Sprint anti-roll bar

[StoatWithToast]

Hi all,

We're just in the process of restoring most the Sprint (started out as a few small jobs, now the engine is at the rebuilders we're splitting the gearbox open and we're stripping just about everything but the body paint back!).

On taking the enigne out we took the ARB off fully for the first time and realised it is not square. The main transvers run is straight and the arms look straight too, but one arm is lower than the other (so when it lies on the floor one arm is raised).

I'm pretty sure of the answer, but should the ARB have vertical offset left-to-right?
I also see that if the car needs a new one they are about ?200! For a bit of bent steel!

Thanks!

Dave

[paddy]

I think what you've got there isn't an ARB but an original "Permanent Roll Bar". Very rare

Paddy

[GrUmPyBoDgEr]

Why not straighten it?
A bit of a twist & Bob's your Uncle

Cheers
John

[StoatWithToast]

Like the idea of a PRB.

I hadn't thougt of trying to straighten it!!
I'll ask around the local engineering shopfloors to see any of them can do it.

[GrUmPyBoDgEr]

:D Like the idea of a PRB.

I hadn't thougt of trying to straighten it!!
I'll ask around the local engineering shopfloors to see any of them can do it.

DIY:- put one end in your "Workmate" then stand on the workmate to weigh it down.
Put a tube or anything on to the other end to maximize the leverage & twist.

John

[Ross Robbins]

I'm no metallurgist but is not heat required to reset a steel bar which functions effectively as a spring?

[john.p.clegg]

I was going to suggest that the sett was caused by the prolonged weight bias of just a driver and was going to suggest reversing it...then rememberer that it is handed....Oh well...

John

[S2Jay]

It may not be an issue, but you may want to first confirm that the entire area of the floor on which the bar lies is flat & level. The concrete in my carport waves like the North Atlantic.

I am not certain that such a bar can be properly straightened by rebending it. It may have become twisted from overuse, striking a curb, etc. An ARB is essentially spring steel similar to a coil spring, or more like a torsion bar. It may need to be heated to put it back right and still have its springing characteristics. Trying to bend it may be acting to work harden it as the original overload apparently did.

Jay
S2 26/5009
B947 0482

[StoatWithToast]

Yeah, I was going to put it in the other way, but the flats don't fit

Will have to get the plumbing torch out with Ron's (RIP) workmate and the long steam pipe to see what we can do.

[types26/36]

I also doubt you can straighten it.....surely it would just spring back? I believe they are made with quite a high carbon steel content and heat treated.
I once tried to adapt another ARB to a Europa using heat.....it was a complete failure as it snapped the first time I used it as I think the heat treatment is quite critical.

[alexblack13]

It will be difficult to straighten at home. It is a big spring and it's bloody hard! Straightening will require heating to remove the spring effect and then re 'springing when finished. Effectively re setting the spring if you like.

I have had a go at this and ended up taking it to a spring manufacturer who sorted it and re - tempered / sprung the thing...

Have a go at it and you will see what I mean. .... Boing ... Boing!!

Have fun...

PS , Ive got a spare if you need one...

Alex B.....

[GrUmPyBoDgEr]

I'm not sure if the Elan anti-roll bar is spring steel but I very much doubt it.
Mild steel is often used successfully for similarly dimensioned bars.
Heating would help with re-setting this bent bar, but if it IS heat treated carbon steel then it would be necessary to re-heat treat it.
Assuming that the minor distortion found happened when cold then re-bending cold should provide the required cure.
In any case quite a bit cheaper than buying new.
When preparing my ARB prior to fitting new rubber bushes I filed the flattened ends round to help pushing the bushes over that difficult area.
The material reacted to my file as I would expect mild steel to do.
OK not a definitive metallurgical test to identify the material but nevertheless I stick by my earlier recommendation.
Bend it back!
Sorry but some of you guys read too much into a relatively small problem.

nix f?r ungut
John

[StoatWithToast]

Alex - you have PM

[elansprint71]

Well it is a long time since I snoozed thro' metallurgy at college but if you heat up your bar to bend it you'll most likely ruin it more than it is now. Even Chapman would not be daft enough to use mild steel for a spring component in the suspension. If you heat it and bend it you will have to anneal it afterwards and without knowing the composition of the steel I would not care to guess about the time and temperature required.

Buy a new one. These cars are about handling, why compromise it?

[reb53]

My experiences of spring steel largely come from my day to day job of restoring clocks and working with clock springs.
Whilst bending an old, "set", spring back into shape is easy I've found that it doesn't seem to last long.i.e. soon reverts to where it was before you started. In clocks I replace them as they don't cost much.
In the case of an ARB I think to do the job properly you'd need to:

1. Heat the bar red hot and let it cool slowly in order to anneal it
2. Bend it to the shape you want
3. Heat red hot again, ( to the correct temperature, "near enough is good enough" won't do)
4. Quench in the correct medium
5. As it is now dead hard it needs to be tempered which means heating to an exact temperature, giving sufficient heat soak time, and then quenching again.
Don't guess at any temperatures or it'll either break or not work.

A spring maker has the furnaces and pyrometers to do this but if you think you can do it at home without compromising the Elan's best feature....well...good luck mate!

Cheers
Ralph.