Chicagoland MG Club:Photos
Door Skin Tech Day
September 18, 2004 - Glen Ellyn, Illinois

Jim Evans crimping a new MGB door skin in place.
We were doing a few things with the door skin this day, not just installing a new one but also demonstrating dent pulling and repair of the infamous MGB "Crack Of Doom". But first we needed a BIG dent. Who has the biggest foot?
Click for BIGGER pictures, average 35K.

One good stomp was enough to produce a realistic looking side impact dent in the MGB door shell. Then in preparation for using the stud welder, the panel was sanded down to bare metal in the area of the dent to provide good electrical contact. The "studs" to be used are copper plated steel nails with slightly crowned heads. The stud welder (now resident in the club tool crib) is a hand held 120VAC transformer with a pair of concentric copper contacts on the front end. Put the stud in the spring loaded center contact, press it against the panel to depress the nose and bring the outer ring into contact with the panel for a good ground connection, pull the trigger for about half a second, and the stud is spot welded to the panel. Attach a number of these two cent studs to the panel, a couple inches apart and an inch or two in from the perimeter of the dent. Mind you this will not work on an aluminum panel, unless you might happen to have corrosion free aliminum studs and some aluminum welding paste flux.

Next comes the small slide hammer. This tool has a collet on the working end with a knurled ecentric wheel to grip the stud. Slip this over a stud, turn the little wheel around against the stud, pull back slightly to grip, then slide the weight back with a little thump to pull the panel out. Start easy at first. If you yank too hard you either break the stud or get an outward dimple in the panel. Work around the ring of studs doing two or three passes as necessary to pull the panel out to original contour. If it's a big dent you may need a few more studs inside of the first circle. When you have the panel back to correct shape, use the angle grinder to cut the studs off and grind smooth back to the original sheet metal surface. This takes just two or three seconds per stud. Sand the panel smooth, tap down any high spots if necessary, finish and paint in normal manner. No bumps, no holes in the panel, and you can do this without having to gut the interior of the car for access behind the panel.


Most MGB owners will be familiar with the Crack Of Doom. This occurs at the top of the outer door panel near the back of the vent window, and may be caused by pulling on the vent window to close the door, or by some interference between the vent window frame and the side of the windscreen frame. You need access to the inside of the door panel for this repair, so start by removong the inner door panel, the window lift mechanism, the window guide and vent window assembly. Use a body hammer and dolly to tap down any rough edges along the crack to put it all back in original plane. Drill a 1/8" hole at the bottom end of the crack as a strain relief to be sure the crack will not start again in the future.

Cut a rectangular piece of body repair sheet metal at least one inch larger than the crack all around. Form this new sheet to fit and match the inside contour of the panel behind the crack. Mark the location of the patch on the outside. Mark at least four locations about 3/8" in from the edges of the patch panel for pop rivets, but do not drill the holes yet. Remove the patch panel and drill a few 1/8" holes (other than the intended rivet holes) along either side of the crack in the door skin. Also drill a few holes along the center line of the crack. Use hammer and dolly to knock down any burrs, especially to make it smooth on the inside surface. Install the patch panel inside and temporarily clamp it in place.

Drill at least four 1/8" holes (where previously marked) about 3/8" in from the edges of the patch panel. Use aluminum pop rivets to attach the panels securely together in double thickness. It is important that the patch panel should be in very close proximity, preferably with intimate physical contact to the inside of the outer skin over most of the surface. Use the body hammer and dolly to form the patch plate closer if necessary. Using a MIG or TIG welder, make a rosette weld in each open hole to weld the outer shin to the patch panel. Then drill out the rivets and weld those holes shut as well. Grind all welds flat on the outside surface. Finish and paint the panel in normal manner.


First step for installing a new door skin is to remove the old one. You could use a chisel and pry bar and pliers to lift the folded edge, but that's a lot of work. It also entails some risk of damaging the inner door shell that you want to reuse, and you're probably not trying to save the original skin. The easier way is to use a grinder to take the creased edge off the skin to separate the flange. Grind along the edge perpendicular to the face of the panel until you see a thin crack at the base of the bend. Then insert a thin blade into the crack to open it, and pull the narrow flange away from the door shell. Continue in this manner all the way around the panel to release all of the crimped edges. With all the flanges removed the outer skin will fall away from the inner shell.

Before installing the new door skin we punch (or drill) a few holes near the ends of the flanges, and occasionally midway in a long run. This is to facilitate later local welding of the edge of the skin to the inner shell to prevent any loosness of the joint to make the finished door very ridgid. For the very observant, we just did a quick switch from left side to right side door, as this one was previously prepared with rust preventative paint along the exposed edge of the inner panel.

Position the new panel on the inner shell and secure in place with several small clamps. Any time you place the new door skin face down on a table you may want to pad it with a blanket or a piece of carpet to prevent scratching the panel. Using the body hammer, tap around the edge of the new panel flange to bend it inward to about a 45 degree angle. From there you could use a hammer and dolly to continue to form the flange downward until flat and tight, but again there is some risk to damaging the new outer panel.

A nice tool to assist here is the flange compression plier. This has a plastic or hard rubber pad on one side to protect the outer panel, and a flat steel crimping jaw on the other side. Work your way progressively along the flange crimping it down a little at a time. Make repeat passes to crimp the flange gradually farther down until it can be smashed completely flat and secure over the edge of the inner shell. Check and verify panel alignment occasionally, especially very early during the crimping process when you may still have a chance to realign something. Pay special attention to the way the top edge of the new panel lines up with the inner shell, particularly in the area of the window guide. To keep the new panel from squirming out of place you may want to crimp a little on each end front and back until it is secure, and then finish crimping all the way around.

When the flange is mostly closed all the way around, but not yet completely tight, you might offer up the door to the car body to check alignment. If perchance the door may be slightly twisted out of plane, this is the time when you may still be able to force it back into proper shape. Two people can grasp the four corners of the door to twist it a bit if necessary. If working alone you might clamp the rear or bottom edge of the inner shell to a fixed bench while you twist on the other end to realign it into proper plane to match the car body.

Where the crimping plier cannot get into a close corner at the step along the back edge of the door, you can use the body hammer to gently tap the remaining end of the flange into place. In the end you should have a clean unmarked surface on the outside and a tightly pinched flat flange inside. When the crimping is finished you can use a TIG or MIG welder to make rosette welds in those little holes that were made in the flanges before it was crimped. This will bond the outer panel very securely to the inner shell so that it will be very ridgid, will not creep out of place during use, and will also protect any paint from chipping along the seam. Grind the welds smooth before painting. You can do a little gentle tapping with the body hammer to tap down any sharp edges and round off the corners a little. If you happened to leave any tool marks arond the edges on the outside panel, a little spot putty and sanding will touch that up prior to finish painting.

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