Project Mini Cooper S | Magazine Series Part 8: Final Bodywork, Filler and Bright-Red Paint To Bring Our Mini’s Shell to Life

[Editor's Note: This article originally ran in the January 2015 issue of Classic Motorsports; for more updates on our 1967 Mini Cooper S, visit here.]

What separates good bodywork from great bodywork? The details–those fine adjustments that keep you poring over your car long after the welder has cooled and the crickets have come out. It’s not unusual to spend hundreds of hours wielding a hammer and dolly, sander and body filler before any paint flies.

Although some enthusiasts turn up their noses at filler, technological advances have made this product an accepted part of a quality restoration. The old days of helplessly watching filler crack and fall are long gone. Don’t believe us? We’ve traveled to some of the most legendary and expensive restoration shops, and they all use the same Evercoat Rage Xtreme filler that we do.

Filling with old-fashioned lead is romantic, yes, but it’s also toxic and heavy. Plus, almost nobody can apply it properly, and it has a tendency to fall off the car. Even if it does stay put, it’s typically tough to paint.

Proper application techniques can also separate good filler work from bad. A 1/8-inch layer of filler–about as thick as two stacked pennies–should be enough to complete the repair. If applied correctly, filler is undetectable by a magnet and able to flex along with the sheet metal. 

Tom Prescott, owner of The Body Werks, served as our expert guide through this phase of the project. He knows how to make a body beautiful.

Step 1:

Gather your basic bodyworking supplies. In addition to a high-quality polyester filler, you’ll need the corresponding hardener and a measuring tool–we prefer a  carpenter's square. The square acts as a straight edge for spotting any waviness in larger panels, like doors and fenders.

You’ll also need filler pallets. Tom uses these custom ones that feature tear-off sheets, but a clean piece of thick cardboard will work fine, too. You’ll also need an array of sanding blocks; Eastwood makes a nice selection that we’ve used successfully.

Step 2:

Okay, time to get started. Make sure you’ve completed your metalwork and wiped down the car using a cleaning solvent, like DuPont Prep-Sol 3919S. Then, prime everything with PPG DP40, a high-zinc primer that prevents rust.

Step 3:

Next, check for any high or low areas with your square. Tom laid his along our quarter panel and instantly realized that it had been pushed in a little bit.

Step 4:

A tip before we go further: Pause frequently throughout the hammering and filling process to check your work with your hands, slowly running them over the panel at all angles to detect high and low spots. You can also mark areas with a pencil or Sharpie to better visualize the terrain.

Now, use a hammer and dolly to apply just enough force–think light taps–to push in high areas and push out low ones. Too much force will cause the metal to stretch.

Adjustments with a hammer and dolly are relatively coarse; your goal should be to get these peaks and valleys within 1/8 inch of perfectly flat. More refined tweaks will come later with sanding and filler. 

Tom’s carpenter's square rested on our quarter panel perfectly after less than 30 minutes of work, but he admits that the same repair would probably tie up a beginner for 6 hours. Metalwork is an art: It requires a certain eye, a certain feel with your fingers. You can grasp the basics in a few minutes, but truly mastering these techniques can take a lifetime.

Step 5:

Use a dual-action sander–one that moves the pad irregularly–to sand the repair area. This step mainly promotes better filler adhesion, but it also slightly smooths minor high spots. If more hammer and dolly work is needed, do it and come back to this step. Finally, wipe down everything again with the cleaning solvent.

Step 6:

Now comes the fun part: slapping on the mud. Your goal is to get the surface absolutely smooth using as thin a layer of filler as possible. As a beginner, you may end up getting more filler on the floor than the car. Our advice? Follow the mixing instructions, be patient, and use the correct squeegee for the job. 

First mask off any panels you aren’t working to keep them clean. Then spread on a smooth, thin coat of filler, remembering that you’re eventually going to sand off most of it. Again, if you end up with more than 1/8 inch of filler on a panel, don’t just ignore it and hope for the best. Insufficient hammer and dolly work is one of the most common reasons for poor bodywork results, along with working in dirty or cold conditions.

Step 7:

Properly mixed filler starts to harden in about 10 minutes and fully cures in 30, so remove the excess quickly. Use a body rasp file–also known as a cheese grater–to quickly rough the semi-cured filler into shape. Don’t be too aggressive, though, or you’ll scrape away too much filler. Don’t go too light, either, or you’ll face hours of sanding. 

Next, switch to 40-grit paper wrapped around a paint stick. The sandpaper is less aggressive than the body rasp file, while the stick keeps the paper flat–remember, the goal here is to achieve a smooth surface. 

Once the filler dries, the real work begins using 80-grit paper on the correctly shaped sanding stick. Move slowly and methodically, covering the whole panel in an effort to remove almost all of the filler. If any low spots form, apply more filler and try the sanding process again. Be patient: Even an expert will have plenty of back and forth at this step. 

When you’re happy with the results, gently sand the whole area with 180-grit paper to prep it for primer.

Step 8:

Bare metal attracts moisture, so begin the priming process quickly. First give the area another wipe-down with cleaning solvent. Then prime the area with high-build, two-part urethane primer. In addition to better filler, the bodywork industry has also benefitted from improved primer formulas. Red finishing putty is largely a thing of the past.

Step 9:

Next comes the block-sanding stage. This laborious step is perhaps the most important factor in producing great bodywork. The entire panel–and thus the entire car–is block-sanded, first with 320-grit and then 500-grit paper. Why is it called block-sanding? The sandpaper is backed with some kind of object, usually one that’s blocky yet flexible–think rubber, foam, urethane or PVC. Companies like Eastwood offer solutions for nearly every surface contour.

Step 10:

Once the basic bodywork is done, it’s time to seam-seal every nook and cranny. You have three goals here: first, to duplicate the factory look (pre-restoration pictures of your car should help here, assuming the car was original at that point); second, to prevent leakage into crevices and the cockpit itself; and third, to greatly reduce the risk of any rust returning.

Step 11:

Wipe away the excess seam sealer to match factory specs. Tom uses Kent’s Flex-E-6020 high-viscosity, maximum non-sag seam sealer on every job he does.   

Step 12:

Next comes 3M’s Rocker Schutz, a lightweight, paintable, chip-resistant undercoating that duplicates the factory look. 

Step 13:

Rocker Schutz can hide a lot of sins, and generally you can use as much as you want. That said, a Mini Cooper should have just a little in the wheel wells for paint protection and sound reduction. Too much undercoating can look nonoriginal and trap water that leads to rust.

Step 14:

One of the final steps in a professional repair job is sealing the entire car. It promotes paint adhesion, traps in minuscule amounts of oil, and helps fill the pores of the body. The Body Werks first washes every nook and cranny with DuPont Prep-Sol 3919S, then seals the car with PPG DCX-61 sealer, a product made for water-based paint.

Step 15:

Time to add some color. Choosing the right shades might be more complicated than you think.

Our car was originally painted Tartan Red, code No. RD9. Unfortunately, BMC had an early and a late Tartan Red. Add in lost records, faded paint and some debate as to when each was used, and the Mini community couldn’t offer a clear answer for what color our car should be.

So we did it the old-fashioned way and found some original, unfaded Tartan Red paint on our car. We feel that this suspension mount cover, protected from the sun, depicts the original hue. We looked through color chips and selected the closest match: Honda Milano Red, code No. R81. 

Our 1967 Cooper S originally came with a black roof, and up until the last minute we were committed to keeping this car totally correct. Then we had a change of heart. We’re based in Florida, where a black roof would make the cockpit hotter than hell, especially since the car doesn’t even have roll-down windows. Plus, the rally cars were all Tartan Red with a white roof–and this would nicely match our white wheels. So, at the 23rd hour, we picked a Toyota white, code No. 041, for the roof.

Choosing the paint itself is an important step, too. We opted for PPG Industries single-stage solid paint. Our Mini is an early, simple car, so we didn’t think a clear coat would look authentic. If you’ll be applying one to your car, we recommend using a base coat/clear coat system from PPG

Step 16:

To prevent overspray, carefully mask all of the body’s holes and openings. 

Step 17:

A car’s exterior must be painted in stages. Try doing it all at once, and overspray will lead to disappointing results. Consider letting a pro handle this part; we enlisted master painter Ramon Quiles of The Body Werks to spray our Mini, and he tackled the job in methodical chunks.

After the top of the Mini was bagged and tagged, Ramon painted the underside, trunk and engine compartment. Then he painted the underside, trunk and engine compartment were masked and bagged so he could paint the interior. After that, the interior, underside, trunk and enginecompartment were wrapped so he could spray the exterior. Finally, he covered everything but the roof to apply that white accent.

Step 18:

Now that the paint has been sprayed, the entire body could be sanded and buffed. First the whole car was lightly dry sanded with 1500-grit paper. This removes any dust nibs. Then the car was buffed with coarse, medium and fine buffing pads using the Norton Liquid Ice buffing system.

If you opted to paint your car with a base coat/clear coat system, the clear coat would be applied a few minutes after the base coat was sprayed. Your buffing wheel wouldn't turn red like ours, either.

Step 19:

Finally finished. We spent some 250 hours doing metalwork on our Mini, and Tom and his crew backed that up with another 250 hours of bodywork and painting. This is why a good restoration costs so much. Just think of how much time and money it would take to do this on a more complicated machine, like a Jaguar XKE or a ’50s American cruiser. 

Now, let the reassembly begin. 

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