weld thru primer

[moose]

WELL, anter much delay I am back working on my Coupe body. The next step is replacing the drip rails.

Does anyone have a recommendation for a quality weld thru primer? My plan is to puug weld the rails on from the back side so I want to do all I can to aid in corrosion protection.

Thanks

Tim

[idrivejunk]

3M's #5917 aerosol "Weldable primer", aka "Weld-Thru II" is the current dominant product on the body shop market and has been that way as long as I can remember. There used to be clogging troubles with the original version, but the current #5917 works well if you invert and purge the nozzle after each use and shake profusely beforehand. I like to carefully use a paint shaker if possible, for half a minute or less.

I would be negligent if I didn't mention however, the downside which you are probably aware of. It interferes with quality welds. Original equipment manufacturer's collision repair warranty requirements are the reason the stuff exists in the first place. Well ... a few years back, about when all the products started having the heavy metals removed from their formulas by new laws ... the OEMs jumped ship on weld-thru. No longer recommended. Coincidentally, this is also about the time that pro grade self-etching primer went away and unleaded epoxy primer became the only legal and warrantee-able "direct-to-metal" primer on the market.

So- in hidden spots I try to brush on epoxy with bent and taped together acid brushes after the work is done, or thin it down and let it run thru the seam a few times. Flashlight and a good eye required. Internal panel coatings or "cavity wax" is gaining popularity and the available products (Rust Fighter and the like) and applicators are not too bad. Eastwood has an aerosol version with a long flexible tube and nozzle. Its an effective alternative for additional corrosion protection.

[chris spokes]

wurth sell a weld through primer third row from the top
http://www.wurthusa.com/web/en/website/produkte_1/chemicals/paints___primers/paints___primers.php

[moose]

3M's #5917 aerosol "Weldable primer", aka "Weld-Thru II" is the current dominant product on the body shop market

I would be negligent if I didn't mention however, the downside which you are probably aware of. It interferes with quality welds.

So- in hidden spots I try to brush on epoxy with bent and taped together acid brushes after the work is done, or thin it down and let it run thru the seam a few times. Flashlight and a good eye required. Internal panel coatings or "cavity wax" is gaining popularity and the available products (Rust Fighter and the like) and applicators are not too bad. Eastwood has an aerosol version with a long flexible tube and nozzle. Its an effective alternative for additional corrosion protection.

The issue on the Coupe is inaccessablity after the drip rails are installed. On a Model A Ford Coupe the drip rails were spot welded to the side of the roof panels. there is no access or gap to apply anything to the joint.

Mine were removed in the distant past by a knuckleheaded 23 year old kid who thought he knew better.. I won't mention the kids name although he goes by moose....

Anyway I intend to replace them by plug welding from the back. There will be no good way to apply anything after they are welded on due to the tight fit...

I will pick up the 3M spray for this.

Thanks

Tim

[unklian]

What about some of the high tech adhesives ?
No welding required.

[parklane]

What about some of the high tech adhesives ?
No welding required.

Just thinking the same thing. That panel bond stuff makes it stick like snot to a screen door.