SLOWLY ON TOP.

Sun (Auckland), Volume I, Issue 160, 27 September 1927, Page 6

SLOWLY ON TOP.

WILL YOUR CAR DO IT? IF NOT. WHERE IS TROUBLE? It is a pleasant sensation to ride in a motor-car that can creep along in traffic at a speed as low as two or three miles an hour as smoothly and quietly as it can at high speed. The fact shows that the enjiine is in good form, knd that the clut ;h, gears, and transmission are O.K. Often, however, a car will begin to jerk or buck at five, or even as high as 10 miles an lour. Yet this may not be the fault of he engine. The trouble in such an event may lie in one or m >re of several points. The clutch friction plates may be worn, so as to cause ihis important part to slip and grab in alternate jerks. If the clutch is in good order, the gears may not be. A tooth may be stripped enough to cause a break in the gear’s hold of the transmission. Back-lash occurs in such an event, and jerking is felt. This may occur in the gear-box or in the differential. It results mostly through lack of proper lubrication. Neglect of the universal joints similarly causes undue wear, and back-lash results. If lubrication is neglected throughout, vear will produce enough play in all moving parts to cause an accumulation in the direction of the drive, and a severe case of jerking. All this assumes a perfect engine, but often the engine is at fault for this jumpiness. One cylinder will miss, and the car will jerk at low speed. It is essential, therefore, that the engine should be t horougnly looked over before the transmission end is accused. The carbumtion and ignition system must be checked for good operation. The flow of fuel must be sufficient and regular; the spark must ignite evenly and be correctly advanced. These remarks apply more particularly to the ordinary touring car, which usually has not a very high compression ratio. With the high compression sports model it is very difficult tc get the car to run slowly on top gear, even when every part of the engine and transmission is perfect. In suet cases, however, a very much better result can usually be obtained by run ning the engine with the spark well retarded. A slight adjustment of the carburettor, too, will often make considerable difference. A little while ago. when he was testing out an Austin Seven, a mechanic found that he could not get it in high gear at less than about seven miles an hour. He adjusted the slow-running device on the carburettor, and ran with the spark control lever fully retar led. He did not alter the magneto timing, but simply pushed the lever back, instead of running with it normally advanced, and, as a result, he got a speed of well under three m.pJi., periectly smooth and even, too, while the alteration did not affect ihe general acceleration and speed performance of the engine in the slightest.