I am starting a delivery business within Nairobi. I am looking to buy a van that can do rounds in Nairobi and carry around 500kg of products per day. I talked to a friend, who advised me to get a Mazda Bongo van, Nissan Vanette or Mitsubishi Delica van since they will serve their purpose diligently. My mechanic, however, advised that I get either the Nissan or the Delica, not the Mazda. He wasn’t very clear why, so I come to you for advice — which, of the three, is better yet they look alike?
1. Between diesel and petrol, which is better?
2. Double wheel or single wheel (rear)?
3. Known shortcomings?
4. Leaf springs: can they be modified so that they can carry more load without affecting stability?
All the best in your fledgling business. I’m surprised your mechanic proposed the Delica for reasons I will not go into lest I get admonished against trashing brands again (I don’t trash brands, just to be clear). Incidentally, the one vehicle he is voting against is what I would vote for simply because there is a blue million of them doing rounds, which means there is no shortage of spares or expertise in maintaining them. And they serve as PSVs to boot: the most strenuous task you can put a vehicle through locally, short of taking part in weekly off-road challenges. Now:
1. Diesel vs petrol:
Diesel engines have better torque and economy while petrol engines are smoother and in some cases more powerful. Petrol engines are also cheaper to maintain and may last longer since turbo-diesel technology seems to have successfully eluded a fair proportion of home-grown grease monkeys. For a few select models of vehicle, petrol versions are cheaper than their diesel counterparts, a circumstance more common among commercial vehicles and Toyota Land Cruisers. It’s the opposite for Mercedes-Benz, where those powered by construction equipment are almost being literally given away, but nobody is talking about Mercedes right now.
2. Double wheel or single wheel (rear)?
This depends on how your business operates because it is a matter of some fine balancing whose final results can only be settled through extensive experimentation. The solution to what you want to achieve lies in the disparity between having a higher load capacity with the dually arrangement which increases tyre life since they suffer less strain per tyre — the trade-off being double the tyre costs come replacement time, and the single tyre wheel set-up which means the tyre experiences comparatively more strain and has a shortened life, but when replacing, you only do so one tyre at a time. Like I said, this kind of mathematical equation can only be solved by actually trying out the two set-ups and drawing graphs using their respective data, which you then extrapolate to find the break-even point at which the dually set-up takes the belt over the single wheel set-up. It may be lower in the graph (two or three tyre changes down the road) or it may need an extension of the x-axis onto another graph, but my maths degree tells me there is a point where the dually wins. Who said controlling overheads in a business is easy? Go for the dually set-up, is my university-educated but patently unverified guesstimate.
3. Known shortcomings?
As I said, I won’t be exploring the Delica any further beyond saying that it is a bit rare, so draw your own conclusions from that. The Nissan Vanette is the Mazda Bongo, so no point trying to split hairs here because there are no hairs to split.
4. Leaf springs
This should be an interesting one because to conclusively discuss it, we first have to go off topic and discuss the Toyota Hiace. Have a seat, because this will take some getting used to.
There has been a spate of road crashes involving the Toyota Hiace H200, and in typical Kenyan fashion, blame has been placed squarely on the vehicle in certain quarters, conveniently ignoring the sack of blood and organs helming the said vehicle, a standpoint I bitterly disagree with since these vehicles don’t drive themselves — they are not autonomous, and if the vehicles were faulty, there would have been recalls and/or a spate of crashes in the land of sushi and sake where they hail from.
It was in the midst of a particularly heated debate on where the culpability for the road crashes lies that someone came up with a thesis that I initially dismissed because it wasn’t thoroughly visited, but I later had to capitulate when more damning evidence was presented by the theorist. He really knows his stuff. Allow me to introduce something called a load-sensitive pressure-limiting valve.
This is a device that regulates brake pressure to the rear axle to prevent locking up of the wheels because locking up of the rear wheels is something only rally drivers and professional drifters do. The rest of us mere mortals will only hurt ourselves if we tried it. The valve has a preset value at which it closes when the hydraulic pressure in the braking circuit becomes excessive. The Toyota Hiace is fitted with such a device.
This much I knew. What I didn’t know was that the preset valve also depends on the actual load of the vehicle, not just the load pressure in the braking system. How does the device tell the amount of load the vehicle is bearing? Through its placement: it’s a height-sensing proportioning valve located between the chassis and the rear axle, right where the suspension is. A heavier load will compress the suspension more than a light one, and the device *(a lever attached to a spring that moves a valve “to restrict fluid pressure as the vehicle’s chassis raises up and away from the axle”) detects this degree of compression. The valve body is mounted on the frame at the rear. The lever arm is connected to the axle by a spring. As the load increases, the frame is lowered (the axle remains at a fixed height) and the arm moves out, allowing increased brake fluid pressure. The length of the spring is the main factor in controlling valve function. *Source: Autozone.com
The man’s point was this: many of these Hiace vans undergo modification once they arrive in the country, one of the modifications being bolstering the rear suspension to accommodate a heavier load. This has consequences because it interferes with the operation of the load-sensing valve by giving false readings since tougher suspension has two effects: an increased ride height (however subtle) and less suspension compression under load; and it is this compression under load that the valve depends on to provide brake balance.
This means that the braking effectiveness of the vehicle is compromised simply by toughening up the rear suspension. I hope you can see where I am going with this: perhaps the people driving these Hiaces are not entirely to blame (they are not blameless, though), others — the ones doing the modifications — are at fault too. It so happens that in modern light trucks and vans, such adjustments require a recalibration of that valve to avoid transforming your vehicle into an oversteering deathtrap.
How serious is this? It is so serious that Hiace vans from South East Asia (Thailand and Malaysia) have an actual notice on the driver’s door that says: “L.S.P.V (Load Sensing Proportioning Valve) must be adjusted whenever vehicle height is changed. Consult TOYOTA dealer”. (Special thanks to Solomon Kimani, who wrote the thesis on the proportioning valve.)
So there you have it. You can change your rear leaf springs to carry more load but it will affect stability, especially under braking unless you also adjust the LSPV. Does the Bongo have the LSPV? Yes.
When launching the MY 1999 Bongo, Mazda proudly declared the presence of an LSPV among other features, so it probably had the device even before, and it was just carried over from previous models.
How far back are we talking? The 1989 Mazda MPV had one as well.
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