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Old 01-24-2019, 06:00 PM   #1
montanatroutaholic
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Undercoating or no undercoating?

Hi All!

I am in the process of buying a 1970 Suburban from the desert and will be bringing it back to the mountains of Montana. Currently, this vehicle is NOT undercoated. We undercoat everything around here to keep the rust away. I was wondering what all of your thoughts are on undercoating these 3 door Suburbans. Look forward to the discussion!

Joel
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Old 01-24-2019, 08:46 PM   #2
pwdcougar
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Re: Undercoating or no undercoating?

I'm using a bed liner material for undercoating on my Suburban. It wasn't recommended by the product manufacturer though if the body was still on the frame.

Paul
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Old 01-24-2019, 09:02 PM   #3
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Re: Undercoating or no undercoating?

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I'm using a bed liner material for undercoating on my Suburban. It wasn't recommended by the product manufacturer though if the body was still on the frame.

Paul
Body is still on frame. I would think bedliner material would work well!

Joel
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Old 01-24-2019, 09:05 PM   #4
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Re: Undercoating or no undercoating?

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Originally Posted by montanatroutaholic View Post
Body is still on frame. I would think bedliner material would work well!

Joel

The manufacturer said that getting it on the exhaust was bad as it doesn't withstand heat well. Also the floor pan has to be really clean.

Paul
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1969 Mercury Cougar Standard 4 speed
1969 Mercury Cougar XR7 convertible
1970 4WD Chevrolet Suburban
1968 2WD GMC Suburban
1997 4WD Chevrolet Silverado Extended Cab Short Bed (purchased new January 1997)
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Old 01-25-2019, 02:44 PM   #5
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Re: Undercoating or no undercoating?

Any coating is only as good as the surface preparation. If you are going over existing crud or old coatings you take the chance of creating pockets or voids that only trap the wet salt water that will eventually dry leaving the salt for later moisture to reactivate.
In my opinion anything other than fresh paint or clean metal under a new coating is a worsing of the situation. I feel you will be better protected by cleaning and spot coating existing rust with a POR 15 type product, then washing the underside regularly to clean the salt away. I have heard good things about this product, but never used it personally.

https://ver-techlabs.com/fleet-washi...uck-corrosion/
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Old 01-30-2019, 09:39 AM   #6
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Re: Undercoating or no undercoating?

After much discussion with some local body shop guys it seems they like good old fashion paint or a product called Carwell T32 which is a penetrating oil you coat the underside with annually. Inexpensive and extremely effective. The only downside is it will drip for a few days after application apparently. I can live with that if it keeps my rig rust free!

Joel
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Old 01-31-2019, 05:33 PM   #7
BGarza13x
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Re: Undercoating or no undercoating?

I'm undercoating with bed liner too, in the fenders, and underneath, doing the frame and under the floor. I am using Lizard Skin inside, thinking of topcoating it with bed liner, as well, under the carpet. When it gets to 105 here in Texas, the more insulation the better.
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Old 01-31-2019, 06:03 PM   #8
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Re: Undercoating or no undercoating?

U-POL Raptor bed liner is great stuff. IMO....power wash under side, clean as possible, mask off parts you don't want under coated.
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Old 02-02-2019, 10:47 AM   #9
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Re: Undercoating or no undercoating?

I spray all my vehicles with Krown inside the panels and.Fluid Film under the truck. It works great. Its messy to work on but last. Mostly all of the 2005 and older truck are rotted put completly in my area. Our 2005 tahoe is still rust free.
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Old 02-03-2019, 06:18 AM   #10
Franks 72
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Re: Undercoating or no undercoating?

I agree .Cant beat oil based spray (rust Check or Krown). Dads truck was originally Ziebarted but it created pockets and rust through occurred . After that it was oil spray for 40 years.The underside was very well protected with the only major issue being the main cross member where the floor pan ends and plywood starts.This is an area where salt sits and usually results in deterioration of the cross member.This is hard to detect but in my case it caused floor pan rust through at the floor pan "step" under the rear seat. I believe this is a common problem and would recomend anyone buying a used rig have a close look at the main cross member bolt area .If your truck is solid , go with oil spray.Use something thin that creaps into cracks.Resist the temptation to pressure was the underside! It wont be pretty but it will be around in 40 years !
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Old 02-03-2019, 08:02 PM   #11
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Re: Undercoating or no undercoating?

I wound up going with a bed liner called Al’s Liner. Friends on another forum used it and liked it. It seems really tough but it was kind of a pain to apply. The tech support at Al’s (Scorpion) did not recommend it unless it was a situation like mine where the body was sandblasted, epoxy primed and on a rotisserie.

Paul
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1969 Mercury Cougar Standard 4 speed
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Old 02-03-2019, 08:34 PM   #12
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Smile Re: Undercoating or no undercoating?

Quote:
Originally Posted by 72MARIO View Post
I spray all my vehicles with Krown inside the panels and.Fluid Film under the truck. It works great. Its messy to work on but last. Mostly all of the 2005 and older truck are rotted put completly in my area. Our 2005 tahoe is still rust free.
I have been using Krown for years. I was told by more than one person that they have changed their formula because of the government restrictions. Apparently the new stuff is hard on the rubbers in the ball joints, tie rod boots, body mounts anything rubber. I now do mine with a product that is a form of liquid wax. The stuff is awesome and doesn't drip. Have a good one. Good luck.
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Old 02-05-2019, 08:05 PM   #13
montanatroutaholic
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Re: Undercoating or no undercoating?

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I have been using Krown for years. I was told by more than one person that they have changed their formula because of the government restrictions. Apparently the new stuff is hard on the rubbers in the ball joints, tie rod boots, body mounts anything rubber. I now do mine with a product that is a form of liquid wax. The stuff is awesome and doesn't drip. Have a good one. Good luck.
Do you know what this liquid wax product is called? I would love to read up on it.

Joel
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Old 02-05-2019, 09:13 PM   #14
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Joel. I don't know off hand but I'll make a call or two tomorrow if I get a chance and get back to you.
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Old 02-05-2019, 11:25 PM   #15
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Re: Undercoating or no undercoating?

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Joel. I don't know off hand but I'll make a call or two tomorrow if I get a chance and get back to you.
Thank you, Jim!
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Old 02-06-2019, 10:43 AM   #16
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Re: Undercoating or no undercoating?

Joel. The product is called Dura Shield. It is a wax base product. For the first two- three years it's done every year and then every other year after it builds up.The oil based products drive me crazy when you touch them and wind up covered in dirty oil. So far I'm happy with this stuff and I guess time will tell if I found another thing to love! Where I got mine done the guy wants the truck the day before spraying if possible. He pressure washes it and it drys overnight in his shop. He sprays in the morning and then lets it sit for a while to work in and set up. Have a good one eh!
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Old 02-06-2019, 12:59 PM   #17
montanatroutaholic
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Re: Undercoating or no undercoating?

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Joel. The product is called Dura Shield. It is a wax base product. For the first two- three years it's done every year and then every other year after it builds up.The oil based products drive me crazy when you touch them and wind up covered in dirty oil. So far I'm happy with this stuff and I guess time will tell if I found another thing to love! Where I got mine done the guy wants the truck the day before spraying if possible. He pressure washes it and it drys overnight in his shop. He sprays in the morning and then lets it sit for a while to work in and set up. Have a good one eh!
Thanks Jim! Much appreciated!

Joel
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