Paint adhesion - best method for axles and chassis etc

I am currently doing work on the underneath of the truck. I am having to change an axle case but have outriggers on my list.

I have noted that corrosion mainly occurs in moisture and crud traps. On my chassis I have been brushing it down and applying Lanoguard. K have chosen Lanoguard as I want to be able to monitor the condition of the chassis- it is 30 years old so need to keep my eye on it.

On cleaning things down I have noted the main areas of corrosion are the nooks and cranies that hold mud etc, and also behind loose paint.

I have come to the conclusion that if you paint something you are likely to create corrosion issues, especially over rust . I have tried rust convertors, but so far I am not impressed.

So, if painting a clean surface, what is the best way to make the paint stick like s**t to a blanket?

My next thing to paint is my rear axle case. It's currently in the electrolysis tub, so I am hoping to get most of the rust off before applying paint.

I currently have the following on the shelf;
Phosphoric acid
Bonda Rust Primer
Zinc oxine Primer
Thinners
Brake cleaner
Single pack top coat.
Aquarust rust converter - (not impressed so far)
Lanoguard
Lanoguard grease

The truck has had bulkhead outriggers before and on brushing and poking these ro remove rust you can see how small sheets of paint have been holding moisture in. I think if you can’t get good paint adhesion then it's better being left bare and painted with Lanoguard or another rust prevention soft coating.

Thanks in advance for any help.

Mick

The blokes down the boatyard actually let the steel rust lightly, then apply some rust treatment then red lead or whatever passes for red lead these days on top, it certainly takes some grinding to get off.
I am not sure what the rust treatment is, but if you weld to close to it it gives you a blinding headache.

The area of the axle that is under where the bump stop plate was.

Replacement axle case being cleaned using electrolysis before I decide how I am going to paint it.



After wire brushing followed by pressure washing.


You can see the difference in cleaning as the axle would only fit so far into the electrolysis barrel.

using electrolysis I can get rid of a huge amount of the rust. I did try using a grinder and wire brush to get rid of the rust where the diff pan is welded to the axle casing, but that method just seems to polish the rust.

lynall said:

The blokes down the boatyard actually let the steel rust lightly, then apply some rust treatment then red lead or whatever passes for red lead these days on top, it certainly takes some grinding to get off.
I am not sure what the rust treatment is, but if you weld to close to it it gives you a blinding headache.

Click to expand...

I understand that some treatments, such as the aquarust, require rust to work, but too much and it can't penetrate deep. I think this is where it has failed on me before as when wire brushing rust it can take off the loose stuff but then polishes the harder stuff which can be quite deep.

With managing to use electrolysis for rust removal it gets rid off so much of the deep stuff. It does leave a black residue, a lot of which can be removed via wire brush and washing, but lots better than just a wire brush. If only you could get the chassis in!!