BMW to get new torque vectoring rear-axle
For quite awhile, BMW has been disappointing many consumers by only offering limited slip differentials on their M-badged models. Competitors such as Lexus and Infiniti have at least offered LSD options on their vehicles, but BMW's argument is that their traction control system is sophisticated enough to fight wheel slippage rendering the extra cost for an LSD unnecessary. But it looks like that long-standing policy at the German automaker will change in the very near future.
The latest news out of GKN Driveline and ZF Friedrichshafen AG is that they have joined forces to produce a torque vectoring system that will be implemented by BMW. The system utilizes two electronic torque managing units that are essentially clutch type differentials, with the plate pressure controlled by voltage supplied to two electric motors. It will be able to independently adjust the torque split between two wheels, without the need for wheel slippage to occur initially. The technology is being dubbed VectorDrive and it's configurable for AWD and RWD vehicles. It's about time BMW joined the bandwagon in moving away from the open rear differential.Catch the official press release after the jump.
[Source: Automotive News]
PRESS RELEASE:
GKN Driveline and ZF Torque Vectoring cooperation CTI Symposium, BerlinBerlin, Germany 4th December 2007
GKN Driveline and ZF announce an extended cooperation in the field of torque vectoring systems. The cooperation agreement covers the joint development, manufacturing and marketing of torque vectoring systems in rear axles for rear and all wheel driven vehicles.
Mechanically this agreement includes two torque vectoring units flanged to the final drive, and two electric motors which drive the brakes to operate the torque vectoring units. The motors are controlled by a central ECU. The software, which communicates with the vehicle controller, ensures that the vectoring torque requirements dependant on the driving condition of the vehicle are realised by the system.
The first production application is planned for BMW, already announced as being ZF's VectorDrive. The Torque Vectoring hardware units produced by GKN Driveline will be supplied to system leader ZF, who is responsible for the final assembly of the system and the supply of the electric motors, the control ECU and programming, and the delivery of the EOL-tested units to the customer.
"The joint development is a significant step forward that allows us to bring the specific competences and know-how of our two companies together, develop cutting edge, high performance driveline technology and make it available to our customers as broadly and competitively as we can," said Graeme Walford, Managing Director of GKN Driveline Torque Technology.
Commenting on the announcement, Robert Paton, Managing Director for ZF's Axle Drive Division said: "We have an attractive 'modular' system concept that is ready for application and specific development with the OEMs. BMW will be the first, but we have already begun talking to other customers and are excited by the prospects for this cooperation technology. "
Reader Comments (Page 1 of 2)
Thetruck454 8:37AM (12/06/2007)
:cough: 135i :cough:
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Guenther 9:17AM (12/06/2007)
Wow- lets um.... do the same thing the rear calipers were doing, but lets ad a bunch of parts and controllers. Just drop a tor-sen differential in there an call it a day. This, boys and girls, is just dumb.
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Richard 11:42AM (12/06/2007)
Yeah!
But needing new rear pads every 24k is dumber and new rear rotors every 35k is plain ignorant.
So....let's add some more weight and continue to green the product. ;-}
Colin Chapman must be smiling down on all this foolishness.
MikeW 12:20PM (12/06/2007)
This differential does more than brake actuated traction control does.
If you have a high enough TBR with a torque sensitive differential, you can have high speed instability issues.
That is why all the M-cars have a speed sensitive differential. The last one with a torque sensitive differential that I can think of is the E39 M5 (and maybe the odd M-coupe)
page 4 http://www.m3resource.com/downloads/M3_Techguide.pdf
Come on BMW, e-gerodisc. http://www.eaton.com/EatonCom/Markets/Automotive/TorqueControls/index.htm
naggs 1:03PM (12/06/2007)
agreed, just put a torsen in there
Lantern42 10:17AM (12/06/2007)
Acura called. They want their idea back.
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Val 11:30AM (12/06/2007)
If Acura really called, they might try to fight this in a patent court. They will lose ofcourse, but still, if they think they are so brillinat...
MikeW 12:23PM (12/06/2007)
Honda's system is 3 wheel drive.
Mitsubishi & nissan have had torque vectoring for at least a decade already.
Lantern42 6:19PM (12/07/2007)
I'm not saying BMW is infringing anything, but they aren't the technology leaders. They even revamped their AWD system after Infiniti came out with ATTESA E-TS. Be nice if they didn't make it so damn complicated though.
MIKE: I don't know what you mean by "3 wheel drive" but you're right about Nissan having it first. Acura just launched it in the US before they could.
Ryan 11:36AM (12/06/2007)
I'll take a standard LSD please. I installed a 4.10 LSD in my 89 325is and its a riot :)
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Guenther 11:58AM (12/06/2007)
That is a hot set-up. Supposedly faster than the M3 of the day.
naggs 1:05PM (12/06/2007)
in a straight line, yeah a 4.10 on a 325i is faster than an e30 m3
Andrew 11:36AM (12/06/2007)
As long as they're upgrading their rear diff, I'm happy. I've been driving in snow all week with an open diff 3-series, and although I'm used to it, it still sucks.
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why not the LS2LS7? 11:38AM (12/06/2007)
Ahhh. German engineering. Why put in a Torsen when you can put in four motors and a crap ton of moving parts?
I don't get why the brakes should be involved either. Any system that puts the brakes on to vector torque seems like it's going to rapidly wear the pads away on the track.
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Dave 11:43AM (12/06/2007)
Bah. First they claim that the cost of a traditional LSD is the reason why they kept it open. Now, their solution appears to be something that is MORE costly and complex than a LSD. Sort of like replacing a $0.25 dipstick with electronic oil level monitoring (if the sensor is suspect, the only way to confirm level is to drain and refill!).
Rather than KISS, BMW seems to strive for overkill wherever it can.
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Bryan 12:03PM (12/06/2007)
I believe it's called "German Ingenuity", over engineer everything. :)
mk 11:50AM (12/06/2007)
Have to agree.
Torsen or Quaiffe torque biasing differentials, or viscous limited slips are easy enough to install (for a manufacturer)
Taking electronic brake-force distribution from the brakes and traction control systems, and putting it on new "internal-differential brakes" and making the system more complex, but not really any better.
Creating limited slip differentials by impedeing torque (and thus wasting it/creating heat) intentionally seems counter-intuitive, when there are systems that manage the application of torque better.
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MikeW 12:51PM (12/06/2007)
The brake actuated traction control can only work when the inner rear tire overspeeds the outer.
This torque bias/vectoring system can work before that happens.
Though with all the bottom end power of the 1/3/5-35, a torque sensitive is more appropriate for that engine.
http://video.google.com/videoplay?docid=3216093230109835629&q=bmw+335i+site%3Avideo.google.com&total=49&start=0&num=10&so=0&type=search&plindex=1
(paging Drs. Quaife & Torsen)
The N53 would be a perfect match with this differential.
White Goodman 11:53AM (12/06/2007)
I don't understand why all vehicles don't have a limited-slip of some sort. An additional $500 for the safety and performance advantages of a true mechanical LSD or posi-trac is a pittance in the scheme of any car topping $15k. Personally, I trust gears, friction discs, and viscous fluids much more than a some ICs and computer code.
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NMT 12:49PM (12/06/2007)
There are some real pessimists here.
It could be a great system. Acura is using something like this on the RL and as I recall it got rave reviews in the auto press.
It seems to me that a system like this opens up a whole host of new possibilities as far as programming the handling of the car. You could counter under steer by artificially directing more torque to the outside wheel. You can't do that with a mechanical LSD.
I would have expected enthusiasts to applaud such a move.
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