Posted by: Mark Polk | 2014

GMC Rocker Panel Rust Job

I was looking for a good deal on a used truck for my son, preferably a 3 or 4 door Chevy or GMC model.  After some searching I found one on Craigslist that had some rust issues,  and because of the rust the owner was willing to let it go for a good price. I knew the outer rocker panels were shot so I figured I could order  some replacement panels, weld them in and come out ahead when it was all said and done.

Rocker panel rust

Rocker panel rust

But when I got the truck to the shop and put it on the lift the problems were more advanced than I first thought. The inner rocker panels were gone too. Since this truck was a 99 three-door model it was a challenge finding the inner and outer rockers. On the passenger side I needed the inner and outer rocker panels and the cab corner, and on the driver’s side I needed the inner and outer rockers and a patch panel for the extended cab section that included the cab corner. With a couple hunderddollars invested in new sheet metal I was still in good shape, but the question was could I tackle a job of this size?

I am not a professional bodyman by any stretch of the imagination and I don’t have equipment like a spot welder, but I am a decent MIG welder and figured I would give it a go.

Inner rocker panel

Inner rocker panel

After cutting all the bad metal out and grinding the entire area I was ready to weld the first inner rocker in place. The new inner rocker had some holes and indentations in it so it was easy to line up with the small remaining sections of good metal that was left in tact. I clamped the new inner rocker panel in place and welded it. With the inner rocker installed it was time to start on the passenger side outer rocker panel and cab corner. I didn’t want to remove the truck’s bed so getting the cab corner welded in place would be a challenge.

New rocker panel

New rocker panel

I clamped the outer rocker to the inner rocker and used the door to make sure everything was  straight and in line.  I decided the best way to weld the new panel in place on the inside of the door was to drill holes about 2 inches apart the entire length of the rocker panel.  This way I could weld the two panels together iside the holes similar to a spot welder. This accomplished two things, it cut down on the amount of built-up material that would need to be grinded off, and it lessened the possibility of creating too much heat from welding and possibly warping the metal.  Once the welds  were ground down it was easy to finish the cosmetic repairs with some bondo.

Cab corner patch panel

Cab corner patch panel

On the driver’s side I repeated the same process, but since there is no rear door on that side the rocker panel was shorter and I had to weld a patch panel in the extended cab section to repair the rust on the lower rocker and cab corner. I couldn’t use my welder to weld the back of the cab corners where the truck’s bed is so I brazed the seam. I got it just hot enough to melt the brazing rod and the braze flowed along and in the seam perfectly without warping any metal. I used a dremel with a grinding disc to smooth out the excess braze and prep it for bondo.

With a little bondo and some sanding the repairs were ready for primer. On the inner rockers I used POR 15 to protect it and help prevent any future rust issues. My rocker rust repairs probably weren’t done the way a professional body shop would do it, but they are welded in place, they are straight and they should last for many years to come.

Mark Polk

Auto Education 101

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