In one of the areas where my sub frames over lap the rocker theres seem sealer and its behind the subframe the sealers really close to where its going to be welded and i know once it start getting welded the sealer is just going to melt away and serve no purpus. Its a seam so it should have some type of sealer to keep water out etc. . .
so i was thinking of taking off the sealer and cleaning up the area to bare steel and JB welding the seam.
iv never used JB weld before would that do the trick? the whole idea is to keep water from getting up in that area

 

I've always used JB weld to fill holes in metal so I don't see why it couldn't be a type of sealer. I would suggest a protective coat of paint/undercoat to go over it. I am also assuming you will do this after you weld the subframes in.

 

It's your car, you can do what you want, and others may tell you differently, but I don't recommend JB welding anything on a car.

That seam sealer is there for one reason. To keep water, air, and condensation from going in between the panels, or inside them. Water trapped inside will eventually cause rust. Air is the main cause of rust. The oxygen in the air breaks down the steel.

Those areas were most likely sealed because the metal inside is either not painted properly, or not painted at all. Most likely because of a weld surface or something along those lines.

If it were me, I'd carefully prep the area like I would for paint, and then reapply seam sealer.

Either that, or completely weld those seams closed, guaranteeing no water or air will get in.

Here's a good discussion to read from another board where I addressed a similar issue: http://www.chevytalk.org/fusionbb/sh.../post/new/#NEW

Mainly as far as JB goes, I just don't think it's the proper application for this job. I will always consider it a hack, and not a proper body repair. It has its uses, moreso in hobbies and for less industrial men to make minor repairs, but there's really no substitute for doing things the right way.

Mathius

 

i agree with mathius. i would rip the seam sealer off and stitch weld that area then paint it and cover it with seam sealer then paint it again. i recomend POR15 as the paint.

the JB weld is hack jobing it. seam sealer is rubberized and flexes with the body/panels it attaches... keeping the seal. JB weld is not a flexable media. dont do it half ***. weld what has to be done then paint it, then seal it then paint it again and call it a day. u'll thanks us in a few months when that panel doesnt rust out on u again and then u gotta rip all that JB weld off.

 

the area where the seam sealer is now is right about where the subframe is being welded so any paint or sealer etc is just going to pille or melt off behind the area.... iv never used JB weld i was just asking if that would work as a sealer but not melt when it got hot like seam sealer

 

im pretty sure it'll melt. the welding creates sumthing like 2000degrees or more. i mean it gets hot enough to melt metal so i would think a chemical like JB weld even if u look at it its still a epoxy, in liquid form then hardens just like epoxy. i would still use seam sealer. im not totally sure where on the subframe your refering to but most points on the car can be reached from the outside or inside of the car.they only used seam sealer on parts of the car where they could reach after being assembled so u should have room for it. if not, seam sealing on the outside should seal it enough

 

I really don't understand the point of your question. If the seam sealer melts, then you reapply it. If it's in the area where you have to weld, you have to remove it first with a wire brush and/or sander, otherwise your weld will contaminate and probably be worthless.

I understand the point of why you want to use JB weld instead of seam sealer? IIRC brush on seam sealer is like $10 a can from J.C. Whitney, so I presume auto zone or one of those type places will have something similar around that price range.

Mathius