dvsmode

I see this on alot of 7's. The damn brake master cylinder overflow or leak overthe years cause the cylinder, subframe and driverside wall to rust.

I will be sanding down the subframe rust. What grit, In order, should I follow before I paint It? Any addtional tips? Thanks.

DigitalSynthesis

Sandblast it. I promise you it will go way the hell faster, might cost less if you have an air compressor already, and gives a much cleaner surface. I have a writeup somewhere around here on the way I did my subframes, underbody, trans. tunnel, and engine bay. Of course you can't do much of that unless you actually remove the engine, etc.. from the car so you don't get sand in it. Whatever you take out, blast in a place that is sealed off, or blast outdoors with the garage door shut. Trust me, you'll still get sand everywhere anyway. But then, just blow off the sand, don't bother messing with the surface unless there is still rust you didn't blast off in which case a quick phosphate treatment and re-sandblasting (after its dried) will take care of you.

Use a killer primer, like an epoxy (I useds PPG DP90LF which is a black, very sticky, and very corrosion resistant primer that costs a LOT - $50 for a quart and a half, but that will do the entire car and then some). Topcoat with an epoxy paint. I used VHT's rattlecan for the topcoat (SP-650 I think) which seems excellent.