MOTORS and MOTORING.

Dominion, Volume 22, Issue 80, 28 December 1928, Page 14

MOTORS and MOTORING.

(By

"SPARE WHEEL.")

THEN AND NOW IMPROVING QUALITY How rapidly and how regularly the breed of the automobile improves, remarks a motorist in an English magazine. Stagnation point, the time when people will buy their motor cars with the same soulless lack of consideration that they give to a pair of boots, is still a long way off. Although the moderate priced car of to-day undoubtedly is reliable; although the expensive car Is refined to a splendid degree, there are still a thousand thrills to be expected from the car of the future. Safefeeling stability, road-careless springing, quicker work from town to town, speed stolen in silence, brakes that breed unwavering confidence, automatic lubrication and easy gear changingall these things are.coming slowly but with certainty. If the recent rate of progress is continued, what will be the quality of the motor car ten years hence? Ten years ago the average car owner drove at 28-30 in.p.h. and averaged about 20-22 miles an hour over a long journey. To-day many drive at.3B-40 m.p.h. and average about 30. The enthusiastic driver of a sporting type of car drives at 50 and averages 36-38 m.p.h. The sports car, tuned for racing, is capable of anything from 90 to 100 m.p.h., and can average round about 60 over 400 miles of reserved road. To-day a small touring car of about 10 rated horse-power can carry a saloon body as well as, if not better than, a 20 h.p. car of ten years ago. It used to be necessary to be an engineer before one could be a successful owner driver. Now the veriest slip of a girl can cover 200 miles a day on a large and fast car with ease. When all these things are taken into account, increased reliability, increased comfort, safer’ breaks, easier handling, and so forth; when one calls to mind that there are now a hundred cars on the road where there was one only, realises that greater traffic skill is necessary to a driver, and that drivers are ordinary non-mechanical people, then surely the speed of progress in automobile design may well be • termed marvellous. Furthermore, progress is accelerating rather than slowing down.

DISMANTLING A SPARKING PLUG Most sparking plugs consist of three parts, namely, a rustproof steel body, a gland nut and an insulated central electrode, the insulating material generally being mica. To take it to pieces two spanners will be needed, one of which is employed to grip the plug body while the other is used to unscrew the gland nut. It is possible then, to dismantle the plug and clean the central electrode with a petrolsoaked rag. Do not damage the insulated material. Also wash out the plug body with petrol and scrape away any carbon deposit you may find. When reassembling the parts take care to set the points correctly; if the car has coil ignition the gap should be .03 in., but with a magneto it Is smaller, namely, .02 in. Make sure, also, that the gland nut is screwed home tightly. HOW TO TAKE A CORNER

The right way to take a bend (left) and the wrong way. To brake or accelerate violently while cornering is a bad practice, as it tends to produce skidding, and little skids have a very unpleasant habit of developing into serious skids when cornering. Another point- worthy of consideration is the manipulation of the steering wheel. In negotiating corners, particularly when they vary in curvature, don’t alter the car’s passage by a series of sharp wrenches at the wheel.

TROUBLES AND REMEDIES WHEN THE STARTING SYSTEM GOES WRONG. Either electrical or mechanical troubles may prevent the starting motor from cranking the engine. If the motor cranks the engine very slowly and then stops, or if the starting mechanism is heard to engage but the engine does not turn, the trouble is almost invariably electrical. The possible sources of trouble are indicated below. Always make sure that the gear shift lever is in neutral before hunting trouble. Hold the clutch out when operating the starter. 1. Battery Run Down.—Lights dim or go out when starter button or pedal is pushed. Have battery recharged and tested for dead cells. 2. Battery Connections Loose or Corroded.—Remove and clean with ammonia. Cover with grease or vaseline and screw up tight. 3. Ground Connection Loose. —Clean and tighten. 4. Starting Switch—Connections Loose. —Tighten. 5. AViring Broken or Insulation Destroyed.—Examine carefully. Replace if defective. 6. Starting Switch Out of OrderShort circuit with a screwdriver or heavy wire the two connections to the switch when starting button is depressed. 7. Starting Motor—Remove cover over brushes and examine commutator. If burned black, clean with No. 00 sandpaper; never use emery cloth. Test brushes for firm contact. Commutator should have a bluish-brown polish, 8. Bendix Drive Gummed or Spring Broken. —Starting motor spins without cranking engine. 'Wash clean with motor spirit. Do not lubricate. If spring is broken, have it replaced. 9. Starter pinion may bind on flywheel gear, engine cannot be cranked by hand. Loosen by putting gear shift lever in high and rolling car forward. Put lever in neutral before operating starter. 10. Roller Clutch.—Starting motor spins or takes hold occasionally. Clutch rollers worn or broken. Have them replaced.

EE CAREFUL DRIVING RULES AND SUNDRY SUGGESTIONS. With the holiday traffic in full swing and the town full of strangers who are not always sure of the general run of the city, it is well for motorists to be particularly on the alert. First of all, a driver would do well to endeavour to abide by the six cardinal rules for safe driving issued by the National ‘‘Safety First” Association: — (1) Always keep your eyes open and your wit alert. (2) Always drive as you would wish others to drive. (3) Always keep yourself and your car in safe driving order. (4) Always anticipate danger. (5) Learn, give, and obey the recognised traffic signals. (6) Obey the law, in letter and spirit. Drivers should also remember the following suggestions:— Don’t forget your driving license — neglect of this may prove costly. Never argue with a traffic officer. Exercise special care when passing animals! Brakes are your life-savers and must be kept in good condition at all times for your own and the other fellow’s protection. The use of the cut-out when passing hospitals, residential areas at dead of nlgth, and churches during divine service, is objectionable and inconsiderate —there are penalties, too. It is a bad policy to neglect any unusual noise or squeak which you may notice in the running of the car; you should investigate it at once. Little troubles which commence by some almost indistinct noise may soon develop into a serious complaint, which will ultimately cost more to cure than had it been atetnded to at once.

THE REAR SCREEN

POINTS TO GUARD AGAINST “L. 5. writing to “The Motor,” gives some valuable information regarding the effectiveness of wind screens on touring cars. “Although,” he says, “every type ot rear screen affords protection to the rear passengers, not all are satisfactory from the driver’s point of view, some being quite unsuitable. How can a screen that protects the rear passengers possibly affect the driver? we ask ourselves. By the use of diagrams and explanations I have tried to make the cause of the discomfort to the driver quite clear. , “On one occasion, when driving behind an ordinary touring-type windscreen and having a rather high rear screen of flat frontage close to my back, I have had my hat, which was not of a very loose fit, blown, to my astonishment, right on to the steering wheel. The wind blowing at the back of my neck made the use of the rear screen in question quite unbearable. “It must be remembered that a flat body moving at speed through the atmosphere creates a partial vacuum behind it. “Let us now see the effect of a current of air striking the front screen. The side currents of air behind it curve inwards owing to the suction; the current going over the top of it curves downwards. They all meet at a point at a certain distance behind the windscreen. The distance increases slightly

with the speed of the car. After this point the air currents straighten themselves out again. Imagine what is going to happen if these currents And their further progress blocked by another flat object. They have to find a means of getting round this vertical plane, which is the fear screen, and so in tlie process of doing this they have to curve back or rebound siden ays and upwards—thus causing the discomfort previously mentioned. “A V-sereen, to a large extent, solves the problem,' in getting rid of the rebound of these air currents. We find that as the angle of the V gets sharper and the slope of the screen gets greater, conditions improve from the driver’s point of view. “On the average tourer, the front screen does not afford the rear passengers the slightest protection, as the air streams meet at a point between the driver and the rear passengers.” PROPERTIES OF PETROL EASY STARTING MAY BE OVER-VALUED Petrols are liquids which will evaporate to form inflammable gaseous mixtures which can be burnt in the cylinder.of an internal combustion engine; they consist of very complex mixtures of chemical groups, boiling at different temperatures. If we say that a petrol is very volatile it is .inferred that a considerable proportion of it will evaporate at air temperatures. The essential properties of a petrol to be used as an efficient motor spirit are: _(l) The necessary volatility to allow sufficient ease of starting up of the car from cold in the coldest weather experienced in any particular climate; (2) A good mileage per gallon; (3) It must burn efficiently in the combustion' chamber without knocking on full throttle work in modern engines; (4) It must be distributed uniformly in the induction system so that the correct mixture is obtained by each cylinder. It is only by careful research work that these properties can be properly evaluated and controlled in refining to obtain the desired result in the finished product. In considering first of all the important feature of ease in starting; this depends solely on the volatility of a

ENGINE LUBRICATION

PROPERTIES OF OILS .Straight mineral lubricating oils are produced as distillates of petroleum, passing through various refining processes before being fitted for use. Lubricating oils are also produced from vegetable, fish and animal sources, but, owing to the greater lubricating value and to its more universal suitability for . all classes of lubricatoin, mineral oil is now used almost entirely. Viscosity of an oil is a measure or its fluidity or rate of flow. Its value depends upon the internal friction between the particles composing the ml and their resistance to separation. It is closely related to the internal properties of cohesion and adhesion. The viscosity of an oil is measured by running a standard quantity at a stanard temperature through a machine fitted with standard orifice. The efflux time is the figure quoted as the viscosity of the oil. For instance, bO cubic centimetres of oil, which flows through a standard machine of 100 deg. F. in 500 seconds is termed an oil possessing a viscosity of 500. The flash point of an oil is the temperature at which the oil gives oft sufficient vapour to ignite momentarily when exposed to a flame or spark. The fire point of an oil is the temperature at which oil gives off sufficient vapour to ignite and continue to burn when exposed to a flame or spark. Setting point or cold test of an oil is the temperature at which the oil, on cooling, will congeal. To give an example. Place some oil and a low reading thermometer in a long narrow tube and chill down to 1 deg. • Take the tube out of the freezing chamber and incline the tube to a 00 deg. tingle. When the oil starts to flow, the thermometer reading will show the cold test. The cold test of a good oil should not be above 5 deg. F i e 27 deg. F. below water freezing point.” "a low cold test is very important in the motor-car engine cylinder oil On cold winter mornings the fluidity of the oil being good, the engine will start more easily, and therefore will help to reduce the load on the electric starter mechanism and power unit by helping them to overcome the retarding agency of the engine compression, and will also help to give longer life to the battery. “Cheap” lubricants are rarely cheap, but are very extravagant. They burn; they carbonise readily; they are rarely made to any standard; one lot may be good, tlie next hopelessly bad, and one bad filling of inferior oil works endless mischief; they may be chemically inferior. Here are a few hints that should help in the care of an engine so far as lubrication is concerned. After a long rest, the oil has ■ tended to work downwards from the various friction points to the sump. Whatever your circulating system may be, it takes time to get the oil back to those points. Allow the engine to idle slowly for a few minutes until the circulating system may be judged to be working freely. Racing at the start means running on dry bearings, and is ' a fertile, though little-suspected, source of trouble and costly repairs. Change down directly the engine labours. . The pressure set up on the engine bearings by the stresses of over-high gearing is enormous, and tends to squeeze all the oil out of them. Oil manufacturers do not, as a rule, sufficiently emphasise this advice, but nevertheless, it is wise to change the oil frequently. Any engine will benefit greatly by a change after every 1000 miles run, whatever the favoured brand of oil may be. The trouble with t’n? modern motor engine is that it apparently uses very little oil.

small proportion of the petrol. It is quite appreciative that naturally the motorist pays a considerable amount of attention to this particular . feature, but it must be borne in mind that there are other qualities equally, if not more, important. Immediately the engine has started the property of the petrol to give an easy start, due to its volatility, has no further value, and does not effect the power output, speed, or pull on hills. In New Zealand the majority of first grade spirits on the market are more volatile than those sold in the United States. With American cars generally, it can be stated that to give the most, economical results the carburettor should be adjusted so that it is necessary for it to run with the choke approximately half on for the first half mile. If it is possible to start a car from cold without employing the choke, it means that combustion and distribution efficiency have been sacrificed for ease in starting, and an economical mileage and maximum power will not result. Before leaving the question of starting it should be noted that an overrich mixture causes difficult starting, as well as one too “lean.” The power of the engine is due actually to the combustion of the oxygen in the air. petrol being a help in burning it. The petrol and air mixture must be in a gaseous state, any liquid petrol present in the cylinder does not burn properly owing to the limitation of the amount of oxygen available and the speed of operation of the engine.