Thread: Parabolic Springs

For those of you who are more interested in articulation than comfort - or want a cheaper option than parabolics (correctly called "single leaf springs") - you can modify and reset your existing springs (if in good condition). If anyone is interested I can dig up the thread on how I did mine...

Originally Posted by isuzurover

parabolics (correctly called "single leaf springs")

I though they are called parabolic because of the shape of the springs, each leaf is parabolic in shape. Rather then the std being semi-elliptical

Originally Posted by V8Hybrid

I though they are called parabolic because of the shape of the springs, each leaf is parabolic in shape. Rather then the std being semi-elliptical

Not true. Contrary to popular belief, they have a Semi-elliptic curve to the leaf, not a parabolic curve. Why they are (incorrectly) called parabolic springs is they have a parabolic taper to the leaves. The SAE automotive leaf spring design manual (which I used to design my springs) has a separate section on how to design "single leaf springs". They are called this because each leaf acts individually (no interleaf friction) - regardless of how many leaves you have in the spring pack.

Well there you go....learn something new every day. Will have to check that manual out.

I have just put Rocky Mountain parabolics and Pro-comp shocks onto my Series 2A. Very happy. It was well worth it.

Originally Posted by Rover457

.........Has anyone registered a NSW vehicle with Parabolic springs ??
Thanks Rover457

I notice nobody has answered your question! I would be interested in the answer myself, as I have been thinking about this myself.

I suspect the situation is that legally speaking the answer is yes, they need engineering approval, since they are not identical to either the original springs or any that were available as an option. However, it is very unlikely that they would be recognised by anyone as non-standard, with the additional factor that it is unlikely that anyone can easily show that they are non-standard on a vehicle of that age. Certainly they are new, but there is nothing to stop you fitting new springs! I would also point out that ADRs probably did not exist when your 2a was built - didn't they come in in the late sixties! (not sure what effect this has)

This is probably the route taken by anyone who has fitted them - in fact I doubt that the possibility of needing engineering approval would have been considered by them. Perhaps the best source of information would be the retailers of the springs.

I wonder if the "normal spring reset" bloke was thinking more about selling you reset springs than about the legal aspects?

John

Thanks for your answer I thought the same of the resetter, and if it looks like a leaf spring and smells like one, then it must be a leaf spring. Hopefully.