David Brown Restoration

By Peter Williams, David Brown Parts Ltd

The starting point

Clutch-less transmissions are now the norm on many vehicles, but before this innovation most tractors could only carry out work in the gear that they were capable of starting from a standstill in. Both John Deere and Ford had offered clutch-less transmissions to enable changing gear whilst on the move, under load, in the 1960’s. Neither had been widely accepted, partly due to the power losses involved. Others, including Massey Ferguson, offered a simple, clutch-less “High” and “Low” facility on each conventional gear, which whilst useful, was limited in its scope.

Meanwhile, building on their experience of making tank transmissions, David Brown had been experimenting with “Autodrive” (a fully automatic transmission) on a 990 Implematic but this never reached production. However, a traditional British compromise rose out of its ashes in 1971. Dubbed “Hydrashift”, it provided 4 clutch-less changes on every gear in a 3 forward 1 reverse manual gearbox. It was fitted to experimental tractors based on the then current 1200. It worked well, except that test drivers reported a lack of power, due to the energy absorbed by the transmission. A simple answer was to increase the power by adjusting the fuel pump, though test driver Mike Funnel rather overdid this on one tractor, resulting in a broken crankshaft! The experimental department fitted a new crankshaft and tested the engine, finding that the output had been increased from the standard 72 H.P. as fitted to the 1200, to over 90 H.P. Mike Funnel says that he was surprised to escape dismissal due to this act! From then on, David Brown did concede to increase the power, but by a more moderate amount.

The system met with widespread approval and went on to win a Queen’s Award to industry. The more powerful 1412 tractor followed with this transmission, then it was offered as an option on the larger models from the 90 series that was introduced in 1979. The subsequent 7 final series of tractors to be built at the Meltham, Yorkshire factory were the 94 series, now branded as “Case”. Now, Hydrashift was also made available on 4 wheel drive tractors. Indeed, the largest in the range, the 4 wheel drive 1694 was only available with Hydrashift. With only 1,200 built, it is now very collectable. During the following years this format was copied and refined by virtually every other tractor manufacturer until gradually being superceded by “constantly variable” transmissions.

With the 50th Anniversary of this innovation in mind, I set about the restoration of what is probably the earliest surviving David Brown incorporating this transmission, a 1212. Built in April 1970, it was the 12th one built, as a pre-production tractor, ahead of the official launch the

following August. It has been suggested that this tractor is the one that Mike Funnel increased the power output on, but even if not, the engine does seem quite lively and there is no paint on the injector pump, suggesting that it has had work carried out on it. As part of the restoration, it will be left in this state in acknowledgement of the tractor’s experimental days.

Restoration work commenced in March 2021, initially concentrating on the non-functioning “Selectamatic” hydraulic system, the Achille’s heel of white David Browns! As work on this system is akin to brain surgery, I enlisted the assistance of friend and David Brown factory trained engineer Cliff Price. Even then, much head scratching was involved as aside from an exchange control valve it was found that other components had been botched, requiring replacement with parts from another tractor being broken for spares. Once the hydraulic system had been sorted, the cab, sheet metalwork, radiator and fuel tank were removed. All oils were drained, the bare engine and transmission were hot pressure washed, then flipped upside down and the underside cleaned. Back in the workshop, the brake and clutch rods were removed and cleaned, much easier this way up! Following a coat of paint it was returned the right way up so that painting & re-assembly could continue. At the time of writing (December 2021) work continues apace. Most of the parts have been painted and put aside for the paint to harden. Many restorers use “2 Pack” paint which hardens much faster, but I

Cleaning the underside

prefer the more authentic finish of Synthetic paint. The“Sta-Dri”, cab has caused a few headaches as many of the fixing holes don’t line up.As the first generation of safety cabs fitted by David Brown, they were rather crude and noisy. However, I do have a soft spot for them as they were locally built, in Bristol, and they are rather more in proportion to the tractor than the later, rather tall, ungainly “Weatherframe” type that was designed and manufactured by David Brown themselves at their Leigh, Lancashire factory.

The aim was to have the tractor ready for showing during its anniversary year. Even with most events cancelled, I had hoped to display it at the Newark Tractor Show in November 2021. Although this deadline could have been met, it was felt that as the tractor is so historically important it was preferable not to rush the restoration. The tractor should be ready to display at “Tractor World” 2022, at theThree Counties Showground, Malvern. This event will take place on May 21st & 22nd, rather than the February date of previous years, where the main David Brown theme will be the 70thAnniversary of the Cropmaster. Plans are being made for a display of these iconic tractors If you are there, do come and see us, the David Brown Parts Ltd. stand will be there together with the David BrownTractor Club.

For more information visit www.davidbrownparts.com or call 01989 562743 (9am-4pm Mon-Fri)

Back the right way up