How is the Quaife ATB superior?

The Quaife ATB Differential provides significantly improved traction and handling for powerful rear-wheel BMWs and Mercedes.

Once installed, drivers will notice an immediate difference as the Quaife automatically biases torque across the axle to the wheel with most grip. Unwanted wheel-slip is greatly reduced, enabling drivers to exploit the full potential of their machines for the first time, leading to a more exciting, rewarding and rapid driving experience.


Widely regarded as the differential upgrade of choice for road car owners, the Quaife ATB was designed to overcome the flaws of conventional clutch-plate limited-slip diffs. Quaife's patented design;

  • requires no servicing or maintenance.
  • is silent and smooth in operation.
  • is guaranteed to work seamlessly with all electronics and OE components.
  • uses a progressive, non-locking helical gear design - allowing for safe and predictable control during moments of oversteer.
  • is capable of biasing up to 80% of torque to wheel with most grip.
  • comes with a limited lifetime warranty.

Watch BBC Top Gear's Chris Harris demonstrate the Quaife ATB in our 335i during his Autocar days!

The clutch-plate problem

'Clutch-plate' limited-slip diffs (Mercedes AMG, BMW M-Performance, Drexler, OS Giken, etc) operate using an internal spring pack and set of clutches that limit the amount of rotational difference between the driving wheels in low traction conditions. However, the wearing of clutches means that they require special lubricant changes throughout their lives, and will eventually need replacing. Due to their finite life, many of them can't be guaranteed for more than 12 months.

Additionally if high locking percentages are used they can cause abrupt locking of the rear axle and significant "snap-oversteer" out of slippery turns. While these characteristics might be beneficial in motorsport, they aren't ideal for road use.

The Quaife solution

The Quaife ATB Differential however uses a unique, non-wearing gear design that maximises traction by automatically biasing torque across the axle depending on which wheel is enjoying the most grip. The result in performance is huge amounts of grip, but in comparison to clutch-plate diffs offers an intuitively controllable rear end during any moments of oversteer. 

There are no clutches, ramps, springs or other wear prone components to replace at regular intervals, because the Quaife ATB’s well-proven system of helical gears is extremely durable. This makes the Quaife ATB a genuine 'fit and forget' upgrade that offers compromise-free performance and unbeatable reliability on the street, strip, stage or circuit, but most importantly, it can be accompanied with Quaife's famous limited lifetime warranty.

Other key features of the Quaife ATB include:

  • Manufactured in Great Britain.
  • Precision manufactured from certified steel billets and inspected to ISO9001-2008 standards.
  • Direct replacement for factory standard open differential unit (no 'shims' required).
  • Uses regular gear oil lubrications systems and maintenance schedule.
  • Has been consistently tested and improved since its launch in the 1980's.
  • Plug and play complete Quaife ATB-equipped differentials available via Birds.
  • Comes with technical support by telephone or email via Birds.

About Quaife

Established in 1965, British manufacturer RT Quaife Engineering Ltd is a global leader in the automotive drivetrain industry, supplying motorsport users, volume OEM and commercial customers with a wide variety of performance products.

From clubman rallying up to Formula One, tens of thousands of automotive and motorcycle users depend on Quaife products to maximise their vehicle’s performance on a daily basis, including their state-of-the art sequential gearboxes, flagship automatic torque-biasing differentials, and hundreds of other associated drivetrain components.

The innovative Quaife ATB Differential, arguably their most famous product, was chosen by FORD to use as OEM in their Focus RS model - a testament to their reputation for quality and reliability. Other major car manufacturer's to use the ATB as OEM include Caterham, Chrysler, Lotus, Radical and GM.

Visit for more information.

Birds' and Quaife's relationship

All BMW and Mercedes Quaife ATB differentials are commissioned, stocked and distributed worldwide exclusively by Birds.

  • We carry an average of 750 BMW and Mercedes Quaife ATB Differentials in stock, and ship to distributors, workshops and customers worldwide.
  • We provide plug & play solutions for technical BMW applications, including complete Quaife ATB-equipped differentials in exchange to eliminate downtime and complications for customers.
  • We provide comprehensive installation instructions and technical support by phone or email.

We are responsible for the research, development and commissioning of new BMW and Mercedes Quaife ATB Differential applications. If you can't find an application for your model on this site please contact us with your VIN. We might already have the correct size of differential in stock!