National Motor Museum Blog – February 2020

Posted  06.02.2020
Comments  (00)

The National Motor Museum engineers are always kept busy maintaining the collection of over 280 historic vehicles. Some cars – such as the 1920 Sunbeam 350hp – are long-term projects that are being brought back to top condition in stages, while others – such as the 1935 Auburn 851 – call for more urgent attention.

The Sunbeam’s rebuilt V12 engine roared into life in 2014, before the car returned to Pendine Sands the following year (below)

Labour of love

The 1920 Sunbeam 350hp is a labour of love for the workshop engineers. Having painstakingly rebuilt its complex V12 engine over a number of years, in 2015 they triumphantly took this landmark machine back to Pendine Sands in South Wales for a low-speed reconstruction of its World Land Speed Record which was set there 90 years before. However, while the engine is now in fine fettle, the gearbox is still the missing part of its puzzle.

At some point after World War II, the original gearbox was removed and by the time the Sunbeam became an exhibit at the National Motor Museum, it was fitted with a temporary gearbox from an Albion 35hp. Only designed to handle a tenth of the engine’s power, this gearbox also lacked a transmission brake – an important part of the Sunbeam’s original brake set-up.

By the time Lord Montagu drove the Sunbeam for this 1962 photo, a temporary gearbox had been fitted

The engineers built bespoke mounts for the new gearbox, using existing holes in the chassis sub-frame

Reinstating a suitable gearbox has been a priority for the engineers, as the next stage of the car’s ongoing preservation. With help from the museum’s supporters, a sturdy Bentley C-type gearbox, which would be better suited to the task, has been sourced and adapted to fit the Sunbeam’s chassis with custom-made mounts. Best of all, this has allowed a sizeable transmission brake to be installed. Once the installation has been completed and the gearbox tested, the Sunbeam will finally be fitted with the robust transmission that its mighty engine deserves.

The sturdy Bentley gearbox is connected to a transmission brake, an important part of the Sunbeam’s brake set-up

The Auburn is usually a very reliable car, but ran into difficulty on the Jewel of Piemonte rally

Transmission woes

The 1935 Auburn 851 has been inflicted with its own transmission woes lately. Regularly driven in motoring events across the world, in 2019 this glamorous roadster was entered into the Jewel of Piemonte rally, which took place in the Piemonte region of Italy, before exploring the Alps and finally finishing in Monaco.

Sadly, on the first day of the event, the Auburn suffered a major axle calamity as it pulled away from a toll booth, when the pinion gear in its differential stripped half of its teeth. This damage ended the event for the car. Considering how many trouble-free miles the car has travlled, including its 2,800-mile adventure from Shanghai to Beijing in 2007, this failure was especially frustrating.

The crown wheel teeth were badly damaged…

Back in the workshop, the axle was stripped down to reveal that the crown wheel had also been heavily damaged by the pinion gear failure. Fortunately, the damage was limited to these two components and, as spares were included with the car when it came to Beaulieu in the 1960s, the workshop engineers will soon have this impressive machine mended and back in action.

…with the damage resulting in this debris

Categories:  Archived