Test of Commer 8-tonner reveals first-class ride and handling, good driver comfort and economical, lively performance
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By John F. Moon, A.M.I.R.T.
ASrecorded in last week's issue, I conducted the first Press road test of one of the new Commer 8-tonners, recently, and was more than pleased with its overall performance. I feel it is fair to say that this latest Rootes design is streets ahead of anything to have been produced by Commers in the medium and heavy classes during the last few years which is, of course, only as it should' be: there is little point in formulating a new design if it cannot be a considerable improvement over earlier types.
Admittedly, Commer Cars, Ltd., have not ventured Into the 8-ton market before, but the complete balance of the design is so radically different from that of their former heaviest model the 7-tanner—that it is obvious that virtually nothing except the engine and gearbox have been inherited. This applies particularly in respect of handling and cab comfort, the new Commer 8-tonner being well to the fore on these counts. The economy is still there, however, while the safety aspect has been improved by the use of a powerful but smooth braking system, first-class all-round vision and the provision of a four headlamp system. The new design is not flimsy either, and its life potential should be long.
Of the two Commer 8-ton models—both of which have a gross solo weight rating of 12 tons 1 cwt.—the one I tested was the CADY 887 15-ft. 7-in.-wheelbase version. This has the longest wheelbase of any goods chassis so far produced by Commer, and makes the design suitable for mounting of 21-ft. 6-in.-long bodies. The other 8-tonner is primarily for tipper applications and has a wheelbase of 9 ft. 7 in. Both versions are available with the new CA all-steel forward-control cab, or, alternatively, in chassisscuttle form with only the front panelling and windscreen framing. Additionally, a steel-lined-timber tipping body with a nominal capacity of 6 cu. yd. is offered for the shortwheelbase chassis-cab.
A rather heavy 21-ft. timber platform body had been specially built for the vehicle tested, so the 8-tonner's kerb weight of 4 tons 6.25 cwt. was higher than it would have been with a conventional body. The chassis-cab. kerb weight was 3 tons 12.5 cwt., so with a light-alloy flat of the same length it should be possible to get the kerb weight of a complete vehicle down to the 4 ton mark. As it was, the Commer was tested with a load of only 7.75 tons, which brought the gross weight with no one in the cab to a few pounds above the manufacturer's rated maximum figure. With three people and test equipment in the cab the vehicle was grossing 12 tons 5.75 cwt.
The roads being dry on the bright but windy morning of the test, I made my braking test first, using a rather narrow but level piece of asphalted road for these trials. The stopping distances obtained from both the test speeds were good, and would have undoubtedly been slightly better had not rear-wheel locking been prevalent. As it was, exceptionally good maximum retardation figures were indicated on the Tapley meter when braking from each speed, and there was very little apparent lag in the airpressure servo operation. Perhaps just a little less power at the rear brakes would result in stopping distances of less than, 50 ft. from 30 m.p.h.
Despite rear-end sliding during these tests I experienced no difficulty in holding the 8-tonner while it came to rest. Handbrake efficiency was high, an average Tapley-meter figure of 30.5 per cent. resulting from stops made from 20 m.p.h. The brake lever is so positioned that a good pull can be obtained on it with the left hand, particularly if the driver's left foot is braced against the near-vertical toe board.
As is usual on road tests conducted in the Luton area, normal-speed fuel-consumption figures were taken over the undulating out-and-return circuit of the All between Barton and Clophill, the length of which is six miles. Without at any time exceeding 33 m.p.h. this course was completed at an aVerage speed of 28.2 m.p.h., fourth gear having been used twice during the run for a total time of about 50 seconds—once at the turn-around point and once when ascending the northern side of the hill south of Clophill,
this climb being made at a steady speed of 25 m.p.h.
was very pleased with the overall consumption rate indicated by the 1-gal test tank, which was 15.2 m.p.g. This result gives gross ton-m.p.g. and time-load-mileage figures of 187 and 5,273 respectively, which are not so very different from those obtained in June, 1957, over the same route with a Commer 7-tonner running at 11 tons gross. This had the same type of engine but a 5.125-to-1 rear axle, and when tested between Barton and Clophill without using the overdrive ratio of the gearbox and at the identical average speed, 17.5 m.p.g. was obtained, giving gross ton-m.p.g. and time-load-mileage figures of 193 and 5,448 respectively. This new 8-tonner is obviously going in prove as economical a proposition in terms of cost per ton of payload as its 7-ton predecessor.
Much as I would have liked to have taken unladen fuel figures with this vehicle, a combination of vehicle unavailability and snowand ice-covered roads made this impossible. However, the 1957 test with the 7-tormer showed an unladen non-overdrive figure of 24 m.p.g. at 30 m.p.h. average speed (between Barton and Clophill) and as the kerb weight of that 13-ft. 6-in.-wheelbase drop-sider was 9 cwt. less than that of the 8-tonner, and allowing for the difference in axle ratios, a fair estimation of the unladen consumption would be 22 m.p.g. This being so, operators working laden in one direction only could expect to achieve a clear 18 m.p.g. overall from trunk operation in undulating country.
The Commer's motorway performance was assessed over a 13-mile round circuit, which was completed without a stop. The total running time from start to finish was 19.25 minutes, which gives an overall average speed of 40.5 m.p.h., but the actual time spent on the motorway was only 17 minutes, indicating the average speed under continuous full-throttle conditions to have been in the region of 45 m.p.h. As the vehicle's maximum speed on the level is just under 47 m.p.h., this is not bad going and shows that motorway gradients do not appreciably detract from the 8-thriller's high-speed-cruising capabilities. Exactly 1 gal of fuel was used during this test, and the resulting time-load-mileage factor was 6,480.
Gradient-performance tests were conducted up and down the 1-in-10.5-average Bison Hill, the length of which is G.75 mile. The ambient temperature at the time was 7°C. (44.5°F.) and the temperature of the water in the cooling
system header tank (the radiator top tank itself cannot be reached with a conventional stick thermometer) was 55°C. (131°F.).
The ascent was competed in a total time of 4 minutes 10 seconds, which is exactly the.same time as that required by the 7-tanner tested in 1957, although on this occasion the lowest ratio employed was second, whereas the lighter vehicle had needed bottom gear for one minute. With the 8-tonner second was used for 1 minute 55 seconds, during which period the road speed dropped to 3 m.p.h. briefly on the steepest section. No exhaust smoke was noted at any time, and the climb caused the coolant temperature to rise to 67°C. (152.5°F.). Overheating should not be a problem with this vehicle, therefore, particularly as the cooling system is pressurized to 4 p.s.i. to raise the boiling point above the normal figure.
As a check for fade resistance I coasted the 8-tanner down Bison Hill in neutral, the footbrake being applied for a total time of 2 minutes 25 seconds to keep the speed down to about 20 m.p.h. Towards the bottom of the hill, where the gradient is not so severe, I engaged top gear and applied full throttle in order to keep the brakes working. At the end of this descent a full-pressure stop from 20 m.p.h. resulted in the Tapley meter giving a reading of 57 per cent., indicating a maximum-efficiency reduction of 0.24g through fade. This is an appreciable improvement on the performance of other Comm ers tested down this hill, and indicates That the Commer engineers are finally getting to grips with the fade problem.
Following this very severe fade test I returned the vehicle up the hill and brought it to rest an the steepest section, the gradient of which is 1 in 6.5. Here the handbrake was proved to be powerful enough to hold the vehicle with ease, after which I carried out several smooth and easy bottomgear restarts. This gradient-restart ability indicates that gradients as severe as 1 in 5 should not present any difficulties to this design.
Throughoutthis test 1 was continually being surprised at how closely the performance of this new 8-tonner resembled that. of the .1957 7-tonner, and this similarity arose. again in connection with acceleration performance. The Commer design team is certainly to be admired for obtaining such consistent closeness of results with the same engine but at 1 ton higher gross weight.
The times for standing-start acceleration up to 30 m.p.h. differed between the two vetlicles by only 0.1 second, although there was a difference of 1.75 seconds between the times taken to reach 20 m.p.h. When it came to directdrive acceleration between 10 and 30 m.p.h. the heavier vehicle was 6.0 seconds to the good, obviously because of the lower axle ratio, and beat the lighter job to 20 m.p.h. by 2.5 seconds.
Thus, it is quite clear that nothing at all has been lost in terms of acceleration or hill climbing by the higher gross weight, and that the choice of final-drive gearing has fully compensated for the difference between the two designs in terms of load rating. Speeds in the gears, incidentally, were recorded as: bottom, below 5 m.p.h.; second, 9 m.p.h.; third, 19 m.p.h.; and fourth, 31 m.p.h. For the standing-start tests only second, third and fourth ratios were employed.
So much for the performance of the new 8-tonner. Praiseworthy as this is, the attractions of this design are equally strong in terms of ride and handling, and driver comfort. The suspension in particular is first class whether laden or unladen (subsequent to my main test I drove for a few miles in an unladen chassis-cab). The steering characteristics are good and, possibly more important, the whole feel of the vehicle is decidedly better than that of the QX 7-ton models.
Although the steering gets a little heavy at walking pace, at normal speeds it is light without any trace of wander, whilst a sensible degree of castor action is of value. The lock of the test vehicle was disappointing, but a turning circle of 62 ft. is to be aimed at in production. When B34 running at full throttle on the motorway the Commer was very steady and felt as safe as houses.
Very little engine noise, penetrates the cab, and the gearchange action is good, although the reversed gate positions are somewhat unconventional. The clutch action is quite light, although the brake pedal of the vehicle I tested was a little heavier to apply than I would have expected.
The all-round range of vision is good, and the high line of the bottom edge of the windscreen did not prove to be the disadvantage that I had anticipated. The large Winguard rear-view mirrors are a big advantage, and their triangulated support arms successfully stop them vibrating. The side blind spots created by these mirrors are not dangerous and are 'worth putting up with in view of the increased rearward vision.
Both the driving and passenger seats are very comfort. able, and there is ample room for two large passengers without interfering with the driver's use of his controls. Instrumentation is comprehensive, and all the instruments are easy to see and the switches easy to reach. Stowage for papers and so forth is limited to one glove locker in front of the passenger seat, for which a lockable lid is offered as an accessory. Additional pockets would be an advantage, and should be easy to provide.
Another improvement I want to see concerns the locking catches on the door quarter lights: those on the test vehicle were poor and difficult to actuate, but a change for the better is to be made soon. The optional heater, which includes four demister outlets, was shown to be very effective and well worth the additional £18 involved. As for the headlamps, I have a similar Lucas four-headlamp system on my own car and would hate to revert to a conventional two-headlamp system now.
The basic long-wheelbase Commer 8-tonner in chassisscuttle form costs £1,614, and the cab adds only £105 to this price money well spent, in my opinion.