nissan gt-r officially released...

[clutch-monkey]

after the dealer markups if anyone is even able to buy a GTR for that increased price they'd be ahead of what everyone else is paying lol..

[Kitdy]

This is and old thread and maybe this post should be in the XJR L thread, but meh this is a newer thread.

Anyways, I know Jaguar uses Aluminum monocoques, but the XJR L is 250 pounds lighter than the GT-R and it's a full-sized extended wheelbase luxury sedan. The press release according to UCP says:

Constructed using lightweight aluminum joined by self-pierce rivets and epoxy adhesive - state-of-the-art techniques learned from the aerospace industry - the new XJ's body is some 60 percent stiffer yet 40 percent lighter than before. The result is that a new long wheelbase model, like the supercharged Super V8, is a staggering 800 pounds lighter than BMW's long wheelbase 760Li.

So this begs the questions why are sportscars (often premium ones - I know luxury stuff adds a lot of weight but contrast once again the XJR L), and the GT-R in particular so heavy? I know the GT-R has fancy crap and AWD but it is a 2WD sports/GT(?) car and is heavier than an XJR L. An XJR L needs all the safety crap that the GT-R does so why can't it weigh considerably less?

What other car makers use aluminum for bodes? Ferrari or Lamborghini? If no, why not? Reading about the 430 Scuderia in UCP's database, it says that it is "body on tubular space frame". Body on frame?! Isn't that for trucks? I suspect I this is a misinterpretation on my part maybe? What would the chassis or body/frame be made of?

What is the difference between monocoque and "body on tubular space frame" or "composite body panels on hydroformed steel frame" (ZR1).

The XJR L being like 800 pounds lighter than the 760Li is frankly amazing/hilarious to me.

Many questions again, but what are the answers?

[nota]

Reading about the 430 Scuderia in UCP's database, it says that it is "body on tubular space frame". Body on frame?! Isn't that for trucks? I suspect I this is a misinterpretation on my part maybe? What would the chassis or body/frame be made of?

1954 Mercedes 300SL (coupe) tubular space frame
http://www.silverstarrestorations.com/300SL-2.jpg

What is the difference between monocoque and "body on tubular space frame" or "composite body panels on hydroformed steel frame" (ZR1).

Different types of Chassis (two pages)

[Ferrer]

Cars getting heavier is a mix of regulations, safety perceptions and gadgets.

It's unofrtunately a plague, but you can still buy a Dacia Sandero...

[Kitdy]

1954 Mercedes 300SL (coupe) tubular space frame
http://www.silverstarrestorations.com/300SL-2.jpg

Different types of Chassis (two pages)

Danke Schön nota - I coulda looked myself I suppose and shoulda thought Autozine.

[LeonOfTheDead]

I saw a Sandero on the road. stop kidding about that, it's not something I would ever want instead of any other used car.

talking about chassis and the likes, instead.
I think Ferrari uses a spaceframe aluminum, pretty similar to the one used by Aston Martin.
The hydroformed aluminum chassis from Corvette is similar to the one you find in aluminum Audi's.
While Jaguar uses (and I think it's the only afaik) a monocoque, something you usually find in carbon fiber cars.

the fact why aluminum isn't that much used is very simple.
besides being lighter, it also demand a bigger section of each part to match the same stiffness of steel and alloys adopted.
the result is a lighter car, but also bigger because of the bigger dimensions of the chassis itself. the car can still be as big as a steel made one, but it would have less room for the interiors.
besides, aluminum is still more expensive to produce, even if with some smart adjustments it can result being very useful for modular architectures (see AM, Audi and Ferrari).
on the other hand steel chassis are also easier to design and easier to modify.
my mate working at Ferrari, and who switched for a couple of months to Maserati, told me it was much easier to work with the steel chassis from Maserati for the simple fact there was much more room for everything else in first place.

probably Knuto can give us more detailed references about the technical differences between steel and aluminum.

[Ferrer]

I saw a Sandero on the road. stop kidding about that, it's not something I would ever want instead of any other used car.

I actually like it.

I like basic cars.

[Cyco]

Aston uses the bonded and riveted technology from Lotus, while Ferrari uses welded aluminium.
Lotus believes that boning is better, but I suspect overall the differences are minor.

The reason for more room when working on a steel car is steel is much stiffer than aluminium. With both steel and aluminium having pretty much identical stiffness to weight ratios, but aluminium being 1/3rd the density you quickly realise why there will be more space in a steel car.

Just look at the tubing diameters of a aluminium and steel bikes to see this in action as well.

[Jack_Bauer]

Aston uses the bonded and riveted technology from Lotus, while Ferrari uses welded aluminium.
Lotus believes that boning is better, but I suspect overall the differences are minor.

Don't we all.

[LeonOfTheDead]

Aston uses the bonded and riveted technology from Lotus, while Ferrari uses welded aluminium.
Lotus believes that boning is better, but I suspect overall the differences are minor.

The reason for more room when working on a steel car is steel is much stiffer than aluminium. With both steel and aluminium having pretty much identical stiffness to weight ratios, but aluminium being 1/3rd the density you quickly realise why there will be more space in a steel car.

Just look at the tubing diameters of a aluminium and steel bikes to see this in action as well.

wasn't AM chassis made out of extrusion? Don't know about Lotus, but I'm pretty sure is so for AM.

Don't we all.

we do.

I actually like it.

I like basic cars.

yes it's a basic car, but it's ugly too, and even quite high.
I would prefer a first gen Clio instead, which I owned and was an excellent car, cheap to buy/run/repair.

[Knuto]

The advantage of a bonded chassis is that you can use extruded profiles with high strength. The instant you start welding extruded profiles the work-hardening will be eliminated or reduced near the welds. These will become weakpoints and be the first to break. With bonding technology the material will have bulk properties at the joint because there is little heat involved. The dimensional accuracy is also excellent because of very little distortion (little heat).

An important disadvantage of extruded rails is that serious repairs cannot be made by welding. That would weaken it because of the heat input. If i remember correctly you have to replace the complete chassis of new Lotus if you damage it.

As for the stiffness the aluminium it's excellent. For a given load you need 3 times the wallthickness compared to steel to get the same axial stiffness. That would give the same weight since the density is a third of steel. But what is often forgotten is the bending stiffness. For pure plate bending the 2nd area moment is 1/12*h*t^3. When you switch from steel to alu you need 3 times the thickness. That would give 2nd a.m. of 27 times greater than for the steel plate. For pure plate bending the displacements are then 9 times less and the buckling strength is 9 times higher for a given load

[P4g4nite]

So this begs the questions why are sportscars (often premium ones - I know luxury stuff adds a lot of weight but contrast once again the XJR L), and the GT-R in particular so heavy?

Size and equipment. There is no magic involved.
The XJR isn't a very big car...and the "L" adds very little to the size of the standard model, a couple of inches if I I recall. I'd wonder at the source of your numbers, what spec is the XJR-L you are speaking of in? basic trim or moon roof and everything included? With fluids?
Doesn't take many options to push a dehydrated base model up 10-20%

[Kitdy]

Size and equipment. There is no magic involved.
The XJR isn't a very big car...and the "L" adds very little to the size of the standard model, a couple of inches if I I recall. I'd wonder at the source of your numbers, what spec is the XJR-L you are speaking of in? basic trim or moon roof and everything included? With fluids?
Doesn't take many options to push a dehydrated base model up 10-20%

My source is none other than UCP. The Jag no less a sedan, the GT-R not so much.