Custom aluminum chassis

[chapmanite]

Newbie with a crazy idea here: I’ve been looking into various chassis construction technologies, trying to think of something that’s, light, rigid, and that doesn’t require (much) in the way of specialized skills or equipment, i.e. welding or composites. Time’s money so I’m willing to spend a little more on materials and save some effort. I’m hoping someone can tell me if the following idea has been done, by whom, and if it works:
Using structural aluminum angle to define the shape of the various sections (sills, center tunnel, floor) and then bonding and riveting aluminum skins to either side of the angle, the space in between filled with foam (honeycomb if I come into some money) bonded to the skins. Ally plate would be used in place of foam at mounting points.


Cheers,
Chapmanite

[KAM]

The specialised skill is getting structural strength without adding more weight than is necessary.. Build a spaceframe chassis instead. That works for many kitcars and custom built racecars. Its not fancy but it does the job right (as long as you have someone who knows how to weld and add triangulation in the right places.

[Peter Dunne]

Originally Posted by chapmanite

I’m hoping someone can tell me if the following idea has been done, by whom, and if it works:
Using structural aluminum angle to define the shape of the various sections (sills, center tunnel, floor) and then bonding and riveting aluminum skins to either side of the angle, the space in between filled with foam (honeycomb if I come into some money) bonded to the skins. Ally plate would be used in place of foam at mounting points.

Its been done before alright and it did work. It certainly makes for a light car but costly to repair after a shunt.

Here is a Ralt RT20 from 1986 with tub clearly visable:


All in all, a pretty mamoth task to undertake if you dont have serious experience. As KAM says, build a spaceframe.

[phoenix]

As far as I am aware, most high tensile steels used in motorsport have a better strength to weight ratio than common aluminium alloys. I believe a tube is also a stronger/stiffer section than an angle, so for the same strength and rigidity a steel tube chassis can probably be made lighter than an aluminium alloy one using your proposed construction method.

7075 alloys can be solution treated to T6, giving a strength to weight ratio better than some steels, but this can make constructing considerably more expensive than steel and I don't believe 7075 is available in angle sections. 6061-T6 is available in angle, but has a lower strength to weight ratio than a typical steel alloy used in motorsport.

Aluminium also age hardens, which in simple terms means a shorter life for an alloy chassis than for a steel chassis.

I don't want to dampen your enthusiasm for trying something different, but overall a steel spaceframe is probably a better solution.

[AU N EGL]

or just buy a proven race car for the class you want to compete in.

[chapmanite]

Thanks for the feedback guys. Slightly different but related question: does anyone know if one has to do anything different when gluing galvanized sheet steel? Also, does anyone have any experience with DIY "quiet steel", e.g. two pieces of 24 gauge with some PolyPro in between? I though something like this might be useful for a floorpan for a road car

[KAM]

cant answer your question, but if you move to a spaceframe why dont you look at kevlar sheet?
Now it may be worth getting a technical blue book and finding what thickness steel is used for cars like rallycross etc. Wouldnt surprise if you need something like 1.6mm thick panelling, but you would at least know you are safe..

[AU N EGL]

What race class of car for what race organization ?


Do need to follow technical rules, not just build what you want.

[chapmanite]

I don't have a particular class of competition in mind (low chance of passing any physical not administered by Nick Riviera), though there would be some potential for AutoX. The most likely track would be back roads in WV, so it could settle for taking inspiration from technical regs rather than abiding them religiously.

[AU N EGL]

WV as in West Virginia? then you want a tank. or a pick up truck.

WV state and country boyz like to stop anything that does not look right.

[Smokey 6 litre]

This is something i would love to undertake as a project myself, however, having seen various aluminium chassis being rebuilt from various states of disrepair i'd say you would need loads of experience, the right equipment, incredable patience, an almost anal attention to detail and bottomless pockets.

The cars i've seen repaired and worked on use Aircraft grade NS4 aluminium which isn't cheap stuff to come by.

As said above...spaceframe.

[jo white]

Originally Posted by Smokey 6 litre

This is something i would love to undertake as a project myself, however, having seen various aluminium chassis being rebuilt from various states of disrepair i'd say you would need loads of experience, the right equipment, incredable patience, an almost anal attention to detail and bottomless pockets.

The cars i've seen repaired and worked on use Aircraft grade NS4 aluminium which isn't cheap stuff to come by.

As said above...spaceframe.

NS4 grade is relatively soft for some applications