How To: S13 240SX Frame Rail Rust Repair

Unfortunately, the above is a common site for S13 owners whose cars have lived through years of harsh winters and salty road conditions.  This is the one of the worst we’ve seen, but, after a bit of work, we were happy to keep another S13 on the road for a few more years by fixing that rust.  Here’s how we did it:

Ewwww, that’s no good.

First things first, we assessed the extent of the damage and got to cutting; removing all the rusted metal.

There we go.  Cut back to good, solid metal.

After a quick session with the cut-off wheel, we were left with the above situation…A BIG NOTCH IN THE FRAME RAIL!!  OH NO!  Haha.  The main thing to achieve is cutting back until you get to solid, not rusty metal.  Rust doesn’t weld, so make sure you get to fresh metal for a solid repair.

Brickhouse S13 Frame Repair Panels
Brickhouse S13 Frame Rail Repair Kit

Shameless plug warning, we used our “Brickhouse S13 Frame Rail Repair Kit” available on our website here.  With the repair panel pieces in hand, we were able to use them as a template to see how much we could cut away and still achieve good coverage.  When designing the repair panel kit, we intentionally added a bit of extra “length” to the repair pieces just to ensure there would be plenty of material for the extreme situations.

Fitting and welding panel in place.

Once the rusted area was removed and we had an idea of our repair area, we could cut down the repair panels to an appropriate size.  You can see we cut the front upper edge off in this case (see the pic of the repair panels above for reference) since we had plenty of coverage on the good metal.

Also, you’ll notice the gold color around the welded area.  This is “weld through primer.”  It’s sold in an aerosol can and is a primer that is, well, weldable.  This is a good step for future rust prevention sinces it give the metal inside a coating to protect it.  We coated the back side of each panel and the cut metal on the body prior to welding.

Repair panel trimmed, fitted, and welded.

This is just another example showing the repair panel being cut down to the necessary size to repair the rusted area.  You can see there is good metal all around it, so there is no sense in cutting out more that what is necessary.  The repair panels are just the template to make your life easier.

All welded up and solid again!

With all welding complete, the surface was scuffed up for undercoating. Also, you can see on this panel, we added a few plug welds since we were overlapping good metal in that section.  The “bottom” in the corner was rusted and cut out, so no plug welds there.  Plug welds are a good idea where possible to add strength to the repair; just drill holes in the repair panel and fill them with a solid plug weld by welding the edge of the circle to the metal underneath while you weld around the circle.

And for those who spotted the hole in the floor, yes, that was repaired as well on the inside.  Worry not!  haha.

Choose your method of rust prevention, but you’ll certainly want to get a good coating on there to provide years of rust free joy!

I hope that helps – feel free to reach out with any questions!  Instagram @brickhouse_products, Facebook Brickhouse Products LLC, or email  And if it looks like the repair panel kit could help with your project, they are available here.  Appreciate the support and good luck!