Hey Guys,
The underside of my Z28 is rustfree and I'd like it to remain that way, so I've decided to tackle this as I await my LS1 to be finished. Initially I wanted to POR15 the entire underside. But the POR15 is formulated for painting over rust or bare metal with the Metal-Ready. So, in order to effectively utilize the por15 I'd have to sand the entire underside down to bare metal. That has now lead me to check out bedliners as an undercoating. I don't mind spending what ever I need to spend as I never plan to sell this car. (Doing this right means a lot to me) I have gotten 95% of all of the grease and grime off (not very fun, LOL) What do you guys recommend on a rustfree undercarriage? Oh, and I prefer it to be black in color. Thanks in advance for your help!!

 

A lot of guys have used the por 15 on thier undersides. I don't think you would have to sand to bare metal at all! That crap sticks to everything!

 

Thanks Eagle223usa for your response!! I believe it would stick ok and look great but my concern is the rust preventative benefit of por 15 that I would lose. Here is a frequently asked question and answer from their site:
Can I apply POR-15 over other paints? Yes, but you will lose the important benefits of POR-15. You must remember that ordinary paints are weakened by exposure to moisture. POR-15 can't stop rust if it isn't in direct contact with the base metal.

That's what is leading me towards a bedliner kind of coating. Plus I'd get more sound deadening and protection from rocks being thrown up. I travel a lot of back roads that are crumbling. Thank You PennDot. LOL. I keep going back and forth on this and that's why I posted this. I used por15 on my kmember and a-arms and they look great but that was bare metal. Either way I realize that it will be work involved, I just want to make sure I choose the method that preserves the car best.

 

Anyone else have any experience/opinions about this?? I'd really to hear several fellow thirdgenners thoughts on this!! Thanks!!!!

 

I like por 15 on bare, blasted metal it's great and won't come off...however i did use some on my 87 where i had some primer down first....the por 15 peeled right off when it dried.....i think if the underside of your car is really clean- as in you washed it with some degreaser and then really rinsed it off, i'd use some black rustoleum....for the suspension i would go with por 15- it has better chip resistance....i've painted control arms with paints other than por 15 and found the paint all gone from road dirt within a year or so...then it starts to rust....good luck!

 

Don't use a rubber compound like Herculiner or bed liner it's like putting a rubber bladder on the bottom of your car once it gets 1 pin hole whatever water goes in gets trapped. Had it happen to a buddy of mine rusted his flore out.

I would use some sort of paint. Rustoleum works great for stuff like that IF it's cleaned well.

 

I agree with hotrodln on the suspension parts

 

Dodgeman thats good advice cause I was about to use Herculiner as an undercoating on my car. I'm glad I saw this post.

 

Thanks a lot guys for your input!! I picked up a can of Rustoleum Professional High Performance Enamel spray paint today for $5.27 at Walmart and painted a metal panel of an old file cabinet. I want to see how it turns out and how durable it is but so far, it looks good and it sprays at any angle so that would helpful painting under the car. What do you guys think, should I buy a quart and brush or use spray cans like I got and should I go to the extent of doing primer too? I'm painting over the existing light blue undercarriage color. Here's a link to what I tested:

http://www.amazon.com/Rust-Oleum-757...741619&sr=1-14

 

i go through allot of that stuff..i do like to brush it on where i can because i think it goes on thicker....but where it's hard to get at then the spray is the way to go....now if you really wanna start having fun....find an aerosol sprayer top that fits the rustoleum can- one that you can put a straw tube on...like an old wd-40 can, or carb cleaner....now you can really get into small areas....try it!

 

That's interesting, it would definately get into the nooks and cranny's. I ran across some threads that guys are using farm/tractor paint to do undersides. I may check into that too. I want to exhaust all options before I settle on a specific gameplan.

 

Tough to beat media blasting followed up with a spraying of chassis black.
http://www.eastwood.com/chassis-black

 

Eastwood certainly makes good stuff..

 

Yeah POR 15 does not work too well at all over paint, I have tried it just to see. We just did my buddy's while jeep in Monster Liner. It is not rubber based and has a semi gloss finsih to it when dry. If it did get a chip it in, it will not trap water since it's a very hard finish. Monster Liner is awesome to work with and at some point I am going to do my whole truck in it as well.

 

Where do you get the monster liner? Sounds like some good stuff if it's a hard Finnish?

 

I want to find out more about that Monster Liner. Sounds interesting. I checked out the cabinet that I painted with Rustoleum and it came out nice and it seems pretty durable. I couldn't scratch it with my fingernail and I tried hard. LOL..

 

Please don't use Rustoleum on anything. Bed liner works great, but it you need to repair something it can be cumbersome to sand off and repair. POR15 and RustBullet are great products if applied over a clean rusted surface, they don't recommend application over paint. Love the Eastwood products as well.

 

Hello Haps, Thanks for your reponse. Why don't you recommend Rustoleum? Did you have a bad experience? I was considering using POR15 but I kind of ruled that out as my undercarriage has the factory light blue paint with no rust at all. I was worried about the effectiveness of por15 over existing paint. Check out post #3. I was considering attempting to remove the factory underbody paint and apply por15 but I'm not sure what the best way to remove the paint would be. I don't have a sandblaster and the car is on jackstands. And trying to sand it would be a b**** with all of the contours of the floor.

 

i would NOT spend any time trying to remove the factory paint under there....if this is to be a show car or summer only car, why not find a quart of rustoleum in a color that is a close match to the color of the underbody now? it would look great and impress judges if you took it to a car show.....then paint the suspension in contrasting black por 15??

 

I hate to remove that paint as well because it has held up this well for 29 years. And yes, this is a summer only car that is and always will be garaged. I like the black underside (personal opinion because I thought it would really make the tranny and exhaust pop) but painting it with like a rustoleum would only add another layer of protection in my opinion.

 

I wouldn't remove it either, especially if it's in good condition. Yes, I've had bad experiences with Rustoleum. It doesn't hold it's gloss and protect long term. Sure it'll be fine for a while, but why, unless you're flat broke, use an inferior product when there are much better solutions out there that accommodate both the short and long term. Assuming your paint is in good condition, I'd scuff it up, (apply a POR15 or Rust Bullet to the clean rusty bits)shoot it with a catalyzed primer and coat it with and Eastwood Chassis black, Hot Rod Flatz, or Hot Rod Black from SEM. That should give nice color with superior protection for the long run.

 

Once mine was cleaned and prepped I used an epoxy based paint, just like Eastwood chasis black

 

Well guys I ordered my Monstaliner kit and if all goes right my whole truck will be done it next weekend. You can only get it at www.monstaliner.com Yes it's very hard, kinda shinny and is very easy to work with, but I have never put it on the underside of a car. The suff is not priced bad. I got all the stuff to do my whole truck and maybe more than I'm gonig to need for $182.62 shipped as I got the promo codes-do a yahoo search. My truck is black and is a nice 20 footer, but the paint has alot of scraches from the PO and as all Rangers it's staring to get a few blisters and I sick of touching them up and having mismatched paint. The truck stay outside and is used in the winter so I wanted to protect it once and for all. Check out the web site and see what you think.

 

FWIW, I have also seen POR-15 peel on some of my projects too.
One thing that I’ve heard quite a bit with regular paint is that spray paint from a can is a totally different product than what you would use with an HLVP sprayer, and they can be had relatively cheap too.

I've been debating using Herculiner as well since I found some on sale at $50 a can. I knew that trapping water is an issue but never heard about that happening before. Thanks Dodgeman79 for the insight.

One other thing I was thinking about recently is the color, and was considering using a lighter color (white actually) to reflect the heat from the road during the summer. I’m not sure how much of a difference it would make but I’m assuming that black might absorb a lot of the heat from warm asphalt.

 

i think the white/black thing is from the sun ....i don't think it would help underneath, but it would look pretty dirty after one drive in the rain.

 

I have never heard of the rubberized bed liner getting a hole in it and then trapping water, I'm sure it could happen. Yeah white under a car is a bad idea IMO.

 

Mine is truck bed lined.

 

From what I know cars come from the factory with the same color underneath as they do on top and I've been under a couple of white cars and they looked fine to me.
I don't look under the car anyways unless I'm working on it so I wasn't really concerned about the aesthetics, just curious if the difference in color would make a difference in heat absorption from asphalt.

On the topic of trapping water, some people would bring cars from southern states and either try to add undercoating themselves or bring it to a place that didn't know how to apply it. The result was that the car would rust out faster because the way it was applied actually trapped water in places that it wasn't supposed to. I kind of took from the previous post that applying bed lining is basically the same thing and thought it was a valid point.

 

Hello guys, Thanks for all of the input. There are some great ideas and I appreciatte everyone taking the time to share their experiences and ideas and help me decide which direction to go. I'm kind of leaning towards paint (likely from Eastwood) The bedliner/ rubber undercoating has me concerned about the possibility of holding moisture if it would be penetrated or crack at some point. And I need to install the subframe connectors and the last thing I want to do is have to remove bedliner coating for the install. I want to do this soon as I have the motor, trans, rear, fuel tank, exhaust, and fuel lines off of the car. I'm going to make a decision in the next day or two and order. Thanks again!!

 

plasti dip

 

Lets hope you're joking.

 

haha, i waiting for that response. Just a joke lol.