Printed in The American Tri-Five magazine in Volume 7 : Issue 4

For those of us not fortunate enough to live in the south, southwest, or anywhere that dry, solid Tri-Fives still exist, rust is a bitter fact of life. And for those starting into a restoration of one of these cars, figuring out how to tackle cancerous metal can often be a daunting task. When it comes to common rusty spots, the one closest to the ground is almost always a common denominator.

The floor can be a tricky area; there’s almost always a “tipping point” as to how much needs replaced versus how to replace it. Its not just one piece in its own; it encompasses the floor pans, body braces, and inner rockers just the same. Sure, a floor that is perfect save for one brace would certainly justify simply fixing said brace. A couple pinholes in a rear footwell from water sitting there? By all means, patch away. But when it turns into patching one brace on one side, one brace on another, a footwell, and an inner rocker, it will simply become MORE work to piece meal the floor together than to simply replace the entire pan itself and wind up with a better finished product overall.

Had most anyone looked at the floor in the ’55 4-door sedan shown here from the top, the general consensus would likely have been to save what was there. But, as the article will show, the one piece easily started to make sense upon further inspection. Even though this shows the process for a 4-door sedan, very little will change for 2-door sedan, wagon, or even hardtop.

As a beginner who had only heard stories from the shop about installing this pan, I’m in the same boat as most reading this. I’m no novice when it comes to metalwork; my old ’55 2-door sedan got the patch job treatment more than a decade ago, and my sedan delivery needed help in more than one spot as I redid it. I’d simply never cut 75% of the bottom of a car out in one shot before. I asked around to multiple sources for different opinions and strategies to see how the best would play out. And being as I learned as I went just the same, what better way to help you all through?

Let’s dive in!

Our subject at hand, my ’55 150 4-door sedan. Admittedly, this project started out as a scuff-n-shoot, drive the wheels off kinda driver. And, just as many projects, the further I dove into the bottom of this car, the worse it got. Still, the money was good enough to start, and the rest of the car merited this type of repair. You’ll notice driveline and front sheetmetal are out of the way, this is a must for this project.

Laid out! Keen eyes will notice, the pan shown here is actually a hardtop pan. Due to the supply chain being the way it is, this project started out with intention of using the hardtop pan, as sedan pans were on backorder. Thankfully, about the time I was ready to start welding, sedan pans became available. That said, you absolutely can use a hardtop pan in this application in a pinch, you will simply need to weld up the extra body mount hole, cut the seat brace out, and cut in the squares for the lower seat retainers. Part number for sedan pan is GDS-FP13-552

As mentioned in the foreword, from the top side, this floor looked more than manageable. Some swiss cheese in the toe board, and a few spots at the seat braces, but the top side was decent…..

…..until you start poking around with a screwdriver. The body brace at the driver’s seat mount was toast. The more you poked, the more it fell apart. Long rear brace was the same at the ends on both sides. Inner rockers had seen better days. This was most certainly going to be a piece-meal type job, and the decision to use a one-piece floor was made.

In order to use the one-piece pan, the body will need to be lifted away from the chassis. Now, there’s most certainly more than one way to deal with this. Some will choose to simply lift the body up away from the chassis and leave it under the body while they work. Rather than fight it being in my way, I made the decision to remove it completely. Granted I have a two-post lift at my disposal, this process is still NOT impossible with floor jacks by any means.

Some body mounts are thru-bolted, some have captive nuts in the floor itself. These mounts underneath the rear seat are some of the beefiest on the car and have a welded, captive nut.

Middle brace. Be prepared to break these bolts off. But, no worries, as this will be all-new on your Golden Star floor.

Rear brace. These may come out, they may not. Again, worst case scenario, they break off and the body is free.

And sometimes, they don’t cooperate at all. Both rear body bolts required breaking out the cutting torch on this one.

Can’t be tight if it’s a liquid! Move along to your two front body mounts at the cowl.

Next step is to get the body on stands, as high up as you possibly can. Now, notice we’re doing this at the rockers….the rockers on this unit were in decent enough shape to do this with. If yours are not, additional bracing and/or rocker repair may be required before this can happen. Always use a piece of wood across the stand to more evenly distribute the weight. And no need to fret, your body does not weight enough to damage the rocker, as long as it is structurally sound to start with.

By multiple recommendations, I used the front fender tab for my front stand. This effectively leaves the stand as far out of the work area as possible. Note the front doors removed as well; this is a must. I left the rear doors in place, as the hinges are an absolute PITA to get off, and there was really nothing to gain by doing so.

Keep in mind, almost no body, and almost no garage floor, will be perfectly square. I used a small wooden shim between the stand and the body to bring everything all together. Also, notice the lack of a front body brace…..starts to make sense why a new floor was selected for this particular car.

One recommendation I received (thanks Ryan Walker) was to brace up the back of the body. Even though we’re working with a 4-door sedan, there’s always risk of the body drooping in the rear and putting undue stress on the roof and quarter panel areas, or even worse, causing a buckle. Simply measure out the body before dropping the frame and cut some wood. Note the use of a wedge to “preload” the wood to the body.

A single self-tapper in the tailpan will help hold these guys in place. And no worries of being seen in the future; these will be completely hidden by the back body to bumper seal.

From here, you can use whatever means you have handy to drop the frame away from the body. Whether it’s a lift, or a floor jack, you can do it!

Note the wheels being removed; the stands on the rocker will not allow the rear wheels to be left on to roll out from under the body. Depending on your stands, you may need to pop the drums off as well. It’ll be tight either way!

Out and about! I’ll be using this time to clean the chassis up, paint, and install a Woody’s Hot Rodz Ultimate Leaf Spring Suspension package, P/N WHR-ULTIMATE.

Up up and away! Get used to this view, you’ll be here for a minute. Again, without the chassis in the way underneath the car, more room is opened up to work.

Before we get too carried away, we decided to brace the body up. With out outer rockers in the condition, they were in, and the fact this is a 4-door sedan and has the added stability of a full b and c-pillar arrangement, no more was required to do so. However, if you were fixing a car with exceptionally rusty rockers, a two-door hardtop or convertible, crossbracing and x-bracing the body itself to maintain factory proportions would be STRONGLY recommended.

With room made, it’s cuttin’ time! You have to start somewhere, I decided to start at the front close to the interior firewall-to-floor brace.

Be careful not to cut too far over. You’ll use the lip on your existing outer rocker (if possible), so you’ll want to leave it intact.

A thin cutoff wheel makes quick work of 67-year-old sheetmetal anywhere there is not a body brace in play.

Choice was made to cut out the driver’s front floor pan as an “access hole”. There is no right or wrong way to cut out the middle section of sheetmetal. You’re not saving it.

Up to now, you’ve seen a cutoff wheel in use. Certain areas, your favorite reciprocating saw will make life VERY easy. Anywhere you’re cutting right next to a seam, you can basically lay the blade up against it and use the seam lip as your guide.

I chose to cut around the floor to a-pillar support, as it was solid enough to save. In hindsight, if I were to do another, I would *probably* cut this out, and weld it back together once the new pan was in, as it’d likely be less time consuming. To be perfectly honest, its not all that important, and could theoretically be left out altogether.

With a hole cut in the floor (mainly so you can climb in and work), you can go ahead and start cutting down the pinch weld at the outer rocker area.

Feel free to cut this all into more manageable sections as you go. Sure, you’ll burn up a few more cutoff wheels, but it sure makes the pieces you’re cutting out a world easier to work with.

One more place the Sawzall comes in handy; anywhere there is a floor brace in play, you can use a reciprocating saw with a long blade, and chop through it all in one shot from the top. This will save you time, headache, and wear/tear on your body going from the floor to the topside.

In case no one told you, or you hadn’t figured yet, this is NOT a clean job. I try to maintain a fairly clean workspace, not only as a whole, but as I go. Between the Sawzall and the cutoff wheel, you’re going to vibrate the bejesus out of a rusty floorpan, and a fair majority will wind up on the garage floor. Take time to clean up as you go, and it’ll make the job easier, and cleaner overall.

When cutting up at the toe board, you do NOT want to remove the pinch weld off the toe board. Cut right up to it on the floorpan side, but don’t cut over onto the toe board side AT ALL. Unless you like a missing pinch weld and a ton more work, that is….

Just remember, “they have to get worse before they get better.” That big hole may look intimidating, but it’s the path to a better car all around!

This is one more spot that will be left up to some amount of “installer discretion.” The Golden Star floor pan has a lip at the rear to meet directly up to the trunk pan. To install the floor in its traditional sense, you’d need to remove the rear seat brace, and cut all the way to the trunk lip. However, the ’55 in question had a very solid back seat area, and the executive decision was made to leave the rear seat brace in place and overlap the two panels. This will leave a little work to be done underneath the car on the finish side, but far less work than removing, and reinstalling, the seat back brace. We used a straight edge to make our cutline across the floor.

With the cutline drawn the last cut to the floor, in the rear seat area was performed. Note the seat bottom retainers in the floor, be sure to remove them and save them. The Golden Star pans do NOT include those guys, and they’re VERY easily pitched into the scrap pile with the old floor.

…and the cutting is done! For now, at least.

This will be the game changer

for the next steps. Flapper discs and your favorite angle grinder will help remove what is left of the inner rocker from the outer rocker, as well as the floor pan pinch weld at the toe board. I went through roughly 25 4” flapper discs throughout the entire project. These Benchmark Abrasive flappers coming in at <$2 a piece made the job easy and affordable.

With your flapper disc loaded up, you can begin to grind at the inner rocker.

This is a tricky process that requires finesse. The trick of it all, is to grind away the metal you don’t want, leaving the metal you do. And if you’re good, you should be able to somewhat figure out your particular assembly welder’s cadence and find the spot welds themselves (the small dot at the right of the picture), which will allow you to simply grind them away instead of the entire remaining inner rocker.

You’ll be able to watch the inner rocker metal turn cherry red as it gets thin, letting you know you’re almost through. Don’t worry, you’ll burn through the good metal once or twice, but it’s nothing the MIG and a little grinding can’t fix. If you’re installing new outer rockers, you’ll simply skip this step all together.

This step gets repeated front to back, on both sides, anywhere that the floor pan meets the body.

If you choose to leave the floor-to-cowl supports, you’ll need to remove all the floor pan from these as well. Being as these will dictate overall height of the floor pan, there can be no excess here. Also, another reason I recommend cutting these off and reattaching them at the end of the process.

The front of the inner rocker will be somewhat difficult to work with if the floor brace is left in place without something like a pneumatic mini belt sander. In case you couldn’t tell, I wish I had removed these all together while doing the pan. But that’s part of learning; sometimes, what looks like a good idea at first, causes you more work down the road.

With the excess floor pan ground off the toe board in the same fashion as the inner/out rocker deal, you can prep the toeboard pinch for welding. Drilling or punching a few holes in the pinch will make for easy plug welding.

Do the same in the transmission tunnel. Even if you choose to trim this later on for TH400/700R/4L60/4L80 trans clearance, you’ll want it throughout this process for location purposes.

With the body prepped, we’ll go ahead and make our measurements for trimming the floor pan. If you go this route, it is almost guaranteed these braces will be in the same place no matter what, so they serve as excellent reference points. Again, if you choose to use all the pan and remove the rear seat brace, these steps won’t apply. You’ll simply overlap the panels, and stitch weld away.

Using the centerline of the body mount hole, measure down to find out where your floor pan ends.

You’ll transfer this measurement directly over to your new floor pan, leaving a small amount of excess on one or the other to provide a surface to weld to. It will be nearly impossible to but these two up perfectly, and only minimal finish work will be required underneath, so forego trying to make this a perfect butt weld scenario. Trust me, the finish work underneath will be a LOT easier.

With your measurements taken from both body mount holes, use a straight edge and your favorite marking utensil to make your cutline.

….then cut the excess off.

Discard the cut section, you won’t be needing it anymore if this is your chosen method of install.

Now in most scenarios, welding through EDP would be just fine. It might not be quite as clean as a bare surface, but its generally do-able. Me personally? I prefer to be to bare steel. It’s a fair bit more crucial on the body side of things; that red oxide primer is NOT welder friendly and will contaminate a weld any way it possibly can. Considering this area will get fully welded, not stitched, we got it as clean as possible to help the process along.

At this point, we’re ready to start mating pieces back together. The resources you have available at this point, and what you did with your frame while you worked, are what will dictate exactly how this occurs. At any rate, the floor needs to be set onto the chassis.

From here, you’ll want to set a few body mounts from a new body mount kit (DAN- 532A for sedan) under the pan, and LOOSELY put a couple of bolts (DAN-497-023 for sedan) in the floor to locate it to the chassis. This makes it nearly impossible for the pan to be out of place whatsoever. From here, you can square the frame up with the body, and lift it into place.

Don’t get discouraged when it just doesn’t fall into place on the first shot, especially if you’re dealing with any part of the original rocker. Some amount of trimming, like what we did at the front corner here, may be required to make everything jive.

Starting to look like a while car again! Again, this is one place a 2-post lift comes in super handy, but this job is far from impossible without one; it can be done with floor jacks, and patience. All you need to do is simply lift until the pinch at the top edge of the floor meets the pinch on the outer rocker.

With your pan and chassis lifted into place exactly where it should be, head to the toolbox and grab some vice grips. You’ll need 4-6 sets at minimum, so if you’re not so equipped, remember that your local Harbor Freight sells them for <$5 each. I prefer the needle-nose variants as shown. Clamp the pinchwelds together in a few places at the toeboard, and each corner of the left and right rockers. From here, you may need to massage the pinch weld of the pan to the body to take up the gap, as shown at left of the photo. Remember, every one of these cars was built different, everyone will fit somewhat different!

With your pan clamped in place, put a tack at each front corner up top.

…then do the same at the rear. Note our plug weld holes on the floor pan to help with this job.

And just like that, that big, giant, intimidating hole is filled! At this time, you’ll want to verify all of your fitment again while there’s only a few tacks in place. Its easier to grind four tacks off, than a few dozen. Take your time, verify everything fits as you’d like it, and as it should, and move forward.

We chose to start by stitching the pan on the top side, at the toe board. It is not necessary to weld this totally and completely; in the bodywork side of things, this will be seam sealed.

With the front welded, you can move to the rear. If you’re welding this at the factory floor-to-trunk seam, this area can be stitched like the front. Since we cut this one further down, the decision was made to fully weld this seam. If you do go this route, work slow to avoid warpage.

Remember this pesky floor to cowl braces I keep talking about? Yeah, you can go ahead and weld those back on now, whether you cut them off to start, or left them in place!

Now, you can go ahead and stitch the upper pinch weld at the floor and rocker together. Fully welding this isn’t necessary. But I like to overdo certain things!

Next, you can stitch the floor to the wheelwells both at the top, and inside the wheelwell at the back of the rocker. This may be an area that will require a patch or two; the lower edges of these guys where they meet the floor can get rough. If you’re lucky, you may just have a pinhole or two to tend to.

Now, time for the lower pinch. Notice, these halves may or may not match perfectly. This can make stitching a pain.

A quick pass with the flapper will take care of this. Even steven, and you’re ready to stitch.

You can go ahead and stitch your floor at the bottom pinch. Note the vise grips; so as not to necessitate a dozen sets of them down the rocker, you can simply use one set, and move as you work. This will cut down on any unnecessary gap and provide near-perfect fitment and easy welding.

All stitched up! Just like the top, you don’t NEED to weld every inch of this. But, it was my personal preference to do so.

And the fruits of your labor! A brand-new foundation to build from, rust free, as solid as it should be. There’s no doubt we could’ve patched this one back together, but there’s also no doubt it would’ve took twice as long, and not been nearly as nice as the finished product.

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