FOR OWNER-DRIVERS.

Auckland Star, Volume LXI, Issue 171, 22 July 1930, Page 16

FOR OWNER-DRIVERS.

(By AUTOSCRIBE.)

CAUSE AND CURE OF PISTON SLAP.

N.Z. CAR SALES FOR 1930.

(All Rights Reserved.)

Pessimism is widespread in the motor trade at the moment, but is hard to justify on the facts, for the registrations so far this year show that cars are still being bought freely. The expansion of sales each year has been so rapid and has continued so easily season after season. that we have assumed that each successive year must see an increase on the previous one. In a period of lowered prices for primary products, every trade in a country such as New Zealand is in-

evitably affected, and the volume of sales of all classes of goods drops. The sales of pianos, gramophones, wireless sets, and even drapery and other essentials, have shown decreases this year, and the sales of motor cars will also be affected, but not to the extent that pessimists imagine, and not sufficiently to affect the soundness and stability of the motor trade. Up to the end of May 6882 cars had been sold this year, as against 8001 for the same period last year, and it is probable that this ratio will be continued throughout the year, unless wool and other prices show substantial increases during the coming season. If that occurred, sales would leap upwards at once, and might then come within close distance of those of last year. If present' conditions are maintained during the year, it is probable that between 2000 and 3000 less car sales will be made this year than last. That may seem sufficient ground for pessimism, but when' this year's figures are compared with those for 1928 the position is shown in a much more favourable light. For the first five months of 1928 car sales were 5433, or actually 1449 less than the s£.les for the same period this year. Looted at in its proper light and in relationship to other trades at the present time, the motor trade is thoroughly sound, and the volume of sales sufficient to ensure a fair measure of prosperity to dealers in sound positions.

Cause and Cure of Piston Slap. A letter from a motorist who is having trouble with piston slap in his car reminds the writer that it is at this time of the year that it often becomes most apparent, because the engine will be very cold when started, and will take longer to warm up. As a general rule the "slapping" noise disappears completely when the engine is thoroughly warmed up, but even if it does not do so there is no great cause for alarm. The trouble is often worse in one make of car than another, because of the different materials used in the pistons. Some expand more rapidly than others, thus needing greater provision for clearance, and these tend to develop piston slap at a smaller mileage than others. It should be realised that there must eventually be piston slap in any case, because there must always be clearance between the piston and the cylinder, and because this clearance will increase with use.

The question that worries the motorist is at what stage should he have new rings or pistons fitted. It is quite impossible to lay down • any mileage basis, because this will vary tremendously according to the make of car. Some rings need renewing after only small mileage, while others will last for 50,000 miles and still not allow much piston slap. Probably the. best test lies in oil consumption. If this becomes abnormally heavy it is time action was taken and either the rings or the pistons renewed. As a general rule, when the job becomes necessary it pays to have the cylinders reground and new pistons fitted, for the labour cost of doing the one is . very nearly as great as that of the other.

English Cars Gaining Ground. An interesting feature disclosed by last year's returns of car sales in New Zealand is that the English car is gaining ground here, there being an increase of 3 per cent in the gales last year as compared with 1928. Slightly over 17 per cent of the cars imported to New Zealand now come from England, while 46 per cent come from Canada. The increased sales of English cars in New Zealand is largely due to the popularity of the "baby" class car solely confined to makes of English manufacture, but the tendency of English manufacturers to pay greater attention to the needs of overseas Dominions is expected to further increase the proportion of sales during the next few years. Canadian car sales last year showed a heavy increase, being considerably in excess of American car sales, but this was expected owing to the production in Canada of a car which had been off the market for a season. The advantages of Canadian manufacture are clearly apparent to American motor, companies, and their percentage will increase in the future.