By all accounts, the folks at Audi are pretty busy with more than enough new projects to keep the design department busy.
The A6 Avant has been launched. The new RS4 has been all but signed off. The next RS6 development process is well underway. A facelift for the A8 is proceeding apace. So, your're probably wondering what's next? Let me tell you.
The latest edition of Car Magazine has an interesting feature on Audi's emerging platform strategy. Audi might not have adopted rear-wheel drive but a whole host of fundamental rethinks on chassis design should certainly spice up the range's front-wheel drive handling characteristics. In summary B8 platform will offer:
1. Gearbox moves to rear end of transmission to improve weight distribution
2. Engines move behind front wheels to improve weight distribution and steering
3. Front axle moves forward with front overhang reduced significantly
4. 4 wheel-drive models get 40:60 power bias, i.e. 60% of power goes to rear wheels
5. Fundamental rethink about supsension design to create a more supple better riding range of cars
The net effect of these changes is that entry level front-wheel drive models will be as fail-safe as they have always been, but 4-wheel drive models will have a weight balance and handling dynamics much closer to those of BMW and MB, but with the added benefit of better traction and more predictable handling in less favorable conditions.
The first models to appear with this new platform are the A5 Coupe and Convertibe (based on the Nuvolari concept), pencilled in for 2007. The next A4 and A6 will also be built on this platform. (The Le Mans mid-engine supercar has also been given the green light for production and will be launched as the RS9.)
According to Car, this is the biggest shift in engineering focus at Audi since Aluminium was first mooted for the A8. Let's just hope and pray this makes Audis not just as good as their German competitors but well-ahead of increasingly threatening Japanese luxury car brands.
Of course, the other thing we can look forward to is body styling that is designed with the new grille incorporated from initial concept stage instead of added as an afterthought. It should certainly look less conspicuous and more organic.
Obviously Car reads this forum, all the above was posted here months ago. However, like most (all) journalists, their correspondent missed the point that by moving the engine inside the wheel base and placing the gearbox at the rear transaxle (like the Maserati Quattroporte which Audi engineers helped produce), the weight distribution is 40/60 front/rear, which is ideal in a dynamic as opposed to static situation.
R+C
Originally posted by Nordschleife Obviously Car reads this forum, all the above was posted here months ago. However, like most (all) journalists, their correspondent missed the point that by moving the engine inside the wheel base and placing the gearbox at the rear transaxle (like the Maserati Quattroporte which Audi engineers helped produce), the weight distribution is 40/60 front/rear, which is ideal in a dynamic as opposed to static situation.
R+C
40/60? Or do you mean 48/52 like the Maserati? I think the Gallardo has a 40/60 weight distribution but not the Quattroporte.
Do you think they'll really achieve 40-front and 60-rear weight bias? And what exactly do you mean by static versus dynamic situation?
I'm not Nord, but he means by static versus dynamic is the weight distribution when the car is parked (static) and not in any motion, versus when the car is braking, accellerating, and turning (dynamic). There is a huge difference between the 2 figures.
For example, with a car like the RS 6 (58/42 front to rear) the figures quoted are static (standing still). Those figures can change drasticly when the car is in motion. When accellerating, more weight will be transfered to the rear (perhaps closer to 50/50) but when braking then more weight is then tranfered to the front (like 70/30). That last figure is obviously not good and contributes to the cars "push" (excuse the Nascar term for understeer). Nord's example of 40/60 would give much more balance under braking and put far more weight over the rear wheels under heavy accelleration (great for wheel rear drive cars). Hope that helps.
Originally posted by Benman 40/60? Or do you mean 48/52 like the Maserati? I think the Gallardo has a 40/60 weight distribution but not the Quattroporte.
Ben
Ben
I mean the target weight distribution for Audi is 40/60, the 'like the Quattroporte' refers to the layout.
As a rule of thumb, the transfer of weight forward under braking is 3 times greater than the transfer backwards under acceleration, given 'very good' brake systems.
Stock Audi rear brakes do very little work, which is why so many people think there is no need to upgrade them. If you do manage a balanced front and rear upgrade, you will be amazed how much retardation you can achieve.
R+C
Originally posted by Nordschleife Ben
I mean the target weight distribution for Audi is 40/60, the 'like the Quattroporte' refers to the layout.
As a rule of thumb, the transfer of weight forward under braking is 3 times greater than the transfer backwards under acceleration, given 'very good' brake systems.
Stock Audi rear brakes do very little work, which is why so many people think there is no need to upgrade them. If you do manage a balanced front and rear upgrade, you will be amazed how much retardation you can achieve.
R+C
Crystal clear now. And yes, I've heard how much force some good brakes can apply to the front of the car. Although this is the ultimate EXTREME example, a F1 car just by lifting OFF the throttle (with medium track areo set up), it applies more weight transfer to the front of the car than a Corvette Z06 under a FULL ABS panic stop!!!:bigeyes: :bigeyes:
And forget about the pressure those drivers face under full braking conditions!
Ben
P.S. Robin, is Audi really targeting a 40/60 goal? I know they can easily acheive that figure with the Le Mans, but with the others, they got their work cut out?
As a rule of thumb, the transfer of weight forward under braking is 3 times greater than the transfer backwards under acceleration, given 'very good' brake systems.
R+C
Wow, when you think of it that way, no wonder 8:26s front tire blew out at the Nurburgring! With just about 90% of the weight of the car at the front (more than 45% of that on the outside tire!) that tire was way overwelmed to cope! That's 1867 lbs on one tire! And now we know why Audi stresses to 99 load rated tires!
Brilliant and interesting responses, guys. Thank you so much.
Nord, you mentioned a while back that Audi had been experimenting with the Quattroporte rear differential. What, if anything, has this led to and will it or something similar become a mainstream Audi system/ technology. And what is the future of the current Torsen system that has served so well for so long. I guess it's fast reaching its sell by date.
You guys were clearly invloved in testing an exotic piece of machinery on the Ring. Care to tell us about it?
It is very difficult to comment directly, if my knowledge is first hand, all those pesky NDAs!
It is a little premature to expect any concrete results from experiments involving the rear mounted transaxle and All Wheel Drive. However, I would expect the central differential technology to be evolutionalry rather than revolutionary.
AS Mercedes and BMW keep discovering, Torsen is a very clever bit of engineering.
R+C
If the transmission is transaxle at the rear , then what's the layout of the basic FWD vehicles? Does a shaft go to the back, and then a second one all the way to the front again (through the engine)? And even the AWD version would need a second shaft, since the Torsen diff would also be at the back. That's a lot of extra rotational mass. That just doesn't make sense to me.
Something I always thought Audi could do is just flip the engine around, putting the gearbox in the overhang. Making it a front-mid engined layout. The shaft to the rear would pass through the engine block.
Sorta like this (Gallardo), but the other way around:
Although I suspect it wouldn't be space-efficient, it's the only configuration I can think of, that combines FWD/Torsen with a good weight balance.
I supsect that Audi will probably adopt a dual platform solution with a traditional front wheel drive layout for non-AWD versions and a more exotic rear-transaxle solution for Quattro versions.
Nordschliefe mentioned something somewhere else on the forum about a front mid-engined solution with the gearbox located ahead of the engine. This could well be an option that Audi is considering. If they are, it would be an elegant compromise between predictable handling characteristics with plenty of driver-feedback and control on the limit. It also might facilitate both FWD and AWD versions without the need for complicated re-engineering.
As you say, such a solution would compromise overall packaging - cars would have longer front ends - but given the need for greater perdestrian safety, moving the engine back must be a good solution.
I don't think they'll be doing a dual layout. The whole back and front subframes would have to be different. And you'd still have the extra driveshaft to the front, on the AWD version.
There's also a vibration problem with rear-transaxle cars, b/c the driveshaft to the rear is always turning, even if the gearbox is in neutral. I'm sure the engineers can compensate for this, but probably at the expense of weight, complexcity, and €€€.
I had a further thought about the mid-engined layout. It does take up a lot of space, but so does the current layout, which demands a short wheelbase. The back seat footwell on an old A8, for instance, is a joke.
In contrast, a midengined layout demands a longer wheelbase than normal. Improved high speed stability, but a wider turning circle.
The wheelbase wouldn't be all that longer, b/c Audi has mastered the art of compact mechanics like no other.
You're right about the pedestrian safety regulations. And a midengined layout would also offer a superior crumple zone. When VW brought out the midengined concept R (confirmed for production), they said in the press release that with these thougher regulations, it's actually cheaper to just move the engine back. Another incentive for Audi to do it.
In the last couple of years, Audi has beaten the competition on every level, except driving dynamics (close, but no cigar). If they get that sorted out, there'll be no stopping them. I really hope they do.
PS: long noses are dead sexy, as these midengined FWD Citröens can attest.
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