Here's what is (was) under mine after I chipped it off. This is what is estentially a rust free South Texas car. I hacked this all out last night. So now I am putting in new 3X2X11 Gauge tubing "subframe connectors" to replace the frame rails and a new floor. Lots of welding ahead.

Rust at the frame rail seams ..

And cracked frame rail at the passenger side firewall. This didn't start happening until I started autocrossing my car.

Those are some ugly photos, John..

that things an arizona cream puff in comparison to what we end up with here on the east coast.

Hey Kevin, that picture is downright disturbing. Makes me wonder how long the car was being driven like that. In my 20 years of being into Z's I've never seen rust like that. Not even here in Nebraska, the Rust State.

yeah this thing was about as swiss cheese as you can get. Def the worst one I have ever seen as well. Scary thing is that this one was already restored years ago. Perfect example to the newbies attempting crappy and inappropriate repair methods of what can happen.

Only you can prevent this from happening to your Z car!!!

From the inside of my car, there wasn't even a hint of the rust that was under the undercoating. Not until the interior sound deadener was completely removed so you could see the telltale pinholes of light. Note that the rust is concentrated at the seams where the frame rail was welded onto the floor and nowhere else.

You can see where that other car had it's floor pans replaced before. Hard to imagine.

That's nothin! You caught it just in time! Yea, that undercoating does deceive, but you have little to worry about. My encouragement!

Now, you may be having some problems inside the frame rails and I suggest you drill holes in the bottom of the rails to clean out what is inside and inspect. Best of luck. :classic:

I think I'd be tempted to either replace the whole floor pan, or at least a strip down the center where you will be welding the new rails on. It looks like the rust has weakened the floor pan for at least an inch on either side of the frame rail.....

Maybe it will look a little better when you get it stripped off better on the underside... let's hope it doesn't get any worse.

Agree. Interior was already stripped down to the paint. I took these pics last night just to document what was there. Then I took the sawzall, spot weld breaker, cutting wheel and pneumatic nibbler to the passenger side and removed the offending metal starting from just behind the T/C bracket all the way back to behind the pass seat so there is no going back now!

Next I'll be fitting in a 3X2 steel girder, I mean tube as an upgraded frame rail. The drivers side is good, but I'll need to do both sides so the car doesn't sit lopsided!

Most of the floor will be replaced, whether it needs it or not, as I find I can fit sheet metal to the structure easier than I can fit the structure to the sheet metal.

I'll post some more pics this weekend if anybody wants to see what I am doing.

Is is correct to say that alot of that floorboad rust is from the car "sweating". I know in my 78 280z I could never keep the floor mats in because the floorboard area seemed to always be damp after running the car for a while. I also had a Mustang that did the same thing.

Vicky

Probably not sweating. This is the only place in the car with anything like this. This happened under previous stewardship and I suspect the root cause was a chronically leaky drain tube/hose from the cowl. If you haven't pulled a dashboard, you might not know it was there. I didn't and discovered the leaky tube after pulling the dash.

The cowl collects water and drains into the inside of the car and then is passed out the side of the car by this tube. It looked like years of rubbing on the heater blower housing made a small hole in it. The water collected in the frame rail and didn't drain due to the drainage hole plugged up with mud, etc.

Aint rust a bite in the arse! That is wht I am sealing both sides of the floorboards! Glad you caught it!

Will