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Rust prevention for troughs

Printed From: TheAMCForum.com
Category: The Garage
Forum Name: Body/Interior
Forum Description: Paint, glass, interior, rust, sheetmetal goes here.
URL: https://theamcforum.com/forum/forum_posts.asp?TID=108407
Printed Date: Feb/24/2021 at 11:37am
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com


Topic: Rust prevention for troughs
Posted By: BU1
Subject: Rust prevention for troughs
Date Posted: Nov/27/2020 at 10:13am
AMX #2 is due back from the blaster soon. What are you using inside the troughs? Is POR 15 still the go to product? Looking for some options. A brushable product would be nice, as I will have to apply with a brush under the gussets at the back of the trough on a 68.  Thank you.

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AMO #2726
1968 AMX Rally Green 343 4spd since 1975
1968 AMX Rally Green 290 4spd since 2019



Replies:
Posted By: hassyfoto
Date Posted: Nov/30/2020 at 4:34am
Like most things on the car, what is the projected use and will the car sit out in the weather. The factory did not always add underlayment's (primer, sealant, e-coat) and/or paint. Combine thinly painted to no paint on sheet metal and several decades of exposure and lots of rust. 
With that said,
Correctly cleaning, primer and paint will perform the functions that you are looking for. By that I mean the car will most likely be garaged kept, will not be driven in bad weather and well maintained. Since the complete vehicle will need paint, this is an easy option. As far as rust prevention materials, they have their pros & cons. I would suggest a little research on the topic before you use these products vs paint. Yes, I use these certain projects and other times I prefer to repair, primer and paint the sheet metal. If its a cavity, like a rocker panel, i will add additional products such as rust prevention after paint.

You also asked if POR 15 is a good product. It is a good product amongst many for it's intended use. But it's use has limitations and certain warranties. I still suggest to everyone to carefully read the product description(s), intended uses, and warranties.

Finally, my answer is, the easy method is not always the best. Rust converters, rust sealers, rust preventers, etc.. may be great for a short term repair, but not necessarily the best option(s) for a full restoration and a vehicle you plan to keep for a long period of time.


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Murphy's Law:
Any given mechanical job you decide to solve alone will imminently require a third hand, at its most critical moment



Posted By: Steve_P
Date Posted: Nov/30/2020 at 8:07am
Since you are having it blasted, I would epoxy prime it and add some sort of topcoat. It doesn't have to be expensive, a few coats of acrylic enamel would be fine.


Posted By: turbo
Date Posted: Nov/30/2020 at 8:11am
POR 15 is great but must not be applied over a smooth, non rusty surface.

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they call me Capt RETIRED!


Posted By: JGRANTAMX
Date Posted: Nov/30/2020 at 8:53am
 I used POR-15 20 years ago it was properly applied to clean media blasted steel I still own the vehicle that's been parked in a dry garage all theses years never driven in the rain and rust is showing through, the stuff is garbage I wouldn't use it for free. To think rust can be covered over and it's gone is wishful thinking, there is no substitute for doing the job right if you want it to last, media blast, self etching primer or epoxy primer then urethane primer and a color top coat. I know several others that had the same results and a professional body man that won't use it. The only time POR-15 works is when you are sending it down the road.

J


Posted By: BU1
Date Posted: Nov/30/2020 at 9:20am
Thanks to everyone for the replies. The hard part is what to use to get coverage under the gussets? Are there brushable primers?

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AMO #2726
1968 AMX Rally Green 343 4spd since 1975
1968 AMX Rally Green 290 4spd since 2019


Posted By: Trader
Date Posted: Nov/30/2020 at 9:42am
If this is a driver and not a show car, you can apply a rocker seam oil or similar product that will creep into the area and displace moisture to prevent rust. I use a high tack rust preventative chainsaw oil, as it's a lot cheaper. If you use it in you doors, it will actually creep out around and up the outside of the door. Great stuff to get into places you cannot, but then you have to clean off the excess that tries to get into and around visible panels before it collects a lot of road dirt.


Posted By: 71SC360
Date Posted: Nov/30/2020 at 10:11am
Originally posted by JGRANTAMX JGRANTAMX wrote:

 I used POR-15 20 years ago it was properly applied to clean media blasted steel I still own the vehicle that's been parked in a dry garage all theses years never driven in the rain and rust is showing through, the stuff is garbage I wouldn't use it for free. To think rust can be covered over and it's gone is wishful thinking, there is no substitute for doing the job right if you want it to last, media blast, self etching primer or epoxy primer then urethane primer and a color top coat. I know several others that had the same results and a professional body man that won't use it. The only time POR-15 works is when you are sending it down the road.

J


I second that!

We were POR-15 dealers at one time. After selling quite a bit of it, we did some of our own testing (quite a few different projects) we were not impressed with anything about the product and quit selling it. Needless to say, I will not ever use it an any of my projects.


Posted By: turbo
Date Posted: Nov/30/2020 at 11:17am
You are not supposed to put it on clean steel!  

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they call me Capt RETIRED!


Posted By: mbwicz
Date Posted: Nov/30/2020 at 11:18am
Nothing says that you can't take a self etching primer and brush it into the places that you cant get to with a gun. Just work it into the seams and corners to ensure that you get complete coverage. Do that area first, then spray the surrounding metal that you can get to.

She has survived almost 50 years, I'm sure that it will have better conditions for the next 50!


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1970 AMX. Holy Crap its easy to spend money on this car!


Posted By: First_Gear
Date Posted: Nov/30/2020 at 5:03pm
I did this on mine. They were in good shape still galvanized! I had the fenders off and had to remove them to get to the cowl. (Inside of my cowl was swiss cheese) I lightly sand blasted them, welded them back on and applied spi epoxy followed by restoration shop 2k urethane (under hood black) recaulked with brushable seam sealer and replaced the rubber seals. I don't expect problems for the rest of my lifetime. 

Here in rainy washington you gotta make your cars water proof or be willing to let the car sit for 10 months out of the year. 


Posted By: Joelfanti
Date Posted: Jan/20/2021 at 11:00am
Look up SEM rust trap. Urethane coating that I’ve used all over my Javelin. It amazing stuff. If you want pictures you can message me. I’m not up to 30’posts yet so I can post yet


Posted By: george w
Date Posted: Jan/20/2021 at 11:44am
Don't forget to paint/treat the underside of the front fenders above the troughs.

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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.


Posted By: sweatlock
Date Posted: Jan/20/2021 at 12:28pm
I’m surprised at the bad feedback regarding POR-15, I’ve been using it for years with no issues. I’ve always thought it was a good product and did what it was advertised to do. Florida is pretty tough on old vehicles, too. 


Posted By: TX390AMX
Date Posted: Jan/20/2021 at 7:57pm
Back in the early 80's, long before POR15 and other corrosion prevention products, my brother-in-law and I used a mixture of STP (remember that?) and mobile home roof coating inside the fenders and troughs of my then-wife's 72 Javelin SST. Also put it inside doors, trunk drop-off areas and anywhere else midwest rust was likely to attack. My daughter still owns the car today, the body looks great, even tho it's been driven in salt/chloride winters in Illinois til about 10 years ago when she moved to Texas. Unfortunately, the floors, trunk, frame rails and other areas we didn't treat or couldn't easily get to are toast, but the fenders and doors still look great.
  If it's going to be maintained with any sort of concern for the elements, any etching epoxy primer and top coat will do. Even brushable Rustoleam would be a good choice for the trough areas. Remember, these areas were either dipped in primer or missed entirely when the cars were new and they weren't expected to last 50 years! A side effect of the STP/roof coating mix was that the car would "leak" from the doors and bottoms of the fenders during hot summer days. Paint it with something and let your heirs worry about it for the next 50 years.


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Terry
68 AMX 390 4 Sp Rally Green
68 AMX 390 4 Sp Caravelle Blue
68 AMX 390 4 Sp Matador Red
68 AMX 390 4 Sp Calcutta   
   Russet
07 Corvette convert
28 Ford Model A



Posted By: Trader
Date Posted: Jan/20/2021 at 10:05pm
After sand blasting/painting or POR15 I always use this in the troughs and on the inner fenders:
https://www.homedepot.ca/product/black-knight-3-78l-fibered-roof-coating-roof-seal/1000164504" rel="nofollow - https://www.homedepot.ca/product/black-knight-3-78l-fibered-roof-coating-roof-seal/1000164504
Have never seen flaking, drying, rust after applying this. Brutal to get it off hands or clothing - just be warned!


Posted By: ccowx
Date Posted: Jan/21/2021 at 7:55am
I would like to second the comment about cleaning and protecting the under side of the fenders. My 1970 had the tops of both fenders soft and rusting through when I got it. Funnily enough, the troughs underneath are fine, to this day. The water and sand and all that collected but the corrosion did not seem to harm the troughs themselves. Worst thing that happened to them was that the staples holding the rubber seals on rusted away!

Chris 


Posted By: Joelfanti
Date Posted: Jan/21/2021 at 8:10am
I raptor liner me inner fenders after painting them 



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