Replacing Your Mopar Trunk Floor

At first glance, this trunk doesn't look all that bad-just a couple of small holes. For those of you who are new to rust repair, what you can see is just the tip of the iceberg. Sheetmetal in this condition is thinner than you think, and there is likely a lot more damage hidden from sight.

At first glance, this trunk doesn't look all that bad-just a couple of small holes. For th

There are two reasons to use a factory replacement part from a donor car instead of a reproduction. The first is if you are building a car that has little or no aftermarket support. The second is if you are an owner of a '69 1/2 440 Six Pack Super Bee (code A12) and you want to claim that it contains all factory stuff.

Muscle Car Restorations (MCR) in Chippewa Falls, Wisconsin, certainly had to learn to deal with the dwindling supply of original muscle over the last two decades, and anxious owners worried about their investments. It's actually common now to replace the passenger and trunk floors in most of the cars the company restores.

We're going to show you the correct procedure for a trunk floor installation on this Mopar B-Body, including having to deal with the annoying overlap you'll find on lesser-quality restorations. The methods used can be adapted to the replacement of just about any piece of sheetmetal on the car. Try it.

A few easy taps with a pick hammer show how bad it really is. Don't mess around with rust, especially on a keeper like this. Treat it like cancer and cut it all away.
A few easy taps with a pick hammer show how bad it really is. Don't mess around with rust,
The replacement floor is from another B-Body. The ideal replacement floorpan should be cut along the trunk extensions and up to the flat area between the wheeltubs. Someone cut this one a little bit short. Get as much trunk floor from the donor as you can.
The replacement floor is from another B-Body. The ideal replacement floorpan should be cut
Chris at MCR drilled out the two rows of spot welds that secure the trunk brace to the floor using a spot-weld cutter. The guys at MCR prefer the Blair 3/8-inch Rotabroach cutter and a Century 1/8-inch double-ended drill bit for this job.
Chris at MCR drilled out the two rows of spot welds that secure the trunk brace to the flo

Chris placed the replacement floor in the trunk and drew an outline around the donor floor. Removing the fuel tank brackets at this point will make the job easier.
Chris placed the replacement floor in the trunk and drew an outline around the donor floor
Using a good cutoff wheel, Chris cut through both pieces in the center of the overlap, peeled back the excess, and placed a tack weld about every inch or so. He aligned the gap by prying up on the floor with a small screwdriver to be sure both parts were perfectly even before placing each weld. Since the new trunk will drop down into place, he made sure to keep the cutoff wheel vertical so the gap didn't get too large. In this case, it was especially important along the front edge where the panel slopes upward. This is why you'll want to get a panel that's cut all the way out to the trunk extensions. Remember where that center brace is located so you don't hack through it.
Using a good cutoff wheel, Chris cut through both pieces in the center of the overlap, pee
Don't be surprised if you need to use a chisel to pop loose a few of the spot welds to remove the last piece of floor from the center brace. You will also need to grind off the remains of the spot welds.
Don't be surprised if you need to use a chisel to pop loose a few of the spot welds to rem