After Market Sway-Bar Modification

[VA61DETT]

G’day All

Just after ppl’s thoughts on welding sway bars.
As I have a spare Ra60 heavy duty bar I was thinking of putting in the MA61.
Only problem is the damn thing is about 50mm too short.
So I was toying with the idea of cutting it in half and using a bit of heavy wall steel pipe to extend the bar.
Idea being to cut 3 - 4 slots into each end of the pipe (length ways about 150mm long), slide sway bar ends into pipe & weld.
Thus allowing bar to be extended, with slightly more stiffness as a by-product.

yes/no stupid??

-A

[Stefan]

I assume you mean front. I have an MA61 Whiteline adjustable bar in the front of my RA65, and it fits completely fine.

Could you use different end links (with brackets so that the end links are still at the desired angle to the swaybar) to make it work? Changing the location of the endlink mount at the chassis end would be a lot better than attempting to modify the bar itself. Alternatively, sell the RA6x one and buy an MA61 one.

[Norbie]

The problem with welding spring steel is that it ceases to be a spring. Given the application this wouldn't be good.

[RA23]

In general pipe is better than bar: much less weight for the same stifness. May be a challenge to make fit though.

[PlacentaJuan]

i reckon it would be a fail idea but nothing bad would happen if it didnt work or broke so why not give it a go especially if your on a budget

[VA61DETT]

Hmm,

Thanks for the input people, I was figuring that welding to the bar may cause unforseen changes to the springy properties of the material.
Was wondering if anyone had attempted a similar mod before?
(The bar is currently up for sale, but not much interest so was considering other options)

-A

[Jt_70R]

It will depend what the bar is actually made out off. Similar to what Norbie mentioned, you may find you cant actually weld it at all.

'Spring' steel has a high carbon content which will not respond well to welding. It is possible to weld higher carbon content steels however you need to use preheat and let it cool slowly.
Anything more than about 0.5%C and you will start to induce weld embrittlement due to rapid quenching of the metal around the heat effected zone.
Ie. you might be able to weld it together but it may just crack under load.

But hell, why not give it a go, theres only one real way to find out!

[sheepers]

you could get it re-tempered after you weld it.
but if you just want to weld it and see what happens, which would be interesting anyway, cut the end of you "sleeve" tube in a spike kind of shape, umm how do i word this....
what I'm trying to say is spread the load of the join along the length of the bar by making the joint like the shape of a kings crown. doing this spreads the load of the joint over a greater area. definitely less stress on the "weak" weld area.

my 2c
sheepers.

[wagonist]

Have you priced up getting an MA61 swaybar?
I haven't bought one for a couple of years now, but the last custom built one was around $300.
Your's "should" be available off the shelf, or at least have a pattern for it to be made easily.

[Duk]

Interesting subject. I have seen welded sway bar/antiroll bars where the spring section is a straight, round bar and the arms the go to the lower control arms of the suspension are formed from flar bar that are welded onto the spring section.

Have also heard (read) of a an antiroll bar made from a thick walled stainless steel pipe in the same way. Unfortunately the guy who made it didn't/couldn't/wouldn't tell what grade of stainless it was.

Would be very handy to have Oldcorollas' input on the subject

[sheepers]

Have also heard (read) of a an antiroll bar made from a thick walled stainless steel pipe in the same way. Unfortunately the guy who made it didn't/couldn't/wouldn't tell what grade of stainless it was.

more than likely it was 431

[VA61DETT]

Thanks for the input people.
I may just give it a go, as there is not much to lose.

Here's a quick drawing of the plan.


Just have to do some hunting around for tough tube now...

-A

[Duk]

I'd say that the added piece would have to have a very similar or higher spring rate to the rest of the material, otherwise it will end up being the section that does the most of the twisting.
Welding and heat treatment procedures will be the interesting bit

[RA23]

Interesting subject. I have seen welded sway bar/antiroll bars where the spring section is a straight, round bar and the arms the go to the lower control arms of the suspension are formed from flar bar that are welded onto the spring section.

Have also heard (read) of a an antiroll bar made from a thick walled stainless steel pipe in the same way. Unfortunately the guy who made it didn't/couldn't/wouldn't tell what grade of stainless it was.

Would be very handy to have Oldcorollas' input on the subject

I designed a sway bar for a GT2 race car which was exactly like that: a straight hollow tube with arms on either side. The arms could be removed, so we could change the tube for a different stiffness one. We had 3 different sizes. We also had adjustable mounting points on the arms for varying the stiffness.

Talk above about "spring steel" is not relevant. Any material can be used - dependent on the design. The main parameters that matter are:

• The diameter of the hollow section - bigger is stiffer
• The wall thickness - thicker is stiffer
• The material properties - higher E modulus is stiffer
• The distance from the attachment points on the arms to the axis of the tube - shorter is stiffer
• The yield stress of the material - no effect on stiffness, but if this is too low and the design has high stress points you may get permanent deformation.

Hollow tube was used to save weight. Much lighter for the same stiffness.
All the above can be calculated very easily if you have a bit of background in mechanical engineering. Just set a baseline stiffness, based on the existing (or stock) sway bar and design a new one that is X% stiffer (and lighter if you truly care about performance).
The only catch is that it may be hard to use a full width straight tube in a car with front mounted engine....

Hope this helps.

Edwin

[RobertoX]

The other factor is fatigue, your sway bar may see stresses under yield however how many cycles will it go through?
I'm not sure what process whiteline use but OEM sway bars are usually quenched and tempered after forming (highish C steel gives a temper martensite structure -apparently) for resistance to fatigue. If you weld the bar and don't re heat treat it the will be some different structures in the heat affected zone around the weld. It'll fail pretty soon.

Bars on race cars wth welded arms are designed so that the highest stress is seen by the sections that are doing the springing (ie the tubular section or the arms for blade adjustable etc). This is to prevent the welded/fastened sections failing, and because the rate is easier to work out