Developing the transmission for Dakar Rally legend Mitsubishi Pajero

Competing in the demanding world of off-road rally presents some unique engineering challenges. This is particularly true for the infamous Dakar Rally, which sees racers rallying through some of the world’s toughest terrain and environmental conditions.

The Dakar Rally, formerly known as the Paris–Dakar Rally, is organised by the Amaury Sport Organisation (ASO), and was traditionally staged from Paris, France to Dakar, Senegal. Since its inception in 1978, the annual rally has seen competitors and their vehicles race up to 15,000km (9,320 miles) across towering sand dunes and rocky landscapes, through caverns and mud in inhospitable temperatures. The perfect blend of ultimate reliability and performance excellence is required to compete and win under such extreme conditions.

Ricardo has a proven track record of delivering solutions to meet the most complex requirements of our clients in the motorsport industry. It was following our successful engagement with Audi in support of their LMP1 programme in the early 2000s, that Mitsubishi approached Ricardo with a new challenge; to develop a transmission worthy of Mitsubishi’s impressive pedigree at the Dakar Rally for the Pajero Evolution Super Production.

Ricardo and Mitsubishi: overcoming the ‘challenge for those who go’

The primary challenge was to design a transmission that would deliver the maximum performance required for the Pajero to be competitive whilst being able to meet the demands of such extreme operating conditions.

A unique transmission solution was specified with reliability, serviceability, and flexibility at the core of the design. Configurable in either 5 or 6 speed variants, the transmission was able to be deployed flexibly to meet different regulations.

To improve the durability of the driveline, a torque limiter was mounted in front of the gearbox to protect it from the excessive torque spikes which are typically generated when landing jumps.

Of course, not all damage is preventable. Getting stuck in sand dunes was a real possibility and this could cause damage to the clutch. When every second counts, getting a vehicle back in the race as quickly as possible is paramount to crossing the finish line in podium position. With this in mind, Ricardo mounted the clutch in a cassette in the back of the transmission for ease of access. This enabled the team to carry spare clutch cassettes for quick repairs on the go.

To address performance demands, integrated oil pumps optimised cooling and lubrication of the transmission. Additionally, building on the foundation of the RS200 programme, a viscous coupling with incorporated differential lock was used in the centre differential. Using this method meant that less cooling was required, and it also provided greater control over difficult terrain.

Despite the significant deployment of technology and protection, the transmission was kept lightweight to improve efficiency and performance. The whole driveline weighed in at just 190kg, the minimum allowable weight mandated by the Federation Internationale de l'Automobile (FIA). The gearbox, excluding axles, clutches and driveshafts, weighed an impressive 70kg.

Continuing a legacy of success for Mitsubishi

The Mitsubishi Pajero Evolution first raced the Dakar Rally with the Ricardo transmission in 2003. It achieved an incredible run of success, securing 1^st, 2^nd, 3^rd, and 4^th positions on its debut outing. This was followed by a run of 5 consecutive victories between 2003 and 2007, ending in 2008 when the Dakar Rally was cancelled following security concerns.

Reflecting on Ricardo’s efforts in supporting Mitsubishi’s legacy at the Dakar Rally, Steve Blevins, Head of Engineering said:

“It was a great pleasure to work on this programme. It combined the endurance elements of our then-recent work in LMP1, and the off circuit demands of World Rally to create an unbeaten transmission for one of the world’s top performing OEMs in one of the most demanding events. Our ability to pull from complementary programmes and experiences means that the Ricardo engineering team get this right first time.”

Martin Starkey, Managing Director of Ricardo’s Performance Products segment added:

“The breadth of programmes to which our skilled Motorsport team have turned their hand to never ceases to amaze me. This unbeaten record with Mitsubishi at the Dakar Rally is a true testament to Ricardo’s ability to review, understand and interpret the regulations to design a transmission which complements the vehicle performance whilst providing the minimum of compromise in package space and usability.”

This outstanding record of performance and reliability reflected in the unbeaten track record of the Pajero’s transmission led to Ricardo expanding into more top tier off-road programmes with Mitsubishi. This includes the Lancer WR04 WRC contender which Ricardo continues to support in historic rally events. This platform was also expanded to other manufacturers with whom Ricardo enjoyed significant periods of success in off circuit competition.

Join us for our next instalment where we will take a closer look at one such program. We will explore how Ricardo utilised their capability to provide a regulation optimised driveline for top tier rally.