BMW all-wheel drive is older than you think


It all started with a 3-Series sedan at the 1985 Frankfurt motor show

 

 

 

When we think German all-wheel drive systems from the 1980s, it is inevitably Audi’s Quattro system that springs to mind. But Volkswagen AG’s competitors were also converts to the all-wheel drive philosophy, even though it took them a little longer to really get going.

 

This fall BMW is celebrating the 30th anniversary of the date when the Munich-based automaker allowed for the possibility that there could be something more awesome than rear-wheel drive… in those rare instances you had to drive on ice or snow. It was at the 1985 Frankfurt motor show that BMW unveiled the 325i “Allrad” sedan, a 3-Series of the E30 generation.

 

 

 

The system wasn’t named xDrive at that point and it was not as sophisticated as it is today, but it immediately gained praise from the automotive press. BMW’s all-wheel drive system sent 63 percent of the power to the rear wheels and 37 percent to the front, with visco locks in the rear differential and in the transfer case sorting out the differences in speed, assuring that the all-wheel drive system felt as much as a rear-wheel drive setup as possible.

 

The first model to feature the new all-wheel drive system was the 325iX, with the wagon arriving for the 1988 model year. North America only received the sedan version of the 325iX, having been shut out of the wagons, but the all-wheel drive sedan was still a bit of a novelty on our shores. The next model to receive all-wheel drive was the 525iX of 1991 — the E34-generation model already halfway through its product cycle. The all-wheel drive system in the larger sedan was now electronically controlled, with multi-plate clutches splitting the power 36:64 front to rear in accordance with signals from the ABS system.

 

Until relatively recently — 1999, to be precise (OK, that was a while ago) — all-wheel drive goodness was confined to the 3- and the 5-Series cars. That’s when the X5 Sports Activity Vehicle (SAV), or SUV as everyone else called it, arrived using a planetary gear system to split the power 38 to 62 percent in favor of the rear wheels, adding such systems as DSC (Dynamic Stability Control), hill descent control and an automatic differential brake.

 

 

 

An all-new reengineered xDrive system arrived four years later, in 2004, to replace the older all-wheel drive system. Debuting in the X3 and in the X5 at the same time, xDrive had the ability to send 100 percent of the power to the front or rear axle, using Dynamic Stability Control data such as accelerator position, steering angle and lateral acceleration to continuously adjust the drive power split.

 

It’s hard to find a BMW model now that does not offer all-wheel drive — one third of all cars BMW sells are xDrive models, over than a hundred in all — more in some markets than in others. But it all started with the smallest sedan in the range at a time when all the various models from Munich could be counted on the fingers of one hand. Now that’s a long time ago.

 

 

 

Source: http://autoweek.com/article/classic-cars/bmw-celebrates-30-years-all-wheel-drive

Author: Anna

October 20, 2015

in AutoExpo

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