Tuesday 23rd May 2017,
Inopian

Bristol 403 1953-1955: Bristol With Reduced Brake Efficiency

Bristol 403 1953-1955 black detail front bonnet light grille black and white
The 1953 Bristol 403 was primarily an updated 401. It had all the improvements and specs of the 404 which went into production at the same time. It must be assumed that customer demand for the 401 dictated the continuation of production but re-naming the car caused confusion. However, it was a classic British luxury sports-car in the Bristol tradition.

It was not a `face-lift` in the normal sense, as virtually no effort was made to cosmetically change the car`s appearance. This would be the last car to wear the BMW `double-kidney` radiator grille. It was simply progress, a piece at a time. If Bristol was embarrassed by the BMW connection, it never showed but the Bristol 400 series was moving inexorably onwards, following it`s own destiny, as was BMW. Their paths would never cross again.

The most important improvement was in the engine department. Bristol could not afford to allow the competition to catch up. The 401 was the finest grand-tourer in production but it would not get any faster without some effort. No attempt was made to reduce weight, luxury naturally cost kilograms and Bristol were happy to accept that. Therefore, to make progress, more horse-power was necessary. Major re-engineering was undertaken on the 2 litre engine.

More engine revolutions were needed and so the main-bearings were enlarged to take the strain. The cylinder liners were already strengthened by the use of `Brivadium` in their manufacture. With the new main-bearings came lightening and balancing of the crankshaft. It was no wonder that Bristol sold so many 2 litre engines to other companies. Bristol`s engineers were the cream of the motor industry and nobody could build better engines.

Even today any company would be hard-pressed to produce a more powerful 2 litre without a turbo or supercharger. The valves were enlarged and the intricate valve-gear system was lightened to allow it to operate faster. Triple SU carburettors were fitted. The bottom-line on these modifications read 105 bhp.

The chassis also got some excellent revisions. Expecting higher cornering speeds the factory fitted an anti-roll bar to the front suspension. This was an excellent investment, it made the 403 handle like a racing car.

After the first few months of production Bristol`s engineers received an unusual request from the marketing department… reduce the braking! The factory had equipped the 403 with `Alfin` brake drums. Alfin drums were the latest thing, aluminium drums with cooling-fins which worked very well. Too well perhaps, because drivers were having tricky moments approaching corners under heavy braking, locking-up the rear wheels and sometimes ending up sideways. This would never do and so the rear Alfin drums were replaced with standard Lockheed drums. The end product was a very impressive and balanced braking system.

With the rack & pinion steering, the new anti-roll bar and the new brakes, the car`s performance was exemplary. No luxury grand-touring car compared to it. The body design did not change very much. The same alloy body was used but with spotlights built into the front-panel, working as a four-headlight system. A much better heater was fitted, giving re-circulated air or fresh air.

The dimensions were same as the Bristol 400, the kerbweight was still only 1265 kg even with all the luxury included. 287 units were produced in two years.

Reducing brake efficiency was unheard of up to this point. The problem was created by the super-efficient Bristol system, proving that you can have too much of a good thing. Hydraulic systems were a little primitive at the time but later systems did not suffer from this problem. There was, however, a simple fix for the problem; Don`t use so much pressure on the brake-pedal!

Bristol 403 1953-1955 Specs
 
 
Body Type5 seater 2 door coupe
Engine PlacementFront
Drive TypeRear wheel drive
Brakes
FrontDrum
RearDrum
Dimensionsmminches
Length4864191.5
Width170267
Height152460
Wheelbase2896114
Cargo VolumeLarger than the Bristol 400
Engine2.0 Bristol 12V OHV Hemispherical
Cylindersstraight 6
Displacement1971 cc120.3 cui
Power78 Kw105 bhp5000 RPM
Torque167 Nm123 ft. lb3800 RPM
Power/weight83 bhp/t
FuelPetrol
Top Speed164 km/h102 mph
Acceleration0-100 km/h - 0-60 mph15.4 s
Fuel consumptionl/100 kmImperial mpg
Urban15.718
Extra-urban10.526.9
Combined13.121.6
Gearbox4 speed manual
Weight1265 kg2789 lb
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About Bev Roberts

Speed, the smell of hot oil, the roar of a straight-through exhaust and the scream of an engine at max revolutions. They have all been a large part of my life for almost 50 years. It is time to share my experiences with you, dear reader. Do you want to know more? Read on through my `Full Bio` and many articles.

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I was born in Hereford UK in 1948 and brought up in Gloucester UK. I played Rugby football internationally as a schoolboy. At the age of 17, a new and wet driving license in my paw, I entered motor racing. I was supported and financed by my parents and so my journey began.

In 1965 I bought a 1293cc Mini-Cooper `S` and campaigned it for a season. Having quickly made some good friends in the racing fraternity, several interesting opportunities came my way. I joined a sports-car team and raced in the Le Mans 24 hours in 1968 and 1969 in a Lola T70. Mechanical failure defeated both efforts. During that period I owned and raced a `D type` Jaguar and an AC Cobra. In those days cars like that were available and not too expensive, now they reside in museums and private collections. I had a chain of interesting cars through my youth including Jaguars, Minis, Mustangs and Lotus-Cortinas.

As a young driver I had my share of accidents too. Often the car would only be worth scrap-metal value by the time I got it home! I worked for an Aston-Martin/Jaguar dealership for a while, which enhanced my experience and gave me the opportunity to sample some very exotic machines, Ferrari, Facel-Vega, Iso and Maserati to recall a few of them.

At the end of 1969 I moved to South Africa to work on my uncle`s farm but the S.A. government had other ideas and drafted me into the army. After five years had passed I was thanked and released from the service. While I was there I bought a beige Cadillac Eldorado, previously the property of Marilyn Monroe. While I was away on a patrol my girlfriend had it re-sprayed pink! I was unimpressed by both the joke and the bill for the work!

When I returned to UK in 1974 I left it behind. On my return I found that the once-mighty British motor industry was in decline and was headed for oblivion. Motor racing was now very expensive so I turned to commercial transport. Driving large trucks gave me freedom and a chance to see some of the world. I don`t remember ever making a career choice but for the next thirty years a truck was my home. For about ten years in that period I owned two trucks of my own.

I also owned a famous MGB-GT, known as `Lucky`. If you`d like to read `The Story of Lucky` there is an article in Inopian`s archive. I finally retired, due to ill-health, in 2008. Since I had varied knowledge and many experiences on our subject I decided to share the stories of the cars I enjoyed (and hated) with the new generation.

Enjoy Inopian… it is constructed and written for you.

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