Does lightweight mean flimsey - no luxuries?

[JJRS4]

I have no problem with Audi making an RS4 to compete with the M3 CSL, but personally I would not want one with a spartan interior. So I hope there will be an RS4 and a lightweight RS4L.

I like the heated comfortable seats and electric windows etc., not drawstrings for doorhandles.

I wouldn't mind an aluminium body though [img]images/graemlins/grin.gif[/img]

[S4_SAT]

of course not, [img]images/graemlins/062802beat_prv.gif[/img]look at the a8.lighter than the rest and luxurious. [img]images/graemlins/kissmyrings.gif[/img]

[runrowsam]

The A8 was an aluminium chassis as well, and unfortunately the A8 was also massively expensive to research, design and build, and it was all done from scratch, rather than starting with an A4 shell and "RS-ing" it.

Aluminium bodywork isn't as easy as we might all think, mainly because the changes in materials means totally redesigning the bodywork itself, as it all has to be safety approved. It's not just a matter of sticking aluminium in the mould instead of steel!

But ooh nice thought, and lots of weight to be saved.

Rock on
Sam [img]images/graemlins/thumbs.gif[/img]

[Dippy]

I also heard that there are not many repair shops which can handle aluminium at the moment. This presumably means that (a) getting your car repaired might be a PITA, and (b) higher insurance costs?

[runrowsam]

The properties of aluminium are very different to those of steel, so the design of the A8 chassis was very different to that of an A6 etc. Audi basically went crazy on developing the "Audi Space Frame" malarkey, and it's built like a brick lavatory house. It runs off the now standard principle of building the front and rear up to the point that it disperses as much energy as possible, with the main frame around the passenger compartment virtually indestructible. I've seen crashed A8's and it's noticeable how well designed it is to be slammed into things! Mercedes' and BMW's etc tend to look rather mangled in accidents, but the A8's I've seen always seem to be fine from the front door back for example.

The crumple zones in the front and rear are very well thought through. The idea is that they crumple up and increase your deceleration time, so basically it doesn't hurt as much. But most cars are a little too flimsy in this respect, in that if you crash at 30mph, the crumple zones are virtually gone, so if you crash at a higher speed the crumple zones deal with that first 30mph, but what about the rest? That's left up to the passenger cell. Whereas the A8 crumple zones are tougher, meaning you do decelerate a little faster ie it hurts a bit more, but it won't kill you. And if you crash doing 60mph you're a lot more likely to survive. It's a clever idea, which basically puts your body through a bit more poo all the time, rather than being all nice and gentle at low speeds, and tearing you in half at higher ones.

As for handling aluminium, the main problem is that you can't weld it using normal equipment. If you do it has a nasty habit of burning somewhat rampantly. And that's not good. You need to use a different type of flame and solder (not too sure of the details, no doubt someone can assist me if anyone's interested). This means machining aluminium isn't as easy and requires a more specialised service. This inevitably puts the costs up a bit, but as time goes by, more cars are using aluminium panels and parts, so the service is becoming more widespread. As for insurance, I don't think it makes too much difference, since most of the cost of most people's insurance (over 25-30 or so) on a car like an RS4 is some git nicking it.

Rock on
Sam [img]images/graemlins/thumbs.gif[/img]

[ChrisB]

Any perspective on how stiff the A8 chassis is?

Everso. I saw somewhere that the aluminium Jag's structural rigidity (measured in Nm per degree of twist) was somewhere in the region of the old A8's, and the new A8 is nearly double that (or some such incredible amount). BTW, the Nm per degree is well into the tens of thousands in both cases!

The main difference is that Audi's ASF uses a skeleton (the space frame) onto which aluminium panels are either bonded, welded or bolted. ASF I (old A8) used a combination of MIG welding and bolting, ASF II (A2) used MIG welding, bonding and some bolting (as an aside, the entire side of an A2 is one piece of aluminium!) and ASF III (new A8 and perhaps new A6?) uses a hybrid laser-MIG welding process, inductive-gelling and rolling/hemming bonding. Sections are generally either cast, vacuum-formed or extruded. Machining is mainly for placement of mounting points, and not actual frame components.

See here for more info on the Neckarsulm upgrades for the new A8.

As to repair? Well, I had to have my wife's A2 repaired recently after somebody shunted it and now my RS 6 has a bent front wing where somebody hit me! In both cases, I think it's a case of buying a pre-made panel and fitting it. Had there been structural damage to the frame itself (in the case of the A2) I think it would have been a bit more complex, as only bolted and bonded component parts could easily be replaced.

I would expect higher repair bills for anything that bends the frame, and consequently a higher proportion of write-offs for structural damage.

[quattroturbo]

Audi have already engineered the structure which will be used on the new RS4, so it is too late to expect an all alloy body. But wouldn't it be nice if they did the bonnet, doors, front guards and hatch/boot in aluminium? I bet they don't!

[ChrisB]

Audi have already engineered the structure which will be used on the new RS4, so it is too late to expect an all alloy body. But wouldn't it be nice if they did the bonnet, doors, front guards and hatch/boot in aluminium? I bet they don't!

The RS 6 does have an aluminium bonnet and front wings, so it's not beyond the bounds of possibility. The bad news is that the use of alum. doesn't make the RS 6 much less of a porker though. [img]images/graemlins/wink.gif[/img]

[DuncS3]

S3 has an ally bonnet too...

Dunc [img]images/graemlins/s3addict.gif[/img]

[drjones]

I TIG weld ali no problem [img]images/graemlins/<beep>_you.gif[/img]

[charlesdash]

Since Audi have just admitted that the new A6 will only be partially Aluminium due to cost constraints, I just can't see the bean-counters letting the engineers loose with a full ally construction format for the RS4. As an idea and one that really garners attention in these rumour mills, it would be high on any engineers wish list, but in reality it will not happen.

Quote me back when I'm wrong, [img]images/graemlins/rocketwhore.gif[/img]but the new RS4 will be NA 4.2 V8 weighing in around 1,750KG, using limited amounts of alluminium.
This should give it a better power to weight ratio than it's arch rival the M3 (or whatever they call the M3 estate) plenty of goodies for a semi-luxo barge (al a RS6 [img]images/graemlins/shocked.gif[/img]and yet not enough to upset Lambo.

I look forward to being proved wrong [img]images/graemlins/thumbs.gif[/img]

I want V6 3.7 TT, carbon/ceramic brakes, fully adjustable shocks and dampers, serious anti-roll bars, reduced weight using carbon fibre panels on full ally chassis, weighing in at 1250KG.
There again I would also like Kylie, and I'm about as likely to have personal experience of her punanhi than get that lot in the next RS4 [img]images/graemlins/blush.gif[/img]

[JohnH]

In a recent inmterview BMW has stated that they will not be producing any M Estates which is unfortunate as the E34 M5 Touring was a cracking car!!

[Joshie]

Perhaps a pity but I guess BMW are producing particular models do do specific things.
The practicality of the RS4 for example appealed to many (and to me although I was never ucky enough to own one) but you could hardly call the RS4 a real drivers car.
So I would be delighted if the RS4 was a more driver orientated car ala the M3CSL to weigh in at 1350Kgs with over 400BHP although I would prefer to have at least a few basic luxuries like adjustable leather seats and aircon [img]images/graemlins/grin.gif[/img].
I guess the key question will be over the target market for the RS4. The M3CSL has not been adapted universally by consumers and there are many models available in dealerships. I wonder if Audi will see this an possibly rethink their strategy?