I want to paint my undercarriage black but need advice on how to clean it first. The frame has about 1/8" of grease and slime covering it. It just sticks to steel wool and sand paper so those are useless. What's the best way to go about cleaning this stuff off?

 

Knotted wire wheel or cup on an angle grinder. It's like a magic eraser for metal.

But also pressure washing, then maybe a blade scrapper if it's really grease and not just the weird rubberized-ish undercoating like what the factory put on my 2007.

 

Simple green or a heavy duty de-greaser. Purple power and a power washer worked best for me. I did it on an old Railroad service F350 with a leaky hydraulic fluid tank that leaked for years. I had about 2 inches thick worth of oily,stinky slimy mess mixed with sand,gravel and rocks. The frame was worse with all the oil and dust on it. It made great rust proofing but it stunk to high hell! I bought 5 gallons of Purple power on sale but any de-greaser, a power-washer and a few hours is all it took.

 

It might just be the rubber stuff your talking about, because I don't know how else it would have got there. Thanks for the tips

 

Yeah, that's why I didn't mention chemicals if it's the factory coating, it seems like dried Goop or rubber cement, rubbery but solid enough to come off with really harsh abrasives. Like knotted wire or a 40 grit flap disc.
.

 

Guys, be careful using powered wire wheels. When you get to the bare metal, the steel wires of those wheels when used on power tools puts some kind of coating on the steel that often times prohibits paints and primers from adhereing to the metal. If you use powered wire wheels, make sure to sand the metal before painting to remove that coating. Don't just wire wheel the steel and then paint over it.

 

Normally it's not that the wheel is "adding" a coating, it's that it won't cut through mill scale or rust and just polishes it. Always use a belt sander, flap disc, grinding wheel or something similar before painting or welding. Wire wheels are for bulk clean up, to remove heavy slag, and to remove paint layers without accidentally affecting the base metal like sanding or a needle scaler will.

That's another option for the inside corners where a cup or wheel won't get, the frame is durable enough that a needle scaler would work.
<iframe width="560" height="315" src="http://www.youtube.com/embed/Xha4xY-dMrQ" frameborder="0" allowfullscreen></iframe>

 

Yep, you're right. It happens with rust, so you already know what I was trying to say. That's good. I was just trying to help.

 

I was just specifically clarifying while generally agreeing with you

 

I know that!

 

I wouldn't bother to clean the factory coating off. It is actually a special type of wax that is self healing, and will not crack or peel off when the frame flexes, which is often.

If you live outside of certain states, you can buy a similar substance in a rattle can to spot replenish areas wear the wax has been rubbed away from floor jacks, jack stands, accessory attachments and removals, etc.

One such product is made by Daubert Chemical Company, Inc. They have various formulations for the same intended purpose that would take a ChemE to understand the differences, but the one I use is NOX RUST X-121-B. It is a one coat rust preventative formulation that can be used over the previously applied coating, and adheres to bare steel, zinc coated steel, as well as weldments.

It is different than paint, or rubberized undercoating. It isn't exactly like Ford's OEM product, where the frames are waxed dipped, but it has properties that come very close to it... the ability to flex and not flake off, and the ability to maintain that performance through a range of temperatures.

My chassis was made in late 1999, which makes it darn near 13 years old now. The axle is painted, but the frame itself (seen in the upper left hand corner is) the original Ford wax coating with a dirt coating on it that adds body to the wax, and protects the frame from rust.



Due to customer demand, Ford no longer coats the frames with this wax. Now they ecoat them. I assume they've come up with a way to put enough flex agent in the paint to keep it sticking to the frame regardless of flex.

I'm continually surprised at just how much the frame flexes and moves. Before I repainted a frame, I would consider this flex and how that might effect the paint adhesion down the road. If the wax is removed, and the new paint cracks and flakes off, then the steel is now more vulnerable than ever to rust.

As you can see, I don't mind a little dirt on my frame in order to keep that wax in place.

 

Wow I definitely didn't expect so much thought to go into this. So should I keep the wax on and continue looking at an ugly frame, or wire-wheel it off, sand, and paint?

 

I recently finished my front end under body
its not so bad but it is good to give it some thought and work it out in your mind B4 starting. just clean and paint basically.

here are the ingredients
1) heavy duty degreaser - from sams club or simple green, krud buster ect from lowes or home depot

2) long rubber gloves

3) Stiff Nylon brushes - one with a long handles is great even old tooth brushes work in tight spaces Lowes has one nice brush thats long and has bristles all along its length and it bends also. I gathered all the brushes i had all sizes shape, what wever

4) Hose with sprayer or pressure washer

5) Paint of Choice - this is where you want to do your home work if you are picky. I Used a paint made for chassis that's meant to go right over rust it actually works best and bonds best to rust so you have minimal prep ONLY cleaning thick scaly rust and degreasing that it. its called chassis saver. And it is very flexible. some dried in a plastic measuring cup i used and when i pulled it out i played with it a bit and it definitely gives. its also chemical resistant. I liked it a lot. but it does not stick to smooth metal you would have to rough sand bare, smooth, clean metal. i put it on with many cheap nylon brushes several coats and make sure you cover it well.

here is my interior rebuild thread on here , Pages 6, 7 and on have some images of what i did to mine that may give you some idea of what you can do not so bad and totally worth it.
https://www.ford-trucks.com/forums/1...project-6.html