Well i have my 85 salon an I have a bit of a prop with rust.The person i got this from had this car sit for over 3 1/2 years so there is a good amount of rust on the under belly of this car.The floors have NO rust butt every thing els does.I went under the car yesterday an start banging on the frame an all and found no soft spots just a lot of surface rust.......I don't want to take the car off the frame cuz i want to drive an fix the car if you know what i mean.So would sand blasting help me with this prop or would i need to remove the car from frame?

 

what do you plan to do with it? if you just want to keep it as a driver i would just try to brush off as much as you can and just get about 10 cans of rubberized undercoat and spray it the way it is. sand blasting would not be a good idea if you were not taking it apart. if you sand blast it you will have to get an etching primer and if you missed a spot that was blasted you will have it rust 2 times faster. someone may give better advice but just giving my 2 cents.

 

Rather than undercoat, I would strongly suggest POR-15 or a similar coating. These rust conversion coatings actually bond to the rust and convert it chemically. Undercoating simply retains moisture.

Also, be aware that the G-body cars have a particular problem with the boxed rear frame rails. They rust out from the inside. If there's any way to spray a coating on the inside of the box section, you'll be in a lot better shape.

 

I used 415 on the underside of my car with body on. After a year it still holds its luster as if it had just been done. Sand blasting is fine but you still have to put something on the bare metal to stop it from rusting again. The way I did the process was to first remove every thing under the car ( Axle,Trans,Rear end etc,). I got the car up as high as it would go with jack stands and got underneath it with a power washer. the power washing part was probably all of 4 hours with lots of Gunk,soap etc. Once it was clean it gave me a goodlook at the underside of the car for rust holes,pin holes etc. I let it dry overnight and started in with the 415 the next day. One thingant to remember though 415 id very toxic and if you breathe it you can cause damage to your lungs. Secondly get an old ski mask for your face because any thing that 415 touch's becomes permanent. I have a pretty big sandblaster and most things like a arms I sand blasted first then used 415 on them.

 

ok so i do have a sand blaster i can use an I can get it jacked up pretty high.+ a power washer.I was thinking of using Rust Bullet RBA52.An yea i know of the rear rails on the g-body cutlass. that 1 of the first places i checked to see if it was getting soft{: