Why all the Rust?

[MiniDave]

When you watch videos of how these cars were made back in the day, one of the prominent parts of the manufacturing line were the dip tanks, in fact that's why they had the holes in the front and rear bulkheads, when the car enters the tank it slowly rotates on the spit, allowing the primer to get into every nook and cranny and completely cover the sheet metal, inside and out...I believe the primer was electrically charged too, to make it bond with the sheet metal.

With that much primer and protection, why the hell  do they rust so badly?

[94touring]

Well I'm speculating but perhaps cheap materials combined with thin materials.  Not sure if they had "epoxy sealer primer" they used or not, which locks out moisture.  Then of course they were in wet climates and I've heard used cheap steel.  Not to mention it's thin to begin with. 

[MiniDave]

I'm sure all of those things are true.....but when you open one up there doesn't seem to be any trace of primer.....

[94touring]

Well inside the cills and such have primer but it just isn't holding up over time obviously.  When I do things like cills I paint and clear them after a coat of sealer primer.  Then weld em on and assume the first areas to go will be around the welds where it burns the paint.  Adding service holes to waxoil will give boxed areas tons of protection.

[MiniDave]

When I did the rustoration on my Jag I used waxoil in every section.......so far so good!

Don't you use weldable primer? It's supposed to "creep" back into the areas of the weld to stop that.....

[94touring]

In my opinion it's not all its cracked up to be.  You're only really suppose to use it in the spot you weld, in which case the primer heats up and provides protection.  SOME protection for a period of time.  My thoughts are this... it's a pita to clean 100 specific spots for spot welding to apply weldable primer.  You'd have to hit both panels in the exact spot.  Then you'd weld and would still be recommended to apply a seam sealer or waxoil type material to creep into the welded seams for maximum protection.  Weldable primer has bad adhesion quality also and isn't meant to be painted over.  To me it makes sense to paint these back sides and seams with high quality materials, use a pneumatic hole punch on one of the seams, expose the metal on the adjoining seam with a quick scrape of a screw driver or drill prior to plug welding, hit the spot quick and hot, then if you are compelled to waxoil go crazy.  Clamped together the paint between the seams doesn't burst into flames and I've found melts as well.  How well it protects at that point is beyond my knowledge but I do know that my plug welds are 100x stronger than say 110a spot welds.  I've yet to aquire a 220a spot welder which is what should be used to get strong enough welds that can't be ripped apart by hand.  I digress..  I'm sure there are dozens of varying opinions and methods but this is what I do.  Either way I'd say it's better than factory.

[Merlin]

I hate it because it splatters like a mo-fo. I can never get good penetration with a zinc weld-through primer.

[MiniDave]

Minutes 4-6 in this vid....

[jeff10049]

 only early cars got that treatment It stopped in 62 I think. my 60 had very little rust considering its exposure. I read a post on MM years ago with the date the rust treating stopped it was early from what I remember chuck heleker over their would know for sure.

Jeff

[MiniDave]

Aha! That would explain it then.......cause it looks like later cars got absolutely no rust preventative treatment at all.....

Chuck Heleker over where? Who is he?

[jeff10049]

Chuck is a member over on mania knows mini history better than anyone. I wish he would join here. I picked my first mini up at his place in Seattle the seller had it stored there he has some amazing cars and knowledge. I might pm him with the question and a invite to here he doesn't post much over there anymore with the forum in the shitter.