What is ATTS?

In past few weeks I’ve noticed that Honda’s Active Torque Transfer System (ATTS) is rather unknown even among Honda fans. If you are not you could stay and learn something new.

Will it fit my Honda, and which Honda?

As Car Rants put it, for a while the Prelude was the car Honda was ashamed to admit was their flagship model until the NSX came along. The Prelude started it’s life in 1978 and was among the first if not the first production car to feature 4 wheel steering, beating BMW 8 series by several months. Keeping in touch with putting innovative technologies in the Prelude, in 1997 Honda fitted the fifth generation Prelude with Actvie Torque Transfer System . The Preludes with ATTS were designated Type SH (super handling) in the US and VTI-S in Europe. Production was terminated in 2001 along with the whole Prelude line.

How did it work

As the name implies ATTS vectored torque. One might say that in it’s basic form the ATTS unit is a really small automatic gear box mated to the differential of the car. Through a series of clutches the ATTS unit sends torque to the wheel that needs power the most to optimize traction. The car uses the ABS sensors to measure wheel slip, yaw and G sensors to determine the load and steering angle sensor to determine the angle of the wheel. All of that data is fed to the ATTS computer which works with the ECU to determine the optimal torque a wheel can get. Once the output is decided, the ATTS engages the clutches. The reaction time of the system is within milliseconds.

What was the point

In the Prelude being a FWD car, the system was mostly used to neutralize the notorious FWD understeer, in addition to the ATTS unit Honda changed the shocks and springs, as well the front lower arms of the TYPE SH/VTI-S Preludes, the sway bars were stiffened as well, the result was indeed a car that handled noticeably better than the base model, the ATTS system was especially helpful and apparent in long sweeping corners. Despite having a 63/37 weight distribution the car equipped with the system managed to obtain a neutral handling. The car critics of the day wondered why that would be necessary since the Prelude was already a superbly handling platform. Nevertheless Car and Driver named the TYPE SH the best handling car under $30 000 in 1997. Only about 5% of all 5th Gen Preludes were equipped with ATTS making it a rather rare sight on today’s roads.

Legacy

The ATTS stopped production along with the Prelude in 2001, but the legacy of the system remains today. The praised SH-AWD system has found its way into various Acura and Honda vehicles in the past few years. The long awaited NSX will feature the system too. At its core the SH-AWD system is an ATTS system mated with Honda’s all wheel drive system effectively making it a true 4wheel torque vectoring system, so next time you see a Prelude Type SH on the road remember that somewhere buried under ‘90s metal and technology lies a little box which is the grandfather of something that made its way inside the new NSX.

This content was originally posted by a Car Throttle user on our Community platform and was not commissioned or created by the CT editorial team.