Poll: What to do with underside of bed

[turbodig]

So, I'm attempting to do some rust control on my 19k mile bed.
It wasn't terrible, but there was a lot of scale where the rear wheels kick up rocks.

Should I:

Touch up the rust spots with KBS coating gray
Spray the whole thing with rubberized undercoat
Spray the whole thing with bedliner material
Keep it original and hit the rust spots with DP 40 primer, and leave the rest alone.

Or, something else I haven't thought of?
Due to the factory undercoat overspray, any paint on it won't entirely look right. Undercoating/bedliner would cover this.

 

["Nickel"]

Re: Poll: What to do with underside of bed

Por-15. Then top coat it with the same color that's on there now? It'll stop the rust and won't chip off later on. Just my :2cents: I don't know how "stock" you want it to be. I wish I could find a bed that was that clean!

 

[turbodig]

Re: Poll: What to do with underside of bed

Por-15. Then top coat it with the same color that's on there now? It'll stop the rust and won't chip off later on. Just my :2cents: I don't know how "stock" you want it to be. I wish I could find a bed that was that clean!

The color that's there now is the DP40 primer. (I think)

In order to do it right, though, I'd need to scrape off the globbed-all-over undercoat that's there now.
I'm not entirely sure I want to spend 3 days scraping that crap off.

I'm coming to the realization that I'm less into making it look 100% stock, and more into putting something on there such that I never have to do this again.

I'm leaning towards KBS/POR on the rusty/bare spots, then spray the whole thing with raptor bedliner.

 

[DaveP]

Re: Poll: What to do with underside of bed

My response in Yellow.

The color that's there now is the DP40 primer. (I think)
It is. I resprayed the underside of the bed and cab of GoodSy with DP-40. Perfect match. Treat the rusty and bare areas with Ospho. Also called "Rust Treatment" in the paint section of Home Depot. comes in a plastic bottle, and is a watery green color. Active ingredient is Phosphoric acid. Read the instructions. I spray it on with a spray bottle. Let dry overnight. Rub the residue off with bronze wool. Shoot the DP-40 right over the bronze wool'd Ospho. Don't sand, or you'll sand the treatment off.

In order to do it right, though, I'd need to scrape off the globbed-all-over undercoat that's there now.
I'm not entirely sure I want to spend 3 days scraping that crap off.
It may come off easier than you think. Many undercoats are asphalt based. Try gasoline as a solvent on it. Be sure your out doors, or the water heater pilot is turned off so you don't blow yer shop sky high.

I'm coming to the realization that I'm less into making it look 100% stock, and more into putting something on there such that I never have to do this again.
Then do the DP-40 over the undercoat. No one is going to look under there except you. POR-15 and "bed liners" add a lot of weight. Something to consider.

I'm leaning towards KBS/POR on the rusty/bare spots, then spray the whole thing with raptor bedliner.
Once again, weight.

 

[turboj91]

Re: Poll: What to do with underside of bed

I'm with Dave 100% on the Ospho. Works great!! I know how you like to stay with an OEM look. Spray the spots where rocks kick up with a chip guard. Use the fine textured stuff then DP over that. POR is tough stuff but will get beat up over time by the rocks. I think your better off with a flexible surface and with the light color, the fine textured chip guard will be barely visible. How many people do you know that realize a GN has chipguard from the lower body line down. Only when you get close and no one will get that close to the underside of your bed. The other thing that comes to my mind (and I think too much) is that primer is not moisture resistant. I bet that you (and Dave) know where I'm going with that one.

One other thing to note. Looks like you have some "blasting wear" were the rocks kicked up. If you just top coat a paint or primer over that (ie DP or POR) the underlying surface defect will be visible. The chip guard will cover it without issue.

Spray on bedliner is for inside the bed of work trucks. Not inside the bed of your truck.

Post pics of your efforts when you get to that point.

 

[turbodig]

Re: Poll: What to do with underside of bed

I'm with Dave 100% on the Ospho. Works great!! I know how you like to stay with an OEM look. Spray the spots where rocks kick up with a chip guard. Use the fine textured stuff then DP over that.

So, you spray paint over the chip guard? I would have thought it would have been the other way around?

I've used the POR, KBS rust converters, as well as SEM's Rust-Mort. They all work pretty much the same, from what I've seen. But they do work.

One other thing to note. Looks like you have some "blasting wear" were the rocks kicked up. If you just top coat a paint or primer over that (ie DP or POR) the underlying surface defect will be visible. The chip guard will cover it without issue.

Some of that was me hitting it with the blaster to get the scale off. I'm not terribly worried about surface finish under there, as you mention, nobody will see it. My primary concern is to stop the rust that was there (I really should have taken before pics), but also to prevent it from happening again.

Pretty much everything outboard of the frame rails is 'blasted' from use, and I may just treat the outer 6" with rock guard or bedliner, once I fix/paint the rusted spots.

I do like the idea of keeping the overall color the same. I'm not entirely against doing the KBS and then the DP40, I had really good luck with that on the rear diff and the springs. I could hit it with all 3...

Spray on bedliner is for inside the bed of work trucks. Not inside the bed of your truck.

Post pics of your efforts when you get to that point.

Actually, I do still plan on bedlinering the inside of the bed. The guy that had it before me used it to haul things, and the bed was all scratched up at 8800 miles. Add to that a few dents in the front of the bed from things thwacking it, and it's not so nice anymore. I figure I can do a nice, light-coat bedliner on it tastefully, and not add an overwhelming amount of weight. Yep, it will be heavier, but I'm not really in the mode of getting rid of every last bit of weight in search of a couple tenths. It will be faster than they allow me to go without a cage, anyway.

I do throw toolboxes, coolers, wash/wax equipment in it from time to time, and a fresh repaint inside the bed would make it almost impossible to do without freaking out.

Thanks for the insight... I'm a bit of an auto-body noob, learning fast.

 

[SEL777]

Re: Poll: What to do with underside of bed

I like the Permatex brand rust inhibitor. You just wire brush it, and then spray this stuff on, it converts the rust, and it turns black. Lasts quile a while too.

http://www.acehardwareoutlet.com/ProductDetails.aspx?SKU=87647

 

[turbodig]

Re: Poll: What to do with underside of bed

It is. I resprayed the underside of the bed and cab of GoodSy with DP-40. Perfect match. Treat the rusty and bare areas with Ospho. Also called "Rust Treatment" in the paint section of Home Depot. comes in a plastic bottle, and is a watery green color. Active ingredient is Phosphoric acid. Read the instructions. I spray it on with a spray bottle. Let dry overnight. Rub the residue off with bronze wool. Shoot the DP-40 right over the bronze wool'd Ospho. Don't sand, or you'll sand the treatment off.

It may come off easier than you think. Many undercoats are asphalt based. Try gasoline as a solvent on it. Be sure your out doors, or the water heater pilot is turned off so you don't blow yer shop sky high.


Then do the DP-40 over the undercoat. No one is going to look under there except you. POR-15 and "bed liners" add a lot of weight. Something to consider.

I'm leaning towards KBS/POR on the rusty/bare spots, then spray the whole thing with raptor bedliner.
Once again, weight.

Thanks for the thoughts... I'll pick up some DP40... any thoughts as to how much I might need?
I'll hit the undercoat with some solvents and see if anything makes it budge.

I'm a bit confused by the weight thing though... undercoat and bedliner I can understand, but if this quart can of KBS gray weighs 5 lb, I'd be surprised. I guess I'd sacrifice a fair amount of weight for having the underside a bit more resistant to chips and rust. Peace of mind kinda thing.

 

[sy605]

Re: Poll: What to do with underside of bed

If you plan to keep it and don't mind spending the extra money soda blast the whole thing underneath and have it Rhino lined or Line-X'ed. Never worry about it again. If you repaint it you'll be doing it again later on. :2cents:

 

[DaveP]

Re: Poll: What to do with underside of bed

Thanks for the thoughts... I'll pick up some DP40... any thoughts as to how much I might need?

DP40 is a 2-part epoxy primer. IIt mixes 1:1. The DP-40 is available in quarts, the 401 and 402 activators usually are stocked in 1qt as well. Plus you can add a little DT reducer if you want it to lay down a little smoother.. Purchasing the minimum quarts, you'll have over 2 qts Ready To Spray. WAY more than enough to do the bottom of the bed.

Here's a link to the product sheet.

I'm a bit confused by the weight thing though... undercoat and bedliner I can understand, but if this quart can of KBS gray weighs 5 lb, I'd be surprised.

I was thinking more of por-15 as far as weight. I'm not familiar with KBS.

 

[turboj91]

Re: Poll: What to do with underside of bed

Dave was yellow, I'll be green.

So, you spray paint over the chip guard? I would have thought it would have been the other way around? Yes, under the paint. Many new cars have chip guard on the lower sections of the fenders and doors as well as the rockers. There is generally 3 grades of texture from fine to heavy. Toyota's usually have it. Have to bend over to get down to the bottom section to see it. Your auto body supply store should be able to give you a sample of all 3 grades.

I've used the POR, KBS rust converters, as well as SEM's Rust-Mort. They all work pretty much the same, from what I've seen. But they do work. Yes they do work and it looks like you will need something. You blasted but your media is too large to get into the tiny pits and blast out all of the rust (typical). This is where the Ospho comes in handy. It's pure liquid and gets to the bottom. The rust converters do the same thing. You can primer over the Ospho then spray the chip guard, then paint. You can use one of your aforementioned rust converters and then spray the chip guard, then paint. One main theme is to seal off the metal from water and oxygen.

Some of that was me hitting it with the blaster to get the scale off. I'm not terribly worried about surface finish under there, as you mention, nobody will see it. My primary concern is to stop the rust that was there (I really should have taken before pics), but also to prevent it from happening again.

Pretty much everything outboard of the frame rails is 'blasted' from use, and I may just treat the outer 6" with rock guard or bedliner, once I fix/paint the rusted spots. From meeting you at "events" and by your posts and reputation of wanting an oem look, I wonder if YOU will be happy with the look and knowing that you have heavily textured bedliner material under the bed???? I know things change and we all mellow out but...???


I do like the idea of keeping the overall color the same. I'm not entirely against doing the KBS and then the DP40, I had really good luck with that on the rear diff and the springs. I could hit it with all 3...




Actually, I do still plan on bedlinering the inside of the bed. The guy that had it before me used it to haul things, and the bed was all scratched up at 8800 miles. Add to that a few dents in the front of the bed from things thwacking it, and it's not so nice anymore. I figure I can do a nice, light-coat bedliner on it tastefully, and not add an overwhelming amount of weight. Yep, it will be heavier, but I'm not really in the mode of getting rid of every last bit of weight in search of a couple tenths. It will be faster than they allow me to go without a cage, anyway.

I do throw toolboxes, coolers, wash/wax equipment in it from time to time, and a fresh repaint inside the bed would make it almost impossible to do without freaking out. Put a light, cut to fit rug in it and a rubber mat on the bed floor. The indoor/outdoor stuff will take a beating, can get wet and may be available in a very dark grey and would match with the black very nicely. The mats weigh a few lbs but can be easily rolled up and removed when needed.

Thanks for the insight... I'm a bit of an auto-body noob, learning fast.

 

[UR50SLO]

Re: Poll: What to do with underside of bed

I stopped using that POR 15 several years ago... It's just not a very good product... Doesn't stick very well unless preped perfect. Will degrade with UV light, fish eye's very easy.

SEM makes a product called Rust Shield... Very user friendly and no problems with UV and will spray over anything and stick/not fish eye.

Not sure if they make it in a grey color but I've used the stuff with real good success VS POR15.

A "Weld through" primer also works pretty good as a prep after taking the rust off .. it has high Zink

content.... The DP 40 (or simialar epoxy) is a good product as well. I'd still over coat it with somthing.

Hope that helps,
Scott~

 

[turbodig]

Re: Poll: What to do with underside of bed

I stopped using that POR 15 several years ago... It's just not a very good product... Doesn't stick very well unless preped perfect. Will degrade with UV light, fish eye's very easy.

SEM makes a product called Rust Shield... Very user friendly and no problems with UV and will spray over anything and stick/not fish eye.

Not sure if they make it in a grey color but I've used the stuff with real good success VS POR15.

A "Weld through" primer also works pretty good as a prep after taking the rust off .. it has high Zink

content.... The DP 40 (or simialar epoxy) is a good product as well. I'd still over coat it with somthing.

Hope that helps,
Scott~

So far, I'm impressed with the KBS coatings stuff. I'm really paranoid about prep, but this stuff seems pretty resilient no matter what you do with it.

Will look into the SEM stuff, though... I used their trim black as a topcoat on the chassis parts, and it's good stuff.

Thanks,

 

[turbodig]

Re: Poll: What to do with underside of bed

From meeting you at "events" and by your posts and reputation of wanting an oem look, I wonder if YOU will be happy with the look and knowing that you have heavily textured bedliner material under the bed???? I know things change and we all mellow out but...???

I've sort of let that idea go.... I don't have an interest in having something that I can't drive anymore.
I'm pretty clear on my goal with this whole thing- it's to get rid of the rust first, make things look nicer second, adhere to "stock correct" is a distant third. It would be nice to have things look really stock, but I'd rather have something that's gonna last 30 years than have something that looks perfectly stock.

Put a light, cut to fit rug in it and a rubber mat on the bed floor. The indoor/outdoor stuff will take a beating, can get wet and may be available in a very dark grey and would match with the black very nicely. The mats weigh a few lbs but can be easily rolled up and removed when needed.

I know where that goes... been there. As hard as your try, you won't be able to keep the inside nice if you use it for anything. I really don't want to go back to obsessing over every object in there, and driving like gramma to make sure it doesn't move around in the back.

It's got 20k on it, and it's not perfect anymore. I've made peace with that.

 

[turbodig]

Re: Poll: What to do with underside of bed

Update.... here's what actually happened:

Basically, I cleaned and scuffed up the whole bottom bedside(and cleaned again), and rolled on the KBS Coatings Gray. That's the color you see in the middle.

Once that was dry, I scuffed the KBS with really coarse scotchbrite to get the "shine" off the coating.
I masked the middle off (I didn't really need/want the undercoat between the frame rails), and shot the 3M 8883 undercoat on.

The 3M undercoat is nice stuff... once dry, it leaves a really nice even finish. (Note the pic of the rear of the bed) I did the fenderwell areas with it too, after painting over the pitted paint with KBS black. I think it gives it a much cleaner look.

The KBS more or less served as a sealer, with the 3M undercoat being the topcoat.

For the folks who mentioned weight, All of the undercoat cans + the paint didn't add up to 5 lbs.
Some might find that to be a big deal, but for me, I can live with that weight addition. Particularly, if it means that I'm not going to have rust/pitting issues.

It's nice to be finally done with the bottom side. I still have some painting to do around the fenderwell lip, but that will go quick. Hopefully, I'll have the bed ready to go back on by Christmas.