N.B.—Opinions expressed are those of our correspondents and Motor Sport does not necessarily associate itself with them.— Ed.
Which is the Best Oil?
I read the letter from Mr. Heywood and think that the following should help clarify the various oil types mentioned: —
Straight mineral oil
The accepted meaning of this term is that the oil is a mineral base. monograde, usually for automotive use, in this climate an SAE 20, 30 or 40 and contains no additives. Alternatively known as a “regular” oil.
These oils can be monograde or multigrade. The term “detergent” or “detergent-dispersant” means that additives have been put in the oil, to prevent particles or carbon and various other chemicals formed in an engine from combining to form sludges and from depositing themselves on engine components. The contaminants are held in fine suspension in the oil and are removed when the oil is changed.
“The viscostatics” [See letter from B.P., last month—Ed.].—i.e. multigrades. This term means that the oil spans several viscosity brackets, for instance, a 20W/50 spans the SAE 20W to the SAE 50 bracket, having a viscosity in the SAE 20W bracket at 0ºF, and a viscosity in the SAE 50 bracket at 210ºF.
The advantage of this characteristic is that the oil is thin enough at low temperature to permit easy starting and quick warm up but has sufficient viscosity at engine operating temperature to maintain efficient protection of the engine components. Current leading motor oils are both multigrade and detergent.
Regarding the “sudden and alarming drop in viscosity . . .” this can happen to a multigrade subjected to arduous motoring conditions if the component which gives the oil its multigrade characteristic (the Viscosity Index Improver) breaks down. The strength of a multigrade oil lies in its Viscosity Index Improver and our own 20W/50’s record of sucess in competition events of all sorts proves its ability to withstand such arduous conditions.
The manufacturers of commercial engines used by fleet owners normally specify the use of detergent oils meeting internationally accepted specifications usually drawn up by the British Ministry of Defence, or the U.S. Ordnance Board. These specifications do not include multigrade oils, but there is a growing trend towards the acceptance of multigrade oils having levels of detergency equivalent to the specification oils for use by the fleet operator. The use of detergent oils and careful maintenance greatly assist the engine in covering considerable mileages between overhaul, plus the fact that these engines do not normally do “stop-start”-type mileage, which promotes the formation of harmful deposits and sludges.
For: Alexander Duckham & CO. LTD.
P. A. Lelliott, Motor Oil Department.
Naturally we were very interested in the letter from Mr. A. Heywood in your January issue and we can understand his feelings. First of all we suggest that it is wrong to consider that there is three or any other number of basic types of oil. It is probably better to think of them as technical developments on a continuous basis because they are all built on mineral oil refined from crude extracted from an oil field. Again we will disregard vegetable-based oils for this discussion.
Straight mineral oils were used in engines in the early days and naturally their shortcomings began to become apparent, one of which is that conditions in an engine give rise to oxidation in the oil so one of the first additives to be incorporated was one to retard oxidation of the oil itself. These, then, were premium oils and the trend had begun. By definition, an additive is a component added to an oil to either (a) retard unwanted behaviour, or (b) to enhance characteristics that are desirable.
Gradually other additives have been adopted so that a modern crankcase oil should have the following properties, all endowed by additives: Anti-Oxidant, Anti-Foam, Anti-Rust, Anti-Wear, Detergent/Dispersant, Low Pour Point.
There is always step by step development on lubricants, alongside engines, e.g., new engine designs may require a higher performance oil so the oil industry develops one. This oil may then give the engine designer freedom to go further into higher specific outputs and so the escalation goes on.
Jumping the pure history of the steps involved, can we next deal with the widely held belief that oils for gasolene or petrol engines are different in some ways from those used in diesels? Very briefly this is only a matter of degree in that diesel engines demand a highly detergent oil in order to run for any reasonable length of time at all because the temperatures are higher in many cases, whereas until comparatively recently petrol engines could run on much lower performance oils, but, nevertheless, have always been very much better running on oils of diesel engine capabilities.
Mr. Heywood specifically refers to the sort of oils used in automotive diesel engines compared with those used in gasolene engines. Many companies operating diesel and petrol vehicles use a common lubricant and have done for many years with remarkable results from their petrol engines. In our own experience, we obtained 107,500 miles from a B.M.C. 1,500-c.c. engine fitted in a Wolseley car using the engine oil which was common to our own commercial fleet and it was also in use by several ‘bus companies in this area. The engine was not disturbed during this time except for routine servicing.
The general situation is quite similar to that with fuel, in that it is a waste of time putting 100-octane fuel into an old, low-performance engine which cannot utilise the characteristics in the fuel. Conversely it is absurd to try and run a modern high-performance engine on a fuel way below that for which it was designed. Modern engines, even though they be petrol engines, now operate with conditions which would have been considered in the diesel engine area a few years ago and thus all modern, high-quality oils are detergent/dispersant in character and incorporate the other properties already listed. There is not a great deal of difference between oils for diesel and oils for petrol engines and usually it is only concerned with the detergent/dispersant ratio.
There are oil specifications which are performance specifications, i.e., the oils must pass actual running tests in specific test engines under specific test conditions in order to qualify and these are generally military requirements, either British or American. A recent development as far as the U.K. is concerned, however, is the issuing of a very comprehensive performance specification by the Ford Motor Company Limited who take a great deal of interest in oils to ensure that their engines are operated in the most efficient way. It is this specification which really triggered off the fairly recent outcrop of new high-performance branded oils on the garage forecourts.
All the above remarks apply to lubricating oils in general, including multi-viscosity or multi-grade types, but it so happens that because the latter are comparatively recent developments, naturally they are also modern oils in every respect. It would be ridiculous at this stage to offer a multi-grade non-detergent engine oil, for example.
Naturally it would be highly desirable for oils to remain at a constant thickness, regardless of temperature. This is not in the nature of things and all oils, we repeat all oils, multi-viscosity included, get thinner as they get hotter.
A particular component is used in multi-grades to slow down the rate of thinning as the temperature rises, but it is worth repeating again that all oils get thinner as they get hotter. A 10W/30 has the characteristics of a old SAE 10 oil when cold and those of a hot SAE 30 when hot, but even so the hot 30 is thinner than the cold 10!
Why do these characteristics change with use? This is because the particular additives used to impart this slowing down to the rate of thinning are not completely stable and when thrashed about in an engine tend, to a greater or lesser degree, depending on the type, to lose their effectiveness so that the oil drifts towards the lower of the two SAE numbers in the title. Diesel engine conditions are that bit more severe, which is why for a long time multigrade oils were not used in this class of engine, but even this is changing as development continues.
Finally, any modern crankcase oil front a reputable supplier is an engineering material. It will have a mineral oil base, it will have additives to suppress the unwanted characteristics, such as oxidation and foaming, and additives to enhance the desirable characteristics, such as load carrying, cleaning power, ability to protect surfaces from scuffing, and so on. It will be a balanced product and will be capable of providing very long life in a modern engine which has been correctly built.
It is virtually true to say that from the reputable oil companies operating in the U.K., and this does not just mean the major international companies, there are no bad oils available. Some are better than others for various reasons and “you know who” is among these, but we would not dream of naming names.
Belper. L. W. Kilbourne.
Executive Director, Dalton & Co. Ltd.
* * *
The Bogus Ones
Now that even the Bugatti Owners’ Club suggests the modus operandi for producing modern Bugatti replicas I suppose one just has to try and live with them. Contrary to you, therefore, I think that, under the circumstances, it is a good thing if they are made as “bad copies”, as you say, so that anyone can tell the difference.
I agree it is disgusting, though, that fine old names and badges should figure on these things.
Broby, Sweden. Lennart W. Haajanen.
[Perhaps our correspondent refers to replicas of the “toy” electric Bugattis—impossible to distinguish from the original, but replicas nevertheless—which are being made in the motor trade? The snag about replicas of pre-war cars made mostly from non-contemporary parts, is threefold—they reduce the fun and effort of discovering and restoring originals, they can combine old-car appearance with mod. cons., the absence of which are part of the fascination, the whole point, of owning and driving genuine old cars to true believers, as distinct from publicity seekers and film stars, and their construction can, in some instances, destroy old cars cannibalised to build them—so let’s ignore them, as Motor Sport always has!—Ed.]
I must take issue with you about the editorial comment in the January issue of Motor Sport referring to the replica Humber built by John Mitchell for the film “Chitty Chitty Bang Bang” as “obviously a very bad copy”. I had the opportunity to examine both this car and the original, side by side, when work was almost complete, and was vastly impressed not only by the accuracy of the replica, but also by the impeccable craftsmanship. From outside, the only tell-tale deviation from standard was the front wheel braking, which I understand was specified by the Daily Express—an error of taste which one would rather expect from that paper. The fact that the replica was rather better made than the original is possibly non-original, but hardy, I think, a fault!
Of course, the Mitchell car was brand-new mechanically, although this could not be seen on the screen. But surely there are the best possible reasons for this? In a film so outstandingly bad as “Chitty” it is too much to hope that the actors could have any sort of sympathy with Edwardian machinery. If such cars are required as part of the setting, in the same way as Emmett machines were used, I for one would far rather see a V4-engined self-confusing-gearbox-equipped replica in use rather than commit the real thing to being hacked around in the aid of cheap publicity.
In final defence of the Humber replica, at least it was just that rather than, like the car of the title, a most elaborate exercise in vulgarity.
London, W.11. Sandy Skinner.
[Outwardly a good copy, yes. I was thinking mechanically. Excusable for a film prop; otherwise, see footnote to letter above.—Ed.]
* * *
Sport or Sports?
I wonder if you could give me some help? I would be pleased if you could enlighten me as to the objectives of the R.A.C. I have in my mind that one of them is “to promote motoring as a sport”—am I right? If so, it would seem incredible that their own insurance scheme refuses to insure sports cars, wouldn’t it? My apologies to them if this is not one of their objectives. I have an M.O. Midget—and a 60%. no claim bonus at present.
Woodford Wells. R. M. Bowen.
* * *
Good for Ulster
Your correspondent R. B. Blackledge, and obviously many other people, are not aware that Ulster, that small British colony 25 miles west of Stranraer, has many miles of roads which are not subject to the “retrograde legislation” Mr. Blackledge talks of.
For example, the Belfast-Dungannon Motorway (M1) offers over 30 continuous miles of motoring, free of traffic jams, and no speed limit.
The so far untapped “phenomena” of Ulster’s clear roads are at the disposal of any magazine or car manufacturer which wish to test high-performance cars; and the natives speak English, an added incentive.
I look forward to seeing British car manufacturers taking advantage of this invitation in 1969.
Belfast. A. P. Brown.
[Ulster obviously retains the excellent motoring reputation it had in 1928, when the first Ulster T.T. was held on the Ards circuit. But until petrol in that area is used for motoring and not for bombs, visitors will stay away.—Ed.]
* * *
Very full fan-h.p. data from leading fan-maker, Wilmot-Breedon, and re V-belts from Ferodo, show that such an unusually large fan, 16 in. diameter, 12 blades, and unusually heavy double-V 21/32 in. belt-drive takes about 7 h.p. at 4,500 r.p.m., and that the belt can just cope with this, plus dynamo anti pump. So appreciable engine h.p. is saved by an electric fan, but only at max. r.p.m.; the fan takes only about 2 h.p. at 3,000 r.p.m., i.e., normal motoring, and the h.p. saving negligible.
It remains perfectly true that for the great majority of car output, small and medium models, using plain 3/8 in. or ½ in. V-belts and smaller fans, the article is incorrect; such belts can transmit a max. of about 4¾ h.p., i.e., about 2 h.p. to the fan, at 5,000 r.p.m.; the fan would take only about ¾ h.p. at normal motoring 3,000 r.p.m.; h.p. saving by electric fan quite negligible. (Dynamo and pump take about 1½ h.p.) From the W B data such belts can cope with, at most, a fan of about 12 in. diameter, 8 blades . . . but failure probable re sustained high r.p.m., motorways, etc., hence litter of broken belts thereon.
Aberfeldy. J. G. Douglas, M.I.P.E.
After reading H. I. Hill’s letter in the January issue readers may be interested to hear of my experience with the Kenlowe fan fitted to a Wolseley 16/60.
On the two occasions when I have motored in alpine country, since fitting the fan, it proved incapable of keeping the cooling water temperature below boiling point on a long ascent to one of the higher passes. The cure was to refit the mechanical fan, carried in the spares box in case the Kenlowe failed electrically, and, although the temperature gauge stood at the high point on subsequent ascents, the water did not boil over. This, I think, supports Hill’s point that good engine designers know what they are about.
I discussed the matter with a fellow traveller on the return ferry, who proved to be a H and V engineer, and it was his opinion that because the fan was, of necessity, mounted outside the radiator grille, the losses incurred by the air stream having to pass through the grille would reduce the fan’s efficiency to a point where it would be ineffective under conditions, approaching the extreme.
I asked Kenlowe’s to comment on this and was told that if I returned the unit, together with £5, they would supply me with a more powerful fan. I did not accept the offer.
It is observed, however, on motoring over terrain other than Alpine that the fan rarely cuts in and one enjoys whatever real advantages obtained. One might query, as Mr. Hill does, whether a fan is really necessary. The answer appears to be yes; when operating conditions require it.
Perhaps my neighbour’s routine, over many years and cars is best. He removes the mechanical fan on October 1st and replaces it on June 1st the following year.
B. K. Hine.
Have any of your readers tried running their cars with the fan blades removed? I run a 1500 Ford Cortina (and previously a 1200 Cortina) without the fan and have no overheating problems. The fan is only re-fitted (a few minutes job) when going on holiday with a fully-loaded boot and five passengers.
Sheffield. Maurice Hall.
[Well, no 12/50 Alvis, of rather similar engine size, power and performance to a Cortina ever needed a fan, or a water pump.—Ed.]
* * *
I was most interested to read your references to the late C. G. Grey. I think I must have read practically every issue of The Aeroplane during his Editorship and I always much enjoyed his outspoken comments on the aeronautical scene of those days (we could do with him now).
One of the best of his caustic criticisms concerned a committee set up by the Air Ministry to investigate something or other. This was: “If Moses had been a committee the Israelites would still be in Egypt.” (I quote this now sometimes.)
Winchester. G. Kingdon.
[Another of C.G.G.’s sayings which remains true today was to the effect that “Daily newspapers necessarily have to publish a certain amount of nonsense. Many of them are produced for people who cannot think, and most of the illustrated papers seem to be produced for the entertainment of those who cannot read. Apart from that the enormous difficulty of finding young men and women who can write, and will check up their facts and figures to assure accuracy in their writing, makes a good all-round newspaper staff practically unattainable.”
Grey wrote that in 1936, when awarding his “Blue Riband for Nonsense” to a Daily Express writer reporting the fatal accident to Campbell Black. It could well have been awarded recently to those correspondents who plied the Guardian with letters relating to last winter’s one-day Motorway multiple fog accidents, who clearly didn’t think before writing them, or its Editor before allowing them to be published.—Ed.]
* * *
Owning a Jensen CV8
Following your road impressions of the Jensen cars and description of the works, you may be interested in a user’s experience with a CV8 over the last 3½ years. The car was bought in July, 1965, to provide Jaguar 3.8 overdrive motorway cruising ability without the penalties of the old-type Jaguar gearbox and clutch.
The indicated mileage is now 96,000 and the total fuel consumed 6,118 gallons, overall m.p.g. 15.7; oil consumption has remained at 600 m.p.p.
Mechanical faults and replacements have included:
Fuel tank and water radiator replaced under guarantee.
Rear axle pinion seals last about 30,000 miles.
Manifold heat valve stops about 20,000.
The speedometer cable was replaced at 70,000.
H.T. leads changed at 94,000.
Universal knots were reconditioned at 82,000.
Front dampers are changed at 26,000. Rears at 50,000.
Brake pads last about 30,000.
Front tyres 18,000 miles. Rear tyres 15,000
Exhaust down-pipes and tail-pipes were changed at 60,000 miles.
Normal service has consisted of oil and filter changes at 4,000 miles, new plugs and points at 24,000 miles. Mechanically it is worthy of note that, apart from one hydraulic tappet which was changed unnecessarily, the engine has had no attention. The gearbox has had no adjustment, no oil change, or oil added. The silencers are still original. Total repair and replacement costs to date are £570 14s. 7d.
The car is sometimes criticised for heavy steering and brakes. The RS5 tyres are sensitive to road ridges when half-worn. The paintwork and chrome could be much better. The CV8 provides reliable, fast, quiet motoring effortlessly. Its engine and gearbox are superb.
The works’ service department is efficient and reliable. Mr. Millard, the service manager, and Mr. Winton, his assistant, are prepared to be helpful and interested. Mr. Hackett in the stores fulfils all reasonable requests. The Interceptor is prettier but for the time being I will stick to the satisfying, economical and reliable “devil” I know.
Coventry. Gavin O. Davies.
* * *
The Ginetta Road-Test Report
I read your appraisal of the Ginetta G.15. A.R.M. was so obviously taken with this little projectile from the Walklett brothers’ stable that I was prompted to inspect the example on display at the Racing Car Show fairly closely. Recently I have had the pleasure of driving in the actual car which was the subject of your test.
It was gratifying to discover that, in the main, I agree with your report, thus dispelling any doubts which readers may harbour about journalists’ licence or vested interest. Your reporter’s exuberance is understandable, but I cannot subscribe to his theory that there is some common ground between G.15 and Lotus 7 addicts. The two cars have virtually nothing in common and appeal to different types of enthusiast. Incidentally, I managed to enjoy my drive immensely, although I have no beard, wear normal clothing and long ago achieved my nuptials. It is a little surprising that no mention is made of the slightly crossways seating position occasioned by the necessity to offset the foot pedals to clear the front wheel arch. Probably longer acquaintance of the car would diminish this impression. Regarding those Perspex side windows, I agree with A.R.M., but not so damningly. Bob Walklett, however, is adamant that Perspex they must be! My final difference of opinion is, if I may he so bold, with D.S.J. himself. Might I ask where he took the car for his “quick half-hour”? Admittedly the suspension is firm but surely no more prone to dental extraction than other small sports cars. Can it be that an enviable continued existence in the world of highly delectable expensive sporting carriages, of which he writes so brilliantly, has dimmed his memory of lesser cars to which the bulk of your readers may aspire?
Thank you for an excellent magazine, which I have always enjoyed and which I now know reports fairly on the cars it tests. The usual disclaimers, of course; I don’t even own a Ginetta.
Maidenhead. Roger Bell.
* * *
Ford Escort Faults
I feel that there is rather more of Ford’s pandering to the 70. m.p.h. limit in their Escort advertisement than Mr. Blackledge indicated. I have recently completed 10,000 miles with an Escort GT registered in May, 1968, and have come to the inescapable conclusion that the performance of this car is geared around the dismal prospect of a 60 m.p.h. limit. At anything over 65 m.p.h. the engine begins to sound shrill and harsh and at 4,500 r.p.m. takes about five miles to settle down to high-speed running. There is considerable drumming from the body just before 70 m.p.h. is reached and the good acceleration is small consolation to one’s passengers as they grit their teeth for a noisy ordeal along the Motorway. I understand that modifications are now carried out on all GT models, but this is of little value to me.
To be fair, the car has been most reliable and it was largely due to lack of time to rectify that the windscreen washers did not work until 9,000 miles. Odd pieces of interior trim have become dislodged, but far more serious is the completely impractical position of windscreen wiper and light switches low down beside the steering column. This has rendered my non-inertia reel seat belts useless, as I drive with the seat well, though not right, back. There is no illumination of these switches at night and they are right out of normal line of vision, so I have operated the wrong switch more times than I care to remember.
Performance shows no sign of dropping off, but this is not surprising as I rarely exceed 60 m.p.h. and the car has reached maximum speed only once.
For the plum long-distance trips I find my Jaguar XK150 infinitely preferable and it still proves capable of out-running almost anything conceived during the post-Fraser period.
Barring mishaps, there is no doubt which car:
1. I shall run the longest.
2. Will cost more in depreciation, leaving a margin to balance running costs.
Llandalf. R. Woodley.
* * *
Clock Tower Saved
Having read your small paragraph on the removal of another landmark—Sunbury clock tower—I would like to point out that this clock tower is now in a “well” near the new shops. It has been replaced by a single beacon with no instructions on. The clock tower is, alas without its perpetually wrong clock, this being, I believe, repaired.
As for history, I am only 13 and cannot remember that far back, but one notable incident was when an articulated lorry sped down the bridge on the Staines Road and could not stop. The tower fell down like a pack of cards in a breeze. (It is made up of small sections each about four feet high.) But the council took it down, repaired it and replaced it to cause more traffic jams.
Sunbury-on-Thames. P. Rush.
[This is only one letter received on this subject. If you want an answer, ask the question in Motor Sport!—Ed.]
* * *
Experiences with Remoulds
In reply to the letter about remoulded tyres and your call for readers’ experiences with same, I offer the following information based on my use of remoulds in the U.S.A.
Between the years 1960 and 1965 I drove two Cadillacs about 100,000 miles on 8.20 x 15 remoulds. The use consisted of nearly every type of American driving, including some sustained high-speed runs across the Mojave Desert. In those years I had two tyre failures which could be attributed to remould usage. In each case the tread separated from the tyre body at speeds over 60 miles per hour. Luckily no harm was done as only a small portion of the tyre came away and there was no deflation.
As all my remould tyres were fabricated at a friend’s remould shop in my presence on tyres both he and I knew the history of, I feel I can make the following comments on what is safe and unsafe in the use of remoulds. Unfortunately my only experience is with crossply tyres and to assume what I say about remoulds holding true for radial ply tyres might be erroneous and dangerous.
(1) Workmanship and the use of proper materials and equipment are essential to successful remoulding. No person in the remoulding trade who cares about his customers would dream of using a tyre that had wall damage, was worn too far or had evidence of severe punctures or heat damage. The care with which the surface is prepared, the camelback applied and the curing is done determines whether a safe remould is produced. I cannot over-emphasise the importance of workmanship: without it a remould is an unsafe item on any vehicle.
(2) Whether a tyre is tube type or tubeless, the remould should be run with a tube and at a pressure about two to four pounds higher than the original equipment recommendation. Balancing is essential and a dynamic balance is preferable over a static one.
(3) It has been my experience that no remould should be in service much after two years from the date it was fabricated, regardless of the amount of mileage put on. In each case of my tyre failures, the trouble of separation came on tyres that had been remoulded over three years prior to failure. In fact, one of them had been a spare for a long time and failed shortly after installation on the car. My friend in the business confirms this policy of the age factor and tries to move tyres quickly enough to eliminate shell time deterioration.
(4) The number of times a tyre is remoulded probably depends type the type of service it is for. Large truck tyres are remoulded many times with good results, and so are racing-car tyres. For the average motorist it would probably be a matter of deciding whether the tyre has sidewall damage from striking the kerbs in city driving, other sources of damage associated with pleasure car driving and the type of driving most commonly incurred. On this point I am not very well acquainted, as I have never used tyres more than twice for remoulding.
In view of the factors I have mentioned relating to the safety of remould tyres, the motorist should probably have some means of determining the age of the tyre and getting a reasonable degree of care in manufacture. Perhaps if the Ministry of Transport were to establish that all remoulds were to have the date of manufacture stamped on them and the manufacturer be required to adhere to set standards and give a new tyre guarantee, the motorist could use remoulds with confidence in the fact that he was offing the cost of driving with no decrease in safety standards.
As in nearly all industries, the tyre remoulders suffer from a few substandard operators and everyone is hurt as a result. When I return to the States I shall continue to use remoulds because I know the ones I buy are good ones and will use them only to the limits I know to be sensible.
Wheatley. William A. Weber.
I am a student living away from home and a confirmed motorist; my limited income has meant many economies, one of which was the fitting of remould tyres to my recently-sold Ford Consul. I bought a pair of remould tyres, manufactured by one of the big-name companies, and fitted by the supplier. At about 1,000 miles one of the tyres developed balloons, or blisters, between the canvas and the tread, one of them about six inches long and the full width of the tread. The blisters came up quite suddenly while travelling at about 60 m.p.h. A letter to the head office of the manufacturer brought a replacement fitted free by my local tyre agent. The replacement tyre was used and after 500 miles developed a split in the wall along the line of the canvas cords. I took the tyre to an agent for the company where I was informed that the split was an impact fracture probably caused by riding a kerb or similar. This to my mind is unlikely as the tyre was fitted to the off-side rear wheel. I was also told the tyre was suicidal (obvious) and that the company would accept no responsibility. The second tyre of the original pair remained in use until nearly smooth after only 5,000 miles’ wear. I subsequently resolved to fit only new tyres and actually fitted oversize wheels and tyres to the rear axle, expense I never regretted. I also had a nasty experience in my early days of motoring with a recut tyre that threw its tread and exposed three layers of canvas with no warning at all.
I wholeheartedly support Mr. Ridley in his condemnation of remould tyres as unsafe, and in my experience uneconomic motoring.
Southsea. Martin H. Critchley.
The conclusion that remoulds are “unsafe” is a hasty one, based on a very unfortunate experience with them. Might I ask Mr. Ridley if he has ever travelled by aeroplane? If so, the chances are that the ‘plane took off and landed at speeds of 100 m.p.h. or so (with the associated extreme stresses involved) on remouded tyres, with, of course, as many as a hundred lives involved in many cases. Aircraft tyres are remoulded as many as five times quite frequently.
Mr. Ridley is also ignoring the experience of taxi fleets, bus fleets, truck fleets and millions of motorists, who find remoulds perfectly satisfactory. Sonic 35%-40% of tyre sales are remoulds.
Remoulds are manufactured to B.S. AU 144, which lays down standards of speed, safety, wear rate, etc.
The rest of Mr. Ridley’s letter is based on his conclusion that remoulds are unsafe. If this were indeed so, remould manufacturers would not last long with the allowances they would have to give on tyres returned to them under complaint.
Reputable remoulds of the right size, type and ply-rating, and at the correct pressure for the load carried, will give perfectly good service. Did Mr. Ridley’s tyres comply with all the above conditions?
Enfield. Ian J. Murray.
India Tyres Ltd.
Over the past 30 years or so (much of it in Rhodesia and S. Africa) I have used remoulded tyres almost as often as new ones. In fact, I have made it a general practice to get my worn tyres retreaded, always provided they were absolutely sound, with no cuts whatever. Such retreads have all proved satisfactory, and gave mileages of about three-quarters what one gets from a new tyre.
However, on a few occasions, some during the last war and some recently when new tyres size 5.50 x 19 were unprocurable, I have reluctantly bought remoulded tyres, i.e., not my own casings. Most of these proved to be pretty poor duds.
I am still quite happy to use retreads on my Alvis Speed 25, and in the past have obtained better mileages from some retreads than I can get now from a new Dunlop, this now being the only make available in my size.
The answer is: Your own sound casings retreaded, yes; retreads on unknown casings, no.
Pewsey. L. A. Heatlie.
I would like to reply to the letter regarding remould tyres in last month’s issue by Mr. N. P. Ridley.
I purchased a second-hand Austin Healy Sprite 12 months ago which at the time was fitted with about one-third-worn remoulds. I have just changed them for some new Michelin ZXs after covering almost 20,000 miles. Naturally, being a young driver, I do not drive the car at too slow speeds; at no time did the tyres give me any cause for concern, except perhaps on corners which were taken fairly quickly; and they certainly did not blow out.
However, it is a different story with the Mini that I owned previously. A pair of crossply remoulds needed replacing after 1,500 miles, but did not blow out. After the remoulds, a set of Pirelli Cinturatos were fitted, two of which had blow outs on the walls after one month’s use.
It therefore seems that new tyres can be just as unreliable. I certainly would not like to think that my insurance company would refuse to cover me just because I had remould tyres fitted.
Stourbridge. M. R. Hill.