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26th July 1986, Page 110
26th July 1986
Page 110
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Page 110, 26th July 1986 — MO THAN ICI N EP
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Which of the following most accurately describes the problem?

There's often more to crash damage than meets the eye, and it usually pays to let a specialist take a look. Peter Wallage reports

• Often, when trucks return to the depot after what seems like a minor shunt, the operator looks at the damage and probably breathes a sign of relief thinking that perhaps a new bumper of grille, a spot of panel beating and a touch of paint will put the matter right. In some cases he may be lucky, but in others he could be due for a nasty shock if he took the vehicle to a small crash repair firm which did not have the facilities for the expertise, to look under the skin and find out the true extent of the damage.

Alternatively, the truck may have been involved in a more serious accident which, to the operator, looks as if a new cab shell is inevitable. In yet other cases, particularly with artics, the vehicle may have turned on its side and the resulting twist in the chassis makes the operator certain that the vehicle is a complete write-off.

It is so easy for an inexperienced person to arrive at the wrong conclusion, about the results of an accident, and the consequences could be costly. In some cases a repair without sufficient knowledge could knock hundreds of pounds off of the residual value of the truck. In cases of a twisted or bent chassis, straightening without the proper equipment can lead to unduly fast tyre wear, and inexpert heating of the chassis to straighten it could set up stressfracture points in high-tensile steels.

In any case, inexpert repairs lead to arguments, dissatisfaction and often mean that the job has to be done again. All this pushes up the costs to an insurance company and could well be one of the reasons why insurance premiums on commercial vehicles have in recent years increased out of all proportion to the current lower rate of inflation.

To find out more about the way to assess the extent of accident damage we spoke to Vince Moore, general manager of Chassis-Cab, commercial vehicle accident repair specialist of Bury St Edmunds.

In the workshops were several examples of apparent superficial damage which had gone much deeper than the skin, and one example of a vehicle on which an uninformed atteiript to straighten a chassis frame resulted in Chassis-Cab having to take the job on at a greater cost than should have been necessary.

One example of the former type of damage was an ERF tractive unit which had been in a low-level shunt on its nearside front. The bumper had been twisted, the GRP bottom skirt broken, and the shock wave had sprung one of the rear side panels and split a front wing. It looked as though this could be the extent of the damage. Not too difficult to put right, you might think. An operator might even do it in his own workshops with a new bumper and some GRP repair materials.

If this particular operator had taken that view, the results in tyre wear and bad road holding could have been very costly. Vince Moore pointed out that the A-frame which supports the back of the cab had been distorted and had lozenged to one side. Even more than this, it had taken the top flange of the chassis with it and the steering geometry had been upset to the point where rapid tyre wear and uncertain steering were almost inevitable. A new A-frame might have made things look nice and square again — at least with a bit of fiddling and a crowbar — but the more serious damage to the chassis would have remained. Yet with the sophisticated equipment in Chassis-Cab's workshops, straightening the chassis and restoring the geometry was a realatively simple run-of-the-mill type of repair.

The ERF had a plastic cab, but another example with what looked like relatively minor damage to the front was a steel Leyland T45 cab. True, the front grille and radiator had been damaged beyond economic repair, but all that seemed to be wrong with the cab was a relatively minor dent in the box section member which stiffened it over the engine.

How wrong this simple diagnosis could be was evident when Vince Moore pointed out me a wave along the engine tunnel, a slight wave across the floor on the driver's side, and, if you looked carefully along the back, there was a slight but definite distortion on the cab rear panel.

No doubt any reasonably competent panel beater, with the help of a few chains and a couple of rams, could have made this cab look reasonable enough. But the chances are that all but a very few main dealers, would not have the necessary jigs and brackets to pull this distorted cab back into its proper alignment so that it sat properly on the chassis, tilted and, even more important, locked properly in the down position. Using its Swedish-built Josam jig, Chassis. Cab made proper alignment absolutely accurate.

For proper chassis alignment and to ensure accurate geometry, minimum tyre wear and the road handling which the vehicles' designers promised, Chassis Cab uses a very large Blackhawk alignment jig that will accept even the longest of commercial vehicles. With this jig the company uses a laser-beam alignment tool which is so simple and accurate to use once it is set up properly that one could quickly detect a degree of twist in a chassis less than 2nun over its entire length. Vince Moore believes that this is one of the most comprehensive pieces of chassis alignment equipment, certainly in this country, and possibly in Western Europe.

What, then, should an operator look for when he is unfortunate enough to have one of his trucks driven or recovered to his depot after an accident? Vince Moore's advice is to ignore first impressions and take a long slow walk round the vehicle to get a fuller picture of what the accident has actually done to it.

Tell-tale points to watch out for are marks round the window rubbers and uneven door gaps. If the cab shell has been distorted, the window rubbers will have moved even though the glass may still be intact. Any signs of primer paint showing along the edges of the rubbers, or indeed any indication of movement at all, means that the cab shell has distorted. Door gaps may not be the same all the way round, but at least along any one edge the gap should be even. If it is not, then again the cab is probably distorted.

These tips also apply should you be looking at a used vehicle at an auction or at a dealer with a view to buying it. Do not be misled by a door which has an even gap down the locking face, but which has an uneven gap at the top and bottom. The thing to look for here is a packing piece behind one of the hinges which has been put there so that the door will open and shut without the cab shell distortion being straightened.

The next step is to tilt the cab and check particularly that the locking mechanism frees easily and locks again securely when the cab is pushed down or comes down under its own weight. [fit does not, then be suspicious. Look for waves and buckles on the underside of the floor. Sometimes this is difficult because of a heavy coating of sounddeadening material, so even if the floor appears sound underneath, it is still a good safeguard to take out all the floor covering and look for any waves or distortion on the inside where it shows up more easily on the plain painted metal.

In more severe cases, the paint may even have cracked along the line of the distortion. Remember that the shock wave of an accident blow can sometimes transmit distortion through a floor to the back panel without the floor itself seeming to have suffered, so look carefully along the back panel for any waves.

On looking for chassis distortion or chassis twisting, Vince Moore's advice is, first, to look carefully along the top and bottom flanges of the chassis sidemembers. If you see any signs of waving or buckling, the chassis is out of line. In the case of tractive units, look carefully at the flanges under the fifthwheel mounting plate. Flange damage here is very common if the outfit has rolled or jack-knifed, yet sometimes the distortion in the flange is apparent only after the mounting plate is taken off. An absolute giveaway is a mounting plate which "springs" away from the chassis when the bolts are undone.

Look also at all the points where the crossmembers meet the chassis sidemembers and look for any distortion on the flanges of the crossmembers themselves. Sometimes a chassis may have lozenged without the sidemembers themselves being distorted.

If all seems well so far, stand at the end of the chassis and look along the sidemembers and crossmernbers for any signs of "winding" which might indicate a twisted chassis. This sounds very simple, but Vince Moor warns that it is very easy to be mislead. Commercial vehicle ladder chassis are naturally flexible so it is important that the vehicle is standing on perfectly level ground. Even then, it is possible to be misled if the vehicle has a weak spring.

In one case, an operator brought his vehicle into Chassis-Cab saying that he could see that the chassis was twisted and would the company please tell him how much it would cost to put it right. He was delighted when, after putting the vehicle on the jig and checking it, Vince Moore told him: "Straightening the chassis won't cost you a thing. All you need to do is go to your nearest Ford dealer and buy a pair of new front springs."

The moral? It always pays to consult a commercial vehicle repair specialist and ask for an estimate before agreeing to have any accident repair work carried out, either by a small crash repairer whose main work is car bodywork, or indeed in some cases, by franchised dealers. However, neither of these people, good though their workmanship might be, has the specialised equipment necessary to ensure that the accident damage can be repaired properly. And the chances are that with specialist equipment the end cost will be lower because the labour costs will be so much less.0


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