The Audi Quattro: The Legendary Four Wheel Drive Drivetrain.
If you are like me and you live in the upper snowy part of North America, then you probably have heard of the Audi Quattro four wheel drive system that has been around since the early 80’s. And if you live where sun always shines, you know how the Quattro drivetrain is a driver’s dream. If you have never tried an Audi A4, an Audi S4 or an Audi TT that are equipped with this legendary drivetrain than you would not know how pleasant it is of a drive when you floor yourself out off the curve and the car just pulls you right out with definiteness of purpose and not even a hint of hesitation.
The origins of the Quattro differential system, goes a long way back to the Second World War. Initially Volkswagen developed military vehicle and required all 4 wheels to have traction for obvious terrain reason. Later on, Audi utilized this early locking center Differential system on its Audi Quattro Model. Since the early days, it has gone through numerous revisions and improvements.
The Audi Quattro was the first road car to combine the Quattro differential with a turbocharged engine. Audi took advantage of the rule change in the rally racing industry to launch its newly developed Audi Quattro. Ahead of the game, Audi won every single race, one after the other for two years in a row. Since, the Quattro brand name has been used on all 4 wheel drive equipped Audi’s until today.
Personally, from the moment I have tried an Audi Quattro equipped vehicle I have never wanted anything else. My first Audi was the 1986 5000 Quattro with the 5 cylinder 2.2L turbocharged inline engine. My dad bought me that car for my 18th birthday, which was back in 1994. I had so much fun with that car even though it only had 158hp. I remember the amazing trips with my friends and those moments where we enjoyed some winter drift time on country roads and shopping mall parking’s. But I must say that my favorite Audi so far when it comes to off terrain and traction, is by far the first generation Audi Allroad.
How does the Quattro work?
Let’s first start to look at the Quattro progression over the years to better understand its functionalities. The First Quattro system was a locking center differential which means it would lock all four wheels permanently and distribute the torque evenly to the front and back axles. It’s not until 1987 that Audi released the Torsen T1 (Torque Sensing) differential which would allow a mechanical and automatic redistribution of torque to individual axles. Under normal driving condition the front and back would get a 50/50 power distribution. When wheel slippage would occur the differential would dedicate a large amount of torque to the axles with more traction. Because this differential was mechanical and didn’t have any sensors attached to monitor traction, it was called the “fail-safe” system. Unfortunately it had its limitation. For instance, when one wheel would lose total traction, the other 3 would not benefit from much extra torque due to all the power being used up by the spinning wheel. So Audi came up with the manually locking rear differential, where you had an option available in your dashboard to lock the rear wheels. It’s in 1995 that Audi launched its first Electronic differential lock system which monitored lost of traction via the ABS wheel sensors and speed sensors. When one of the sensors would detect a lost in traction from one of the wheels, it would apply the brakes to that wheel and redistribute the power to the opposing one. Further down the timeline, Audi introduced other variations of electronic sensing system to improve on traction and drivability.
The Haldex system which is commonly used on a wide range of Audi Models will run primarily on front wheels (97.5% front and 2.5% rear) until it detects any lost in traction by monitoring abs and speed sensors. When the front wheels loose total traction, the Haldex controller will lock up and can send up to 100% torque to the rear wheels. Using the open differential system, the Haldex can redistribute the power to the wheels that need it most. A great little system that will only use the four wheels when really needed allowing you to save on gas.
Aftermarket Haldex systems are available and they allow you to set the amount of power ratio (front vs back) you would rather have. There is even an option to control this front vs. back ratio in real time via a knob witch you can install inside your car. Today you can even get the Haldex system with a wireless remote control to play around with your traction settings in real-time. For enthusiasts this is a great option that allows you to have full control over your power distribution.
The “Crown Gear” central differential is the latest and has seen such and advance in innovation and technology that it allows the electronics to control the car in any given situation. It will apply up 70% of torque to the front wheel and up to 85% to the rear when necessary. This allows the system to take full control of the vehicle dynamic in any driving situation or condition. This 6th Generation Quattro system was launched on the 2010 Audi RS5. We will probably start to see it more often on the newer models.
So why is the Quattro System so Great?
Without going to much in the technical aspect of things, Audi has been and still is using a variation of differential system which have been developed and improved of the years, since its initial release. All the variations fall under the brand name Quattro and are chosen ultimately for the type of vehicle you choose to buy. So you may buy a 2014 Audi A4 and get a totally different Quattro system than if you buy the 2015 Audi TT or the latest Audi Allroad. Before putting the car into production, the engineers down at the Audi headquarters will select the best possible Quattro system with a number of factors in mind, allowing you to benefits from the best possible traction available. So you can always be sure that Audi will use the best and latest technology to get you out of the snow and out of the curve.