Alif27 and i are contemplating a bec and making an all alloy chassis ali wish bones and with Grp body Coverings for a very light car ...trackdays only.
Anybody Know of anyone that has done this previously for the crack?

Purdy

Do a search. Alloy chassis has been discussed ALOT

I don't think anyone on here has ever done it (or not that they'd admit to anyway ).

It has been mooted a few times on here but I think the conclusion is usually that it would be about as strong and durable as a chassis made from cheese.

Discussed many times that I'm aware of. Spooky that you have the words "alloy", "chassis" and "crack" in the same post.

This has been discussed a LOT over the years....

The general consensus is that without a lot of very expensive and complex processes you will end up with a chassis that is dangerously weak....

Space frame chassis (Haynes roadster) are best made out of steel....

If you want an ali chassis you need to look at monocoque...and perhaps gluing it rather than welding to avoid some of the heat issues assosicated with welding...


A well desigined and built mild steel chassis would easily be lighter than an ali chassis unless you really really know what you are doing...

MMMMMMMMMMMMM Cheese








Vorstsprung Durch Purdys Technic

But has anyone tryed it?

Have a shoofty at the Robin Hood lightweight shenanigans.....

Most SVA test centers refused to pass them as they were worried they wouldn't take the normal loads of road driving. Just think how yucky the handling would be on a track (if it didn't twist itself up like a pasta twirl)....

That's not to say an ali chassis couldn't be made- but its seriously tricky....

Someone will have although whether they admit to it or not is a different matter.

that robin hood lightweight shananigans looks poo and is only a few kilos lighter than a erw frame!

its just a product for the unable....

You can do it, but it needs to be a monocoque rather than a space frame.

The Elise is a good example, which was designed by the same guy who did the Renault Spider. He was obsessed with the concept of extruded aluminium window frames and that their inherent strength could be applied toa car chassis.

There's a new book I'v e just bought called 'how to build motorcycle engines racing cars' which describes the various components and considerations needed in designing and building such things. I has a section on how to make a monocoque chassis using honeycombali panels and strong adhesive. Looks a fairly reasnoable concept, though it does require a ery thorough design up front as their are none of the opportunities to go back and make changes like you can with a space frame (the author describes frustrations of having to scrap in faulty monocoques for £0.75p/kg because he didn't mke certain considerations).

I would have to say that unless you've built a few spoace framed cars previously or have a lot of experience working with alloys, it's probably best to stick to designs that have been previously tried and tested.

I have the same ideas, but I've built an Indy as my first car to get some practical experience. I'm going to have a crack at designing a chassis, but it'll more than likely be a space frame chassis, despite my will to do something a bit different.

[Edited on 3/8/08 by StevieB]

"have a crack"- quite appropriate considering we're talking about ali chassis!!!

Someone on here did make an ali spaceframe chassis... can't remember them making a great song and dance about how successful it was, so that may give you an indication of how good an idea it is!

The basic chassis is such a small percentage of the weight that it is difficult to make worthwhile savings in it. Much easier to make the savings in component selection such as wheels, tyres, uprights, brakes, drive train, diff etc . (although expensive)

If you are serious about going all out to save weight look at the fancier high strength steels and a structural (FEA) redesign of the chassis to suit the material - you might get away with smaller sections with better grade and section selection.

Of course if you choose the above path you better make sure your designer knows his materials and FEA processes and understands the life cycle properties of the material selected and manufacturing processes and controls needed to weld (join) it. (This would apply to aluminium and Titanium Carbon fibre, and rarium as well)

I asked the same Question a few months ago and after everone telling me it was not i good idea i went out and made it anyway lol.
i used 25 * 25 * 3mm ali which is still lighter the 25 * 25 * 1.5mm mild steel
The chassis is all done I havent got any futher yet though.

interesting reblerider

I feel the idea will work too, do you have any pics? and what do you think of the final example ie. The ridgidity of the frame?

purdy

it will work - for a short time.

Welding creates a weak zone around the joints and when the frame flexes this area will work harden and crack. You can bolt all the sections together but then you won't save any weight.

I only know of one hillclimb car that has an aluminium spaceframe and the owner "lifes" the chassis every half season, impractical for a road car.

The only way to go aluminium is to build a Honeycomb monocoque, if it was viable then they'd proliferate, racers are fanatical about weight, they'd have made it work and they haven't.

Sorry but it's a non starter and a criminal waste of money.

Cheers

Chris

I've used ali box section in work , mainly for making up and fixing hand rail up rights on powder tankers.

As said before is like cheese considering all it was doing it would break where drilled or welded . In the end we got that pee'd off fixing the stuff we used to get the solid bar or stainless and just tell foreman the supplier was out of stock of box :p

ill take some pictures and post them when i get a chance i also thought about cutting chassis from flat sheet and forming the shape of the car (instead of space frame) as i have lasers and i can program.
as for the waste of money its not a waste if you dont have to pay for the material