Assume it can be Googled too, but where's the fun in that?

[Gfhug]

"The process known as ‘scragging’ or ‘pre-stressing’ or some- times as ‘pre-setting’ or ‘overstraining’ may be described as the treatment given to torsion bar springs and also to helical compression and other types of springs when they are loaded to such an extent as to produce yielding of the surface layers of the material"

I've learned something new and knew I could rely on PC at some point to give us the benefit of his knowledge. Thank you Peter.

Considering this I'm surprised there is nothing more than a small LH or RH to identify them nor anything in the manual by way of a warning as to which side they should be fitted.

Geoff