Roy recounts how the White Horse came together:- “It was myself and Brian who spent a good deal of our time on the tractor, but we also had a lad named, Nick Bass. He was a first-class engineer and worked with us in the early days on the tractor until he was dispatched to the Falklands to look after Volvo machines on the island there during the war. The tractor came to us as a bog-standard T800 machine with a D50 engine rated at 105hp – no good, of course, for tractor pulling, so some major development work had to be done. The first thing we did was fit a turbo, but we didn’t leave it there as we increased the boost pressure from 6psi to somewhere around 40psi. We also had to increase the volume of fuel being injected into the cylinders, so we opened up the elements on the pump and installed larger bore injector pipes. These we had laser cut to prevent the fuel atomizing, and at the same time, the engine compression was lowered significantly.” Back then, Volvo BM produced a ‘universal’ axle which was installed in several models of their loading shovels and articulated haulers, so it was no surprise to find the T800 sporting an axle out of an 860 hauler. Roy continues: “We had all sorts of problems with clutch burn- outs – just from testing in the yard at Duxford. “The solution was found by going to Borg & Beck, who already supplied bespoke
clutches for the truck racing world. So we went from a fibre to a sintered bronze clutch plate for the tractor, whist strengthening the pressure plates to prevent slip. I certainly learned a lot about rebuilding clutches and turbos back then! We carried out a great deal of testing, and fine-tuning of the engine with the tractor either anchored down in the newly installed dynamometer at Duxford, or simply by opening her up at full chat in the yard. Our colleagues in Sweden said it was impossible, but we were revving out the D50 at a whopping 3000rpm with a wheel speed of around 70mph and proved it could be done!
By 1985 we were ready to start competing with the tractor and attended events throughout that year and the next, with 1986 being particularly successful. Kevin Perry, Des’ son, was the principal driver, although we all took a turn in the saddle competing in both the British Tractor Pulling 8000lb and 10000lb classes. Our first competition took place at Whittlesea, Cambridgeshire, and I recall we blew the engine up on its maiden voyage. When necessary, we could carry out a rebuild easily within five hours, and a clutch change in just two. In fact, we always did an engine check after two meetings anyway and always had a spare set of pistons to hand at all events – just in case.”
CONTINUED OVERLEAF a
Roy with Kevin Perry (left) in the yard at Duxford circa 1985
26 THE VOICE MAGAZINE No38 2020
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