Larry’s retirement goes into overdrive

SIX-TIME Bathurst 1000 winner Larry Perkins has turned his retirement project into an automotive success story, developing an overdrive splitter gearbox for Mercedes-Benz’s Unimog heavy 4x4 vehicle for sale around the world.

The project came about because the former V8 Supercar race driver, team owner and engineer wanted to drive his new $240,000 Unimog – fitted out as a camper for outback adventures in his retirement from the racing business – at sensible highway speeds on his long treks to Western Australia, while at the same time cutting fuel consumption.

When ‘LP’ discovered the official factory overdrive splitter option had been discontinued when the latest Unimog model was introduced, he set out to make his own by modifying an older unit to suit the new Unimog.

The three prototypes worked so well that he then decided to pursue the project as a commercial enterprise, ultimately with the approval of Mercedes parent company Daimler in Germany.

The first run of 50 units is about to go into production in Germany at Mercedes-Benz parts supplier Claas, to be sold as an aftermarket accessory under the Perkins Engineering label in Europe, Russia, South Africa and Australia from about February next year.

Left: Mercedes-Benz Unimog.

And because the unit was developed on a shoestring compared with the typical automotive industry engineering project, the units are expected to sell for about $12,000 – some $3000 cheaper than the similar factory-produced overdrive splitter sold for the previous generation Unimog.

“With the fuel savings this can achieve, you can pay for it pretty quick,” he said.

Mr Perkins, who retired from race driving in 2003 and sold his V8 Supercar licences to the Kelly family early last year, told GoAuto he enjoys the serenity of exploring the outback, often in the footsteps of pioneering explorers.

“I go to Alice (Springs) and turn left and wander around,” he said “It is a peaceful sort of existence – a lot different to my previous life – and you realise how big Australia is.”

Mr Perkins owns three Unimogs – a heavily modified previous model on a stretched wheelbase and decked out with a queen-sized bed, shower, flushing toilet and two television screens “for when the wife comes along”, an ex-Army crane truck, and a new-generation, U4000 – dubbed “my man-truck” – for more rugged off-road travel in areas such as the Gibson and Tanami deserts.

He said that when he drove the new Unimog about 3000km from his home in Melbourne to the West Australian outback, he found driving at 80km/h a chore, as well as potentially dangerous on roads where most vehicles travel at 110km/h“I don’t want to make a race car out of my Unimog, but at 80km/h on a road in Australia, you are a danger to everyone else,” he said. “It is bad news.”

Mr Perkins wanted to be able to drive at 100km/h instead of the recommended 80km/h, with the five-litre, four-cylinder diesel engine revving at a more sensible 1800rpm instead of 2300-2400rpm.

“They (Unimog) needed this overdrive," he said.

Mr Perkins said the current Unimog had not been designed for the long-distance highway travel favoured by Australia's grey nomads.

"It was not designed for the sort of things guys like me get up to," he said.

“So I said to Mercedes, ‘I am going to do this’.”

Mr Perkins put his idea to Mercedes-Benz Australia national manager for special trucks Philip Leslie who could see the value of the project and thus put Mr Perkins in contact with Mercedes truck head office in Worth, Germany.

In January this year, two Mercedes engineers on a visit to Australia called into Mr Perkins' workshop in Sunshine, in Melbourne’s western suburbs, to check out the unit, and formally started the ball rolling to help get the necessary company approval for Mr Perkins to use Mercedes intellectual property and permission to approach their supplier, Claas, with a production proposal.

Mr Perkins recently travelled to Germany to finalise the arrangements for both production and distribution.

Mr Leslie told GoAuto that while the unit will not be sold as an official accessory on Unimogs in Australia, he would happily recommend that customers have one fitted.

The Unimog is best known in Australia as an army vehicle, with about 2500 doing service with the armed forces from about 1980 to 1995.

The vehicle line was discontinued as official Mercedes line for several years in Australia (some were independently imported), but was reintroduced as an official factory niche model about two years ago. About six have been sold since then at prices starting about $200,000.

Mr Perkins said his device was fitted to the back of the regular engine, replacing the original automated gearbox - an eight speeder with a low-range drive - with his splitter unit that offers up to 32 ratios.

One of the biggest benefits is a top gear that is 22 per cent taller than the regular gear, allowing faster but more relaxed highway cruising at a lower fuel consumption.

“At 100km/h towing my trailer (carrying a diesel-powered quad bike), the original fuel consumption was about 31 litres per 100km, which is quite high, but when you put the overdrive in it, it instantly comes back down to 24-25L/100km,” he said.

“If you drove the truck as it was designed around 80km/h, the fuel consumption was considerably less than 30L/100km. But 80km/h is just too slow for Australian highways.”

The three splitter gearbox prototypes, along with the precision digital drawings necessary for production, were crafted by long-time Perkins collaborator Hollinger, which is famous for its racing gearboxes.

It is not the first time a Perkins invention has made an impact. He recently sold the rights to his world-first aircraft ‘black box’ to a subsidiary of Air New Zealand.

Designed as a safety check on aircraft engines and systems, the device was developed over 12 years by Mr Perkins, a long-time amateur pilot of both planes and helicopters.