Auto body repair & detailing: Questions regarding epoxy primer over roughed up paint, rust, corrosion

Question
Hi Gary,

I'm replacing the U bolts that hold the rear leaf springs to the axle housing of my Chevy pickup. I'm also replacing the U-bolt anchor plates that go under the axle housing.

The new U bolts don't seem to be painted, but the new anchor plates are painted.

I would like to rough up the paint on the anchor plates with some 60 grit, clean the parts good, and then spray two coats of aerosol 1K epoxy over the roughed up factory paint. I would then follow up with one top coat of rustoleum enamel.

This is the epoxy primer I have (you recommended it before)
http://www.repaintsupply.com/pd_re_epoxy_aerosol.cfm

I want to use the epoxy in hopes that it will resist abrasion from road debris and provide better protection than regular paint. I know that in general epoxy primer is intended to be applied over bare unfinished metal.

Is this a good or bad idea ? Will the epoxy adhere good or would I be better of to just rough it up and prime and paint it with rustoleum ? If the epoxy does adhere well, will it provide better protection than regular oil based enamel paint, i.e., rustoleum ?

Would I be better off applying some wax based rust inhibitor and/or some wax based undercoating rather than paint ?

The paint that came on the part from the factory looks half way decent, for some reason the part for one side is a high gloss looking finish and the part for the other side is a flat black finish. There's no way for me to tell what type of paint was used by the OEM (general motors).

Perhaps it's not worth fooling with, I just thought I would try to give it some more rust protection if I could do so without too much trouble.

Any feedback or alternatives would be appreciated.

Thanks
John

Answer
Hi John,

Anywhere the epoxy gets to bare metal it will give corrosion protection. Alternatively, where the factory paint is direct to metal there will be no corrosion benefit from the epoxy. However, I believe you will get a better adhesion and abrasion resistance when using the epoxy as opposed to using another type of primer. You can then just paint with whatever color scheme you plan to use for the undercarriage.

For undercarriage stuff I have also used POR-15. I absolutely love it. It's tougher than nails and sticks like crazy over rust or sanded bare metal. I hope this helps you out and if you have any other questions please feel free to reply.