Computerised car hire
When a staff car suddenly let us down last Summer and we urgently wanted a hire car to get a staff member to a Thruxton race meeting, we found the…
FOR THE AMATEUR
The Owner’s Worksho
HAVING previously stressed the point that it is desirable to ensure the sound condition of the chassis before increasing the power output of the engine, we will consider how the amateurs’ equipment can be best used to this end. In the last article of this series some of the the braking system were dwelt on, and now that this is assumed to be in order, the safety and driving qualities of the car in other directions must be looked into.
It has often been said that the most important part of a car is the steering, as whatever else may cease to function in an emergency, if the steering remains intact there is always a chance Of averting trouble. In a sports car there is far more in the question of steering than the mere avoidance of failure (an almost unheard of occurrence On any modern car) and careful Attention to the various factors which govern good or bad steering will be amply repaid in the additional control available, and in the pleasure of driving a car which feels right.
F. W. B. and Steering Wear.
The general use of front wheel brakes has increased considerably the wear and tear on front axles and steering medianisms, and made it even more important to overhaul these parts carefully as ‘soon as any signs of wear develop. If all swivel pin and track rod bearings were of the ball or roller type, and totally enclosed, wear would be almost negligible. However, on a light car at any rate, the necessity for keeping the size and weight of these parts within reasonable limits apart from the question of cost, has made the use of plain bearings general, and the chief attention required by the front axle is the periodical renewal of these parts. There seems to be a general idea that any replacement in this department must be both complicated and expensive, whereas in actual fact such work is very much simpler than many of the engine overhauls which are generally considered within the scope of the intelligent amateur. The necessary bushes are quite Here, in this article, the third of the series, the writer discusses hiting tackle, front axle repairs
cheap, while the work of fitting them is also straightforward, given adequate tools.
In addition to the equipment already suggested in previous articles the only necessary •additions will be reamers of the correct size for cleaning out the bushes after fitting. These may be considered rather expensive tools to buy for such occasional use, and if so they may often be borrowed, or hired for a small charge from the garage where the owner normally gets his supplies.. Here a word on the borrowing of tools in such a manner will not be out of place, and may save unpleasant argument between the parties concerned. One good turn deserves another, and it is only reasonable that any favours asked in this way should be repaid by the custom of theirrecipient wherever possible. No type is so unpopular with garage proprietors in general than the owner who only appears when he wants to borrow something or ask advice, unless it be the man who, because he makes a hobby of doing his own overhauls, imagines that he is connected with the trade, and should therefore get things ” on the cheap.” The garage trade exists for the convenience of motorists and a reasonable profit is their due, and any suggestion of cutting this down for the benefit of the amateur tuner is about as reasonable as asking a grocer for a discount on the grounds that you are rather a handy fellow with a frying pan ! Furtnermore, if you ever wish to borrow any more tools from the same source, return them promptly. However, to return to the question of
front axle upkeep, and the weapons required. Although, as already stated, the only necessary tools are the reamers, there is one thing which is a great convenience in all branches of tuning, especially in engine work, and that is some device for easily raising the front (or rear) of the car well clear of the ground, so that work may be carried out in comfort on the more inaccessible parts of the chassis.
This is very useful when dealing with axles, and is represented in the more pretentious forms of service station by various cranes of impressive aspect and considerable cost. For dealing with sports ears of normal dimensions the required apparatus can be quite simple and cheap, consisting merely of a chain block and tackle, obtainable from any of the large factors for a pound or so, or often secondhand from some local scrap merchant for very much less. Naturally, unless one is an expert at the Indian rope trick, a block and tackle is per se of little use for lifting anything, and the next step is to find adequate means of anchoring the upper end of same.
If the .owner’s garage is a flimsy affair of asbestos or light boards it will not be likely to support the weight of a car, but if the building is somewhat more substantial there may be a suitable rafter or cross beam, which will be capable of supporting the required weight. If there is any doubt at all about the ability of the natural surroundings to cope with the situation, steps must be taken to provide something. If the walls are of brick or stone, and a suitable iron joist of I section can be obtained, an excellent job can be made by letting the ends of the same into the said stone wall–well in mark you—and suspending the tackle from this beam. Of course, the ideal scheme is to have the beam running parallel with the car and over the centre of it. As this is rarely possible, as it would mean one end of the beam being suspended in the atmosphere
round the door, it is usually necessary to put the beam across the car and over the front end, or where this will normally occur. It is hardly necessary to point out that by driving the car into the garage the other way it will come over the back of the car, which can then be dealt with ! If the walls of the structure are obviously insufficient to support the weight of the loaded beam, it will be necessary to arrange for such support by inserting a strong, framework in the garage which will include the beam. If the garage is fairly Darrow a wooden crossbeam supported on similar wooden uprights made fast to the wall will serve the purpose excellently, while of course, wood may well be substituted for iron in the first mentioned instance provided an adequate section is chosen. Those whose education included any dealings with mechanics of structures, will not require to be told that a rectangular beam when loaded should have its greatest dimension in the same direction as the load, that is vertically in this case. Naturally the greater the span, the greater the size of section required, but in any normal one-car garage a piece of pine 6″ x 4″ should cope with most medium size cars and their
The great thing to remember about this lifting tackle is that it is not used for permanently sustaining a heavy load, and as soon as the car is raised the required amount some permanent supports must be substituted and the car lowered on to them. 5-gallon oil drums, or heavy packing cases inserted under the wheels, make good supports, and it is then possible to crawl under the vehicle and execute the required operations, without the fear of the whole affair landing on the back of one’s neck at any moment.
Having worked both in pits and under cars, hoisted clear of the ground, I have no hesitation in condemning a pit as an inefficient, not to say thoroughly insanitary, piece of equipment. The bottom of it is bound to get in the most devastating mess, and as it is impossible to clean it out effectively it becomes worse and worse, while the cost of tools, and small but vital parts which get swallowed up in this inferno, would very nearly furnish the owner with a new engine in a year or so.
Pits have the additional disadvantage of having to be covered up when not in use, and their whole construction is a matter of considerable expense, and even when installed it does not affect the desirability of some lifting tackle for removing engines and similar jobs. If expense was a matter of paramount importance it would be possible to use a rope block and tackle with a several-fold purchase, but there are many disadvantages in its use.
One is the fact that rope wears, and is also liable to be rotted by the accumulation of oil and grease which would be inevitable in a motor car workshop. The greatest reason, however, is in the very fact that the low efficiency of a chain tackle of normal type makes it safe to use, as it will not overrun. That is to say it” stays put” at whatever height it is pulled up to, whereas a rope tackle, as our nautical readers will be already aware, has to be securely cleated to avoid the whole outfit coming down with a run. The actual use of the tackle will be more really appreciated when we come to deal with engine overhauls, but as we started this article with a few remarks on front axles we will confine its use to them for the moment. When wear has taken place in the front axle to a sufficient extent to justify its refitting, it is a great convenience to use the lifting tackle, attached to the dumb irons or other suitable point on the chassis, to lift the -wheels just clear of the ground. The advantage of raising the chassis as opposed to just jacking up the axle, is that it will then be a simple matter to remove the axle completely, and although this may mean a
little extra work at the beginning of the job, it will make the actual work of refitting the swivel-pin and other bearing very much easier, and it is probable that the final job will be better and more lasting. It will also give a chance of examining the springs, which should be taken apart and greased before refitting. Incidentally, the road holding of the car must be watched after this is done to see that it is not too lively, and in all proba
bility the shock absorbers will need tightening considerably. It is a remarkable thing how much damping is caused by a fairly dry spring, and how this is lost when they are properly greased up. This damping effect is, of course, a very valuable property of the leaf spring, but if carried to excess the leaves merely become as one, owing to rust, and the spring will break as a result. Hence the need for periodical cleaning. The actual methods of removing swivel pins and other front axle parts are fax too varied to discuss here, though in most cases they are obvious enough when subjected to intelligent survey. The chief thing to remember is that when a in will not move, in spite of applying the remarks made in the last issue about the respective uses of large and small hammers there may yet be some cunning device to be undone, and a further look round is indicated before becoming too brutal. The old bushes can usually be driven out with suitable drifts, and the new ones tapped into place. As they will usually be a fairly tight fit in their respective housing, this will cause them to shrink somewhat, and will explain the fact that
a new bush and pin, which have fitted each other perfectly, will no longer do so when the bush is in place. Hence the need for reamers to get the bush out to the right size. If the reamer is a few thousandths of an inch undersize, this may be remedied by using it in conjunction with a piece of brass foil of the required thickness, slipped into the bush alongside the reamer. It should be at least as long as the bush, and should cover about onethird of the circumference of the reamer when bent round it.
Caster Action and Swivel Pins.
The track rod pins are very important, as if there is any great amount of play here it will be impossible to get correct tracking of the wheels, on which good steering so much depends. Another point which seriously affects the steering is the angle at which the swivel pins are canted back in the vertical plane along the car. The angle that these are canted, in the vertical plane at right angles to the car, is a matter settled (we hope correctly) by the manufacturer, and can only be left as it is. The first angle, which affects the trail of the wheels, which in turn gives the steering that self centreing action, which is so desirable, is not irrevocably settled by the maker, and even if it is, it is frequently unsettled again by the action of the front wheel brakes. The torque of these is in most cases taken by the springs, which in consequence are liable to acquire a set which will make a car have gradually less caster action until the spring has finally settled down. As only a few degrees will make all the difference
[Continued on page I793.
between good steering and steering which is absolutely dead, this can usually be remedied by fitting a suitable wedge between the spring itself and the spring pad on the axle. These can be filed up from steel strip, brass, or aluminium. If it is desired to experiment with various angles to decide which gives the best steering, hard wood wedges may be made up for trial, and the one which gives the besi. result. can be copied in metal. Wood is not advisable for anything but experiment. as it will always tend to heel down, and so allow the axle bolts to loosen. Honourable exceptions to the usual method of taking brake torque may be found in the Frazer-Nash and AstonMartin cars. In the former the axle is held in clamps, and the spring arrangement is such that in braking, the spring is in direct tension, and the radius rod is in direct compression, in place of the nor
mal bending strain on a half elliptic spring. In the latter design half elliptic springing is used, but the brake torque is taken by a special member bolted to the axle from which a heavy steel cable is anchored to the chassis, thus relieving the springs of all strain.
I am not saying that these are the only exceptions, as the Lancia will immediately come to Many minds as an example of a foreign car with special .front suspension, but the majority of cars today use the springs in some way to take the strain of front wheel brakes. There is nothing wrong with this provided the springs are designed to stand it, and it is far the commonest system, but when overhauling the front mile and steering connections this point should be looked into, and if the steering is not satisfactory, some wedges should be made and tried. One more item of eqnipment which will be badly needed on many occasions, is a
set of really good files. Probably some will be already included, but if they are getting at all worn do not hesitate to get some new ones, as worn files are a waste of time. The actual method of using affects their life, as the correct method, a slow heavy stroke on the forward direction only, which really cuts the metal, will not only remove far more metal in less time, but will not damage the file nearly as much as the light rubbing method so often practiced by amateurs. Brass and Other soft metals need sharper files than steel, which may seem contradictory, but is nevertheless true, so try and find an unworn file when making up anything in brass.
When the owner has thus attended to his chassis and made the car reasonably safe to handle, we can next consider the methods of attending to the engine.
W. S. B.
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