A beginner’s guide to quattro

Introduction

Since the launch of Unbound vol. 6: From head to headwe rode the Audi hype train to celebrate the automaker’s return to the inside Need for speed‘s digital world.

We have has revealed the in-game updates and even looked back on our top five tuned Audis on display Speed ​​chasers over the years. But for this week’s theme, we’re taking you all back to school… quattro school.

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By 2024 you will encounter a quattro variant of almost every production Audi. Yet its origins date back to the 1970s, with engineers Jörg Bensinger and Walter Treser widely credited with pioneering (and driving) the technology prior to its global debut. in the 1980 Ur-quattro road car.

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When Audi rolled this out in their rally campaign from 1981 onwards, it quickly became clear that this four-wheel drive revolution was here to stay. Not only did Audi claim two World Rally Championship titles and 24 wins between ’81 and ’86, but there hasn’t been a two-wheel drive WRC winner since Lancia’s 037 in 1983.

With Audi Tradition on the 2016 classic car tour

Audi’s quattro may be the most famous all-wheel drive system in the world, but it was far from the first of its kind. Early four-wheel drive transmissions date back to the dawn of the internal combustion engine. The Dutch brother Jacobus and Hendrik-Jan Spijker paved the way in 1902 with their Spyker 60 HP

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Over the following decades, several 4×4 systems were developed for military and off-road use, including the Willy’s Jeep and Series 1 Land Rover.

What about ‘normal’ cars? Well, Jensen’s 1966 FF and Subaru’s 1971 Leone both used all-wheel drive long before Audi joined the party. What made quattro different was How it powered all four wheels.

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Instead of using a heavy, inefficient transfer case to drive both axles, Audi developed a lighter, smaller center differential to provide power front and rear. Then, when traction became even more limited, the center differential could be locked with a vacuum-operated button, allowing the front and rear differentials to rotate at the same speed without slipping.

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But the real game changer came in 1987 when Audi introduced the Torsen center differential (torque sensing). Unlike other systems, this allowed Audi to continuously distribute power between the axles when needed. So instead of sending 50:50 power, it can send 25 to 75% power to the axle with the most grip. That kind of technology seems commonplace today, but if you go back almost forty years, you’ll see why quattro gained such a reputation in both passenger cars and motorsports.

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In 2024, the term ‘quattro’ now exists in several variants, depending on the model and intended use. Some you may already know, others you may not. So grab a pen and paper; The class is now in session.

Beginning: When did it all start?

40 years, 40 figures, 40 images: fascinating facts and stories abo

In 1976, Walter Treser became head of Audi’s ‘Advanced Special Vehicles’ program. One of his first tasks was to oversee the secret development of a high-performance all-wheel drive car, commissioned by Audi CEO Ferdinand Piëch.

The project didn’t even have a proper name, with the original prototype known simply as A1 (which stands for number one four-wheel drive). Moreover, no one except Piëch and the Audi engineers – including Treser and Bensinger – knew about the plan. Especially not Volkswagen.

40 years, 40 figures, 40 images: fascinating facts and stories abo

The story goes that during a conversation with Volkswagen’s head of chassis development in Ingolstadt, the engineer bragged to Treser about how great the handling was in their four-wheel drive, off-road VW Iltis, before making a quick off-hand comment about how good it would be. case if the Iltis could have even more power to surpass its rivals.

VW Iltis and Audi quattro

When Treser heard this, he became more intrigued by the idea of ​​using all-wheel drive in a sporty passenger car, a coupe or a two-seater. Piëch shared the same opinion, which eventually became the basis for Audi’s first four-wheel drive production car, the Ur-quattro. Ur means ‘original’ and quattro means ‘four’… in Italian.

However, the Ur-quattro was almost called something completely different. Carat – an abbreviation of ‘Coupé All-Wheel-Drive Turbo’ – was the favorite name of Audi management, but because this name was already used by a women’s perfume brand, it was Treser’s earlier suggestion (Audi quattro) that prevailed conducted.

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Meet Torsen

‘Torsen’ may sound like another Audi engineer, but the term actually means torque sensing. It was this development in 1987 that revolutionized the way four-wheel drive transmissions work.

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The first Ur-quattro used an open center differential with the option of manually locking it via a dashboard switch. But from 1988 this was replaced by a Torsen differential – the Type 1 – which allowed engine torque to be automatically sent to either axle, depending on which was needed most.

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By default the split offered a 50:50 split, but as grip or traction changed, up to 80% of available torque could be sent to both axles without the need for manual input.

However, this was not without limitations. Like a conventional limited slip differential, the Type 1 Torsen is limited by the amount of torque that can be delivered to an axle. So if one axle has no grip, the other axle will not deliver substantial torque either.

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To combat this, Audi initially offered the second-generation Quattro with a manually locking rear differential. Later developments (and a shift to electronically controlled differentials) meant that every corner of the car could be controlled to limit wheelspin and allow torque from a low-traction wheel to be passed through the Torsen diff to wheels with high traction.

What about Haldex?

In the case of early quattro systems, Audi used a longitudinally mounted engine with a center differential for permanent all-wheel drive, with the ability to shift torque between the axles with the Torsen center differential.

A timeless design icon: the Audi TT turns 25

But what about those predominantly front-wheel drive Audis? Simply put, ‘Haldex’ refers to the name of the original manufacturer, and this powertrain is designed to provide optional all-wheel drive on front-wheel drive cars equipped with transverse engines. Consider, for example, the first generation TT and S3 models.

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To keep the package tight, Haldex uses a multi-plate clutch at the rear differential (rather than a center differential) to engage the rear wheels when necessary, rather than being permanently driven as on previous models. The disadvantage? Because the clutch was in place and the front wheels were always driven, previous Haldex models could only send 50% of the available torque to the rear axle. This means that Haldex – for the most part – didn’t feel quattro ‘right’ compared to the models before it, something Audi later addressed…

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For most modern Audis, quattro ‘Ultra’ is most commonly used. This is (as the name suggests) the best of both worlds, combining traditional torque sensing with the ability to use front-wheel drive without the drawbacks.

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Why would you especially want to have front-wheel drive? Well, Audi discovered that 90% of driving doesn’t require power to all four wheels. Anyone who has seen a dyno chart knows that all-wheel drive takes energy, which in turn uses more fuel and reduces overall efficiency.

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The solution? Use an electronically controlled clutch at the rear differential (just like Haldex), but with a different clutch also at the transmission, which completely disconnects the driveshaft. According to Audi, this improves fuel efficiency by almost 20%.

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The fun doesn’t stop with quattro ultra either. Using data from the various sensors around the car (including GPS position and outside temperature), Audi’s quattro ultra system can even predict when a driver needs front- or all-wheel drive, without any other intervention required .

What about the rear-facing Audi R8?

So far we have looked at quattro in transversely and longitudinally mounted forms. But what about the oddity of the range: the mid-mounted, V10-powered R8 supercar? Naturally, it is equipped with a unique quattro variant that uses an electronically controlled hydraulic multi-plate clutch.

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Due to the heavy rear engine, the R8 is rear-facing as standard with a distribution of 85% to the rear axle and 15% to the front. But when grip or driving demands change, an electric axial piston pump (which can build up to 40 bar of pressure in just milliseconds) compresses the friction plates in the clutch, ensuring a constant variation of torque between the front and rear is possible. shafts.

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In the second generation versions of the R8, quattro can even distribute 100% of the available torque to the front or rear axle. But if you Real If you want a rear-wheel drive R8, then the R8 RWS built between 2017 and 2018 is your answer. It is lighter, faster and has only permanent rear-wheel drive.

What is your favorite?

That’s a lot of technology to process in a short time, and we know this barely damages the quattro surface before you point out what we missed. But quattro is Audi’s party piece; This technology not only put them on the map in the 1980s, but will continue to do so into 2024, with more vehicles than ever featuring all-wheel drive.

The Goodwood Festival Of Speed ​​​​2014

Naturally, this prestige has produced some pretty special quattro editions over the years, from the screaming IMSA GTO race car to the Le Mans-winning R18 e-tron. But if we had to choose just one? We go for five cylinders and five doors: the Audi RS2 Avant.

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A fast car that was developed together with Porsche and also had quattro in the early 1990s? Even by today’s standards, they’re obscenely cool – and fast.

Let us know your favorite quattro-equipped Audi in the comments section.

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