MOTORING & MOTORISTS

Evening Star, Issue 20311, 21 October 1929, Page 14

MOTORING & MOTORISTS

[BY RADIATOR.]

TIMES FOR LIGHTING UP. To-day 7.43 Tuesday 7.45 Wednesday 7.46 Thursday 7.48 Friday 7.49 Saturday 7.50 Sunday 7.51 FIXTURES. October 21.—0.M.C. annual meeting. new type of brake. A now and very interesting type of hydraulic brake for automobiles is being manufactured in America, in which the braking effect is produced within the brake ‘itself and not transferred to brake bands The brake is in the form of a rotarv pump which is keyed to the drive shaft, hack of the transmission, and which, when the brake is on. pumps oil through a very short closed circuit in which is located the control valve. The braking pressure is established by closing down this control valve so as to place an excessive back pressure on the oil pump. The blades of the pump arc withdrawn and held within the l"ner rotor when the brake is in the off . sition, thus producing no pumping a - n, circulation of oil, or pressure of any kind. When the brake is required for service the blades are instantly released, and the braking pressure established at once. The control is by means of the usual foot pedal, more or less braking effect being produced as the foot pedal is moved forward or back. The braking effect is the same, forward or backward. _ No pressure' is carried when the brake is in the “off” position, and since brake bands with their attendant rods and connections are eliminated, it follows that there are no brakes to be relinod or adjust°d. The braking effect does not change from time to time, as when brake shoes and brake lining are us-’d, but remains the same at all times, as there is nothing to wear out and no adjustments to be made. The'brake is self-oiling.' and therefore rennires almost no attention. In addition to the automobile, it is claimed that this system adapts itself to many other machines whore brakes are required. It would seem that such a system stalled on automobiles would be an ideal form of braking.

DETONATION. CAUSE AND EFFECT. In these days of high compression onlines much attention is being directed to the problem of detonation, and the various petrol companies are vicing with each other to produce standard fuels which, they claim, are free from this drawback. This, of course, is all to the good, as motorists generally benefit no less from the application of scientific study to the problem of fuel perfection than from the improvements effected in metallurgy, rubber manufacture, and external finish, to mention a few points, where racing or tire pressing demands of the general motorist have influenced the manufacturer. Many explanations have been advanced to account for detonation, but it is generally believed that the most correct are those of the great English motor engine designer, Mr H. 11. Eieardo, and another scientific man, Mr Midglcy. Mr Ricardo, whose name is, perhaps, host known from its association with a special -ylinder head which is claimed to give all the advantages of the overhead valve type, whiF retaining the service value ol the side-by-side valve, considers that detonation is r-ns?d by the setting up in the cylinder of an explosion wave, or an extremely rapid rise in pressure. The first portion ignited presses before it the unturned portion. "When the rise in temperature of the unturned portion . clue to this compression cannot be dissipated by radiation from the cylinder walls, it ignites spontaneously, and almost simultaneously, producing the explosion wave which causes the knock or “ ping ” by actually springing the cylinder walls. Mr Eieardo is of the opinion that detonation depends on the rate of burning of that portion of the charge winch is firstignited. and that it remains to bo discovered what controls that rate. AXOTTTEE THEORY. Mr Midgley does not altogether agree with Mr Ricardo, his theory being that when the fuel is ignited the wave, of combustion spreads out from the ignition point at a relati-My slow but increasing rate Under certain conditions, before the (lame has filled the combustion space, its rate of motion increases to what is termed the velocity of detonation. This velocity may reach as much as from one to two miles a second, but the entire mixture is not burned in the passing of the wave of flame Combustion continues in its wake, and tire pressure wave may rebound through the mixture several times. It is, of course, now well-known among motorists that all fuels are not equally subject to detonation, some, like alcohol, being capable of very high compression without detonation or preignition. Mr Midgley classifies ether, paraffin, napthenes, olefins (that is unsaturated Imfro-carbons), aromatics, such as benzol, and alcohol, as the order of liability to this unpleasant drawback Carbon is the best known as most complained of factor influencing 'detonation. Sulphuric ether is vcrv_ volatile, but extremely sensitive, and it detonates violently, while alcohol will operate without knocking up to extremely high comnves'ions Carbon bisulphide is elearlj subject to nfito-igni-tion during the compression stroke, but, nevertheless, it is stated that it will not cause a knock.

Brief accounts of holiday trips, roads, and places of interest are invited for this column.

Carbon being the great cause of knocking, by becoming incandescent and causing pre-ignition,_ it is necessary to guard against it in every way possible. It is stated that carbon will not remain in highly polished combustion chambers, hence ‘the advice given always to finish up a decarbonising job by carefully polishing the piston head and other parts of the interior,, while it has been suggested that in the more expensive engines the pistons, cylinders, and combustion chambers may yet be plated with chromium, thus preventing the arch enemy from obtaining a footing. Where features of engine design or operation tend to promote carbon formation and deposit, the manufacturer should select an oil which will tend to minimise the trouble, and therefore it is always advisable to accept the manufacturer’s advice on the most .suitable grades of oil for use in any particular make of car. As the effect of carbon is to restrict the flow of heat from the charge to the cooling arrangements, it follows that where the compression is high, making the engine critical, any factor indicating the likelihood of high localised temperatures will bo certain to promote knocking, even when the carbon deposit is only slight in selecting an oil for engines which arc sensitive to detonation, care has also to be exercised to see that the temperatures in the combustion chambers are high enough to burn cleanly the surplus oil which reaches the piston head, otherwise carbon will accumulate and cause detonation. BLUE IS MOST. POPULAR COLOUR The most popular colours in the motor car field, according to a report of a survey just released by General Motors, New Zealand, Ltd., arc blue, brown, grey, green, and black. Maroon, yellow, red, orange and beige also are great favourites. Light blues of intense luminosity are very popular on medium-priced ears. Clear, dark, rich blues continue in favour upon cars of more expensive make. The acceptance of brown, especially the lighter shades, has increased during the past year. It is possible that the brown trend may surpass blue in importance. The relative movement of green and blue trends is interesting, the formci having declined in almost the same ratio as the* latter has gained in popularity. Black is more popular in the fall and winter. The trend of grey is declining, but there is an interesting movement in the grey group (brownish nr bluish tints) which is gaining favour for use in colour schemes where strong accentuating and intensifying notes are needed. Neutral greys are losing ground rapidly, due to the interest in bright colour. Maroon is advancing steadily in popularity, while yellow, red. and orange are losing to it in preference. In general, contrasting colours are gradually losing favour for use on motor cars. Chromatic sequence (tints and shades of a single colour family) is the most harmonious and most -opujar colour treatment in use to-day, and is already firmly established as the vogue of the year.

THE CARBURETTER. DON’T JUMP TO CONCLUSIONS. Tlio varieties of carburetter design are endless, but the underlying intention is in every case the same—namely, to feed to the engine at all speeds a mixture of air and petrol vapour in ol'e right proportions. When the amatein sets out to investigate the pros and eons of the fuel consumption of his engine, even where, by the inquiries we have already suggested, he finds that an excess of petrol is being Osed, ho must not jump at once to the conclusion thht it is the carburetter which is at fault. Let him rather check such matters as quality of the engine oil, condition of the spark plugs, and the freedom of the combustion chamber from heavy carbon deposits. In short, givo the engine a “top overhaul’ before indicating the carburetter. Out should all circumstances point to its being the culprit it naturally must be dealt with, but with respect and care rather than in a revengeful frame >1 mind. Pause first and ask yoarseti these questions: “How many miles has the car run?” “Have I at any time meddled with the adjustment and el tered the setting of the carburetter from that made by the agents?’’ “ In the case of new cars which m.vjust completed their running-in process it is frequently desirable to make some modifications to the mixture. Many factories deliberately set the carburetter so that it will give an over-rion mixture during the early miles ol the car’s life, when all working parts are stiff and have not acquired their final polish. One of the most popular cheap cars on the market is a good example of this, for great improvement in petrol mileage is being secured by varying the jet sizes after the engine has “ run in,” Speaking first of all of the new car winch at the end of a thousand miles’ running is not giving good petrol performance, the owner should at once consult the manager of the ihicf service station handling that make ol ear, and if the carburetter is one with un adjustable jets h© should ask whether or not a new set of jets of lifferent sizes might not bo substituted with advantage. Sometimes, too, it is helpful to vary the size of the choke tube, and all the leading manufacturers specify what diameter- choke tube should normally he used in conjunotipn with cer tain- jets. SETTING THE ADJUSTMENTS. VVhcro the carburetter has adjustable jets, and perhaps also an adjustable auxiliary air valve, no great harm is likely to come of the amateur trying to vary the carburetter settings, provided ho knows how the different parts function and follows religiously the sequence of adjustments prescribed in the instruction book. It is very important that experimental variations in the setting of the adjustments provided should bo carried out in the same order as laid down bv the manufacturers, and if this precaution is not observed the homo, tuner will find that he will go hopelessly astray. The ideally adjusted carburetter will allow the engine to idle slowly, without any “hunting” or irregularity of speed. When the throttle is opened, no matter how suddenly, the engine “revs” should pick up without any momentary hanging fire or spluttering. At high speeds the mixture should not be so rich tha) when extra air is admitted to the in take the oar bounds forward with in creased power and engine revolutions Ono must, emphasis© yet again than all adjustments and tests of perform anco must he carried out with a pro perly heated; engine. Half the com plaints one hears about disappointing petrol consumption are not due to faults of the carburetter at all. Especially in winter time are there numerous cars

whose cooling system is too effective, and on short runs the engine never approaches , an efficient temperature. The obvious course is to manipulate the shutter controls if manual shutters are fitted to the radiator, but if not, a piece of aluminium sheet can be attached to the front of tho radiator, and can be removed when prolonged runs with heavy climbs are undertaken. Prodigal, habits of driving also play their {jart in emptying the petrol tank with dismaying rapidity, and one of the most common errors in connection with this is unnecessary acceleration—in other words, the bad practice of always “ driving on tbo brakes.” The carbur retter is a good friend of the man at tbo wheel, provided it is kept free of dirt and is allowed to pursue the even tenor of its way -without well-meant attempts to encourage in it a love of frugality. A QUICK OIL REPLENISHMENT. It h a good plan when the oil has been drained from the engine to refill it pint by pint, checking and marking the readings on tho dip stick after each addition. .Thereafter it will bo easy to gauge from an inspection of the stick just how much oil is needed to bring tbo level to its correct height. In some engines the oil filler is still very inconveniently placed, and it may be possible to have an extension fitted. An alternative which sometimes can bo employed in an extension of flexible metal tubing, which is obtainable in all sizes, slipped over the end of a widefitting funnel. Filling the gear box or differential is apt to be a tedious process in winter, oven with an efficient oil gun. It is best done after the return from a run, when the oil in the housings is more fluid, and it is a good plan to warm the fresh oil by standing the tin nr the gun before a fire. EUROPE’S CHEAPEST. CAR FOR LESS THAN £75. A new small car is being made in France, where it is being sold for Jess than £75. It is of tho baby class, with a wheelbase of 884 in and a 40in track. Only single-seater models are being produced, and these are said to have a maximum speed of 48 m.p.h. on a petrol consumption of 48 m.p.g. The motor is unusual, being a twocylinder, two-stroke, with a rotary distributor, which delivers the mixture

to the cylinders under a slight pressure. This obviates the usual i-«o----stroke principle of crank case compression. The ignition distributor is mounted on the top of the combined starter-generator, while the blowerdistributor, situated at the rear of the starter motor, draws the mixture from a Solex carburettor and delivers it to the cylinders. The throws of the engine are at ISOdcg, and the motor is said to have the rhythm of a four-cylinder fourstroke. Lubrication is by splash: the clutch is a cone type, and the gearbox lias only two forwa.d speeds and a reverse. A traverse spring is used in front, and quarter elliptics at the rear. Four-wheel brakes are fitted.

GREASE GUNS. SOMETHING BETTER WANTED. Are other car users as tired of the grease-gun system as 1 am? Do they put oif using the offensive weapon until they are forced to it? And do they dislike the job of lubricating the chassis details to a garage band, who may not be thorough? I think they are, and that they do. Using a grease gun is too messy and too hard work. In days gone by we used, once a week, perhaps, to grow very busy with a grease tin and an oil can. and go round the car carefully, filliim up the screwdown grease mips ml squirting oil over the odd spots in the brake rod forks and lever _ eyes, where no lubricators were provided. We groaned, but wo did it, some of us, and on each day wc used the car wo went round with a rag in one hand, and gave a couple of turns to each cup to keep the lubricant moving through the bearings. Then came a change, a now era was hailed; maintenance made easy? The arrival of the grease, or oil, gun. Practical motorists were thrilled, car makers rejoiced aloud in their catalogues. The day had dawned when the owner could take in hand a little brass barrel with a plunger in it, hitch tbo spout on to or over a little nipple on each of the vital bearings in the mechanism of the chassis, turn or push a handje, when “ Hold and Below,” as my old nurse used to sav, every point was splendidly lubricated under heavy pressure. It was a beautiful thought. NATURAL AVERSION FOR DIRTY TASKS. But now we have tried it for a year or two, is_it so satisfactory? Do wc like it? No! Do we neglect it? Yes 1 And why? Because it is a nasty" messy operation that takes as long as filling grease cups, requires the expenditure of much force, and makes one so dirty and so hot and bothered reaching out to the several extremely awkward spots' that seem to exist in every car, that the evil day is put off and put off again. I have found places on some ears where it required more physical strength than I possess to force thick oil into an inaccessible nipple. Car owners are all human, so ! ar.i going to make an admission. A little time ago I was unable to obtain delivery of a new car I had ordered, and the makers loaned me an old machine Looking in the tool kit I found the grease gun absent. I ran back and tapped lightly on the works door, asked for a grease gun, and obtained a new one all neatly wrapped up in paper. That car was in my bands a month, but the grease gun was never taken out pf- its wrappings! I occasionally took the cm into garages, and left instructions for it to be greased. Presumably it was so treated, for nothing evei seized up. When it comes to using a grease gnu the spirit is willing, but the flesh is very weak! Now I.have my new car I do go over the chassis with an oil gun. But I don’t do it as often as 1 should, and I partially neglect things under floorboards. If every single oil nipple were arranged outside the frame and •-et at an angle where one could reach it, there would be more incentive- or les-- antipathy towards carrying out the job of oiling thoroughly ami properly. Possibly the saloon habit is weakening the morale of motorists. We have become accustomed to wearing respectable clothes when motoring, for there is no justification now for the wellmatured trench coat or the oil-soaked leather garment. So we become more and more averse from tasks that make

us dirty and oily, and we seldom have overalls handy. Children of circumstances are wo motorists When wo had ,to face breakdowns on the road we were prepared.to got dirty, and then the matter of looking after lubrication was relatively a triviality. The thrill of motoring was in the uncertainty of reaching a destination. Tb-day the thrill lies in the sublime easiness, the smoothness, the silence, the certainty with which the journey is made. It is no longer essential to perform work in order to make a trip. The work can be neglected without immediate trouble, or it can be loft to be well—or badly—done by someone else. Nevertheless, the correct and propei lubrication of a car demands a certain amount of technical knowledge. AN OPPORTUNITY FOR THE INVENTOR. The time has come when a really drastic impdovement in chassis lubrication is imperative. Such a change will benefit the man who looks after his car by making the process superlatively easy for him. It will meet the man who neglects a car by making the lubrication as nearly as possible independent of him And it will help the maker by ensuring that bis product is self-lubricated and therefore a credit to him, who ever may buy it. The remedy is automatic lubrication of the chassis parts, a central pump, hand or engine operated, that serves up the right amount of oil where it is needed. There are many such systems already in use, particularly on American ears, although the idea was conceived in this country and adopted to the pre-war Fergus car. Inventors should bo encouraged, and manufacturers coerced, until wo, the motoring public, get what wc need. And wo need automatic lubrication more urgently on inexpensive cars than on costly machines, because the owner of the cheap cars have little money to spend on garage service.—Montague Tombs, in the ‘ Autocar.’

VIBRATOR HORNS, .Horns of the vibrator typo may be divided into two classes—those in which the sound is produced by the vibration of a single diaphragm, and those of the high-frequency typo, in which a vibrating diaphragm conveys its movement to a resonator plate. In cadi type there are no rotating parts, as in a motor-driven horn. Instead, there is an armature Htted with a makc-and-break contact, and an electro magnet. Upon the circuit being closed the armature is attracted to the magnet, but the circuit is immediately broken bv the make-and-break, so that the armature returns to its original position, thereinagain closing the circuit. This function occurs some thousands of times per minute, and the movement of the annaturo is conveyed■ by various means, according to the make of horn, to" the diaphragm.

A similar arrangement applies in the case of a high-frequency horn, hut the resonator place has the effect of producing -the characteristic high-pitched nate._. I’hc only attention which need be given to the horn is to remove the cover, brush out any dust which may have accumulated, and, very occasionally, to trim the contacts with a magneto file, adjusting them afterwards, ns may ho necessary, to produce the required note. On some types of vibratory horn an additional adjustment is provided to enable the clearance between the armature and the diaphragm to be varied. IS'o special instruction can bo given with regard to correct adjustment, but the lines upon which rhe operator should work are to secure the necessary note with the least possible sparking nt the contacts; thus, if what is considered to bo the ideal note can bo produced only by an adjustment which causes excessive sparking, a sacrifice in the musical qualities of a horn must bo made in the interests of the contacts. FIND THE FUSE. Those owners who are taking over a new car, for that matter, a second-hand one, with which they are unfamiliar, should make a point of ascertaining the position of the fuse, as it is much more convenient to do this in the comfort of the garage than late at night on the road! It goes without saying, also, that ■spare fuses should always bo carried. DRIVING COMFORT. Increased comfort can bo obtained in a saloon car by fitting a piece of thick felt beneath the llnorboards. The felt, which should be cut to the same shape as the floor mats, will tend 1o insulate the feet from vibration, and, furthermore, it will be found to exclude draughts and to deaden, to a certain extent, any noise coming from the gearbox or rear axle. TYRE CUTS. A recent American invention takes the form of rubber mushroomheaded rivets for stopping holes in outer covers. These rivets have their stems very tightly compressed within a pointed metal quill, which is pressed througn the hole in the tyro from the inside. When in place the quill is removed, allowing the rubber .stem to expand, thus sealing the hole.

FIGHTING A MENACE. The world-wide use of steel has resulted in an energetic light in the laboratories and experimental workshops of all manufacturers who have to use steel in the construction of the articles for which they arc responsible in order to discover some effective treatment which shall make it impervious to the menace caused by rust. Sir Robert Hadfield, probably tin* greatest steel expert in the world, has estimated that the world loses £'soo, oUUjUOU per annum owing to the corro sion ot steel. Experts aim at rustproof metals, but until these are avail able the war must proceed on present lines, consisting chiclly of painting. The struggle is deadly, and although many believe that, by ■ painting with good anti-corrosive paints, metai struc tures jast indefinitely, the Eiffel Towel and other such engineering masterpieces prove that such is not always the case. Jn 1889 three coats of a special mixture of red lead and linseed oil, and a final coat of thick paint, were given to every portion of the Tower, but in two years rust was found to be eating through that covering. The mighty Forth Bridge provides another striking example of the ceaseless struggles against the rust fiend, thirty painters being engaged continuously coating it with ' preservatives. Fifty tons of paint are used in coverring tho, mile and a-half bridge, three years being the time occupied in completing the huge task, which must then bo started over again. The perfect con dition of the bridge, however, is the reward for this unceasing effort, for. after forty-six years of continuous ex posure ( to the elements, it is still the only bridge in the world over which ex press trains can thunder at sixty miles per hour. British . motor vehicle manufacturers view the deterioration which is caused by rust just as seriously as do those responsible tor the erection and maintenance of mighty structures, and they are engaged in ceaseless experiments to discover a process for making ajl metal in their vehicles rust-proof.

CIRCULAR WASHERS. Washers of thin sheet metal or fibre are often needed when repairs arc in progress, but many amateurs find them difficult to make. In the case, for instance. of a fibre washer for a petrol tap, the material should be about one-sixtcenth-inch thick, and fairly hard. It is very difficult to drill a clean-cut bole in fibre with an ordinary twi-t drill, but a carpenter’s auger bit will do the job perfectly, provided the fibre is backed up with a piece of hard wood whilst being drilled. The hole should be of a diameter which will just allow the screwed portion of flic tap to pass through. A pair of tin snips or a wood chUol can be used to cut tho washer to shape, taking the drilled hole as a guide. There is no real need for the outer circle to bo absolutely true, hut after cutting it can be made reasonably so with a file. Finally, both faces of the washer should be rubbed gently on a smooth file to remove any hum which the cutting may have formed. Both fibre and thin shoot metal washers can readily be cut by the use of hollow punches, provided that a blocK of lead or the end grain of a inoco of bard wood be used as an anvil.

BETTER BODY EQUIPMENT. FOUND LN CLOSED CARS. A visit to motor car showrooms reveals many improvements in the interiors of closed cars, in tho opinion of Mr W. M - Hardy Forman, managing director of General Motors, New Zealand, Ltd. Manufacturers have become increasingly practical without in tho least sacrificing the beauty of a car. There is something about mere practicability which lends beauty to the experienced eye. because it does not create the feeling of contempt which is often aroused"*by mere ornamentation without use. There have been some real . fundamental improvements in the interior fittings of the more popular bodies. Probably the most important of all is the adjustable front seat At last a satisfactory type has been developed, and is in "use on all General Motors’ models, as well as on many other makes. It is very nice to be able to sit before the steering wheel and reach down and turn a handle moving the seat forward or hack until just the proper position is secured for a pro per reach to the pedals and the steering wheel. It makes a big difference in'" the amount of fatigue experienced after a long drive. It is also a relief on a long trip to be able to shift the posture once in a while by changing the adjustments. Another fresh set of muscles is brought into action, and the tired sinews are given a chance to recuperate. As for smoking sets, toilet sets, and the other articles to he found in the more expensive sedans, these have been worked to a point where real utility is provided. The gaudy but useless equipment of the old limousine lias gradually given way to a practical set of useless articles. One wonders if dash equipment is not getting back to the time when the instruments were all strung in a line across the dash. Some of the new -'ash arrangements are more spread out than seemed to lie the tendency a year n"0. The ■ dials will always b" kept under a glass bowevei, and indirect Bahtin" of the instruments, so they can he read nt night without the need for glaring dashlamp, has been one of the improvements that should come in for favourable mention. When speaking of better dash, equipment the windsheld wiper should not be overlooked. In this pampered age one would almost as soon be without horn as without a

windshield wiper, and the best part of ■it is that tho newer models are more sturdy and more positive than their predecessors. MOTOR CYCLING FIXTURES. October 28.—Labour Day trial. Novcmbei 2.—Dirt track racing. Novembci 9.—Wannatt run. November 20.—-Monthly meeting. November 23.—Beach races. Docombci 7 Dirt track racing. February 3.—Dirt track racing. iMarob B.—Dirt track racing. 'LITE NEW MOUNT. No doubt, wo are all impatient*, to really test the capabilities ot a new mount, both for speed on level and power on hills, but the owner who expects consistent service for an inde linito period will do his best to resist such temptations for the first SOU miles, anyhow. It is quite possible, indeed it requires no skill at ail, to ruin a machine in the first 100 miles by over-driving before all the wearing surfaces have had time to get properly run in and to be furnished with a dead smooth, hard, protective skin. Surfaces that to the eye appear to be machined and ground to a dead true surface will bo found on examination under a microscope to have a surface something like the moon viewed through a telescope. Rubbed together gently with plenty of lubricant, the hills and valleys will gradually bo reduced to a common level. Roughly treated, however, the hill tops are torn off, leaving broken and roughened surfaces that will only become rougher and rougher as they grind against each other. The need for gentle treatment during rhe first few hundred miles is not confined to tho engine, however, and it applies to every moving part throughout the machine, so that tho careful owner will not he troubled with the squeaks and rattles that bother the man who has been impatient to try the paces of his mount. Plenty of oil is desirable, of course, and after the fii-st 500 miles the cylinders should 100 decarbonised and all oil drained from crankcase and gearbox. These may with advantage bo flushed out with paraffin, but care must be taken to get rid of it all after. Under no circumstances should the engine be allowed to overheat when new, as it is quite easy to produce cylinder distortion in this way. A cylinder casting by its varying sections and thicknesses is generally left with some parts more stressed thqn others Us a result of some parts cooling slower, and these local strains can only be fully released in time by the gradual running and cooling of the engine under normal running conditions. ft is remarkable what different results can be given by machines ot the same kind that have received different treatment when new, and it is not worth while risking future trouble for tho appeal of tho open throttle when the machine is brand new.

CENTRING THE REAR WHEEL. In the case of most machines, to set tho rear wheel true between the frame members, an ordinary match box will serve, a writer in ‘ Motor Cycling ’ suggests This can be used as an ad-dista-ce gauge. Place the edge ol the box against the frame, then push out tho inside until it makes contact with the wheel rim. Then hold the box firmly so that the slide does not move, when it can be used as a gauge for the other side of the wheel. If necessary, a pin stuck through the box will prevent tho two parts from-

moving while one is walking round from one side cf the machine to the other. SPECIAL MODELS. Experience with dirt track work has resulted in the production in England of a new model for this purpose. The machine has a 488 c.c. o.h.v. flat twin engine, fitted with racing cam-shaft, and mechanical lubrication and twin carburetters. These carburetters draw their supply of air from a. large box, the only entry to which is through a gauze-covered opening, so that no cinder dust can enter. The drive is through . a . fixed-gear counter-shaft running on ball bearings, and the final drive,is on the olf side, where it is well clear of the cinders. The primary drive may Ire enclosed, if desired, but it is so arranged that it is clear of the ground even when the side frame members are touching. Actually there are four parallel frame members belo.v the engine. The engine and geai box are fixed to the centre pair and cannot, come out of alignment The outer pair not only act as stiffeners, but also-prefect the engine in tin event of a tail. With 28in x 2$ in tyres the ground clearance is oin and the wheelbase 4ft lOin ; the centre of gravity is low, and the machine promises to handle very well. NOTES'. Over 200 men from all ranks of the Navy, Army, Air Firce, and Civil Scrbice competed m the annual motor cycle “Services Trail.” In a recent sound news reel presented at a London cinema the motor cycle hill climb was included, and the noise of the machines as they roared up the gradient was faithfully reproduced. The German Silencer Competition is proving very successful, 127 different types having already been entered. The tests are likely to extend over a long period, as entrants have had six months to submit designs The Southport ‘ 100,” a race run annually .on the beach at Southport-, England, over a 100-mile course, was won by J. H. Simpson (490 c.c A.J.S.). Simpson was unchallenged in the latter stages oi the race British export trade in motor cycles continues to flourish. April returns,

at £‘465,416. show an increase of £62,* 199 over the corresponding figures last year, while the four months’ total of £i ,039.320 is in advance of 1928 figures by no less than £209,293. Imports were oomparatmcly negligible, being only £1,024 for the month of April. In a recent road race conducted near Romo, in Italy, British machines ridden by Italians performed very creditably. W. L. floodlcy (Motosacoche) won the 250 c.c. race, while Velocettci obtained second, third, and fourth places in the 350 c.c. event. The senior, or 500 c.c. race, was a complete British victory, the placings being: Rudge-Whitwnrth 1, Sunbeam 2, Norton 3, Sunbeam 4. HERE AND THERE. Some French tyre manufacturers employ a type of valve inside different from the now almost universal Schrader. With French tyres, therefore, it pays to verify this, and to purchase a spare typo from the agents if they are not of the ordinary type. ® * * * ♦ Difficulty which sometimes is experienced in forcing lubricants into the king-pin bearings may usually be overcome by jacking up the front axle. « « * • Before removing a tyre which gives trouble with slow deflation, immerse the end of the valve, with air-retaining cap in positior, in an eggeup of water to test for leakage at this point. Road accidents in England were fewer by 3,497 during the first quarter of this year than in the corresponding period of 1928. • • * • Apprehension was expressed at the last convention of the American ,’ !edical Association concerning the high percentage of poisonous carbon monoxide from motor car exhausts found in the air of some city streets The dangei is non-existent where streets are wid" and buildings comparatively low. • # *■ « An enterprising London garage has established a. • “ dog creche” to care for it. customers’ pets.