BMW xDrive

Last updated
xDrive system in a BMW X5 (E70) BMW xDrive.jpg
xDrive system in a BMW X5 (E70)

BMW xDrive is the marketing name for the all-wheel drive system found on various BMW models since 2003. [1] The system uses an electronically actuated clutch-pack differential to vary the torque between the front and rear axles. Models with the DPC torque vectoring system also have a planetary gearset to overdrive an axle or rear wheel as required.

Contents

Prior to the introduction of xDrive, all-wheel drive was available on several models since 1985, based on an all-wheel drive system that uses viscous couplings.

Predecessor

The first BMWs available with all-wheel drive were the 1985-1992 E30 325iX and 1991-1996 E34 525iX models. [2] [3] [4] These cars use centre and rear differentials with viscous couplings to vary the torque split between wheels. The centre differential has a default front:rear torque split of 37:63, due to the planetary gear. [5] Up to 80% of the torque can be transferred to the tripping axle, using the increasing shear force of the silicone fluid in the viscous coupling (due to the slotted/grooved plates inside the unit) as wheel slip causes one axle to spin faster than the other. The same principle applies to the rear differential varying the torque split between the rear wheels. The front differential has no locking function. All-wheel drive was discontinued when the E30 3 Series and E34 5 Series were replaced by the E36 and E39 respectively.

All-wheel drive was reintroduced in 2001 for the X5 SUV and E46 3 series 325xi, 330xi and 330xd sedans/wagons. [6] The system is similar to the earlier version, except without the viscous couplings. Instead, the electronic stability control (DSC) system applies the brake to wheels that are slipping, helping transfer power to the wheels with traction.

Design

Unlike its predecessor, the xDrive system uses an electronically actuated clutch-pack differential that engages to send torque to the front axle. [7] In the case of the 2018 X3 through X6 models, the default torque split is 40:60 and the system is able to send 100% of the torque to either axle. [8] However, full torque transfer to the front axle can only be achieved if the rear wheels have absolutely no traction, as the rear drive shaft is hard-coupled to the transmission output,. The wet clutch is applied through a high speed electric servo motor turning a cam-shaped actuator disc. In most vehicles, the system uses open differentials at the front and rear, relying on the brakes (controlled by the electronic stability control system) to transfer torque away from the slipping wheel on each axle.

A different system is used on BMWs which are based on a transverse engine front-wheel drive platform, such as the BMW X1 (F48), BMW 1 Series (F40) and BMW 2 Series Active Tourer. These models use a GKN Driveline system which sends 100% of the torque to the front wheels by default, only sending torque to the rear wheels when the front wheels are slipping. [9] [10]

Dynamic Performance Control

An upgraded version of xDrive with torque vectoring, called 'Dynamic Performance Control' (DPC), was introduced on the 2008 BMW X6 and has since become available on other vehicles including the BMW X5 M. [11] [12] As per most torque vectoring systems, the primary function is to increase agility in cornering. [13] The DPC system is also used by the electronic stability control (DSC) to correct for understeer/oversteer, with one reviewer commenting that it provided smoother results and avoided the temporary power loss associated with the traditional method of using individual wheel brakes in such situations. [13]

The DPC system can distribute torque between the front and rear axles, and between the two wheels on the rear axle. [14] The system uses a clutch pack and planetary gearset within the differential to overdrive a wheel or axle as required. [15]

Applications

The first xDrive models (as opposed to the earlier all-wheel drive system) were released in 2003. These consisted of the newly released BMW X3 (E83) - ATC400 Transfer Case, facelifted BMW X5 (E53) - ATC500 Transfer Case. In the following years, the availability of xDrive increased throughout the model range, and it is currently available on most models.

The first BMW M models to use xDrive were the 2009 E70 X5M and E71 X6M models. The first non-SUV BMW M model to not be rear-wheel drive was the 2017 F90 M5, which was only available with xDrive. [16]

In Canada, 50 percent of BMWs sold in 2005 were fitted with xDrive. [17] As of 2010, BMW Canada stopped offering rear-wheel drive versions of models that were available with xDrive, for example the only BMW 6 Series (F12) 650i version available without xDrive in 2012 was the convertible version. [18]

Related Research Articles

A traction control system (TCS), is typically a secondary function of the electronic stability control (ESC) on production motor vehicles, designed to prevent loss of traction of the driven road wheels. TCS is activated when throttle input and engine power and torque transfer are mismatched to the road surface conditions.

<span class="mw-page-title-main">Four-wheel drive</span> Type of drivetrain with four driven wheels

A four-wheel drive, also called 4×4 or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.

<span class="mw-page-title-main">BMW 5 Series (E34)</span> Third generation of the 5 Series executive car

The BMW E34 is the third generation of the BMW 5 Series, which was produced from November 2, 1987, until 1996. Initially launched as a sedan in January 1988, the E34 also saw a "Touring" station wagon (estate) body style added in September 1992, a first for the 5 Series. BMW replaced the E34 with the E39 5 Series in December 1995, although E34 Touring models remained in production until June 1996.

<span class="mw-page-title-main">Limited-slip differential</span> Differential gearbox that limits the rotational speed difference of output shafts

A limited-slip differential (LSD) is a type of differential gear train that allows its two output shafts to rotate at different speeds but limits the maximum difference between the two shafts. Limited-slip differentials are often known by the generic trademark Positraction, a brand name owned by General Motors and originally used for its Chevrolet branded vehicles.

<span class="mw-page-title-main">Quattro (four-wheel-drive system)</span> Sub-brand by Audi that designed for its all-wheel-drive cars

Quattro is the trademark used by the automotive brand Audi to indicate that all-wheel drive (AWD) technologies or systems are used on specific models of its automobiles.

<span class="mw-page-title-main">Drive shaft</span> Mechanical component for transmitting torque and rotation

A drive shaft, driveshaft, driving shaft, tailshaft, propeller shaft, or Cardan shaft is a component for transmitting mechanical power, torque, and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them.

<span class="mw-page-title-main">BMW M</span> High-performance car manufacturer owned by BMW

BMW M GmbH, formerly known as BMW Motorsport GmbH, is a subsidiary of BMW AG that manufactures performance cars.

<span class="mw-page-title-main">4Matic</span> All-wheel-drivetrain developed by Mercedes-Benz

4Matic is the marketing name of an all-wheel drive system developed by Mercedes-Benz. It is designed to increase traction in slippery conditions. With the introduction of the 2017 E 63 S sedan, Mercedes-AMG announced a performance-oriented variant of the system called AMG Performance 4MATIC+.

<span class="mw-page-title-main">Viscous coupling unit</span>

A viscous coupling is a mechanical device which transfers torque and rotation by the medium of a viscous fluid.

ATTESA is a four-wheel drive system used in some automobiles produced by the Japanese automaker Nissan, including some models under its luxury marque Infiniti.

Jeep uses a variety of four-wheel drive systems on their vehicles. These range from basic part-time systems that require the driver to move a control lever to send power to four wheels, to permanent four-wheel systems that monitor and sense traction needs at all four wheels automatically under all conditions.

<span class="mw-page-title-main">All-Trac</span> Proprietary full-time four-wheel drive system by Toyota

All-Trac was a proprietary full-time four-wheel drive system used on a variety of Toyota badged models from 1988 to 2000. It was considered a revolutionary advance for four wheel drive automobiles into the mainstream consumer market and its electronic/vacuum controlled locking center differential was rare in a passenger car. The system originated in Japan under the GT-Four name in 1986, but was not released in the U.S. until 1988 under the All-Trac name.

<span class="mw-page-title-main">BMW X6</span> Motor vehicle

The BMW X6 is a mid-size luxury crossover SUV by German automaker BMW. The BMW X6 is the originator of the sports activity coupé (SAC), referencing its sloping rear roof design. It combines the attributes of an SUV with the stance of a coupé. It is built in BMW's North American plant in Greer, South Carolina alongside the BMW X5, whose platform it shares. Prior to the release of the X7, the X6 was considered a flagship SUV for BMW.

ControlTrac four-wheel drive is the brand name of a selectable automatic full-time four-wheel drive system offered by Ford Motor Company. The four-wheel drive system was designed and developed at BorgWarner under its TorqTransfer Systems division in the mid 1980s. BorgWarner calls the system Torque-On-Demand (TOD). ControlTrac was the first automatic system to use software control and no planetary or bevel geared center differential. Instead of a planetary or bevel geared center differential, the system uses a variable intelligent locking center multi-disc differential.

<span class="mw-page-title-main">Mid-engine, four-wheel-drive layout</span>

In automotive design, an M4, or Mid-engine, Four-wheel-drive layout places the internal combustion engine in the middle of the vehicle, between both axles and drives all four road wheels.

<span class="mw-page-title-main">BMW X5 (F15)</span> Motor vehicle

The BMW X5 (F15) is a mid-size luxury SUV manufactured and marketed worldwide by BMW since 2013. The car was unveiled at the 2013 Frankfurt International Motor Show. Early X5 models include xDrive50i, xDrive30d, M50d. BMW xDrive40d, xDrive35i, xDrive25d, sDrive25d were to be added in December 2013.

<span class="mw-page-title-main">Symmetrical All Wheel Drive</span> Drivetrain developed by Subaru

The Symmetrical All-Wheel Drive is a full-time four-wheel drive system developed by the Japanese automobile manufacturer Subaru. The system consists of a longitudinally mounted boxer engine coupled to a symmetrical drivetrain with equal length half-axles. The combination of the symmetrical layout with a flat engine and a transmission balanced over the front axle provides optimum weight distribution with low center of gravity, improving the steering characteristics of the vehicle. Ever since 1986, most of the Subaru models sold in the international market are equipped with the SAWD system by default, with the rear wheel drive BRZ and kei cars as the exceptions.

<span class="mw-page-title-main">All-wheel drive</span> Powertrain providing power to all its wheels for use primarily on paved surfaces

An all-wheel drive vehicle is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.

<span class="mw-page-title-main">BMW X5 (G05)</span> Motor vehicle

The G05 BMW X5 is a mid-size luxury SUV produced by German automaker BMW. It is the fourth and current generation of the BMW X5. It was launched in 2018 as the successor to the F15 X5. Sales of the X5 started in November 2018. The X5 M and X5 M Competition (F95) performance models were revealed on 1 October 2019.

<span class="mw-page-title-main">BMW X5 (F85)</span> Motor vehicle

The BMW X5 M (F85) is a mid-size luxury SUV that is based on the BMW X5 (F15) which has been built by BMW since 2014. Unlike the BMW X5 M50d the X5 M is a full BMW M series car that has the M Powered engine. In comparison, the M50d is classified as an "M Performance Car" which means it isn't a full M car unlike the BMW M3 or the BMW M5.

References

  1. ↑ "First Look: 2019 BMW 8 Series Preview". NY Daily News. Retrieved 2018-06-16.
  2. ↑ "1985 BMW 3 E30 Sedan phase-I/2 X (4WD) full range specs". www.automobile-catalog.com. Retrieved 31 August 2019.
  3. ↑ "BMW E30 3 Series 325ix Technical Specs, Dimensions". www.ultimatespecs.com. Retrieved 31 August 2019.
  4. ↑ "1991 BMW 5 E34 Sedan X (4WD) full range specs". www.automobile-catalog.com. Retrieved 31 August 2019.
  5. ↑ "BMW xDrive and 4x4 Systems Explained". www.unixnerd.demon.co.uk. Archived from the original on 5 August 2017. Retrieved 5 September 2019.
  6. ↑ "Model selection - 3'E46 - Touring". www.realoem.com. Retrieved 31 August 2019.
  7. ↑ "BMW XDrive Vs Audi Quattro - How Do They Differ And Which Is Best?". www.carthrottle.com. 19 January 2017. Retrieved 1 September 2019.
  8. ↑ "BMW xDrive". www.bmw.com.au. Archived from the original on 25 August 2018.
  9. ↑ "Which to Buy: BMW X1 or MINI Countryman?". www.bmwblog.com. 12 March 2017. Retrieved 1 September 2019.
  10. ↑ "F48 technical training docs" . Retrieved 2016-12-19.
  11. ↑ "2008 BMW X6 xDrive35i and xDrive50i". Car and Driver . Retrieved 2012-09-30.
  12. ↑ GmbH, Interone Worldwide. "BMW X5 M : Dynamic Performance Control".
  13. 1 2 "2009 BMW X6 xDrive50i vs 2009 Infiniti FX50". www.automobilemag.com. 2 June 2008. Retrieved 5 September 2019.
  14. ↑ "Dynamic Performance Control". www.BMW.com. Archived from the original on 4 March 2016. Retrieved 4 March 2012.
  15. ↑ "BMW xDrive - From the First Analog System to Hybrid All-Wheel-Drive". www.autoevolution.com. 20 April 2016. Retrieved 5 September 2019.
  16. ↑ Damon Lavrinc (2010-10-18). "Six Things We Learned at BMW M". Autoblog. Retrieved 2012-07-28.
  17. ↑ "Winter driving test: BMW xDrive". www.autos.ca. Retrieved 5 September 2019.
  18. ↑ "Car Review: 2012 BMW 650i xDrive". 10 November 2011.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.