Bristol of Filton
Motor Sport visits the home of Britain's most exclusive car
Since the end of World-War-Two the Bristol has earned a great reputation as a car manufactured to immaculate engineering standards, such as would be expected of a product of a leading British aircraft company. Originally it used a better made and properly adapted version of the 328 BMW power unit, this making the 400 to 406 models outstanding 2-litre luxury sporting motor-cars (the 406 was actually a 2.2-litre). From the Bristol 407 to the present 411 and 412 models the power has been provided by large Chrysler V8 engines, again specially adapted to Bristol's purpose.
Whereas Rolls-Royce intend to step-up production of "The Best Car in the World", Bristol Cars Ltd. are content to protect their exclusiveness by keeping to an almost ridiculously small output of cars which some people believe to be the best-engineered high-quality cars available anywhere.
It was to look into the reputation enjoyed by Bristol of Filton that I went to the factory recently and had things explained to me by Mr. Anthony Crook, the Chairman and Managing Director. I was conducted round in the company of Mr. Dudley Hobbs, the Chief Designer and Stylist, Mr. Dennis Sevier, the Chief Engineer, and Mr. Syd Lovesay, the Production Manager.
The Company was originally part of the Bristol Aeroplane Company and, although in 1961 it passed into private ownership, the original factory buildings on the Filton airfield are retained and many of the personnel are ex-aircraft employees, so that production and inspection methods to the highest standards prevail. Not only that, but the excellent facilities of such an important airfield are available to the car company on a contract basis, and Tony Crook is able to commute between there and White Waltham in his four-seater Aerospatiale Minerva light aeroplane, which enables him to move urgent spares, carry personnel, etc. in this convenient and quick manner and to bring his showrooms in Kensington High Street, London, and the Bristol factory within an hour's travel-time. Recently the old Hudson Motor Company's premises on the Great West Road were acquired as the London Service Depot of Bristol Cars and it is significant that stocks of spares are held for every model, right back to the 400, in the form of engine parts, body shells, axles, etc., down to small components. Apart from which, excellent servicing and crash-damage repairing facilities are available to owners of more recent .Bristols.
I was soon immersed in the care and conscientious standards used in the manufacture of Bristol cars, which owe so much to the enthusiasm and extensive knowledge of Anthony Crook who, as is well known, has a long and successful record of racing Bristol-engined Cooper and Frazer Nash cars and who drives a modern Bristol when not flying his aeroplane. His nonchalant one-hour-run at 104 mph with a Bristol 401 saloon at Montlhery in 1950 has not been forgotten. Since becoming Chairman of the new Company Mr. Crook reckons to do a 60-hour week in the service of Bristol.
The factory is a single storey white building, with workshops leading off the frontal office block. Small, but very impressive, is the Inspection Department where Mr. Radford is in charge. Here a 100% check of all mechanical parts is made, as it is of all the glass and chromium-plated items used in the cars. Bought-out components, such as the Salisbury back axles, Girling disc brakes, etc., are inspected individually if the need arises, but in any case 20% of outside supplies go through this Department.
The 6,556 cc (400 cub. in.) F-series Chrysler engines are shipped to Avonmouth and brought to the factory in Bristol's own trucks. These engines have been tested in America, but at Filton every one has its sump pan removed for an inspection of the bearing bolts, etc., and Bristol put their own gaskets between engine and gearbox bell-housing. Moreover, before the Chrysler engine was adopted, Bristol made very careful tests and altered certain aspects of this excellent 90 deg. V8. For instance, a fuel pump test-rig was used to measure the time various Chrysler pumps took to pass a pint of fuel at delivery pressures of up to 5 lb./sq. in., so that the most suitable one, for the high speeds Bristol engines would be required to maintain, could be fitted. The Chrysler Torque-flite 3-speed automatic transmission was likewise altered to meet Bristol's exacting requirements. The part-throttle kick-down has been eliminated, as not giving a sufficiently smooth action, and the full-throttle kick-down adjusted to suit the lower weight of the Bristol against that of a massive Chrysler sedan. Otherwise the power units of the Bristol 411 and 412 are standard Chrysler, apart from changes in the engine mountings, dip-stick, etc., for installation purposes. These blue-painted power packs come over in batches of 100 and seven at a time are kept beside the Bristol assembly line.
The Bristol 411 and 412 have a separate chassis frame of great rigidity; therein lies the durability, in conjunction with all-aluminium body panels, of the car, and its impressive strength from the crash-impact aspect. The frame is made at Bristol and undersealed before any components are fitted to it. It may, indeed, take four days to dry after this treatment. The rear suspension assemblies, with the self-levelling mechanism which has it own engine-driven pump, are then fitted, after which the frame is turned over on its stands by the operatives, for the engine and front suspension assembly to be mounted. Engines are brought to the chassis on a small hand-operated crane. Two assembly bays are in use for the production of axles, suspension units, etc. Bristol use their own castings and do their own machining for such parts but the broaching for the torsion bars of the rear suspension is done by an outside specialist. The suspension units are checked very carefully on their own jigs for hub alignment and balancing, etc. Mr. Jenkins is in charge here and if one ex-aircraft fitter completes his check in, say, half-an-hour, whereas another fitter takes half-a-day, this is regarded as quite in order, the aim being to ensure that the assemblies are absolutely right before being mated to the chassis. Much testing was undertaken to eliminate the parasitic effect of rubber bushes, reducing the front wheel rate from 118 to 76 lb./in. and the lateral frequency of the front suspension from 39 c.p.s. to 20 c.p.s. This made the action more compatible to radial-ply tyres. The iron hubs were subjected to 60,000 cycles with a maximum cornering overload of 1.75 on a Dunlop-Wohler fatigue machine, and showed no sign of failure or cracking. When Armstrong self-levelling was applied to the rear suspension the effective travel was increased from 8" to 10¼", which enabled superior damper-settings to be used. Extra pre-setting of the torsion bars was introduced to absorb the increased stresses involved.
In the same conscientious way, when Tony Crook finally agreed to permit power steering to be used, exhaustive tests of the ZF units were made to ensure that the action would be acceptable to Bristol drivers and that it would remain consistent under oil temperature variations of from 20 to 90 deg.C. The original two-stage metering control was unacceptable to the Filton engineers because it gave a noticeable difference in steering feel when changing lanes at high speed on a Motorway. Careful development of the pump and the employment of hoses of differential diameter eliminated the problem. In the same way as they developed the steering, the most careful investigations were carried out to make certain no exhaust fumes could enter the car, by making observations using a Redex/ paraffin smoke-screen, and it should be noted that the silencers have stainless steel baffles to obviate condensation corrosion after short periods of use. Such is the detailed near-perfection they aim for at Filton.
Engines, having already been tested by Chrysler, are not bench-tested at Filton. But any small adjustments needed are done there, such as replacing a non-standard valve spring, etc. In fact, Bristol have the best possible working relationship with Chrysler, who have taken up improvements instituted in the first instance by the Bristol Cars. After the chassis is complete the body is assembled onto it in sections, being welded to the frame. Any dents incurred are removed by operatives using mallets, etc., and the body is then taken on a hoist to the paint shop. The entire inside of the shell is first rust-proofed, and the exterior finish is then applied. This latter is a very thorough process involving sanding the undercoat, using a plastic filler to remove cavities, applying six or seven coats of polyester, flattening down, spraying on three coats of surfacer and a guide coat, followed by further flattening down, treating any exposed parts with a surfacer, and finally using four colour coats, followed by further flattening down, before doing the final polishing.
The paint is baked in the single-car booth under a 140 deg.F infra-red arch, which automatically traverses above the car. Only three of these De Vilbiss dryers are thought to be in use in this country. They ensure a uniform finish and do the job with three traverses, representing a time of from 25 to 35 min., depending on whether the paint finish is plain or metallic. Bristol offer 15 different colours but do not encourage special finishes, as these can be disappointing to the customer on completion and therefore detrimental to the car's reputation. The finished cars are inspected for blemishes under uniform lighting. If satisfactory they then emerge through double doors into the trim shop. Here the head lining, soundproofing, veneered facia (from an outside supplier), etc., are fitted but not the seats, because a slave seat is used during the intial road testing, as are slave wheels and tyres. I was amused to be shown in the trim shop, amongst the later Singer sewing machines, one which was originally used by the British & Colonial Aeroplane Co., fore runner of the Bristol Aeroplane Co., before 1914, presumably for making fabric wing covering. Incidentally, 261 pieces of Connolly's finest hide are used for the seats and door trim of each Bristol. The man roof covering of the 411 can be scrubbed if it gets soiled and it goes without saying that the most searching final inspection of the paint and trim is undertaken.
Before the carpets and seats are fitted two test drivers have been out on the road, first doing 30 miles, then two spells of 20 miles each, with a final ten miles, any rectifications required being made between these runs. The completed cars are then ready for delivery to London - there were three waiting to go while I was there. They now receive yet another road test, because a chauffeur who has been with the Company for many years, or perhaps Tony Crook himself, will drive the car up to London, keeping to a maximum of 2,000 rpm, and if any further attention is deemed necessary on arrival this will be done at the London Service Station where the car's accessories are installed. The car is now ready to be run-in by the customer, who is advised not to exceed 2,000 rpm for another 1,000 miles.
Briefly, that is how this small factory, making these highly exclusive cars, operates. The 411 body was deliberately designed to be compact and even self-effacing, which is the Bristol hallmark. The doors are protected by the side structure of the 14 gauge chassis member and the required rigidity is maintained in the 412 drop-head by a gusset-plate under the chassis, apart from stiffening afforded by the roll-over protection. The detachable top of this ingenious body is stored in the boot when the cabriolet hood of the car is opened up; this steel roof-panel is regarded as too heavy for a lady to remove easily and is to be replaced by a fibre-glass panel.
It is unique that Bristol have no agents, selling every car themselves. Output of the 411 exceeds that of the new 412 d/h by more than 2 to 1 at present but 17 of the new coupes, the styling of which was finalised by Zagato, were on the way at the time of my visit. Output is pleasingly small, as befits such an exclusive car — 145 to 170 a year; say three per week, on average. The American safety requirements have made Bristol close this market down but sales to Malaysia, Switzerland, Canada and the Middle East absorb the export section of the market.
Driving the Bristol 455
Following my factory visit I was sent away for a weekend in a 411 Series V saloon. It was registered MPH 100, which seemed likely to act as a magnet to any prowling Police cars, so I was fairly pussy-footed; anyway, this is a misnomer, for the top speed of the Bristol is around 140 mph. Its acceleration from 0 to 100 mph is variously quoted as occupying from 16 seconds to under 20 seconds. This is the sort of performance to be expected from the big Chrysler engine, for which no hp figures are normally quoted. The car achieves all this in an absolute hush, a quietness the equal of any other top luxury car. The Bristol runs so quietly, in fact, that you can hear the seats creaking. It comes as a surprise to find that the engine runs on 2-star petrol, economical consumption of which is aided by several factors. Firstly, the axle ratio is 3.07 to 1. Then, the engine is encouraged to run hot, safeguarded by two special electric fans which blow air through the radiator (Jensen suck it through with their Chrysler installation) if the temperature rise becomes too high, while a facia control enables the thermostat of the fans to be over-ridden in conditions of extreme heat. Then there is the Speedhold, that enables any speed from about 24 mph upwards to be held automatically, at the most economical throttle-settings, without using the accelerator. A touch on the brakes puts this out of action but it can be re-set at a touch on the slender rh stalk. The lh stalk is for turn-indicators, lamps-flashing and the horn, lamps dipping being by a foot-operated switch. Whereas R-R use an American speed-hold, Bristol buy theirs in Coventry.
The two-door body on the 9' 6"-wheel base chassis is deliberately somewhat old-fashioned but is beautifully made, so that doors, boot-lid etc, fit and shut impeccably. It was amusing to hear the MOTOR SPORT photographer say, after being shut in the 411's boot while changing a film, that he had never before been in greater darkness in a car's luggage compartment ... Extensive rig-testing of torsional and bending stresses has eliminated "Motorway shake" from the body, built up by radial-ply tyres, and Bristol are proud that whereas in compulsory crash-tests many cars produce in excess of 80g. decelerations, which far exceed those the human body can withstand, the maximum reading obtained from five decelerameters fitted to various parts of the Bristol body was 30g., while its steering-column moved only 0.9" and there was no visible rearward movement of bulkhead and toe-boards in a stop which reduced the length of the car by two feet. Electro-magnetic vibrators were used to check that the shell was also rigid from the viewpoint of not transmitting resonance or vibrations from the transmission drive-line.
I have probably written sufficient to show how well a Bristol car is made. This is reflected in the pleasure derived from driving one. As soon as you sit in the 411 the quality and practicability is evident and this is clearly a car to enjoy by appreciating its ingenious layout and skilled design, before so much as starting the engine. Since the 404 model, the spare wheel has been accommodated under the near-side wing, with the jacking-up apparatus, while the battery, wiper motor, twin brake servos and fuse-box are under a matching panel on the o/s, thus improving weight distribution, luggage space and keeping these components cool. These panels are opened with a carriage-key, neatly stowed before the driver's right leg.
The leather seats and high-gloss facia veneer are reminiscent of the older Bentley and Jaguar cars or a pre-Camargue Rolls-Royce. The smell as well as the feel of the seats is a luxury worth having! In a veneered binnacle before the driver 'are the seven Smiths instruments, black with white needles and digits, as befits a car of class. They comprise 160 m.p.h. speedometer, 6000 r.p.m. tachometer, clock, and heat, fuel and battery gauges. On the right of the facia, sensibly apart from other switches, are the lamps and wipers controls. If the hazard-warning switch is required in a hurry, there it is, as the driver's left hand falls directly onto it, behind the gear selector lever. Every switch is very clearly lettered (not labelled) and is conveniently to hand. The controls for the quiet and smooth electric window-lifts are recessed in the doors, with neat covered ash-trays ahead of them. There is a similar ash-tray on the screen sill. The two rotary heater controls in the centre of the facia are clearly lettered, one for defrosting or demisting, the other for car heat or ventilation; there are four fascia vents and it is possible for warm air to go the driver's side of the car while cool air is delivered to the passenger's side, and vice versa. This is a notable refinement, but I can also mention two minor ones, typical of the thought that has gone into the Bristol - the two-speed heater fan is inaudible on the slow setting and you hear only a slight hiss of air when it is running fast, and the petrol low-level light does not wink, it is either on or off'. And there is, of course, a facia controlled, 3½-gallon, reserve fuel supply. There is rheostat control of instrument lighting and a cigar-igniter each end of the facia. Air-conditioning is a £600 extra.
Space precludes going over this enthralling motor-car in further detail. But let me say that it is handsome in a completely unobtrusive way, that there is ample head room in the back seat, which has its own two seat-headrests and folding centre arm-rest (each front seat also possesses a little folding arm-rest), and that the Bristol looks very generously shod, with those 205 x 15VR Avon tyres on Avon Safety wheels, which Tony Crook so bravely tested and demonstrated in a high-speed tyre burst at R.A.F. Keevil not long ago. The rear of the car is rendered exciting by the four exhaust outlets and I was intrigued to discover that each of the two silencers is flexibly slung on rubber-links. The exhaust system generates a good deal of heat, noticed as you step out of the car, but on a hot day the water thermometer showed 92 deg.C and oil pressure was steady at 74 lb./sq.in. The boot takes more luggage than external appearance suggests, its lid and the bonnet self-prop, and there are internal stowages in the doors, on the back of the front-seats squabs, and in a large lockable cubby. In brief, the Bristol 411 is endowed with all the convenience and luxury the most discerning owner could require. The Radiomobile radio has an automatic aerial with its own little switch, front/rear speakers and incorporated tape player. There are red warning lamps in the edges of the doors and night driving is simplified by the four Lucas halogen headlamps.
The automatic transmission has two hold-positions but acceleration is normally more than adequate in "D"! I have never sat behind a smoother or better behaved automatic box, and its cranked-rearwards selector lever is well placed, with clear P, R, N, D, 2 and 1 indications. The suspension is firm, on fast corners, ground clearance is excellent, vision good, and the power steering nearly as pleasing in feel as the best and quick - 3 turns, lock to lock. Fuel thirst came out at 15.4 m.p.g.; the tank, with lockable cap, holds 18 gallons. I felt I needed a long Continental journey to do full justice to MPH 100 but in this country it was virtually faultless. There are still times when it is good to be British ...
If any criticism can be levelled, it has to be qualified by the job the Bristol is designed to do. It is a long-distance express, faster than a sporting saloon. The front coil-spring, rear torsion bar, live axle suspension is not flabby, so some lurch and bump-thump sometimes arises but the 411 corners as a fast touring-car should; it hasn't quite the precision of a sports car or some lighter saloons.
The floor of the boot gets exceptionally hot. I got somewhat confused by the four keys, although an owner shouldn't, because they are of different sizes and shapes. I would have appreciated an outside mirror. That is the sum total of rather niggardly adverse comment. Further items on the credit side a Triplex laminated windscreen is fitted and electric windows and horn function with the ignition switched off:
The 411 sells for what I can only call a modest £12,587 (£2,875 less than an admittedly more spacious Silver Shadow) and the openable 412, which can be said to be in the Corniche class, costs £14,584 (the Corniche convertible is £22,792). Nowhere else, surely, can such old-style quality and dignity allied to such exclusiveness and high-performance be obtainable for this kind of value-for-money, as in the modern Bristol twins? W.B.