C3 Wheel Well Detailing: Undercoating and Paint

Detailing the wheel- or fender-wells is a dirty job, but if done correctly the difference will be nothing short of stunning, and the amount of time and effort is well worth it.

It transforms a car completely and makes it look showroom fresh.

Don't believe me? Read on...

I've been meaning to tackle this job for quite some time.

A while back I detailed the front wheel wells, but it was a half-hearted effort and it showed.

This time around I wanted to do the job right.

I detailed the rear LHS wheel well since it was easily accessible in my one-car garage, and as I write this, so far it's the only one I've done. I plan to tackle the front LHS next week, followed by the RHS wheel wells.

In the unlikely event that your car was not undercoated at some point in the past, you may be in luck as prep work would be limited to thoroughly washing the wheel wells in order to get them ready for undercoating and paint.

If, on the other hand, your car was undercoated when new, you will need lots and lots of elbow grease in addition to a few sharp scraping tools.

I started with a couple of putty knives but quickly gave them up in favor of a sharp ¾" woodworking chisel that I sacrificed for this project.

Anything larger than a 1" chisel is going to make it tough to reach some areas so I suggest keeping the scraping blade width under 1-inch.

Also, taking into consideration the fact that the Corvette underbody is mostly fiberglass, I did not want to use any power tools for fear of damaging the surface. I also purposely avoided using a heat gun or any sort of chemical paint remover for the same reason.

In several instances, it was necessary to tap the chisel with a hammer in order to get it going, but I removed most of the old undercoating in less than an hour.

Once I was happy with the results, I wiped the whole area with a rag soaked in acetone. This removed a lot of the coating that was left on the surface and also helped prep it for paint and undercoating.

I chose to paint the exposed frame rails since I felt they would look better and more professional (they do). I also masked the fender edges and used an old plastic shopping bag to protect the rotor and caliper.

Again, this is a dirty job, so having a shop vac will help tremendously come clean up. Besides, you want a clean working surface when you're ready to start painting and undercoating.

The following photos show the area before I started scraping. When they did the original undercoating they sprayed everything, so I had to pay special attention to the frame portion that was to be painted.

The cover that you can barely see in the first photo above is for one of the body mounts. I did not like the idea of just sloshing undercoating on it so I scraped the stuff off and then sanded it down in order to paint it. I also cleaned the bolts that secure it to the body.

Like I said earlier, removing most of the old undercoating took less than an hour thanks to the sharp chisel, plus some of the stuff was just brittle and broke off once I applied a bit of pressure with the chisel.

The following photos show the LHS rear wheel-well after undercoating removal.

And this is after I wiped the whole area with acetone. That removed a ton of dust and small particles in addition to helping prep the surface.

The access door was glued to the body with what appeared to be a seam sealer. I used a different approach when I reinstalled it.

But before it was ready for that, I had to clean it thoroughly.

The chisel and a wire brush allowed me to get to every nook and cranny and remove the stuff they used to weatherproof it.

The photo below shows the front of the cover, which I'll paint satin black to match the frame.

The inside of the cover showed a slight amount of surface rust, so I brushed on a coat of Loctite Rust Neutralizer.

This is the inside of the cover after the Rust Neutralizer had cured.

The photos below show the frame rail portion that I painted before applying undercoating to the rest of the area.

I started by wiping it down with a rag soaked in acetone. Originally I was also going to paint the trailing arm but decided to use undercoating on it instead.

After the acetone had dried, I brushed a generous coat of Loctite Rust Neutralizer with a disposable brush.

When the rust neutralizer had dried, I thought about leaving it like that but at the end decided to paint the frame rail for added protection and looks.

A couple of coats of satin black paint provided plenty of coverage and added a factory-like finish to the frame. I did not mind a bit of overspray since the undercoating would cover it.

Now, I have to make one clarification before I continue.

Even though I've been using the term "undercoating" since it is to be applied "under" the car, I used Rust-Oleum Truck Bed Coating instead since—from past experience—I've come to learn that it dries faster, does not smell as bad (even though it will permeate your garage and most-likely your whole house), and it's a LOT easier to mix.

Of course, you're free to choose whichever you like and I've provided links to both products at the end of the article.

If you decide to use pickup truck bed coating like I did, you can apply a couple of coats to really cover the wheel well area properly. Allow the first coat to cure for an hour or two before applying the second coat.

It is highly advisable to do the job outside or keep the garage door open if you plan to work indoors. These products have strong odors that may reek for days.

If you work in an attached garage and would like to keep the peace at home, keep the garage door and any windows or side door open, for as long as possible, in order to help ventilate the space.

A shop respirator may also be a good idea.

Make sure you mix the product thoroughly before application. It's also advisable to read product usage directions on the label.

You will need a mixing stick since solids settle to the bottom of the can when the product sits on a shelf for some time.

Take your time to mix the product completely. Once it looks as in the photo below, you are ready to start brushing it on. I kept the mixing stick in the can so I could mix the undercoating from time to time as the solids will slowly but surely find their way to the bottom.

Brushing the product versus spraying it onto the area gives you so much better control of the application, which almost guarantees professional-looking results.

The photo below shows the contrast between the frame rail and the body of the car which, again, looks very professional. And this was just after one coat of undercoating!

Since I was able to reach a portion of the battery compartment exterior wall, I also coated that area.

The picture below shows a portion of the wheel well toward the back of the car as well as one of the rear body mounts.

The photo below shows a close-up of the wheel well after the second coat of truck bed coating. The product builds up nicely.

Here's the body mount cover after I sprayed it with satin black paint. I wanted it to stand out a bit and I felt the contrast would look great.

Of course, the sheet metal screws that secure it to the body were also detailed. I chose a cast metal paint for them, again, mainly for looks.

Since I did not want to glue the cover to the body, I decided to use two layers of 3/8" self-adhesive window foam seal. It will provide good weather protection for my car as well as easy access to the body mount bolt when necessary.

And here's the finished product!

Quite a difference from what I started with. And while there are other things I could do to make the area look even better, such as replacing the brake lines and replacing (or painting) the shock absorbers (I said painting since they are fairly new), such things would add additional contrast and I may do that down the road.

But, for the time being, this is a major improvement and something that anyone can do at home with a few basic tools.

I hope you find this article helpful and it motivates you to work on your Corvette and make it even better.

Thank you for following my '76 Vette Blog!

Product Links... (#sponsored)

Loctite Extend Rust Neutralizer
Foam Weatherstrip Seal Self-Adhesive | 3/8" x 3/16" x 30' | Part No. 284427
Tekton 3/4-Inch Wood Chisel | Part No. 67554
Stanley Wet/Dry Shop Vacuum | 4-Gallon, 4-HP, Stainless Steel Tank

Anti-Dust Gas Spray Paint Dual Respirator with Activated Carbon Filter
Rust-Oleum Black Truck Bed Coating | 32-Ounce Quart | Part No.248915