Front wheel drive was unique
and fluid suspension unheard of
This is the system already made famous by the Morris 1100 and Mini De Luxe.
This miraculous fluid suspension is the simplest yet most effective suspension system ever devised. No moving parts to repair or maintain. Gives cushioned riding comfort, free from bumps, bounce, pitch, lean and sway.
Gives miraculous roadholding, even on the most tortuous tracks. BMC Australia's advertising statement.
Here is what BMC engineers had to say about both.
As for the 'east-west' engìne layout, the theoretical attractions of driving the front wheels from a front-located engine transmission unit are:
1 . The engine and transmission occupy a space so restricted by the need for wheel clearance on full lock that it is of limited value for the alternate carriage of luggage.
2. For a given length of car the cubic content of the rear luggage boot is considerably enhanced, as there need be no intrusion from a rear axle beam. The absence of this also provides space beneath the rear seats.
3. As there is no intrusion by the clutch housing, gearbox or propeller shaft, the floor can be set a ground clearance level and, from this, good headroom given within low overall height.
4. The reduced height improves maximum speed by diminishing frontal area, and this enhances stability by lowering the centre of gravity and lessening roll angles.
5. On straight roads directional stability is improved by the forward position of the centre of gravity in relation to the centre of wind pressure.
6. On corners maintained power through the tyres promotes the understeer condition best suited to the technique of normal drivers but, in an emergency, shutting the throttle will bring the car back sharply onto a closer radius - that is, to its own side of the road.
7. In extreme conditions of ice or snow, the car will follow the direction in which the front wheels are steered, even in conditions of wheel spin, provided any adhesion remains.
8. By comparison with front engine and rear driven cars, adhesion on the driven wheels is improved in that they carry considerably more than half the laden weight.
There are four major reasons why Alec lssigonis did not hesitate to apply his ADO 15 (Mini) philosophy to the ADO 17 (1800). In all the years and millions of miles experienced since the first ADO 15 Mini took to the road in August 1959, it has been proven that:
l. An all direct drive from the crankshaft to the final drive does not bring with it objectionable noise, even when big mileages have been reached.
2. No disadvantages attend a common casing and a common lubricant for the crankshaft, the gearshaft, and the final drive.
3. The use of Moulton elastic inner universal joints gives a sweet, cushioned drive with absolute reliability.
4. The employment of Birfield constant velocity joints (built under Rzeppa and Cull patents) confines reaction transmitted to the steering wheel to that arising from the self straightening properties of the tyres, and permits an angle of lock which provides an acceptable turning circle.
Simplicity is the keynote of the Hydrolastic suspension, as no glands or wearing parts are used anywhere. The hydraulic system is hermetically sealed during assembly of the ADO 17 and needs no further maintenance. Seasonal temperature changes in any one territory do not affect the trim height to any considerable extent, but provision is made for trim adjustment under global extremes of temperature. As is now well known, fluid is the medium used within the Hydrolastic unit to transfer the weight of the car to the main springs and also act as the main damping medium. The design is such that no glands are needed to prevent escape of fluid. lndeed, if glands were used, it might have been necessary to incorporate a motor-driven pump, and very complex levelling devices to control this pump's action. There are essentially three parts in the Hydrolastic unit:
1. The hydraulically actuated rubber spring, which resembles an inverted cone spring but has the bonded area of the pressed-steel inner cones less than that of the rolled-steel outer canister. Under hydraulic pressure the spring deforms axially, and has the desirable rising rate characteristic. Attached to the top of the inner cone is a flexible rubber hose allowing for movement of the spring, and uniting it with ½" diameter Bundy tubing which is, of course, the inter-connecting piping.
2. The damper assembly, positioned between the hydraulic spring and the displacer, comprises simply of two rubber flap valves, one either side of the pressed-steel port plate which is pierced by four identical ports, each flap covering two ports. The upper flap damps the bump movement, and the lower the rebound. These flaps are prevented from rotating by steel clips; there is a permanently open bleed hole.
3. The displacer, which consists of the diaphragm with its separate impermeable butyl liner, to contain fluid pressure: it has its outer 1/4" diameter bead clamped between the rolled-over periphery of the port plate and the flanged upper end of the skirt, and its inner 3/16 " diameter bead buttoned on to the pressed-steel piston.
The development of this diaphragm by Dunlop was a vital factor in the success of the entire Hydrolastic system. lt is, in fact, a rubber moulding of 'diabolo' construction, reinforced with 424 nylon cords each 0.022 " diameter, and it can withstand burst pressures of over 200 lbs per square inch. The effective area of the diaphragm increases as the piston advances into the tapered skirt, so that the load on the piston with a given hydraulic pressure also increases: the rate due to this effect, whìch the Hall christened the taper rate, contributes to the overall rate of the unit. Finally, the complete Hydrolastic unit is formed by contracting the rubber lined outer canister of the hydraulic spring around the displacer assembly. This joint is capable of withstanding a static pressure of 1,500 lbs per square inch. An essential feature of the Hydrolastic system to ensure constancy of trim height is that of sizing the unit. This is done by machining the top of the canister so that the overall height of the unit is held to within ± 0.02" at a constant pressure of 200 lbs per square inch, and a dead load of 2,000 lbs.
You can see on examining any ADO 17, the Hydrolastic unit at each wheel carries the vehicle weight through a suspension arm. This provides a leverage of 3.95:1 at the front, and 4.4:1 at the rear. These different leverages were chosen to accommodate the heavier front load of the ADO 17, at the same time using common units front and rear. The complete Hydrolastic unit weighs 9 lbs, of which 1.9 lbs is the weight of the rubber spring. On the assembly line each side of the system is evacuated to an 80% vacuum through a Schrader valve fitted into the front connection between the hose and the inter-connecting pipe.
The liquid, (there is no Moulton secret about this) ... is a solution of 49% alcohol, 49% distilled water, 1% sodium mercaptobenzthiazole, which is of constant viscosity, and has a freezing temperature of 31 degrees Celsius, is then put in and pressured to 400 lbs per square inch, lifting the vehicle on to its rebound stops. Pressure is held for 30 minutes and this eliminates primary creep from the rubber spring; it is then reduced to the standard figure (unladen) of 205 lbs per square inch.
Why We Did the 1800.........
"I am proud that in 1964 my team has been able to round off the front drive family with the Austin 1800, which benefits from all the knowledge and experience accumulated over the past years. We retain the east to west layout with a new five bearing engine whích once again drives down to four gears, transmitting power to the front wheel.
The independently sprung wheels are placed as near as possible at the four corners of the car. This contributes to accurate steering control and high standards of road holding.
As pioneers of bold projects in the past few years we have been most grateful to the support that we have received from all kinds of people all over the world. This new design consolidates our position in this field. We believe that this new car will set new standards for performance, economy, longevity, and comfortable travel for up to five people, their luggage, and personal effects.
Planned obsolescence is foreign to Austin thinking where engineering for economic long life is, and always has been, a first principle. Many of Lord Austins cars are still giving useful service with thírty years' life behind them. Ten years from now the new Austin 1800 will still have an up-to-date engineering specification."
FRONT WHEEL DRIVE EAST WEST ENGINE
The Monte Carlo Rally has proved the outstanding virtues of front wheel drive.
In fact, the last five Montes have been won by cars with this unique feature, in 1964, and again in 1965, the honours going to the BMC Mini Cooper 'S'.
These hard-fought performances have demonstrated the vastly improved traction and roadholding on all road surfaces.
The Austin 1800 combines this valuable feature with the space saving virtues of BMC's east-west engine design. BMC Australia's advertising statement.
These drawings, from the pen of Alec Issigonis, are arguably the best sketches for a family car ever produced.
His bold concept of front wheel drive and fluid suspension, were unheard of at the time.
Simple in design from an engineering viewpoint, with many safety features built in. These sketches epitomise the sheer brilliance of Alec Issigonis.
Original BMC 1800 drawings from the sketchbook of Alec Issigonis