What You'll Learn
Aussie Conditions
Look, most blokes spend all their time waxing the bonnet and forget the most important part of the car is the bit they can't see. If you're near the coast or heading out bush, rust is your worst enemy. I'm going to walk you through how I protect chassis rails and suspension components using gear you can actually get your hands on at the local shop.
The Hidden Killer Under Your Floorboards
What You'll Need in the Garage
What You'll Need
While you're here...
Preparation is Everything
The Deep Clean
Give the underbelly a massive wash. Use a salt-dissolving solution if you've been near the beach. You need to get every bit of mud and red dust out of the chassis rails. If you think you're done, keep going for another ten minutes.
Let it Dry Properly
Don't skip this. If you trap water under a sealant, you're actually making the rust worse. I usually leave the car in the sun for a full arvo or use a leaf blower to kick things along.
Inspection and Sanding
Get under there with a torch. Look for any bubbling paint or orange spots. Use a wire brush to take it back to bare metal if it's just surface stuff. If it's flaky like a croissant, you might need a professional's opinion.
The Main Event: Protecting the Metal
Convert the Rust
Any spots you've sanded down, hit them with a rust converter. It'll turn the rust black and chemically neutralise it. Give it the time the bottle says to cure, usually a couple of hours.
Mask Off the No-Go Zones
Don't be a cowboy. Mask off your brake discs, exhaust manifolds (unless you want a smoke show and a fire hazard), and any rubber bushings you don't want getting slippery.
Choose Your Weapon
For most daily drivers and weekend warriors, I reckon a Lanolin-based spray is better than a hard bitumen coating. Hard coatings can crack, trap water, and rot the car from the inside out without you knowing. Lanolin stays 'self-healing'.
Spray the Inner Rails
Chuck the long extension wand into the holes in your chassis. Spray as you pull it out slowly. This is where the real protection happens.
Coat the External Surfaces
Spray a nice even coat over the chassis rails, floor pans, and diff housings. You don't need it dripping off like a deep-fryer, just a solid film.
Target the 'Mud Traps'
Spend extra time around the top of the fuel tank, the spare tyre carrier, and inside the wheel arches. These are the spots that hold damp dirt the longest.
Check the Drainage Holes
Make sure you haven't plugged up the little weep holes in the chassis or doors with your coating. Poke 'em out with a toothpick if you have.
Wipe the Excess
Give the areas near the brakes and exhaust a final check. Wipe off any overspray before it gets tacky.
The 'Old Timer' Trick
Watch Out
Keeping It Clean Long-Term
Common Questions from the Workshop
Can I just use old engine oil?
Will this void my new car warranty?
How do I get the smell of Lanolin off my hands?
Is an electronic rust stopper worth the money?
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