Bentley DNA<br>Bentley 4 1/2 Litre Vanden Plas

Bentley DNA
Bentley 4 1/2 Litre Vanden Plas

By Keisuke Baba

The Heat Haze of Les Hunaudières

It would be unthinkable to write the history of Bentley without recalling the glorious vintage period when the automaker dominated the 24 Hours of Le Mans. For so much of its rich history springs from this moment, establishing the prestige of the Bentley marque which lives on today. As the Bentley 4 1/2-litre Vanden Plas powers ahead with its mighty torque, the hazy horizon, still flickering with the spark of yesteryear, can be glimpsed through the racing screen of this 80-plus year old racer.

text: Takuo Yoshida
photo: Hidenobu Tanaka
cooperation: Towa Body
cooperation: Rustic Gold
transration: Mako Ayabe and Michael Balderi

The Battle Plan

As we waited on the starting grid for the formation lap at Thruxton Circuit, one of Britain's fastest tracks, dark clouds rapidly gathered over our heads and the rain came pouring down. At one point the rain was so heavy that we couldn't even see the red signals at the edge of the track, and the track itself was flooded up to the ankles of the press photographers scattered to the side. Thinking the race would be postponed, I stopped blipping with my right foot to calm the racing engine. Soon after, though, the signal cruelly turned green and, without the slightest hesitation, the race cars paddled off in a rip current onto the pond-like track. At that dizzying moment, I was suddenly thirsty and choked up trying to catch my breath. I can still clearly recall putting every scrap of strength I had into my lower stomach, telling myself, ‘This is more of a battle than a drive.’
The stage for the drive is a public road, but it could just as well be a battlefield. The jet-black Bentley 4 1/2-litre is clad in a sporty, lightweight fabric body made by Vanden Plas, just like the Le Mans models of the fabled past. The vehicle's wheelbase is a couple of centimetres longer than that of the Continental Flying Spur, but its narrow width - just narrow enough to fit into a Group 5 body size - makes it look like a locomotive carved from a block of steel. W.O. Bentley's background as a steam locomotive engineer may have given it this impression, but this W.O. exudes a kind of steadfast determination that keeps it moving forward, rather than dexterously turning and stopping.
Stepping over the mechanic's seat (No, it's not a ‘passenger seat’), I settled into the driver's side and gripped the cold shift lever. I still feel goosebumps all over my body as memories of Thruxton come rushing back. I have driven more than a handful of pre-war 'vintage cars', including racers, but through it all I have never driven anything as commanding in presence as a Bentley. Unlike modern automobiles, the weight of the controls on a vintage car is proportional to its size: 5.25mm wide tyres are equivalent to the width of a high-end sports car in the late 200 range by today's standards. You can, perhaps, imagine the struggle in the upper body when handling them and steering without power assistance.
Yet still, the challenges of the lower body easily outweigh those of the upper body. Surprisingly, the pedals are arranged in BAC rather than ABC from the right. As the name 'centre-mounted throttle' suggests, the throttle pedal is positioned in the middle. Some Bentleys have been converted to the more common ABC by owner request, but a genuine vintage Bentley enthusiast should modify their own common sense, not the bodywork. I explored the brake and throttle positions with my right foot to get a feel for them. If I dare downshift, will I have to go toe-to-heel instead of heel-to-toe? Rather than a struggle against the lower body, it has now become a mental exercise—but a mental exercise that can't be redeemed if I fail. With the F1 cars I had driven in the past, I had to think of myself as a brawny wrestler in the upper body and a lithe ballet dancer in the lower, but with this one, the driving position is not firmly fixed, so the lower body needs to be stronger than strong. I’m not sure if I’m ready for this, but the battle is on.

Runaway Locomotives on Four Cylinders

After turning on all the magnetos and other switches, I pressed the starter button between the speedometer and rev counter. The mechanical noise increased all at once and the engine fired up. The volume was more subdued than anticipated, as the exhaust system was not completely straight-through. Instead, the driver is surrounded knee-deep in the engine clatter piping through gaps in the cast magnesium bulkhead. The fact that the Bentley's power unit has only four cylinders, despite its 4.4 litre displacement, may seem slightly odd. Modern knowledge would have led one to imagine a so-called ‘multi-cylinder unit’ with six to eight cylinders or more, given the displacement and the brand's status. Common modern practice, however, does not apply to engineering techniques from 82 years ago. In addition, it is unusual in that it has four valves per cylinder, despite the single camshaft located in the overhead. The vibrations transmitted to the cockpit through the strong ladder frame are as powerful as the '82-year-old-four-cylinder-engine' specification. On the other hand, the centre-mounted throttle pedal has a strangely short stroke, and I wasn't confident that I could handle the engine well across the entire rev range.
Gearboxes with four forward gears and one backward gear have no synchronisation mechanism. Racing-specific gearboxes, such as those produced by Hewland Transmissions in the UK, are sometimes described as having 'no synchronisation', but this is not quite right. Instead of a synchromesh as in ordinary automobiles, they have a mechanism called a ‘dog ring’, which instantly facilitates synchronisation between the gears. Vintage Bentleys, by contrast, are direct-shifted, with bare gears colliding into one another. This means that when the vehicle engages in first gear, which has no way of adjusting its rotation, you feel a considerable shock through the gearshift lever. However, if you try shifting from second to first quickly with the shift lever—standard practice for historic cars—you’ll find that the engagement is somewhat smoother.
The clutch is a relic from the past, when modern diaphragm springs did not yet exist, and the connection is, of course, abrupt. The engine never stalled during this battle, thanks to the Bentley 4 1/2-litre's impressive torque. In fact, the problem is that it has so much torque that the engine cannot be stalled by simply hitting the brake pedal, but rather it seems to steam forward against the driver's will. Like a runaway locomotive with a mind of its own, it struck me with a sense of dread that I’d never felt before.
The 4-speed gear ratio, which is set to match the torquey engine, is uncomfortably high, so even if the rev counter is only set to 4000 r.p.m. on the full scale, and the vehicle is actually running in a rev range of less than 2000 r.p.m., the speed remains very high. Once the tyres start rolling, the steering weight is halved, but even so, one-handed steering is out of the question, and shifting while cornering takes some getting used to. I tried different approaches and timings for shifting from second gear upwards, including using a double clutch, but it seemed that the best strategy was to pull the engine to 2500 r.p.m. or more and then, without hesitation and with great determination, to slam it into the shift gate. Sometimes there was a clunk, at others it went smoothly. This is not a skill that can be acquired on a short drive. Only the seasoned owner can master it.

Beyond the Racing Screen

The noise that envelops your body, the vibrations that numb your nerves, the smell of the mechanic’s mixture that lulls you into a driving high, the heavy steering that pulls to and fro wildly like a busted floodgate valve, the torque of a runaway locomotive, and the gear shifting with its extreme tension: the initial impact of a vintage Bentley is completely different from driving a ‘normal’ vehicle. That's why it's hard to describe the feeling you get when the jet-black behemoth starts to slide along at your command, and you even feel a tinge of satisfaction, as if you've been written into a page in the lofty history of the automobile.
After surviving all the initial jolts and standing tall in the cockpit, taking a deep breath and containing your emotions, the weighty doors that had previously been shut open before your very eyes. There it is, the pure vintage Bentley character and driving feel, minus the NVH (Noise, Vibration, Harshness).
Contrary to its bold and rather grandiose image, the Bentley 4 1/2-litre's touch on the road as it surges forward has been quite subtle up till this point. The vibrations are loud, but there is no unnatural rattling of the numerous bearings, and the leaf springs are still supple enough to absorb the vibrations and support firm roadholding.
The combination of a throttle pedal with an extremely short stroke and a surprisingly sharp engine response is also easy enough to handle if the driver's mind is locked into an aggressive mode. By modern standards, the acceleration is astonishing, but it's as heavy when cornering as it looks, and the brake power is admittedly poor, even when compensated for by the handbrake with its lever growing outwards from the body. Still, you can tell that the vintage Bentley has been assembled with a timeless precision, and its performance is commendable. History has proven that, going back 80 years, these vehicles reigned supreme at the pinnacle of automotive technology.
This Bentley's outstanding capability could not only have been developed in order to win races such as Le Mans, but rather as a natural result of W.O. Bentley's pursuit of his ideals as an engineer. Victories in numerous international endurance races were probably a mere residual for those who had reached the top. The scale of comparison with other marques is different, although they do at least have four tyres in common. The outstanding Bentley DNA, also present in current models, is rooted in vintage ones like the 4 1/2-litre.
Spread out across the small racing screen is a shimmering horizon, a gauzy blend of green plants and brown earth. I wonder if the Bentley Boys, who once bravely tamed this runaway locomotive, saw the same heat haze in the middle distance along Les Hunaudières.

About 1928 Bentley 4 1/2 Litre Vanden Plas
Bentleys produced from 1919 to 1932 are regarded with distinction today because of the involvement of the company's founder, W.O. Bentley himself, in their development. The body was fitted by a specialist called a coachbuilder. The model covered in this article, chassis and engine No. HF3195, registration No. YV1471, originally had a Vanden Plas saloon body, which was replaced by a Le Mans-type fabric body later in its history.

Le Mans models often have a polished aluminium dash and black bezel instruments, but this model has a walnut panel and gold-ring instruments. The steering wheel is the spring-spoke type.

The steering wheel has a hand throttle and ignition timing control at its centre, rather than a horn button. The hand throttle functioned like modern cruise control.

To the right of the steering post is a switch panel typical of vintage cars. The top one is a dynamometer, the middle a fuel mixture adjustment and the bottom a magneto switch.

The patent plate illustrates that Bentley has been an innovative manufacturer since its foundation. The braking system seems to have been born of particularly original ideas, especially in the racing models.

The 4.4 litre four-cylinder engine looks like a straight-six engine from the front and rear lengths. The system of driving the overhead valve train by means of a vertical shaft at the front end is characteristic. The appearance is both stoic and luxurious, with plenty of aluminium and magnesium.

The bulkhead, made from magnesium casting, is a structural component at the heart of the Bentley chassis. Some have been replaced by reproduced aluminium during rebuilds.

The Worm-and-Sector steering system is quite heavy in proportion to the vehicle's size. The controls are suitably heavy, but the feel is very precise and the straightness very good.

The oil cap on the side of the engine has the letter 'B' cut out of it. It also has a hole in it to relieve pressure below the waist. When the cap is opened, a wire mesh like a tea strainer is inserted to prevent the oil from flowing backwards.

The letter B is embossed on the door lining. Not many designs show the brand name, but a wooden emblem in the lining is a classic modification.

The engine and chassis have the same number–so-called 'number matching' –which is said to be a prerequisite for a superior model. Here, HF3195 is stamped on the engine.

The chassis number is engraved on the unique magnesium casting. The same numbers are found throughout the chassis. 

*This is a revised version of an article that appeared in Flying B No 004 (2010). The information provided here was accurate at the time of publication.