Rocker Panel Replacement  – The Whole Story

The rocker panels on my 1965 Triumph TR4A are rusted out.  They were in good shape when the car was painted in 1995, but are full of holes now and must be replaced.

I have done a lot of work on this car over 23 years but the rocker panel job has not been easy. Starting has been the hard part.

We’re talking about a car I have driven nearly 90,000 miles since I bought it 1985 and drove home from California.  Since then, we have been many places along the East Coast, to Nova Scotia twice and back to California in 2001.  And, it gets put into storage for 4-5 months each winter, so you see that it gets driven a lot when the weather cooperates.  It has been a joy to drive.  It is comfortable, reasonably quick and gets mileage in the 22 to 30 mpg range.  It looks good and sounds good. 

So what’s the problem with the rocker panel job? 

It’s like taking a scalpel to your best friend.  I know it must be done but hate to make that first incision.  And I hate to take apart a vehicle that I so carefully assembled fourteen years ago during its complete restoration.

All the rust is below the feature line on the rockers and no one has noticed it but me.  That has allowed a year or so to delay the inevitable. It will be pretty messy for a while: fenders and bumpers off, interior gutted; probably a lot more prior to having it repainted.  Each part that comes off causes pain, almost as if I was poking myself with an awl.

At this time, the right side of my friend is raised up about a foot and the right side wheels and fenders are removed.  The passenger seat is out and all upholstery and carpet pulled away from the doorsill, where welding will eventually take place.  When this side has been completed, the car will be turned around in the garage to attack the driver’s side.

My first observation was that the rocker panel was replaced once already.  Not all of it, just the part that shows when the door is closed.  The sill is part of the original panel, with the seam joining the old and new metal pretty much hidden by the bottom of the door.  Clever.  In addition, the lower portion of the inner sill panel has been replaced, giving the last guy something to weld the bottom of the rocker panel to.  The bottom edge of this piece is now ragged with rust, too.  No rust prevention is evident and that’s why the rocker panel rotted out again.

My plan is to remove all of the old rocker panel metal, repair the inner piece and fit the (whole) new rocker panel as it was when new.  The plan also calls for spot welding the pieces together like the factory did.  What I didn’t expect was a replacement rocker panel that is incorrectly shaped.

The door was left in exactly the same position as before, providing a reference for fitting the new rocker panel. The gaps all around the door, to each fender and the old rocker panel, were acceptable the last time around and I’ll try to duplicate them.  Moving the door would have given me no basis to start with.

With all the chards of old panel removed, the new panel sure doesn’t fit well.   Moss Motors has a disclaimer that new panels may require some alterations, and this is clearly gonna be true here.  The surprise is that it is so far off.  Only after flattening and reforming one flange does it even fit in place correctly and there is still a difference between the contour of the rear fender and the contour of the rocker panel. 

Dilemma time: should I try to locate some better-fitting rocker panels from Rimmer Bros. or try to compensate by more reforming, which may require the addition of some body filler?
That’s all for now - check back for the next installment soon – George Haynes