I've been slowly working on the underbody of my car since last fall.It's on a rotisserie, and I have all the udercoating scrapped off.I can see some light surface rust on the inside of all the braces.I have used some long metal wire brushes(sort of like oil galley brushes,but about 1 in. in diameter)To try and knock off as much of the loose rust that I can, then blew them out with air.What is the best way to get inside there and keep that rust in check? Any and all opinions welcome, Thanks in advance, Don

That is the same issue as trying to get inside the frame rails. When I did my underbody last year, I just cleaned it up as good as I could. If you supect a lot of grease in the rails, you can try cleaning them out with something as simple as brake cleaner. I my case, I had pressure washed the underside thoroughly before stripping it and flushed those areas with degreaser and then water. Short of cutting the floorpans open, how much can you really do. Once clean you have to address a coating of some sort. Some guys use undercoat, I just sprayed mine with RedOxide primer. May sound crude, but I used a spray nozzle that had an extended stem (brake cleaner for instance) installed on my red oxide spray bomb (plain old Rustoleum) and just shot it in there as best I could.

That's about the only option I have right now. The braces don't have any grease inside that I can see, just dry and thin rust.Might try Eastwood's rust encapsulator aerosol can and see if I can rig up a long tip nozzle. Thank's for the come back! Don :cool:

What about the "undercoating" system from Eastwood? wand (http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=10966&itemType=PRODUCT&iMainCat=373&iSubCat=376&iProductID=10966)

I am also in the proceess of cleaning down the underside and still somewhat clueless as to what I will use to recoat....POR15, Eastowood RE, good old rubber undercoat....and how to get in those how to reach areas.

If you can do it, I pressure washed the underside of my body with a gas powered pressure washer and degreaser. It really blasted dirt out of every crevice. I then hit it with a knotted cup on my 4" angle grinder, primered and painted with an industrial enamel. I think you can get a little overt on some of this. The big issue here is to get rid of all the contaminants and road salt residue. Obviously the best thing would be to dip the body to clean and then flood the remote areas for corrosion protection. That said, the next best thing is to get it the best you can. As long as you don't run it through salt baths, it will last a long time. I just saw the underbody of a buddy's '64 GTO ragtop that we did 24 years ago. The car has been driven annualy 2000 - 3000 miles per year and the chassis still looks good. Good enough that the car is going to get a repaint and another run through the 389 tripower motor, but the chassis will not be touched other than some cleanup of overspray.

Pressure Washing graemlins/thumbsup.gif then prep an paint. My 68's underside still had the original paint and virtually no rust (thanks to the road grime, no doubt). All I had to do was touch up a spot or two and use underbody coat. What you choose is a matter of preferrence I suppose...

(sorry to hi-jack the post)...Pressure Washing??...how does it do on taking off the undercoating? I just bought about a pressurized 10 gallon blaster...maybe blast a bit for the rust and tough stuff, but rely on the power washer to cleanout all the media and maybe the majority of the crud on the underside?

some auto paint shops have a product thats a lot like ziebart-(i think 3m makes it) it comes in a spray can, and you use the small tube that comes with it, and spray it in the hard to get places-it kinda runs and covers everything with a wax like coating
my floor rusted out above those braces, so i know its a problem area

I used the pressure washer and degreaser both before and after I removed the undercoating. First to remove all the road grit and dirt, after to blast any reaming dirt from the crevises. Maybe overkill, but did it anyway.

...did the power washing take off the undercoating?