Novice needs help w/firewall chassis paint
 

I need some quick opinions/help. I'm doing an LS swap, have finished the mock up and now am in the middle of preping the firewall and frame for paint. I've welded in a block off plate for the heater and a few other areas. I am buy no means a body man but am a good fabricator and very fussy about getting things right.

As long as I'm at this point I would like to smooth the firewall. I've already spent way too much money and want to take care of this myself. My questions are very basic. I'm assuming I sand down the high spots - ridges of spot welds and so on, and then use a thin layer of filler to smooth out so....

To do this work, should the entire firewall be sanded to bare metal for the filler to stick?

This will be a rattle can job, what primers, paints are recommended for the firewall and chassis. I do not want a gloss finish.

I've done a few searched with limited results. Your quick response is very much appreciated.

"rattle can" and "doing it right" don't go together

Well... I asked for opinions and I guess I got one. Not everyone is capable of spending 30 grand on their pro-touring transformation, if it was limited to those who could only do it perfectly or not at all this hobby would be dead.

Let's see.. I spent 8 G on the car, 2 g on brakes, 3 g on rims and tires, 2 g on the suspension. 3.5 g on the LS donor and much more. I can't pay a body man this year too.

There's got to be middle ground here guys. I would really appreciate some help here besides carting the car to the nearest body man. If it means buying an inexpensive paint gun then so be it, I'm capable. I just need some of the wealth of knowledge easily shared on this forum.

Thanks again in advance.

I had pretty good luck with Por-15 and their chassis black paint and brushing it on with 25c foam brushes from Osh.

Before:
http://i328.photobucket.com/albums/l...e_After001.jpg

After:
http://i328.photobucket.com/albums/l...e_After002.jpg

Just did my interior floors as well:
http://i328.photobucket.com/albums/l...orFloor014.jpg

(Before shot)
http://i328.photobucket.com/albums/l...orFloor002.jpg

Also painted my trans and rear end the same way:
http://i328.photobucket.com/albums/l...ssion016sm.jpg http://i328.photobucket.com/albums/l...pension021.jpg

Engine block:
http://i328.photobucket.com/albums/l...Engine001z.jpg http://i328.photobucket.com/albums/l..._Engine029.jpg

Trunk is next at some point.

For the do it yourself guy w/o access to a good air system and spray gun, Por-15 is a nice alternative (can also be sprayed).

One thing thou prep is key and killer don't bother if you aren't going to follow the directions to the letter and make sure everything is perfectly clean. The slightest grease and it will peel off in sheets. Nice thing thou when done right its bullet proof similar to powder coat. Solvents and hammering on it won't phase it.

Another option might be Eastwood's Rust Encapsulator and Extreme Chassis Black in aerosol had good luck with small parts done up that way.

Eastwood Chassis Black

Looks great! Thanks for the detail on your response. Sounds like both POR 15 and the Eastwood product would work well on the floors and chassis. As I mentioned though I am going to smooth the firewall, will these products adhere well to a little filler as well?

Thanks again.

I usually rough up the parts I paint with some steel wool or 400 grit emery cloth, should be fine if you are willing to do the same.

POR-15 is a great product, but I have had it flake off of smooth surfaces before. I did used the Marine Clean and Metal Ready before applying. It also requires a top coat as it's not UV resistant.

As far as what it sticks to, the manufacturer would be a good initial source for recommendations. But I would try it out on something first and see how well it holds. Here is a link to their website, scroll down for a quick example of how to prep it and then look at the information sheets below that for more information you'll need to know. >Link
(Note that the Metal Ready leaves a zinc coating, so I doubt that would stick to filler.)

As far as the comment on the rattle can, from what I understand, the formula or type of paint is not as good as what is sprayed. I have heard of paint shops filling individual cans though, but I haven't tried this option and I'm pretty sure it's expensive.

Over all, I understand not having funds, but if you take a step back and consider how much you've already invested in this, and the fact that it won't be as assessable as it is now, then doing the job right would be at the top of my list. Personally, I would probably try the POR-15 having prepped it and then do a scrape test on it before applying a top coat to it. Be careful of areas with smooth surfaces especially if they've had grease on them before as it's my understanding that metal can leach oils even thought the surface may be clean. I have heard of powder coating places heating parts to get rid of residual grease as well.

With Por-15 I think its less to do with a smooth surface and more to do with not being completely clean. My engine block was the first item I used Por-15 with and I had to redo around the oil gallery plugs as there was some grease that leaked out which resulted in Por-15 coming off in patches. Once I recleaned and repainted it was fine.

I had no issue with Por-15 sticking to my floors and they were pretty smooth (though roughed up with 240 grit)

http://i328.photobucket.com/albums/l...nterior006.jpg

But I spent weeks getting where I thought they were clean enough for por-15. Then used boiling hot water to reduce the Marine clean and a stiff wire brush several times to get any remaining grease off. In my experience you have to have the surface crazy clean or don't bother, since it will just come off in sheets.

And you have to topcoat when your finger still drags on the por-15 otherwise you need to reprep the por15 surface so the topcoat will stick.

Great information guys. I can relate to what has been said about POR-15 surface prep and peeling. Last year I spent countless hours prepping the bottom side of my 5 foot mower deck, doing everything by the book and coated it with POR-15. It came off in sheets in less than three weeks. I gave up. That being said I'm a little gun shy of using it. I'm torn on what to do here.

As far as finishing the job by a professional, I plan on having the car repainted within a couple of years and will have it done right then. Meanwhile I should be able to make it look pretty darn good myself. Besides, the suspension is all off as A comes before B so to put it back together just to take it someplace is not something I have time for.

To use any filler, does it need to be applied to bare metal or can it be applied to a roughed up existing paint? I would assume to "do it right" it should be bare metal correct?

Thanks.

I don't know about filler, but for my floors I put down Por-15 first then seam sealed and the seam sealer didn't have a problem sticking to the por-15, nor the top coat to the seam sealer.

As far as prep goes, for por-15 this is what I do:

1. Usually paint stripper or wire wheel down to bare metal.
2. If any rust is present I wire wheel it off.
3. Get metal as clean as possible using the wire wheel.
4. Then rough up with 240-400 grit paper.
5. Then I use their marine clean (not laquer thinner or any other solvent) cut with boiling water and go over the area 2-3 times, let dry thoroughly.
6. Then start with Metal ready, 20 minutes or so till the surface turns cloudy then rinse and let dry.
7. Apply por-15, allow to dry till only slight finger drag.
8. Now a 2nd coat of Por-15 same deal with allowing to dry.
9. Then seal if needed then top coat.

Works very consistent now. I was still apprehensive about doing my floors (since I spent so much time cleaning them up) but I really scrubbed the heck out of them in step #5

Hmm, I didn't wire wheel the parts that flaked, or use hot water on it, so that may be why mine didn't stick as well.

I haven't seen anyone specifically address "smoothing" the firewall.

You can certainly use a little filler over the spot welds and slight waves....but that's not gonna address the numerous holes and that giant seam running down the top few inches of the firewall. Filler will not fix those. Doing the firewall "right" which means lots of cutting and welding... any filler over that now would have to be "mudded" on (bad) and would be over a seam (bad) and would probably crack pretty quick (bad).

My suggestion would be to just clean up the spot welds and smooth those out....and leave the seam alone. Clean the heck out of everything and shoot a coat of satin black and it will look very good. Clean up and detail the wiring and hoses under the hood and it will look better than it came from the factory.

That'll cost ya nothing but some time and labor and a few bucks in paint and it won't come back to haunt you shortly after the car is back on the road.

Filler doesn't work like plaster.... at least not when done right.

-R

Yah, I know mudding the seam would be a no no with cleaning out out and probably welding it up. I've already welded in a plate for the heater hole - going to aftermarket heat/AC - still need to weld up the fan hole and a bunch of small ones. I'm quite good at getting it all even prior to any mud. I just haven't mudded before.

Thanks

Get yourself an affordable HVLP gun and single stage paint....you will be suprised how well you actually can do! And it will turn out a lot better than a spray can.

I would strip the firewall to bare metal first, finish welding up your holes...then move to filler. Probably start with a thin layer of Bondo and then move to a glaze...and finish with blocking out primer, clean it, tack it off and paint it.

There are like a million magazine articles covering this stuff...I think Hot Rod has a good paint article this month. You will be fine, just get a plan together and don't rush it!