BMW to go all wheel drive route

Billy 2 Sips said:
Have you done any mods to try and counter the understeer Housey?

I have the H&R antil roll bars and it helps a lot with understeer, will be getting the KWv3 soon to hopefully get rid of it for good.
Click to expand...

Nah, it's my daily driver so not really fussed. Understeer is not an issue 99.9% of the time as it's pounding up motorways or stuck in traffic. On the odd occasion I really push it hard it's noticeable but most of the time it's no problem and I am not really a 'modder' as such.
 
If they do go 4wd, they'll presumably have to move the engine forward to get the gearbox into a position that can access the front wheels? With the big inline 6-cylinder engines which BMW currently like to use, I don't see how they will do this unless the engine is parked way forward?

They'll have to contend with all the criticism which Audi took for have their engines so far forward, which Audi seem to be getting on top of these days with lightweight compact v-formation engines. I can't see it happening unless BMW also drop their inline lumps.
 
They won't do that (or if they do, it won't be excessive) - they'll just redesign and repackage the front end by changing subframes, crossmembers, putting axles through the sump, raising the engine and lowering the intake system, and things like that.

Audi's engines are typically so far forwards because their models are mostly based on the lower-end FWD standard models that have longitudinally fitted engines - where the engine is in-line ahead of the front wheels with the transmission behind it. This means the drive shafts come out the side of the transmission, and because the engine is so far forward - relatively in line with the front wheels, minimising excessive drive shaft angles.

BMW's system will no doubt involve (and has been the case before) a transfer case coming off the rear of the transmission, in the middle of the car, and running a propshaft forwards to drive the front wheels via a differential underneath or alongside the engine - not like Audi, where the transmission is typically at the front of the car, driving the front wheels, with power being transferred backwards from that to the rear wheels.

An example of BMW's older system:

bmw325.jpg
 
Last edited:
BMW has been selling X drive versions of their saloons for years, though normally in left hand drive countries only. I'm quite surprised that they're looking at re-tooling for rhd cars too.

According to this link, the E90 X versions use a multi-clutch 4wd system:
http://en.wikipedia.org/wiki/BMW_xDrive

Here's a review by a Canadian group of the system in snow.
http://www.canadiandriver.com/2006/04/06/winter-driving-test-bmw-xdrive.htm

According that, the default torque split is 40:60, i.e. a rear bias.
 
From BMW:
BMW said:
xDrive.
The BMW all-wheel drive system, xDrive, ensures your BMW has the best possible traction at all times, enhancing agility and keeping you safely on track, even on fast bends.

xDrive is the permanent all-wheel drive system from BMW: under normal circumstances, it distributes driver power between the front and rear axles in a 40:60 ratio, and changes this figure variably when the road surface or overall driving conditions change.

Acting virtually instantaneously and a manner so subtle as to be go virtually unnoticed by the vehicle's occupants, xDrive can direct up to 100% of drive forces to one axle. Enabling the driver to start up effortlessly even on slippery surfaces or steep hills, xDrive routes all power to the axles with the greatest traction. When parking, the system reacts to the need for high manoeuvrability at low speed by opening the clutch completely so the powertrain functions optimally.

At the first sign of understeering, drive power to the front axle is reduced. If oversteering is detected, xDrive directs more power to the front axle. Thanks to this dynamic redistribution of power, vehicle stability returns to normal even before the driver notices anything amiss.

Driving on a winding road or taking a fast bend in dynamic style is particularly enjoyable with xDrive: you feel as if your BMW is being guided along the curve. xDrive ensures that none of drive power is wasted on a loss of traction: every kilowatt of power is effectively brought to bear on the road.

xDrive is regulated by Dynamic Stability Control (DSC) and uses information from the latter system’s sensors to monitor road conditions. In addition, brake force courtesy of DSC is used when there is traction difference between the two sides of the vehicle and wheel spin is likely.
Click to expand...
http://www.bmw.com/com/en/newvehicles/5series/sedan/2007/allfacts/engine/xdrive.html

There's a picture of it too.
 
Well I shall chalk this one upto Sunday journalism then. Unless your BMW 'contact' is a valater at the local dealership. :p
 
anticonscience said:
Well I shall chalk this one upto Sunday journalism then. Unless your BMW 'contact' is a valater at the local dealership. :p
Click to expand...
Cleaner Clive has never let me down :p

It's possible that it's still officially a secret and therefore anything in writing will follow the company line, but I'd say it doesn't look promising.
 
Still think this would be a great idea and that they should have done it ages ago. I would buy one over an audi with AWD., and they sell a fair few of them!
 
rare said:
Still think this would be a great idea and that they should have done it ages ago. I would buy one over an audi with AWD., and they sell a fair few of them!
Click to expand...
The trouble is, would you buy an Audi with AWD over a BMW with RWD? That's the question they have to find the answer for. Right now they outsell Audi with just a RWD offering, so if they offer AWD, are they just going to eat into their own RWD sales more than Audi's AWD sales? I imagine the number of people who do not choose a BMW because it is not AWD is a very small number indeed.
 
You must log in or register to reply here.
Back
Top Bottom