[Penguinator29]

Hey guys i was wondering the best way to go about painting the undercarriage like diff and frame and under bed I live in New England and there is surface rust so idk what’s the best way to go about it clean and sand first then paint?

 

[GotToGo]

You might try a spray on converter that turns rust into primer. But be careful painting assembled parts that you may want to disassemble at some point.

 

[Penguinator29]

Does that cause it to rust more? And is that safe to use?

 

[Hertz]

You may want to use something that is meant to go on a rusted surface, like POR15. That’s rusted NOT dirty. It still has to be clean and prepped (chemically, sanded, loose stuff scraped off, etc.) you’re looking at a lot of work to do it right.

 

[GotToGo]

Does that cause it to rust more? And is that safe to use?

No, it stops rust and converts it to a primer. Yes, safe to use. Go check it out at a parts store or Lowes. I don't remember the name, but I'm sure you can find it.

 

[arjadian]

I used corroseal which I ordered through home depot. It was a little pricey, but worked great. I live in the rust belt and started using it years ago. I love the stuff.

 

[mtyler11]

Hey guys i was wondering the best way to go about painting the undercarriage like diff and frame and under bed I live in New England and there is surface rust so idk what’s the best way to go about it clean and sand first then paint?

You can either paint it with a tough "paint" like POR15 or Chassis Saver or Eastwood has some rust encapsulator paints.

This just kills the rust, doesn't prevent rocks & gravel/salt from re-attacking. I know that POR15 & Chassis saver is pretty robust (like an epoxy paint or powder coat) but you really ought to spray everything down with something like Fluid Film or NH Undercoating or Krown Rust Proofing A jeep friend went to town with Eastwood Internal Frame coating and is pretty happy with it.

Name of the game is annual maintenance. Also if you are going to off-road, I'd lean more heavily on the FF, NHUC or Krown as they give a thick waxy film that will last all winter.