Moss Motors, Ltd

The most feared four?letter word in a British sports car owner's vocabulary must be rust. I once saw a TR250 collapse in the middle when lifted by a tow truck; when set back on all fours, the center portion of the frame was resting on the pavement. Rust, caused by road salt and neglect, was responsible.

Even in areas where road salt is not used, rusting agents may be present which literally eat holes in automobiles. Dilute sulfuric acid is present in many areas in the highly publicized form of 'acid rain'. Some crop spraying chemicals are also active rusting agents, while salt spray in coastal areas often turns cars into dangerous hulks of rusty steel lace. Once the rusting process has begun (often by the time the car reaches the dealer), it is too late for protection - remedial action must be taken immediately to remove existing rust, no matter how seemingly insignificant.

The only way to remove rust which hasn't yet eaten entirely through its ' host' panel is to sand down to clean metal, treat the sanded area with a rust remover (most proprietary solutions containing phosphoric acid work well), wash thoroughly to remove all traces of the rust remover, prime and paint. It's a lot of work, even for a relatively small area. If rust is forming between two pieces of metal spot-welded together, or otherwise lapped over each other, acid treatment is not recommended, as it can't be adequately neutralized.

What can be done to de-rust a sealed, boxed-in area? Unless you can get to all rust-contaminated surfaces and derust them, there' s not much that can be done. Generally, the compounds advertised as 'rust neutralizers' and such, have some rust retardant value, but they don't seem to effect permanent cures.

Body cancer' is one of the least pleasing pseudonyms of automotive rust, but one of the most accurate. Once rust has eaten through a panel, even in pin-holes, the only cure is to cut out the affected part and weld in a new piece. This can be more trouble and certainly more expensive than prevention or immediate first aid when rust is first noticed, but it is the only way to cure the problem. Body-putty, lead, pop-riveted patches and other commonly used ' repair' methods only hide the problem, they do not cure it.

Rust has an even more dangerous cousin electrolytic corrosion of aluminum panels where they join steel as on Big Healeys. In this case, the aluminum and steel, in the presence of moisture, act as an electric battery, especially when the moisture is salt?laden and the temperature is warm. When this occurs, the aluminum crumbles and turns into white powder, leaving the steel rusty, but usually sound. What makes this form of 'body rot' worse than rust is that it is much more difficult to perform 'cut and weld' repairs on aluminum than on steel.

Prevention of corrosion is much easier than repair. When washing your car, wash it thoroughly underneath as well. Do whatever you can to dry it - blow with compressed air, mop it dry, or open doors, trunk and hood to allow water to evaporate. Letting it sit out in the hot sun will dry it quickly enough. Above all, do not put a wet car in a heated garage - heat, combined with high humidity, is what rust thrives on. Check the car thoroughly underneath for raw or rusty metal areas- clean and protect them with paint, undercoating, or even grease. Have you ever noticed that the bottoms of your front floors never seem to get rusty- the oil from engine leaks protects them. (This won't prevent floors from rusting from the inside, though.) Do whatever you can to prevent rust from starting. Most commercial undercoatings work very well when properly applied.

Checking a car for rust and finding all the rust is not as easy as it sounds. For example, by the time rust bubbles appear under the point at the lower front of MGB rear fenders, it' s a good bet that at least the rear portion of the rocker panel (covered by the fender) and the vertical inner sill panel are in much worse condition. The only way to find this dangerous structural rust is to explore. Remove the outer rusted fender section, probe deeply and try not to be horrified by what is found. On most cars, removal of the front bulkhead sealer plates will show if there is any rust 'inside' the lower rear of the front fenders. This is one of rust's favorite spots. While exploring, the traditional 'ice pick' method works, but I prefer to tap suspect areas with a body pick hammer which has the pick ground to a hemisphere about l/8" in diameter. Light tapping with this won't damage sound bodywork, but it will, by sound and feel, if not by penetration, find all rust damaged areas which are not usually apparent.

So your car' s like mine, well past the prevention stage, and ready for major surgery. Moss helps hundreds of us each year by supplying not only complete fenders, rocker panels, and floor boards, but also repair panels which are designed to replace those areas of your car which are prone to rusting. Check the Moss Catalog for the car of your choice and you will likely be surprised by the number of such body repair pieces available.

---

Working on automobiles is inherently dangerous. Moss Motors, Ltd. is not liable for injury or damage due to incorrect installation or use of their products. All products are sold with the understanding that the safe and proper installation and use of the products is the customer’s responsibility. Follow factory workshop manual procedures and instructions, but use current shop safety standards and common sense. Some tasks will require professional advice or services which Moss Motors cannot provide.

If you have a specific comment or question and you'd like an immediate reply from Moss Tech Services, don't post here - please first email: BritishTechnicalSupport@mossmotors.com Please include the Title and Location of this tip if applicable.

Forum FAQs here.

Before repairing a rusted area on a car, a "battle plan" must be carefully worked out. If there is any body filler or damage nearby, consider replacing more than just the rusted area. If adjoining panels are also rusted, a logical sequence of operations must be planned. Above all, have your Moss repair panels in hand before cutting rusted/damaged areas out of your car. This not only makes planning the job easier, but it lets you see exactly how the repair panel will fit. It's also a good way to prevent cutting out an area larger than the repair panel - a potentially costly mistake. Careful measurements and marking are essential.

Plan with care. Star from the inside out. Floors and sills (always before removing the body from the frame if the car has a separate frame) are followed by inner fender and door pillars, after which come rocker panels and then fender patches. This is, of course, a very general outline.

Equipment needed to produce professional quality repairs is generally beyond the tool inventory of the average enthusiast's garage, but it is often cheaper to purchase needed tools and equipment than to take the car to a body shop, especially if only "skin" repairs are required. The most expensive item required for this is most likely a M.I.G. welder or oxy-acetelene torch set-up to do the actual welding. (If only mon-stressed areas are to be repaired, pop-riveting is usually adequate.) A few years back, an "inexpensive" M.I.G. welder cost just under $1,000.00. Recently there have been "tabletop" models available starting under $300.00, which puts these invaluable devices within the reach of many.

For cutting the rust out of your car, I have found a hand-held 4" grinder with a cutoff disc to be quick, clean, and accurate. These have the added advantages of producing virtually no distortion in the metal, and can be used with grinding discs for grinding welds. Chisels, hand shears, and cutting torches should not be used on most external panels, as they produce too much distortion in the surrounding metal. Cutting torches are great for rough or preliminary work. Nibblers maybe used, but are generally slow and leave a slightly ragged edge. They are good for cutting small radius curves, however.

Spot welded panels such as rocker panels, can usually be removed by carefully drilling the spot welds with a drill of slightly larger diameter then the welds. If the welds are drilled out through the entire assembly, the new panel maybe plug welded from the "back" of the holes. If done carefully, appearance of the original spot welds can be approximated. In any case, once the spot welds are drilled, the old panel may be separated from the piece it was welded to with a thin sharp chisel and vice-grips. Rocker panels are easy to remove if the main part is cut away from the welded flanges, and the flanges removed separately.

Repair panels maybe mated to the cuts made in the car by overlapping or with butt-joints. Overlaps are easily made, and may be welded or pop-riveted, but they leave a grossly unfair surface unless the edges of the "hole" are joggled, so that the surface of the patch and any rivet beads are slightly below the surface of the main panel. The time and effort to do this properly makes this method more difficult than butt welding. Butt welding is the joining of two pieces by their edges, and demands careful matching of the edges.

Which ever method is used depends on equipment available and what sort of panel is being installed floorboards and trunk pans can be installed with lapped edges, while exterior "patch panels" should be butt joined if a minimum of body filler and finishing is to be used.

Plan where to run the joint. Fox example, some MGB lower fender repair panels run just above the waist line (where the chrome trim goes). It is much easier for many reasons to trim the repair panel so the weld is along the bottom of the original joint line, and will be hidden by the chrome trim.

Plan for drainage - there was a reason the car rusted where it did. Figure out why, and add inconspicuous improvements such as extra drain holes where required.

To install a panel, mark on the body of the car approximately where you think the edge of the repair panel will be. Remove all of the original pieces to be replaced except for an inch or so along where the main joint or weld will be. It should then be possible to scribe an accurate line on the body for the final cut where the two panels will join. Cut this carefully with as little distortion and with as smooth an edge as possible.

Hold the repair panel in place, and note any areas which need attention. These could be unfair mating flanges, ragged surfaces (remnants of old welds, barbs left from rough chisel work, or slag from cutting with a torch), or poorly mating edges. Look for imperfections in the repair panel itself. Trim, grind, hammer (gently) or do whatever is required for a perfect fit all over.

With the repair panel held or lightly clamped in place, place a small "tack" weld at the center of the major joint. In the case of a lower fender repair panel, especially when the weld will not be covered by trim and the joint is straight, allow the contraction of this "tack" to pull the bottom of the panel away from the car slightly - when later "tacks" are made, and the bottom of the panel pushed into place, the joint will (usually) be slightly below the "correct" surface. The idea is to have the finished (ground-off) weld slightly "low", so a light coat of body putty or lead is all that is needed to bring the repaired area to smooth perfection.

With the first tack in place, wiggle the panel around a bit for perfect alignment, and place more tacks at 2-3 inch intervals from the center outwards in both directions, one on one side of center, the next on the other side, and so on.

By leaving a small gap between the two pieces to be butt-welded (about 1/32" is fine), a small thin screwdriver or other object may be used as a lever to pry the two pieces as required to perfectly align the two surfaces at each tacks.

With the "cosmetic" joint(s) well tacked, weld the flanges and other edges of the panel, being careful not to allow enough heat to build up to cause any distortion. The best way to do this is by "skip-welding", in which short welds are made at long intervals around the work until it is finished. Now go back and put a tack weld between each of the previous ones on the "cosmetic" or "exposed" joint, aligning the surfaces as before. Do it again - a tack between the ones just made and the original ones. If the resulting gaps are more than about 1/2" long, do it again. With a hand grinder, carefully grind off the tops of all these little tacks welds. After aligning the surfaces as before, use the skip-welding procedure mentioned earlier, to carefully weld in the gaps, again being careful not to cause adverse heat distortion.

Grind off the excess weld carefully, without hitting the body panels. If you find the weld to be in a slight depression, congratulations! If the ground weld is still slightly raised, do not try to grind it and the edges of the now joined panels flat - you will make the metal to thin, and cause the weld to crack. Careful hammer work or heat shrinking is the only cure - consult an experienced body man and/or a good book on bodywork.

Common questions about repair panels are: (1) Why not braze them?, (2) Why not sell galvanized panels?, and (3) Why aren't all the repair panels supplied in primer? Brazing can be used, but causes paint adhesion problems unless proper preparation and primers are used. Galvanized panels should not be used, as the fumes from welding these are highly toxic. Furthermore, as the zinc is burned off at the welds, protections is lost where it is most needed. All body panels should be stripped to the bare metal before finishing, and properly prepared for paint. It is easier to work with oil covered or even slightly rusty panel than one already covered with primer that must be removed, as it must be thoroughly cleaned anyway.

---

Working on automobiles is inherently dangerous. Moss Motors, Ltd. is not liable for injury or damage due to incorrect installation or use of their products. All products are sold with the understanding that the safe and proper installation and use of the products is the customer’s responsibility. Follow factory workshop manual procedures and instructions, but use current shop safety standards and common sense. Some tasks will require professional advice or services which Moss Motors cannot provide.

If you have a specific comment or question and you'd like an immediate reply from Moss Tech Services, don't post here - please first email: BritishTechnicalSupport@mossmotors.com Please include the Title and Location of this tip if applicable.

Forum FAQs here.

As most of our readers know, Moss Motors sells a wide range of Rust Repair Panels. We are often asked how easy it is for the amateur to install them. Provided you have the right equipment, a reasonable level of mechanical aptitude, and a car that is not totally rusted-out, the procedure is quite straightforward. Using these pre-shaped panels is infinitely preferable to trying to repair rusted sheet metal from sheet-stock, so, even if the job requires the services of a professional body shop, Moss repair panels cut costs and make for a much better job.

As a guide to how easy the job is for amateur restorer, we asked Peter Cosmides to detail his experiences with installing rear fender repair panels on an MGB. As you will read, a very satisfactory job can be done at home. Peter presented the procedure as a series of steps as follows:

1) Collect the equipment necessary to do the job. This includes: An electric high-speed grinder with cutting disc attachment; a hammer and sharp cold chisel; gas welding equipment; your Moss Motors rust repair panels; a piece of chalk or welder's marking crayon, jack, and stands.

2) To prevent heat damage to the car's interior, remove the seats, peel back the carpets from the area around the inner fender, and buy yourself a candy bar with the change you found under the seat. Jack up and support the corner of the car and remove the wheel. Remember, if you're working inside a garage with welding equipment, remove cans of gasoline and make sure your home-heater pilot light is alight (or else turned off completely). Take your repair panel and place it over the area it will replace. With your chalk or crayon, carefully mark the fender where it is to be cut. Be sure to allow for the 1/2" of the fender that has to cover the lip of the repair panel! Cutting with a disc grinder is much better than using your welding torch, because the heat will warp the fender. Care is important when cutting; one wrong cut and you've got another repair job! The inner rocker panel protrudes inside the fender; don't cut into it! You might want to (a) Cut a square window in the rusted section you are about to remove to see what's inside and (b) make your first cut about 1/2" below your marked line, so that you can trim to fit.

4) The top line you marked is the only place that needs to be cut. The other edges are spot-welded and can be separated with your hammer and chisel (or by drilling out the welds).

5) Once the old panel has been removed, you can wire-brush away any surface rust, dirt, etc., that is exposed. If you find any other rust holes in the inner area, it's decision time! Professional repair, small patches welded in, or fiberglass patching might be needed, depending on the extent of what you find.

6) Now you can begin fitting the new repair panel. When eveything is trimmed and tidied so that the new panel fits to your satisfaction, clamp it in place with vise grips or C-clamps. You then carefully weld it in place, making sure you do not concentrate in one spot long enough to warp the panel.

7) After the welding is finished, grind the welds down and, using body filler, surface the join area nice and smooth. It is now ready for priming and painting. (Don't forget the inside, rust-inhibiting paint or rubberized under-coating will help prevent you having to go through all this again in the future!)

---

Working on automobiles is inherently dangerous. Moss Motors, Ltd. is not liable for injury or damage due to incorrect installation or use of their products. All products are sold with the understanding that the safe and proper installation and use of the products is the customer’s responsibility. Follow factory workshop manual procedures and instructions, but use current shop safety standards and common sense. Some tasks will require professional advice or services which Moss Motors cannot provide.

If you have a specific comment or question and you'd like an immediate reply from Moss Tech Services, don't post here - please first email: BritishTechnicalSupport@mossmotors.com Please include the Title and Location of this tip if applicable.

Forum FAQs here.

well before i do some repair in the rusted part of my car, i first clean it to see if how am i gonna do the repair thing for my car.and then bring it to the auto mechanics. so that's it.