Hmm so perhaps the wire wheel i got was too whimpy. it goes on my drill and its prob only like 2 inches in diameter. i got it from homedepot. is there a wire wheel you suggest or a specific size one??
I thought that might be the case. As I said earlier, a heavy wire wheel on a grinder will blow right through any surface rust or thin under coating.
Now that you've used it, you probably understand my statement earlier about wearing safety glasses or a full face shield when using a grinder with a wire wheel. It's moving A LOT faster than a drill and those individual wires do snap off from time to time. They sting a little when they hit your arm so I have no doubt they'd go striaght into an eye.
Also remember to keep the wire wheel such that it is pulling away from you at all times as opposed to driving toward you. And watch your shirt sleeves or any loose clothing as well as the power cord itself. Grinders don't play around. If it catches a sleeve, your arm will be tore up be fore you know what happened.
By the way, did you see the sanding disc adapters for the grinder? You'll need that if you really want to smooth your frame out. There are lots of burrs and edges on the frame from the factory besides the pitted areas. As far as removing any pitting, keep in mind that you are working on your frame, the structural part of the car. Don't go crazy trying to grind out/remove deep pits as you will simply weaken the frame by making the metal thinner. If it has some pitting, just hit it with the wire wheel to scuff down inside the pits and then smooth the frame in general with 80 grit and then apply some body filler or fiberglass to fill in the pits. Then sand that smooth with 220 grit.
I have three grinders simply due to the fact that the wire wheel, sanding disc and grinding wheel(stone) are all needed when doing a job like this and it's a pain to have to keep changing out the wheels/discs.
You'll have that frame done in no time now.
Have fun,