SPECIALISED MOTOR ENGINEERING

SPECIALISED MOTOR ENGINEERING A VISIT TO THE LAYSTALL WORKS AT SOUTHWARK

" Crankshaft by Laystall " appears almost inevitably in the specification of any British racing or high-performance sports car, and a visit to Ewer Street, on the southern side of Southwark Bridge, S.E.1., is an essential part of the racing man's education. The tour of inspection we made under the guidance of Mr. F. T. Bersey, M.I.A.E., the Managing Director, was all too short to appreciate the many branches of tuning and overhaul undertaken, but some of the principal' activities can at any rate be described

The average sports car, and the same applies to a lesser extent to the racing machine, is built to have a mechanical margin of safety sufficient for the use for which it was originally intended. To succeed in competition, however, one needs that little extra bit, fairly easily attained nowadays by raising compression and engine speed and possibly altering the head and the camshaft. This increase of power inevitably throws extra strain on those long-suffering components, the connecting rods and the crankshaft, a strain which can only be withstood by specially-designed parts, and these are the special care of the Laystall works.

Considering first of all the crankshaft, it is found that good material and good balance are of equal importance. An imperfectly balanced shaft made of good material will crystallise and break just as surely as the inferior one, since the out-of balance forces soon destroy the tough grain. With a free hand to design, there is not much difficulty in evolving a crank

shaft which will be rigid and allows of proper balancing. The shaft is then roughed-out from a solid billet, and heattreated in oil baths. The grain of the metal then flows from end to end of the shaft instead of being severed, as it would be if the blank were treated before machining. It is then turned up to the desired pattern, and in the process can have the journals hollowed out, special oilways fitted and other refinements which would

be uneconomical to embody in a massproduced component. The balance weights take form, and the polished shaft, usually twice as heavy as the one it was designed to replace, is transferred to the balancing rig. Here the crankshaft is supported on

rollers, which are in turn free to vibrate on rubber supports, and is caused to rotate at any chosen speed up to 4,000 r.p.m., by a belt passing over the centre journal. Long pointers attached to the supports indicate the slightest out-ofbalance force. Lead weights of varying size are then attached to the crank pins until each half of the crankshaft runs without a tremor, a job easier to describe than to perform, as it sometimes requires the services of a skilled workman for four or five hours. This operation may often be performed with advantage on existing crankshafts, thereby raising the first period of the " crank " by 1,000 r.p.m. and putting it well out of the working engine speed. When the balancing is completed, a weight of metal

equal to the lead weights attached is removed from the balance weights and webs of the shaft, and all is then ready for the final hardening. Only the bearing surfaces need this treatment, so the whole of the shaft is given a coating of tin, which is then re

moved from the journals and crank-pins. Hardening is carried out by the nitriding process, in which the part to be hardened is heated to a comparatively low temperature, not more than 500 degrees Centigrade, in the presence of ammonia gas. Nitrogen is abstracted from the ammonia and combines with the special aluminium-chromium alloy steel to give a surface of tremendous hardness and resistance to wear, the actual figure being 900-1,100 by the Brinell test.

A set of connecting rods with visible bends in them demonstrated all too clearly the effect of super-tuning on unsuitable components. Laystall rods are machined from solid billets, and a gradual taper from big-end to the centre of the rod prevents the fractures which are liable to happen where a sudden change of section takes place. Unlike the average commercial rod, a great thickness of metal is left on the big-end caps between the bolts, then a thin section on either side, with a cooling and strengthening rib round either end of the cap and bearing support on the rod. The total weight is therefore actually less than with the conventional design.

The finished rods are then suspended by rods passing through the big and small ends on special balances graduated down to drams, which enables the centre of gravity and therefore the balance to be determined. Not until the complete set have been brought to the same figures, by removing metal from the heavier ones, are they passed out for service. Mention has already been made of special camshafts. These may either be produced to the customer's own design, or based on the wide experience of the Laystall specialists. A dummy camshaft with two blanks, one for the inlet and one for the exhaust cam is first produced. The blanks are then shaped by hand in

accordance with the working drawings, and then checked by means of micrometer gauge and a graduated dial, on which each degree is represented by a quarterof-an-inch of travel. These cams are then used to operate a profiling machine which cuts a double master-cam in hard material and, from this, an unlimited number of camshafts with exactly the correct setting can be cut. Despite the amount of work involved the complete set of operations and the production of the finished camshaft can be put through from .28.

Many ether intricate operations such as the production of experimental clutches and the components of an intricate epicyclic gear-box for a new racing car held us enthralled at the Ewer Street premises, but time pressed, and we moved on to the Gravel Lane Works to see the overhaul and assembly of complete chassis.

The ground floor was devoted to welding, and we were shown some magnificent work in which cracked cylinder blocks, crankcases and the like were restored to their original form at a tithe of the cost of complete replacement and, in many cases with increased strength. Above this floor were situated two engineerecting bays nearly a hundred feet long. Apart from making new components for sports and racing cars, many well-known machines have received their final tuning in these, shops, and three test beds complete with water brakes are available in an adjacent bay. An unusual feature is the mounting of the beds on pneumatic tyres, a practice which is better for the engine, and which allows it to run under conditions approximating to those it will encounter on the road. On the top floor are situated the four large " Nitriding " furnaces which play such a large part in the production of tough, long-wearing components. Amongst these may be mentioned

Laystall cylinder liners and brake-drum liners. Fitting cylinder liners is little more expensive than a normal re-bore, while the surface is so hard that no wear should take place during the subsequent life of the car. The original pistons can be re-fitted if in good condition. The brake-drum liners are actually grown into the drums by a patented process which locks them immovably in place. Like the cylinder liners, the brake liners have a Brinell hardness of 1,000

and, besides being proof against wear and scoring, actually improve the coefficient of friction of the fabric brakeshoe linings. Laystallising is another interesting process carried out under the same roof, and is used for the restoration of worn parts of all kinds, from the wearing surfaces of overhead valve rockers to the bevel shafts of commercial vehicles. In essence, it consists of welding to the worn

surface a layer of suitable hard metal. This is reduced to the Original contour by machining or grinding, allowing the parts to be used again at small, cost and with full efficiency. From the foregoing it might seem that the Laystall works is only concerned with building special parts for sports and racing engines, but its scope is much wider than that. We saw sports cars, touring cars, and commercial vehicles, all in for anything from a re-bore to a corn

plete overhaul, and all being undertaken with a care which augered well for complete satisfaction and long service. To have a car overhauled under such conditions is to be sure that the work will be 100 per cent. efficient, and the trusty sports car or the low-priced bargain will profit equally from a tonic administered by the old-established firm of Laystall.