The weather cleared up for a few days recently so I was finally able to do a little bit of rust inspection/cleanup in the front driver wheelwell. In doing so, I discovered that the rust I knew about was just the beginning (no surprise there), and that there was quite a bit of rust underneath the rubberized undercoating.

I began peeling off the stuff in one area where it seemed loose, and it came off in several rather large swaths, but became much harder to deal with at the edges (much like peeling off sunburnt skin).

In a couple of places that seemed "moist," I dug in with a blade and managed to break adheasion, only to find more uglyness.

That undercoating can hide rust very well indeed.

Here are a couple sets of photos to show ya what I mean.

I am curious as to how everyone has managed to remove their undercoating.

To deal with the rust on a temporary basis, I applied rust convertor religiously to the area, after cleaning it with prep all (both products by cleanstrip). Since the fenders were off at the time, I did the same to them, the hit them with (1) rustoleum primer and (2) regal red topcoat.

The undercoating on my Z appears to be a petroleum based product. I use a small angle grinder , like a die grinder , with a disk that has small ''fingers'' and is made of rubber with some sort of grit mixed in it. They come in yellow and green and brown I think . The different colors are different in coarseness. For me green worked the best. They remove paint and rust too. Any auto paint supply should have them. The disk doesn't clog or gum up. Harbor Freight has the angle grinder for around $20.00. I is great for tight places . Gary:rambo:

As the converter works, it turns the iron oxide black(ish), and provides a good primer after curing for about 24 hours. Next on the list is a good spray primer, then rattlecan black to seal the primer. Of course, some of this will be nullified during the welding process, but who knows when that will be.

Gary, thanks for the tip, and the excuse I needed to get a grinder :stupid:

My undercoating seems to have some foamy substance in it, hard to explain, but the stuff is really tough. I'll try to get some detail photos tomorrow of the it.

Petrol and a pot scourer pad will dissolve the stuff too, after you've scraped most of it off.

With the rust converter. I use that, wait a day or 2 for it to do its thing, then hit it with a wire brush attachment in an angle grinder, then repeat the process until there is no rust left.

A heat gun and a plastic or wooden scraper works well to get the undercoating off. Then a little solvent to make it pretty.

guys, i am new at this and wondering if my car is set up to rust also. the fellow i have helping get my z back together, sprayed the undercoating all in the fender wells, and also underneath the car. (this was done without even asking me if i wanted it or not) not sure what product he used, it came in a spray can. the car was rust free, as best i could tell, before applying the undercoating. now you have me thinking i need to remove all of this and start over.

I did all of my wheel wells with a heat gun and a scraper, then solvent and a scour pad to get the rest off.

zak

I am NOT fan of any rattle can paint or primer for this fix. There are some great products available that will do a great job of sealing these areas to help prevent further rusting action. If applied as directed by the manufacturer I recommend using one of them. Rustoleum IS NOT ONE. Any regular primer is not acceptable either , for me. Personally I use and have used POR and have been vary satisfied with the results. I know there are others but I haven't used them on my car. POR cures extremely hard and will deflect rocks better than any paint I have ever seen . It brushes on and cures like it was sprayed. Do not use any short cuts or substitutions on the prep. The company make several products for use on rust repair and various applications on Cars I have used several and have them to be good products. I have heard of Rust Bullet , and a few others . Since I haven't used them personally I cannot comment on them. There is plenty of information in the threads . If any one wants more do a search , or send me a PM Gary:)

Absolutely, Gary-the car will be recieving a healthy dose of POR15, once the rails have been replaced. What I am doing is just a temporary fix until it can be done right, and done at one time.

Sleepyzzz-It might be a good idea to remove the undercoating so that you can see for yourself the condition of the metal, then treat them with POR or some similar substance.

I have seen the ?Rustoleum rust converter stuf in the rattle can at the DIY store, and I've used it on the kid's wagon, but I wonder about using that on my car... OTOH, at the auto parts store, in the paint isle, there was a Permatex product, but I have never tried that.

thx