MOTOR NOTES.

Putaruru Press, Volume VII, Issue 295, 4 July 1929, Page 7

MOTOR NOTES.

COO3LE OE-GLUTOKIN3.

HOW TO DO IT. “ Double de-clutching ” is a term applied to a method employed in changing gears of the type in common use in modern motor cars. Its employment is not as common as or.e might expect, but the driver who is keen to develop “ good hands ” very early acquires the knack of using this method and nothing else. It can be taken for granted that double de-clutching means a very much easier task for the gears throughout the life of the car because they will not be damaged in any way through bad changing once the driver has learnt the succession of events that go to make up the complete movement. Actually what occurs is:-

(1) The clutch pedal is depressed and held down while (2) The gear shift lever is moved into neutral, then

(3) The clutch pedal is released. (4) The engrine is “ revved up ”by ■ depressing the accelerator until its speed is comparatively high. . (5) The accelerator pedal is released and the clutch pedal depressed and held down while (6) The gear shift lever is moved into the next lower gear, then (7) The clutch pedal is released and car speed controlled, as usual, by the accelerator. This is a simple oneration, and if desired can quite easily be practised upon a stationary car before applying it with the car in motion. It should he borne in mind, however, that the reason why ‘ some drivers find it rather cVfficult at first to acouire skill in double de-clutching is simply, the result of a natural hesitancy about sneeding up the engine while none of the gears are engaged. Others, again, object to a “ racing ” engine, but the experimenter in commencing to learn double de-clutch-ing must side-track such objections until praetice teaches just how much acceleration of the “ free ” engine is rcouired.

He can derive a lot of help from the recollection throughout his practising that, firstlv, the speed at which the car is travelling when the change is made does not matter at all, and, secondly, the movement must be gently but deliberately made. Naturally, a practised driver in changing down at high speed will "■o through the motion in a shorter t’me than he would were he to change down at low car speed, but the movements will never be hurried or jerky.

The novice cannot do better than to get his car on to preferably a level road after getting a thorough grasn of the succession of events mentioned above, and there applying what he remembers. Do not

have more than 15 m.p.h. on the speedometer when the initial attempt is made; do not be afraid of “ revving up ” the engine for the | short period that the gear shift is actually in neutral. The main thing to strive for is a knowledge of just when to release the accelerator before engaging the lower gear. Changing down, then, from second to low will require more engine speed prior to engagement of low gear than will be the case in changing down from high to second. The “ key ” to a quiet change is engine speed, which fact will become apparent very early in practising double de-clutching. When the rudiments have been mastered and slow changes have been made speed up the car a little but bear in mind that, as the speed at which the change is to be made increases, the shorter must be the j interval between the depression of the clutch pedal as in (5) above, and | the movement of the gear shift lever ' into second, or low, as in (6). When confidence is acquired after practising on the flat, take the car into the neighbourhood of a hill, j Approach the hill at, say, 20 m.p.h. J in high gear, and as the car rises on ! the gradient, i.e., without waiting I for momentum to he lost, practise j the change down. This will increase 1 the driver’s confidence, and will de- | monstrate that he is capable of changing down by double de-clutch- 1 ing on a climb—if he can do it at low speed at the bottom of the hill, , he con do it at any other point on 1 the hill, and low car speed will re- | suit as the neutral effect of the ! grade (which makes it necessary to j '•bon~ e down). After this a good finishing off can be obtained hv driv- 1 ing to the crest of a hill and changing down, by exactly the same procedure, as the car dips down the gradient. In this case a little more determination will be required in voluntarily revving up the engine while the cor i s being pulled down the grade by gravity, hut if the drnom can do it on the flat and on a climb, he can do it just as well going downhill.

This method as a habit in changing down has its advantages. D applies over quite a wide range o r cars and enables the driver to get more satisfaction from the use of low horse-power, hecause it entirely eradicates that which to so manv motorists is bugbear, i.e., jerky and uneven gear changing.