Hey guys I have an 89 GTU with some pretty rusty rocker panels and some rust on the frame rails (although they seem to be ok). I bought the car as a track machine and thus I didn't pay a lot for it so it doesnt need to look pretty I just want some good fun years of track and hard weekend street use out of it. So instead of fixing it up the right way and cutting everything out and replacing it I am looking for a way that will slow the rust down so I can get some fun out of the car. I was thinking about grinding a lot of areas down applying a lot of por-15 to everywhere I can reach and using a closed cell urethane foam to fill the frame rails, rocker panels and most other open structural voids in the car to stiffen up the chassis and slow the formation of rust. This is the foam I am thinking of using.

http://www.shopmaninc.com/foam.html

It seems like high quality stuff. I actually tried to use it on the subframe connectors on my maxima, but it was too thick to pump through any sort of tube into the subframe connectors, also it sets very quickly (45 seconds) so its hard to mix and move large quantities of it at a time.

I was planning on using the 8 or 16lb stuff in the frame rails, and that lateral brace behind the front seats under the storage bin, and some 8lb stuff in the rocker panels.

From there I would have to see if any wires run through the pillars, and if it seems like they are possible to do I'de probably do them too.

How do closed cell foams work with rusty areas? I am pretty sure they will keep any water out of those areas, and as long as the rusty areas are dry when the foam is applied it should stop any further rusting.

 

Covering the rust will do nothing, you need to remove any rust if you wish to stop it. Cut out the affected areas and replace with rust free metal.

Then you can foam.

and your bump was deleted. Bumps are forbidden here in the 2nd gen tech section

 

Duely noted

Thanks for the info

 

POR-15 will stop the rust from spreading, but of course to actually FIX major rust you need to cut it out and replace it. Then coat it with POR-15 to prevent it in the future.

 

I had the same issue. My frame rails were good, but the floor pan and rockers had a fair amount of rust. Well... the rockers were pretty much toast. I cut out all of the infected areas, then filled 'em with foam and covered the visible rocker holes and floorpan gaps (which were no bigger then 2" after cutting... and not in any place that could cause seats to come loose or anything like that) with fiberglass.

After all that was done I repainted the rockers, undercoated the rest of the car and it hasn't rusted through again two years later. I autocross it too and haven't had any abnormal chassis flex and all of my repairs have remained in good shape (so they aren't flexing causing cracks, etc.)

 

What kind of foam did you use?

 

An FYI - foam will ACCELERATE the rust as it will hold water against the metal.

Go big or go home on this one.


If you intend on using it on the track, I'd highly recommend fixing it the right way because if 1 scruteneer at the track spots pooched rockers filled with spray foam - they'll boot you out of there faster than a fat kid on a smartie.

Its really not all that difficult to repair rust and make new rockers, they've gotta be one of the easiest shapes out there to re-produce. Hell, even riveting on new steel over the rusty areas will be better/more structually sound/pretty much just as easy as foaming that poor neglected biatch.

But do what you like, its your car.........

 

I think your grouping all foams together in one bunch when there are great differences between them. The foam I am using is high density and has a great deal of structural strength. It also is meant for marine applications and wont break down or absorb water. Its deff not your typical home depot foam.

 

i cut a large amount of rust out of my rear rockers and fender

and then treated the rust with a neutralizing agent

and then filled them with foam

and then encased it with fiber glass and resin

and haven't had a problem sense

the fiber glass can support the weight of the car as i found out when it slipped off the jack and he fiber glass section landed on the jack...

 

no no, trust me. Im a body man and own a body shop - Ive seen it all. In fact, we also do work on boats here at the shop and don't think I've never had anyone get any ideas about the two part foam used to fill boat transoms...

The point is that any foam will hold water against the surface of the metal...not whether or not the foam itself will hold water. The foam will NOT (any foam) seal as water tight (when takling about metal/corrosion) as panel bonding or a solid weld. And there's no chance foam by itself will be anywhere near as strong.

And the point still remains that if you're caught at the track with a cobble repair like this (the can see alot of things, duct taped bumper, and so on, but structurally the car has to be good....and rockers fall into that category) they WILL kick the car off the track.

But as I said, you acn make your own decisions, Im just warning you.

 

You gotta cut it out. Why do you think they call rust "chassis cancer"/"body cancer"?

 

Wire-wheel all the surface rust out to see just where all the HOLES are. If you can eliminate all the surface rust (meaning make it shiny silver again) and there's no holes, you don't have much a problem. If they're small holes they can be patched with small peices of metal, or just welding if they're very small.

After that primer and use some sort of undercoat (they sell it in cans if it's just a little bit you need...black of course).

 

can anyone tell me the best way to repair my rocker panels and wheel wells and info will help im a grease man not a body man and i have a bit of rust on my fc