Bodyshell - Repair or Renovation | Classic car restoration, servicing, technical advice, surveying and valuation

Bodyshell - Repair or Renovation

One question frequently occurs in the classic world, and quite often I am asked to give an opinion.

How can one tell what is a 'Value for money' restoration?

This is an understandable concern given many people's experience of body structure repairs by some sections of the general motor trade.

We can, at this early stage, try to define repair (to make good) as opposed to renovation (to make new). By repair we mean that a failed system or structure is returned to use. Specific failure or failures are rectified. To renovate is to return a system to its original manufactured specification. A repair might be done at minimal cost, just sufficient to return the system to use. A renovation will only be achieved at high levels of cost. This clear distinction is blurred in the motor trade as an insured loss repair of vehicle. Accident damage is in fact a renovation process, i.e. the damaged vehicle is returned to as new condition (or at least that is the intention). The difference in cost of an insurance repair quotation against an owner financed repair is considerable. On the one hand the repair will replace all damaged sections and parts with new and the finished repair should be virtually undetectable. On the other, it is likely that some or all panels will be reshaped, damaged parts made good and the repair will be easier to detect. The less the age of the car the more important it becomes that the accident repair should not significantly reduce its sale value.

All this is not just an academic point. It brings in to focus the cost decisions that must be made, for instance, to repair an old car rather than to replace is simply a question of economics. To renovate an old car to its original state is a matter of personal desire, to own something remarkable at whatever the cost. This cost may be financial or a major commitment of time and effort and the result will be a prized and cherished possession. However, it would be foolish to assume that resale value of a restored car is not of importance. In order to protect the investment of time and money, the owner will have the restored car valued and insured against consequential loss. It is from this point that difficulties occur. How should the car be valued? If it is based on the car's general market values alone, it is unlikely that the insured value would cover the actual cost of restoring an identical vehicle. We have as a result the so-called agreed value system. The problem is who is to decidethe value? What happens if the vehicle is extensively crash damaged and the insurance assessor finds the structure to be poorly restored are badly corroded? Even where there is no disagreement over the general condition there can be difficulties. At the moment there is little reliable data available on the costs of high quality restoration. Indeed, there seems little agreement at present on the appropriate quality standards for such work. Also many restorers seem reluctant to quote realistic prices and the final cost overruns can be substantial. All this makes it difficult to plan costs and properly estimate replacement values. Perhaps the time is ripe to have something like a British Standard on vehicle restoring.

The Bodyshell

Where we are considering renovating an old car, the bodyshell will be the most difficult and costly element. To achieve a satisfactory and sound structure, is a labour intensive business, and therefore expensive. Unfortunately, it is all too easy to disguise poor quality workmanship. It is quite common for damage or corrosion repairs to have been carried out using large amounts of plastic filler supported by newspaper, bits of tin etc. The repair being made quite presentable when finally painted or covered with copious amounts of thick underseal materials. There are many examples of apparently sound classic car bodyshells which, when stripped of paint and plastic filler, are found to be in a very sorry state indeed.

Even when the repair has been carried out properly using correct repair panels, there is significant difference from renovation work. The repair panel is normally designed to lap over sound original structure areas. This method of joining is not satisfactory if the long term life of the repaired area is to be considered. The overlapping panels become sites for corrosion systems which once established will rapidly destroy the strength of the weld areas. The onset of this process is normally only delayed by treating these areas with anti rust materials. Regular retreatment would be necessary if significant corrosion damage is to be prevented. This is a costly and time consuming exercise and requires meticulous attention to detail if it is to be properly effective. In most cases this retreatment lapses after a year or so and the vehicle structure rapidly degrades. This should not be confused with the highly desirable injection treatments used to protect enclosed sections of the structure. What is of concern is the difficulty of protecting panel lap joints, particularly those in the floor areas, inner wing sections and points where fore and aft load pathways join.

This criticism of methods of joining various vehicle panels can of course also apply to the original manufacturers structure. The common method of body assembly is to use overlapping spot welded joints, cheap and fast in production and giving minimal heatdistortion difficulties. However, as we know unitary bodyshells that have not received specialist anti corrosion treatment during and after manufacture have a very limited life in wet climates such as ours. The problem of course is far more complex than whether panel joins are jointed or lapped. Considerations of road deposit traps, adequate drainage provision for enclosed sections, the prevention of water ingress into the cabin floor areas etc. must be considered carefully. What we must do, if the long term life of a classic bodyshell is to be maximised, is to eliminate or reduce corrosion traps during restoration repair. There will be significant differences in repair processes for vehicle body structures depending on the customers requirements. For instance many owners will simply require a minimum cost repair sufficient to maintain the apparent roadworthiness of their vehicle. In this case the vehicle will deteriorate, an accelerating process, until it becomes uneconomical to repair further. This deterioration can be disguised by shiny paint and thick underseal cover and can often be an unpleasant shock to the owner. On the other hand, we have someone who wishes to restore their classic to a very high standard. They may be capable of undertaking a substantial proportion of the work themselves, or as in the majority of cases their skills will limit them to a smaller proportion of the restoration. In either case there is a considerable investment in time and money which requires a careful examination of the ways to gain the longest life possible for the restored vehicle.

This brings us to the idea of quality and its relation to cost. It is obvious that if a restoration involves more labour time it will have a greater cost. The greater the attention to detail the greater is the time spent. Even if much of the labour supplied is ones own, it still must be considered as having a cost. Loss of leisure activities, or perhaps loss of time that could have earned additional income.

If we consider where complete restoration is carried out professionally then costs can appear high. However when we consider the labour intensive nature of classic restoration we should not be surprised. In many cases the labour content of a complete bodyshell-up restoration can have a labour cost of 60% of the total. A classic car, for example, may well require 400hrs of time to carry out the major renovation tasks. at a cost to the renovation company of say £10 an hour equalling £4000 plus a material cost of perhaps £3000 totalling £7000 and with a selling price of £11662 at which a 40% gross margin has been added allowing the restorer to stay in business . Remember that the vehicle would be using expensive workshop space for 8 weeks or more, meaning a maximum of say 6 such jobs realistically in that space, returning a maximum gross margin of £27972. Out of which must come all the fixed cost of the. business and of course such tax as is liable. Looked at in this way the costs of a professional restoration are moreunderstandable.

Please note the figures above are for exercise purposes only and that costs will vary according to the nature of the contract at any given time.

Bodyshell Check List

The following points should be considered when arranging a bodyshell-up restoration.

(1) complete restoration must entail the vehicle being completely stripped of all components and attachments

(2) The bodyshell should then have all paint, sealers and filler removed.

(3) Accurate measurements should be made of the structures dimensional accuracy and any distortion corrected.

(4) All corroded areas must be cut back to sound metal, preferably to original body panel joins.

(5) New panels pressed or hand formed, should be but welded in place where flat or curved sections are rebuilt. Enclosed sections should be inserted taking into account the original construction.

(6) Lap joints should be kept to a minimum and, where used should be sealed using modern techniques i.e. heated plastic strip seals.

(7) Major new panels should be corrosion protected.

(8) During assembly and welding The proper use of jigs and fixtures should be made.

(9) Dimensional tolerances of the bodyshell must be maintained to factory levels of accuracy.

(10) Where possible the completed shell should be zinc dipped or hot sprayed prior to painting.

Assembly

(1) Following the complete reconstruction of the bodyshell. The assembly process of the vehicle, should ideally be carried out in in a clean area, separate from any fabrication and welding process. New and refurbished parts being available from stock as required.

(2) Appropriate mechanical handling systems should be available.

(3) Each stage of the assembly must be carefully controlled for proper levels of build quality.

(4) The complete vehicle should be fully tested including a 500 mile extended road test. Final vehicle checks completed the car would then be released to the customer.

This build programme ensures that proper attention is given to every detail during the assembly process.

Coupled with all the processed work full documented records should be made as follows.

(a) Quality specifications, inspection, reports.

(b) Test results such as power outputs from final rolling road testing.

(d) Ideally documented photographs at various stages should be made.

(e) Finally, the restorer would supply a certificate of value approved by an appropriate insurance company.