ettore bugatti
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| posted on 5/9/06 at 07:12 PM |
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alloy wishbones
Has somebody here constructed their wishbones from aluminium tubes?
It should be a good option, I think.
It lowers the unsprung weight even when increasing the tube diametre and thickness and doesn't rust.
I cannot find any info on this forum about this. Which seems strange since almost every month questions are raised about alloy spaceframes.
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nitram38
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| posted on 5/9/06 at 07:27 PM |
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Bad idea.
Aluminium has a tendancy to fracture, so most aluminium suspension parts are castings.
Tubular chassis would have the same problem. That is why the elise/renault spyder/vx220 are made in a monocoque design.
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t.j.
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| posted on 5/9/06 at 07:30 PM |
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I can't weld it at home, and even when i would not make any suspension-parts of it due the cracks which prob. will occur.
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JoelP
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| posted on 5/9/06 at 09:51 PM |
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Ally or alloy? Totally different things...
assuming ally.... work and age hardening, and stress fracturing, are the problems.
I wouldnt say its impossible to make a bone that would last and be lighter, but it would take research and testing to be sure.
At least with steel arms, if it last a week, its likely it will last a year. With ally, you would have to life the parts.
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chrisf
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| posted on 5/9/06 at 10:31 PM |
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I considered having a go at using 6061-T6 for the upper front wishbone.
--Chris
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Gunner1
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| posted on 6/9/06 at 04:01 AM |
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I did not go with aluminum for the bottom wishbones as this is what takes most of the shock and stress. Instead made up some out of 1" dom. The
top however does not take so much stress and I went with an "off the shelf" item from "Joe's Racing" in Washington
State. Very light piece, especially when used with monoball upper ball joint. This upper arm is a Mustang design and provides full adjustability along
with great quality control on the construction. (They arrive powder coated too)
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JB
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| posted on 6/9/06 at 04:38 AM |
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Aluminium
The problem with aluminium is it is a specialist material. Properly designed, manufactured, installed and inspected they will be fine. However I think
that is beyond most of us and not low cost.
I did see some neat ones when I was judging formula student. Basically machined ends with aluminium tubes Loctited onto the stubs. Its very simple to
replace tubes and as there is no welding no heat related problems.
For the rest of us stick to CDS.
John
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bimbleuk
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| posted on 6/9/06 at 07:46 AM |
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Even Lotus didn't get it quite right. The original Elise uprights were made from extruded alluminium. Fine for road use but on track with
slick/semi-slicks the lower ball joint mounting point cracks. They replaced them with steel uprights which were lighter and stronger.
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MikeRJ
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| posted on 6/9/06 at 08:38 AM |
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The Elise uprights even look ultra flimsy, doesn't surprise me that they fail under duress.
Note that even the Elise uses steel wishbones! I don't think there is a huge amount to be saved in terms of unsprung weight over a decently
made steel wishbone, especialy as not all of the wishbone is unsprung.
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ettore bugatti
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| posted on 6/9/06 at 09:17 PM |
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Thanks for your replies.
But wasn't aluminum more ductile and more elastic them steel?
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chrisf
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| posted on 6/9/06 at 11:00 PM |
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This honestly might fall into the "Why Bother?" category. I think I'm just going to go with the tried and tested steel arms.
--Chris
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nitram38
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| posted on 7/9/06 at 03:13 AM |
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Aluminium is less dense than steel. In other words there are bigger gaps between the molecules. This might make it lighter but also makes it weaker as
the bonds between the molecules are much weaker. Aluminium parts tend to be thicker than there steel counterparts.
Wile I have seen aluminium used on race cars etc, they are also the first bits to break.
Stick with steel. The 0.00001 mph you gan, will not be worth the extra cost or hassle.
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Syd Bridge
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| posted on 7/9/06 at 08:41 AM |
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So, all you people wouldn't use aluminium for suspension components!
That's a quantum change after what was said in defence of a certain manufacturer trying to sell those untested aluminium things not so long
back.
I notice he has wisely deleted the thread now.
Yes, the alu will fail due to the ageing process and brittle fracture. The parts I deal with regularly are lifed. Some as little as
60km, depending on road surface, then destroyed immediately after removal.
I'll repeat: for an aluminium part to be as safe as a steel part for road use in similar applications, it will end up heavier and far bulkier.
This is due to the need to design for ageing and impact resistance. All that said, the parts would still have a finite life far shorter than steel.
Cheers,
Syd. 
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