Saturday, September 11, 2010

Rear inner wing (bodywork mount reinforcing panel) repair

Within the rear wheelarches. the prime rust spot is the reinforcing panel which contains the rear body mount and (on souse cars) the 'Z' or anti-jacking bar. It's the old story: mud (sometimes salt-laden) is kicked up from the wheels and settles in any suitable cranny, such as the folded pressed steel body mounting. If this area is not well protected, then it will succumb to rust quite quickly and, in the UK, fail its roadworthiness test.
The first step is to raise the rear of the car and rest it on axle stands, then remove the roadwheel and clean up the area so that you can establish the extent of rusting. Also clean the bumper bracket bolts, the wing bolts, the damper bolts and the body mounting bolt and apply penetrating oil to them in order to make removal easier.
Disconnect the battery and the wires leading to the generator, then remove the tail lamp lens, remove the wires from their terminals (use masking tape tags to remind you which is which) and pull the wires back into the wheelarch. Remove the bumper bracket bolts and When welding up the nearside rear bodyshell mount repair panel, do remember that the wiring loom runs very close to the line of your weld. It is advisable to remove the rear half of the loom before undertaking this task — new loOms are quite expensive.
Remove the rear wing bolts and place the wing and filler strip to one side. This improves access, and it may be wise to double-check the inner wing condition at this stage, including the bumper mounting areas.
Using a hexagonal socket if possible, undo the 17 mm body mounting bolt. This might prove very reluctant to start and, if you resort to brute force you can easily shear off the bolt head, so clean out the recess and then apply more penetrating oil and leave it until later. If you do manage to shear the bolt head then try putting a blob of weld on what remains of it; this can break the seal (by the heat from the welding process) and give you something to grip with a mole wrench. If this fails then you have no alternative to drilling out the bolt. Remove the rear damper, again, if the fittings are too tight, apply penetrating oil and leave this to soak well in.
Locate and drill out the spot welds which hold thereinforcing panel in place then, using if possible a 'chisel'fashioned from a 1 in. hacksaw blade, part the welds.You may discover that the lower trailing edge is MG orgas welded if this panel has (as is likely) been replaced atan earlier date, and any weld should be ground down.
Clean the newly exposed and surrounding metal bright. As ever, it is not necessary to fit the entire repair panel and, in fact, it may be preferable to cut down the panel provided that you can find sound metal to weld to (see illustration). Any future rusting is likely to occur around the area of the welded joint, and by fitting in effect a smaller panel, you then have the option to fit the full repair panel if rusting occurs. Trimming the repair panel also gives you less welding to do!
inside the car, remove the rear seat and any combustible material from the parcel shelf, plus any combustible material on or near the inner rear wing. If you have a fire extinguisher then place it inside the car, and if you have an assistant then ask him to assume the role of fire-fighter! If you are working alone then you
will have to check for (and possibly deal with) fires inside the car every few seconds, which will make the welding process a protracted one.Clean the edges of the panel which are to be welded (then apply weld-through paint to all the newly exposed bright metal if you want the repair to last), then bolt the panel onto the damper top mounting bracket. Use a self-tapping screw to pull it roughly into the shape of the inner wing. then push it further inwards, tack it and beat it until the panel edges touch the inner wing. It is as well to tack weld the repair panel edges perhaps as close as at 1 in. intervals, and to check during the welding that the repair panel is not bucking away, which would increase the chances of burning through. Continuously seam weld the repair panel edges, grind down surplus weld then apply plenty of paint to slow the rusting process.
On the inside, the panel has to be welded to the parcel shelf panel, but all too often this will be found to have rusted away at its edges. If so, make up an 'L' shaped repair panel and continuously seam weld this into place.
Don't forget to use copper-based grease or similar on all bolt threads when you come to reassembly. Remember to test your rear lights before taking the car out onto the road; if there are any problems and the wires are connected to the correct terminals, then clean all of the spade connectors and retest. Any faults remaining will either be due to bulb failure or, more commonly, poor earthing.

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