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1955 Chevy Hardtop Rocker Panel Repair - Rocker Rehab
Fixing a common rust spot on Tri-Five Chevys.
May 2, 2011
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Classic Automotive Restoration Specialists Inc.
Belews Creek, NC 27009
Santa Ana, CA 92705
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1955 Chevy Hardtop Rocker Panel Repair - Rocker Rehab
Here you can see the other common area for rust on two-door Tri-Fives, the front corner of the quarter-panel just before the door. Also visible is the seam between he outer rocker and quarter, where rust ate away at the seam. The lead filler used at the factory for seams is notorious for trapping moisture and creating a breeding ground for corrosion.
While the outer rocker ends with the door, the inner rocker panel goes all the way back behind the quarter panel. The bubbly surface tells us there's trouble lurking behind here too, which we'll expose when we cut away the quarter so the inner rocker can be replaced. We'll cover the quarter-panel repair in a later.
Up top, the sill area looked OK minus a couple of pinhole rust spots. In places like this, you can still sea a lot of the car's original coral paint. The sill cover plate wasn't so lucky, but Danchuk shipped us new ones to install once all the bodywork is finished. If you've got a Tri-Five and are wondering about its original color, the sill area is a good place to look for remnants of it.
To start, Tommy Barber uses an acetylene torch to cut away most of the old outer rocker. This will make drilling out the factory spot welds and separating the old rocker from the inner easier. And let's be honest, it's always fun when you can break out the
Since we're going to be patching this part of the quarter anyway, Tommy went ahead and cut into this section of the quarter-panel to make rocker removal easier.
It wasn't really a surprise to see how badly the inner rocker was eaten up with cancer when the outer finally came off. Being careful to cut around the floor braces/body mounts underneath, Tommy cut away as much as possible of the old inner rocker so there'd be more maneuvering room to drill out the spot welds and separate the inner rocker from the floor braces.
Here's our new Danchuk inner rocker. You can see how the inner goes all the way back behind the quarter-panel. If your car's quarters are fine and you just need to replace the inner rocker, don't fret. You can do it without cutting on the quarter like we did. It'll just take some extra time and patience. On a Tri-Five, the inner rocker butts against the floorpan and doesn't slot into it like later-model cars.
Using a can opener bit on an air chisel, Tommy cut away the lower portion of the quarter to get better access to the inner rocker, revealing a probably 40-year-old rust repair job that had been done using a piece of metal from a donor Tri-Five. From looking at the metal, it seems the donor car wore Larkspur Blue paint.
On the backside of this bigger piece removed from the quarter-panel, you can see where the donor metal was welded in place to repair some sort of damage to the quarter.
Tommy pulls away the rest of the lower quarter metal, revealing more rusty inner rocker panel and coral paint that hasn't seen the light of day since Eisenhower was in office.
Using an air chisel, Tommy splits the last bits of old outer rocker away from the floo and inner rocker panel. The air chisel makes quick work of the old welds, but you should always be careful when using one that you don't get crazy and end up chiseling away good metal you didn't have to replace.
After using the air chisel to carefully split the inner rocker away from the floor braces, Tommy put the cutoff wheel to work removing the last bits of inner rocker from the floor braces.
When the old one gone, Tommy slips the new inner rocker in place to check for fit and help mock up the position of the new outer rocker too.
Because its alignment depends on the bottom of the door line, make sure that the door(s) on your car are aligned correctly and aren't sagging. Otherwise, your outer rocker will be crooked and the door gap will look terrible.
Before welding in the new inner rocker, we cleaned up the ends of the body braces we're keeping (more on that later) some more then coated them with weld-through zinc primer so the rust couldn't return. While you're doing an install like this, if the opportunity comes up to clean up normally inaccessible rusty parts and coat them with some sort of protection, do it. You can use rust neutralizers and encapsulators like Por-15 on certain areas, but if it's an area that will see welding, you must use a weld-through primer. If you're not sure, then use zinc primer to be safe.
Normally we would've used Por-15, but we couldn't find a drop in the shop. As a substitute we used this SEM Rust-Seal on the areas of our body braces that wouldn't be welded on.
Tommy has marked on the inner rocker where the braces butt against it, so he knows exactly where to punch holes for the plug welds that will attach and the new rocker to the braces. Also visible is a new rust hole in our floor brace. Rust from the rockers has spread to a couple of our braces, so they'll need to be changed out. We'll cover brace replacement in a future story, but in the meantime we can attach the inner rocker to the good braces and everything will be fine to finish our rocker install.
Here the inner rocker is being drilled for plug-welding to the inner rocker and floor pan.
To prep the outer rocker, this nifty pneumatic punch gun was used to make the holes for plug welding. You can pick one of these up at most tool shops, and it'll plug into any standard air compressor.
With the prep finished the new inner rocker clamped in place for welding. One thing to note: make sure to wipe down new bare metal parts with some sort of solvent/cleaner because they usually come with some sort of protective grease/oil coating to protect them from rust while on the shelf.
Using a MIG welder, Jim Barber plug-welds the inner rocker panel onto the body brace. When welding on the zinc-primered parts. Be aware they can throw some extra sparks because of the zinc in the primer.
Here's a finished plug weld. This can be ground down and disguised to look like a factory spot weld if your car is destined to become an original resto-style vehicle. After all the welds are done and cooled, we'll go back and grind them smooth just for a clean look.
With the inner rocker secured, the outer is clamped in place for welding. Before we started the insides of both the inner and outer rockers were coated with weld-through primer, and we double-checked our door gap to the outer rocker and made sure it was right.
This is an especially critical area that makes getting the outer rocker located in the proper position paramount. The end of the rocker attaches the lower mounting tab for the front fender. If this is off, so too will be the front fender alignment, and you might even have issues with the doors opening and closing.
Using the other side as our guide, we measured and set the mounting tabs so it would match driver side. Once set, the tab was tacked in place.
Now Jim goes across the bottom of the outer rocker and plug-welds it to the inner rocker through the previously drilled holes.
Here the front seam is welded in where the outer rocker meets the bottom of the cowl ear and inner rocker.
This seam is where the A-pillar comes all the way down to the rocker. You can see the rusty edges of our front floor pan. This replacement will also be covered in a future story. Since the rocker panels help locate the floor, we had to replace them first before we could start work on the floor, toe board, and kick-panel repairs.
Here she is, all fixed up. Now we can plan out our floor repairs, along with our forward quarter-panel replacement and patching.
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