A project that kept me busy for the last few months was to bring back our "new" Roadmaster to its former glory. The car has only 23k miles on the odometer and in many areas still looked like new. The undercarriage was not protected very well from the factory and like on all cars had developed some surface rust over the last 2 decades although the car never was stored outside nor regularly driven in the rain. It also never saw road salt or snow during its entire life. Below are some before pictures where you can see the fantastic condition the car was in before I started cleaning it up.

All the original factory markings were still in place

I decided to make sure that all the rust was gone and that I wanted to give it a new undercoating to protect it as best as possible should I ever encounter wet roads.

The first step was to have the undercarriage
dry ice cleaned. During this process all the old undercoating gets removed completely and even most of the old paint was removed from the frame.
You can see the result of this process in the video below - it shows the car right after the first clean up - before painting and removing some more surface rust:

After that I chemically removed all the remaining surface rust completely with rust removing gel which leaves only perfectly clean and rust free metal behind.

The new and the old Roadmaster together

The next step was to make sure that the metal was 100% clean for the paint to stick perfectly. I used "Marine Clean" and "Metal Ready" to prep the bare metal after I had wiped everything with acetone multiple times until all rags stayed clean after wiping.

For the repaint of the undercarriage I wanted to make sure to use a paint that would be able to prevent rust and chipping. After a lot of research I found a company called "Timemax" which produces some fantastic rust preventive paint and special undercoating products. They won some long term tests in a classic car magazine. Their products are also used on ships.

I bought their undercoating paint and sprayed three coats onto the undercarriage and frame. In the wheelhousings I also applied two coats of their rock hard stone guard
which I had already used on my 74 as well.

Some of the Timemax products which I used.
The first coat of fresh paint.
The undercarriage after the repaint. The exhaust system is still the original one installed by the factory and the only part left with some corrosion.

After I had finished the undercarriage, I sprayed a special hot wax into all the cavities of the undercarriage and the rest of the car. Now there is no chance for rust to form anywhere ever.
Afterwards I cleaned and detailed the rest of the car.
The paint got a full compounding where I could remove all the scratches and swirls and afterwards I polished the car to perfection and sealed the paint with 3 coats of a highly praised ceramic coating by "Carpro" called "CQuartz UK 3.0"
I also fully cleaned all the rims and sealed them too and installed white wall tires from my old Roadmaster which are only 2 years old. I also removed the spoiler the previous owner installed to the rear window and changed the brake fluid and oil.

The car is back on its feet with "new" tires installed.

All that is left now is to get the dents out on the rear quarter panel, and repaint the rear bumper. After that the car should again look like it just left the factory. I wanted a nice driver, but as it turns out the car will be in show quality condition once I´m finished, and I will have a hard time driving it, as it will be so perfect…



I´m restoring the undercarriage of my 1974 Cadillac Coupe DeVille. See below.
As I want to do it as perfectly as possible, I wanted to remove all the undercoating which was applied when the car was new.
I do not like rubberized undercoating, as you cannot see whats going on underneath. It can trap moisture and once it flakes off due to corrosion, there is already some major damage in the metal underneath.

There are different methods for removing the undercoating and most of the methods are a pain in the a**.
This stuff can be removed with a scraper and chemicals, or with heat and a scraper. Both methods will damage the metal underneath and scratch the paint on the underbody, and it takes forever…

As I did not want to use any of the methods mentioned above, I decided that I wanted to try dry ice blasting.

Dry ice-blasting is a form of carbon dioxide cleaning, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurized air stream and directed at a surface in order to clean it. An alternative media for non-abrasive blasting is water-ice, known as ice blasting.
The method is similar to other forms of abrasive blasting such as sand blasting, plastic bead blasting, or soda blasting but substitutes dry ice as the blasting medium. Dry-ice blasting leaves no chemical residue as dry ice sublimates at room temperature.
Dry-ice blasting involves propelling pellets at extremely high speeds. The actual dry-ice pellets are quite soft, and much less dense than other media used in blast-cleaning (i.e. sand or plastic pellets). Upon impact, the pellet sublimates almost immediately, transferring minimal kinetic energy to the surface on impact and producing minimal abrasion. The sublimation process absorbs a large volume of heat from the surface, producing shear stresses due to thermal shock. This is assumed to improve cleaning as the top layer of dirt or contaminant is expected to transfer more heat than the underlying substrate and flake off more easily. The efficiency and effectiveness of this process depends on the thermal conductivity of the substrate and contaminant. The rapid change in state from solid to gas also causes microscopic shock waves, which are also thought to assist in removing the contaminant.

Unlike abrasive media blasting you cannot remove rust with dry ice blasting.

I found a company through the website of a classic car club, which is only a little over an hour away. I wanted to have it done before the first snow and as soon as possible, so that I could continue working on my car during the winter. The owner of the company did a great job. He is a very friendly and competent gentleman and it was a pleasure working with him.
Here is a short video how it was done: (make sure to watch in HD for proper image quality)

You can find all the pictures I took today in my restoration album.

The car was lifted with a forklift and then covered in plastic.

One of the rear wheel-housings before blasting - you can see the undercoating everywhere. edge
The same wheel housing after blasting - all the original paint was still very well preserved under the undercoating. As you can see originally the wheel housing was brown. During painting a lot of overspray from the body landed in the wheel housing. Then Cadillac added rubberized undercoating to protect the metal from stone chips and to keep the car more quiet. Luckily there is no rust to be found anywhere.
During blasting.
The original brown paint showed up underneath the undercoating. The paint is still in perfect condition.

The original paint showed up underneath the undercoating in the wheel housings as well.
After cleaning - it came out really nice! I will touch up some areas and conserve the others with a special transparent coating.
I´m very happy with the result of the cleaning and will now have to protect everything and paint some areas.