MAN-VW POWER
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AT 7.5 TONNES
The engine of the 8.136F will appeal to drivers but its thirst won't to operators unless they really need the tight journey times it can manage. Brian Weatherley reckons specifying the correct rear-axle ratio is crucial
JLIMING by the sales of MANVW's 7.5-tonne MT range, it is not difficult to see that power is uppermost in the minds of their customers. Out of all MA N-VW's UK 7.5-ronne registrations, 80 per cent are taken up by the I 00k W (136hp) 8.136F, leaving the lower powered 66kW (904) 8.90F to account for the rest.
This cleat preference for higher powered six-cylinder 97kW (130hp) plus 7.5-tonners is not unique to MAN-VW. The same split can be seen in both Mercedes-Benz's and 1veeo's sales figures. It does appear, however, that together these importers are snaking the running at the top end of the 7.5-tonne market. leaving Bedford, Ford and Ley:kind to dominate the sales of vehicles in the 07-86kW (90-115hp) sector.
One question we at CM keep coming back to when testing non-hgv rigids, is: Do operators really need [UAW (135hp) in a 7.5-tonner? If firel consumption is the prime concern, then the results of the six-cylinder 8.136F tested around our Welsh route would seem to reinforce the argument that to achieve maximum economy, lower powered engines must be specified.
Since hgv vehicle speed limits were increased last year, CM has tested 14 7.5-skinners all dropsiders of which
eight have been equipped with 97kW (130hp) plus six-cylinder power units. Of these eight, not one has achieved more than 17.7 lit/100km (16mpg) and our 8.136F was no exception. It returned 17.87 lit/100km (15.8mpg), slightly better than the previous best, the 814 Mercedes.
Many operators, however, such as those running with box bodies over hilly terrain or with extended motorway work, need to maintain acceptable Journey times. For them power is more important and in this department the 8.136F has plenty to offer.
Even with busy A-road traffic around our 210-mile route, the 8. I 36F fitted with a 3.9:1 rear axle returned a good average speed of 70.96kin/h (44.09mph). And during 0-50mph acceleration tests at Mira it proved quicker than both the Bedford TL and 1i/cc() 79:14, only losing out to the Mercedes 814 which was fitted with a faster 3.63:1 rear axle ratio.
The 8.136F MT's mid-range acceleration is particularly impressive. Its 30-50mph time of 22 seconds is the fastest recorded by a 7.5-tonner, and worth comparing to the 37 seconds taken by the four-cylinder 66kW (88.5hp) 809 Mercedes, which, at the opposite end of the power scale, holds the 7.5-tonne fuel consumption record of 15.65 lit/100km (18.05mpg).
Along the 52-mile M4 stretch the 8.136F, which has a maximum geared speed of 72mph with the 3.9:1 rear axle, maintained 70mph easily, only dropping to 65mph on sharp inclines. At these speeds the interior noise levels of 81dB(A) were noticeably higher than those recorded in the 814 Mercedes and Bedford 'IL750.
ENGINE PERFORMANCE The six-cylinder naturally aspirated MAN D0226MF engine is certainly not the most economical power unit at 7.5 tonnes, hut it does have impressive lowspeed pulling power. Although maximum torque of 353 (260 lbft) is delivered at 1,600rpm, the engine will comfortably lug down to 1,200rpm. This flexibility is not only useful when hill climbing, but makes for very lazy urban driving. When tackling roundabouts the 8.136F will pull through quite happily in fourth gear at 1,300rpm without the need to change down, vet have enough power to accelerate away.
Specifying the correct rear axle ratio is crucial if an operator is to get the most from the MAN engine. The optional 3.9:1 unit fitted to our test vehicle appears to be the best for dropside and tipping vehicles with motorway or inter-urban work. MAN-VW, however, recommends the fitting of the 4.44:1 standard ratio with a lower maximum geared speed of-64mph for those vehicles with a lot of hill work, or if fitted with box bodies.
CAB COMFORT
The compact VW cab has car-like proportions which will no doubt appeal to those drivers hiring a 7.5-tormer for the first time. There is, however, an excessive use of black in the interior trim including the dash, door panels and flooring. The use of grey stripes in the scats and grey headlining livens this up. The overall effect is that of a practical but rather oppressive environment.
All main instruments are sited within a wide well-equipped binnacle. The use of four small gauges for oil, fuel, air pressure and engine temperature is, however, rather confusing and they would be better replaced by a single large dial split into quadrants rather like those in the Mercedes LN2 range. The tachograph and well marked out rev counter are clearly visible to the driver, although the large 495mm (19in) diameter steering-wheel obscures the air gauge when the driver's seat is well forward.
Access into the 8.136F cab is simple enough. Two entry steps are built into the front of the wheel arch, although it is better to ignore the first and climb in using the second while holding on to the well mounted A-post grab handle. Cross-cab access takes a little more time and requires the driver to thread his way past the long gear lever.
If the 8.136F's engine performance is impressive then so too is its ride and handling. The front twin lead parabolic and rear multileaf springs give the 8.136F a firm yet comfortable ride while the standard fitting of front and rear anti-roll bars clearly contributes to the 7.5-tonner's good roll-stability, and excellent roadholding.
Around the twisting 50mph A-road section between Wantage and the M4 the long — 4.25m (13.91t) wheelbase — 8.136F was able to maintain a good average speed, tackling tight corners with ease.
The five-speed synchromesh VW gearbox appears generally well matched to the MAN 5.68-litre engine although there was a noticeable gap between second and third ratios. Our MT demonstrator had completed well over 10,000 miles, but had been recently fitted with a new gearbox with the result that although the shift pattern was precise, the long gear lever was still stiff to operate, particularly when engaging first.
Unlike Mercedes-Benz, Iveco or Bedford, MAN-VW does not offer power-steering as standard. It will cost operators an extra £680 for the optional power-assisted ZF-Gemmer unit which has a light but precise feel to it.
With heavy goods vehicles up to 7.5 tonnes now allowed to travel at 70mph, good braking is of prime importance. The 8.136F's air over hydraulic braking system gave a good overall performance . both on the road and on the Mira test track where the 100kW (136hp) 7.5tonner pulled up undramatically from a 40mph full-brake stop without any hint of wheels locking.
Although all daily service checks can be carried without raising the manually tilting cab, engine oil can be added only when the cab is raised.
SUMMARY If power rather than fuel economy is the main requirement then MAN-VW's 8.136F should be on the shortlist of any prospective 7.5-tonne buyer. While its basic specification cannot quite equal that of its Continental rivals like the Mercedes 814 and Iveco 79:14, its £12,720 chassis price — including the £680 for the optional power-steering — is hard to beat.
Like Mercedes-Benz, MAN-VW is not exactly renowned for building lightweight chassis and the 8.136F's 4.46-tonne body/payload allowance is certainly not the highest. The situation is not helped by the fact that MAN-VW fits twin 100-litre (22gal) fuel tanks as standard on the 4.25m wheelbase 8.136F which bumps the kerbweight up significantly.
The MT's VW cab may not be the most up to date, but it has a compact design with a practical interior and the flexibility and power of the MAN engine will appeal to drivers.
. When journey times are critical the 8.136F can maintain good average speeds even over tough terrain. Prospective buyers, however, should ask themselves whether their work really justifies the extra horsepower — particularly as the 67kW (90hp) MT 8.90F could well prove a more economical buy, especially when it comes to paying the fuel bills.