“Salt and moisture can be detrimental….”
STANCE Suspension USA main facility is located near Chicago, IL in the Midwest. When it comes to extreme weather, we have experienced it all! Chicago is located next to the second largest lake in the United States, Lake Michigan, which keeps humidity levels higher than other nearby regions. Chicago is also near Canada and we get to experience the cold fronts from the Arctic in the winter! Also, lake-front winds don’t make it easy when it comes to freezing temperatures. Due to below freezing temps and winds, the roads become extremely dangerous, if not for the tons of rock salt that get caked over the streets and highways. While it provides a safe commute for many, the combination of salt and moisture can be detrimental to all types of metals, including cars and any metal attached to them.
Here is the reason why cars rust very quickly when road salt is introduced. When calcium chloride is exposed to moisture, it dissociates into calcium (Ca2+) and chlorine (2Cl-) ions. The chlorine ions are what causes metal corrosion: together with the moisture in the air, they form hydrochloric acid by pulling one H+ ion from the water molecule. This acid dissolves the iron by stripping it of electrons. Since the iron is now short a few electrons, it becomes a positive ion, which then reacts with the remaining hydroxide (OH-) group from the water molecule to form rust, or Fe(OH)3 and other hydrated iron oxide compounds.
Electrophoretically Deposited Paint
What is the solution? Stainless steel is an option that we’ve considered, but due to its cost, machining, weight, etc; we wanted to find an alternative option that can match properties of stainless steel without the cost it brings. We’re excited to introduce EDP coating on our XR Series coilovers!
EDP coating, also known as Electrophoretically Deposited Paint, is best described as a cross between plating and painting. It is a process where a metal part is immersed in a water-based solution containing a paint emulsion. An electric voltage is applied to the part causing the paint emulsion to condense onto the part. There are various types of EDP coating; our dampers go through zinc phosphate emulsion and get plated with a hard epoxy coating. Due to the process, EDP coating provides better coverage on the threads where other coatings, like powdercoating, have a hard time getting into such small crevices.
Most of our competitor’s coilovers on the market are using powdercoating, which is fairly effective against corrosion and impact. To see just how good they are in comparison to our own, we have performed salt spray testing on other brands’ coatings, and we have seen around 300~400hrs before the corrosion starts to make the threads useless. Our EDP coating has been tested at 1000hrs before any noticeable corrosion starts to happen. Stainless steel coating is rated at around 1200+hrs.
We wanted to expose our new coating, along with other brands, to extreme test to replicate the Chicago winter, which we believe is one of the worst conditions that a car would see. So we set up a container and diluted the same rock salt used on the streets at 30% solution. But that would be too easy, so we added 15% bleach to the solution to accelerate the process. The active ingredient in bleach is a chemical compound called sodium hypochlorite. It acts as an oxidizing agent, ionizing other materials by removing electrons from them. The oxidizing properties of bleach accelerate rusting; iron loses electrons more readily in the presence of bleach than in plain water. We tested 2 competitors damper bodies to compare the results. Our baseline model would be Brand A’s stainless steel damper body and a very popular sub $1000 Brand B’s powdercoated damper body. We exposed each damper body to the same amount of the solution in the same container to keep the test unbiased. We ran the test for about 20 days, until the Brand A’s stainless steel body showed signs of corrosion.
Brand A’s Stainless steel damper showed very little signs of corrosion, which wasn’t surprising. Most of the corrosion was at the threaded section and the rust was mostly on the surface. Threads were still in very good condition.
Brand B’s powder coated damper body showed signs of corrosion almost immediately once introduced to the solution. After 4-5 days, we could see the rust building up heavily on the threads and we could tell that the acidic solution with rust had worked through the coating and started to eat away at the threads. Brand B also uses fine threads, which made the situation worse. We noticed that some threads had fused together due to heavy build up of the rust. This is definitely not something that could be fixed or used.
XR Series damper body showed very little if any signs of corrosion. Some of the corrosion that is in the picture is surface rust and we could easily remove it with some oil and soft rag. XR Series does not use fine threads, keeping larger surface area for the coating and gave it less chance of accumulation of rust building up between each thread. Another advantage of EDP coating is that its PH balance is very neutral, so the rust is not attracted to it. Its a natural barrier unlike zinc coating, which sacrifices itself to protect the steel underneath it.
Our test shows how durable the new EDP coating is, even compared to a stainless steel damper body. Not only does it protect the dampers from corrosion, EDP coating is also highly resistant to scratches and debris, making it an excellent barrier to all situations. When combined with our neoprene shock covers, you can be assured of getting the most value of your investment!
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