Steel Vs Aluminum in the FT86
 

Ive been reading up on aluminum being used in place of steel and am aware there is a torsional difference between the two, with steel being much stronger at the cost of weight. So, in your preference, which frame would you prefer, aluminum or steel? Are there any confirmations on which one the FT86 will have? Also, what are the upsides and downsides of using each in body panels, suspension, wheels etc?

Im no expert on metals - i barely scraped though Chemistry with a pass...

But i've used 6082 Billet Aluminium on lots of auto related things in the past and its a VERY strong metal.

I'd be perfectly happy for the FT86 to be entirely made out of Aluminium.

But i doubt much of it will be as it really drives up the production costs of the car.

Would be nice to see things like the bonnet/roof being Aluminium though. Being the two biggest flat sheets of metal on the car it would help keep the centre of gravity as low as possible and keep the weight of the car down.

I used to have an Audi TT and I think they used both steel and aluminium and positioned the heavier steel to balance out the weight of the car. Maybe they might do that with the FT-86 ?

It's more likely that they use high-tensile strength steel to keep the weight down, which tends to be more economical. Not all steel is created equal, and you can keep weight down depending on the steel used.

How much lighter is it? Does it come close to aluminum?

Not many cars iv heard of that use a Aluminum frame...actually i cant think of any off the top of my head other than a few Corvettes.

Advanced High-tensile strength steel (AHSS) keeps evolving, but it's something like 10-15% heavier than aluminum I think? But you're also able to keep things more compact with AHSS compared to aluminum, which is why it's used a lot in areas like the A, B and C-pillars in cars. Aluminum is also about 50% more expensive than high-tensile strength steel.

^ especially when it contains certain levels of carbon

Both Lotus and Aston Martin use extruded and bonded aluminum. In the Lotus the aluminum extrusions create a chassis "tub", and in the Aston Martin's the extrusions are assembled to create their "vertical/horizontal" superstructure. The Corvette Z06 and ZR1 use hydroformed aluminum chassis rails, however base Corvettes and Grand Sports use hydroformed steel chassis rails.

If you want to start talking about aluminum unibodies, then Audi has been doing that for many years in their A8.


Regarding the FT-86, it's price point is simply too low to be able to afford aluminum in any significant quantity. Perhaps an aluminum hood and/or decklid, but the main structure will almost certainly have to be steel/HSS panels formed into a unibody to fit the price-point.

Is the FT86 likely to be heavier than the Audi TT ?
The TT body is 69% aluminium and the whole car weighs 1260kg.

Aluminum only makes cars expensive to fix. Definitely not suitable for a budget-minded car like the FT-86.The TT is likely not any lighter because of AWD.

The TT here weighs 1470kg (3241 lbs). I imagine the FR will be closer to the number you posted above but we'll have to wait and see.

It's not a fair comparison, regardless of the materials used. The TT, being both Audi and German, means it's over-designed and generally over-weight. You'd be hard pressed to find a current German production car that resembles light-weight. Japanese cars are generally more svelte, delicate, and smaller. The FT-86 is a small car, barely larger than a Miata.

A Bugatti Veyron is built using a carbon-fiber chassis tub with titanium fasteners, yet weighs a scathing 1,888kg. A Mazda Miata uses a steel unibody and weighs 1095kg. Even though they're both small 2-seaters it's not a fair comparison.

The whole package needs to be considered. Size, strength, powertrain, luxury accoutrements, everything.

i doubt there will be much aluminum do to the scion price point. bmw //M suspension components are all aluminum and audi uses aluminum space frames to save weight but these drive up the cost. i think they can get away w/o using aluminum by just dropping the luxury features. heavy luxury seats and big engines/drivetrains (ie awd) are the source of most of the weight in new cars.