How To Protect A Chassis From Rust…
When you take your 4×4 off-road you are exposing the chassis to a whole range of elements which are ultimately going to shorten the lifespan of it, if left untreated, this guide explains how to protect a chassis from rust.
Three things together cause rust to develop: iron, water and oxygen. Iron oxide, commonly known as rust occurs when water starts reacting with the carbon dioxide in the air resulting in a weak carbonic acid to be formed.
The iron starts to dissolve, the water begins to breaks down into its basic components, oxygen and hydrogen. Oxygen and iron bond into iron oxide, releasing electrons in the process. To prevent the process of oxidation and rust from occurring, iron that is exposed to air and water needs to be protected.
There are many options for protecting your vehicles chassis , some more expensive than others, some easier to apply than others. You need to decide which is going to be best for you.
You can galvanise your chassis which is not always the most cost effective option, dipping an old chassis isn’t going to give you the best results, so if you decide to go that route, buy a brand new replacement chassis from one of the reputable suppliers.
Reasons for not galvanising an old chassis
1. Modern dipping methods are very different to the old methods, mass production means cut backs such as a lack of pre-heat and faster cooling which leads to warping.
2. Acids are not always removed.
3. Slag is often left on surface causing poor finish
4. Usually have to sign a disclaimer
5. Process weakens steel due to high temps. An old galvanised chassis usually suffers delamination internally and reduced wall thickness as a result. Combine the two and you have ripe conditions for warpage fatigue or cracking/ failure
A Galvanised chassis can still suffer from the dreaded rot over time, treating the chassis inside and out will prevent this from happening and prolong its life. Another upside to painting a brand new chassis is that it may not catch the eye of thieves, Land Rover theft is big business these days.
Prepping A Galvanised Chassis For Paint
You will find that your new chassis may well be shiny, but it certainly wont be smooth! The galvanising process leaves spikes that will need removing carefully before painting, this is important to give your paint the best surface to adhere to. The surface will also need cleaning and an alkaline solution should be used to remove the oxidisation which forms during the first 24 hours after hot dipping.
Step 1: File down any sharp spikes left after dipping.
Step 2: Use a quality degreaser to remove greasy marks. Spray on the degreaser or apply using a brush, rinse the detergent off after a 5-10 minute period and then make sure the chassis is fully dry inside and out before moving on to the next steps.
Step 3: Brush T-Wash on to the chassis and wait for the chemical reaction to occur, the surface of the chassis will turn black at which time you should wash the chassis for a final time and leave to dry fully. If the T-wash doesn’t go fully black after washing down thoroughly it must be redone. Streaky grey/ silver/ black will result in low adhesion.
Step 4: We don’t use an etch primer after t-wash. But most do. It’s just another layer, another point of failure. We do t-wash or etch, not both. This keeps cost down, makes the process simpler, faster and results in less points of failure later on.
Step 5: It has been a long process but you are finally ready to apply the topcoat of your choice, we would fully recommend using Buzzweld Chassis In One or even 2k Extreme, these products have a proven track record. There are of course other products and the choice is entirely yours!
If you do not want to go down the galvanised route for whatever reason and you decide to paint your vehicle’s chassis, you must still properly prepare before painting, poor preparation will lead to whatever product you choose failing a lot sooner.
Preparing a chassis for painting
Step 1: Clean the entire surface with a degreaser making sure you remove any grease, tar and any other contaminants that have built up on the surface, wash off then leave to dry thoroughly.
Step 2: Once dry, strip the old paint to expose the bare metal underneath and to remove any existing traces of rust. After exposing the bare metal, now repeat step 1.
Step 3. Once the chassis is fully stripped back and free from contaminants you can begin applying a primer. We recommend using Buzzweld Rust Control Primer (RCP), mainly because it has zero rust creep and modifies existing rust. Drying times are dependent on the environment, but you should leave 4 days before applying a top coat.
Step 4: Before applying a top coat make sure the surface is clean from contaminates. We would now recommend using two coats of Buzzweld Chassis in One. CIO contains self-leafing glass flake for extreme abrasion resistance compared to standard coatings giving longer protection. Top coats can be applied within as little as 30 minutes of each other.
Most people shy away from using sandblasting mainly due to cost, however it probably isn’t as expensive as you think! Factor in the materials you will need and the time it will take for you to lay on your back and prep your chassis yourself and sandblasting really doesn’t cost all that much.
If for some reason you still cant consider getting your chassis sandblasted then its time for some good old elbow grease…
Manual chassis prep
Before you start you need to clean away all the oil, tar, road grime from the surfaces, it is going to make life a lot easier in the long run and save on materials, wire wheels and flap discs do not work very well when they get coated in old oil.
Choose your weapons!! There are many abrasive materials to choose from, wire wheels, flap discs, 80 grit sandpaper etc..
When painting any surface, preparation is not only a basic fundamental, it will also dictate how long your chassis stays protected from the elements.
Always spend a little extra time making sure that surfaces are free from contaminants, and leave as much time as possible between coats unless the manufacturers directions advise otherwise.
When prepping your chassis with wire wheels or flap discs, be sure to wear the appropriate safety gear, googles to protect your eyes and gloves to protect your hands.
Spray and Pray coatings
There are numerous amounts of coatings which you can apply with a reduced amount of preparation. Some of the more popular brands being Waxoil and Dinitrol. Some people swear by these treatments, however they do not always work as intended.
These treatments can harden and crack allowing moisture and salt to get trapped against the metal, when this happens the product actually masks the rotting that is occurring behind the surface.
From a personal point of view I would much rather treat a chassis with a product that has rust inhibitors and modifying properties than a spray and pray product.