Undercoating technique?

[cvar]

You guys have painted lotsa trucks. So may I ask for your wisdom?:

What techniques would you recommend to paint the underside of a RBV?
Paint-brushes? Spray-gun on air compressor? Handheld squirt/spray bottle? Garden-insect-sprayer? Otherwise?

Truck bed is easily stood up (yay). But how to paint the frame, axles, underside, etc., all while lying on my back? Close up. (drip, drop.) Yuck! I'll be painting it all 2 or 3 times: primer (1x or 2x?) and then topcoat. I bought this: <<MasterSeries paint kit>>. I am NOT looking fwd to painting it. So many nooks & crannies under there, some impossible to peek inside! How to actually paint them? And to breathe?

I wire-wheeled and descaled most rusty bits of the frame & underside that I could easily reach. Then I used Rustoleum primer on just a portion of the frame (underneath the bed). Then with a plain squirt-bottle, I sprayed this: <<Zep Industrial Degreaser>> everywhere, front-to-back. Lastly, I'm spraying Naval Jelly or Ospho to convert rust into benign Iron-Phosphate, but I didn't finish yet. I admit, it looks pretty darn good, so far. After that will be paint.

Also, I don't own & never used a fancy sprayer, but it would seem impossible to get one into all those tight spots & around corners. And my air compressor sucks (4 cfm).

Your suggestions, please?

 

[Mark_88]

Well, being the lazy guy that I was, I paid someone to sand blast the frame and put an epoxy primer on. He did a good job on that.

But in order to do that I removed the cab and box and had the motor and transmission pulled off (I did all that myself with a forklift). Once that was done I just rattle can sprayed it with rust paint (yellow on the inside rails for better visibility) and then covered the outer side, top and bottom of the frame rails with rattle can rubber guard.

Mine still looks good after two years of mud and slush (maybe I should clean it though) and the inside rails are still bright yellow where everything stands out clearly.

When I had the rear spring mount replaced last year the guy suggested I take care of a bit of rust on the frame that I didn't notice. Still looking to do that some day, but the rest of it is in good shape.

Definitely worth the effort...but you can simply rattle can it if that's all you've got.

 

[armadillon]

I usually tip the truck on it's side and get the paintbrushes out

 

[JoshT]

I undercoated my 86 with spray on bed liner. We removed the bed, found an old mattress to set on the frame, and flipped the cab over on it's back on top of the mattress. Next time I'll take the cab off the frame, and do pretty much the same thing. My 86 is older and in a little rougher shape than your Mazda, the truck was also stripped down to the point where it was pretty much a bare cab and nearly bare frame, but the process left no marks on the cab.

 

[Mark_88]

I undercoated my 86 with spray on bed liner. We removed the bed, found an old mattress to set on the frame, and flipped the cab over on it's back on top of the mattress. Next time I'll take the cab off the frame, and do pretty much the same thing. My 86 is older and in a little rougher shape than your Mazda, the truck was also stripped down to the point where it was pretty much a bare cab and nearly bare frame, but the process left no marks on the cab.

I actually did this the second round with the cab...flipped it up on the back (protected by something but I can't remember what) and had the guy sandblast the bottom of the cab and the firewall...then it was epoxied before I took it home and did the rubber guard to the cab and firewall.

One big word of caution...if you happen to have someone do this for you...cover the hole in the floor for the shifter...and anything else...lol...

I still find sand inside the dash and there are splatters of paint and whatnot on the dash panels as well as the steering wheel (how it got there I have no idea)...I did mean to clean them all off and resurface/repaint the dash a different colour but haven't gotten to that yet...it's only been 6 or 7 years so no rush...

 

[cvar]

Don't you have to gut the cab to remove it, or flip it back? Incl, heater hoses, fenders, cables, dash, etc? That seems a nightmare! I was hoping to avoid that by painting with the cab in place. Mine's an auto trans, so no shifter hole. I'll remove anything that's easily unbolted, like the bed, gas tank, spare tire, bumpers, tow-hitch, bolted cross-members, leaf-springs, and so on. I hope it's OK to paint the calipers.

Looks like paint brushes are in order. Gotta get latex gloves, cuz this MS paint won't wash off skin (just like Por15).

Ospho rust converter really works. Burns my lungs though, cuz I can't hold my breath long enuff. Spritz the acid & run, breathe & hold, then repeat. Milk helped make the headaches go away.

 

[Mark_88]

You don't have to remove the cab, but I found it much easier to get at the parts under the frame rails and was able to completely clean the metal of all the flaking rust proofing from the factory.

But it's actually not that hard...not sure about the wiring harnesses on your model year, but mine all disconnecte right inside the hood. The heater hoses would have to come off for sure, but you can just disconnect the steering column under the hood also...once the six bolts are removed from the mounts it's pretty much free and clear....speedometer cable (unless computer controlled) just undoes from the transmission with one bolt...

I discovered after removing the cab that the mid mount surfaces were toast. Had to weld a big washer on top of them both to be able to fasten the cab properly.

Also destroyed my mounting hardware and had to replace them because they were seized with rust (and a very inexperienced person (me) doing the work) so that ended up costing me an additional $600 (OEM parts were very expensive but probably could have gotten them cheaper elsewhere...I just didn't know where to look).

If it's not too bad you can probably get away without popping the cab...especially if it's a DD and you don't want to hang it up too long. Mine was a spare at that time so it was OK to let it sit around till I could afford the parts and have the time.

 

[JoshT]

I'm not saying it is necessary to remove the cab, or that it is necessary to gut the cab to remove it. I was simply telling you how I undercoated mine. The cab was already gutted and the frame was nearly stripped before I decided to undercoat, I sure wouldn't have gutted it to do so. If I were doing this on a complete truck and had a way to handle the weight I would have left everything except maybe the seats installed. I am in a very slow process of completely rebuilding, lowering, and V8 swapping the truck, so it was easiest to do the undercoat while everything was removed.

 

[Mark_88]

Had my calipers off when I painted them...surprisingly, they are still holding the paint and haven't rusted...need to check them some day and grease the pins...

Haven't use the POR-15 stuff but from what I've read it may help the spot on the frame that needs attention...not even sure if they sell it in Canada...haven't looked lately.

 

[BackyardWarrior]

I took my bed off to do some suspension work, and while i had it torn apart (knowing fords are notorious for rusting out) i decided to undercoat it. I used a stuff called RustBullet (bought of Amazon). It was a little on the expensive side, around $200 a gallon, but it was enough for two coats on everything cab back including the entire underside of the bed. Used $20 worth of disposable foam brushes and did it in one afternoon. stuff sticks like crazy, took a month to get off my skin constantly picking at it, and its still thoroughly stuck on the truck. IMO well worth the effort and price!

BEFORE:

DURING:

AFTER:

^^I apologize for the terrible angles

 

[87rangerxlt]

put my ranger on jack stands as high as i could get it. used a old heavy duty airless paint gun and crauled under there and did it. very very very very messy!!!!!! good rain suite helped to keep it off me. it takes weeks for it to come off your skin. i used KBS under coat. i really like how it turned out and seems to be holding up good so far

 

[killj0y]

Or use this lol

http://m.gizmodo.com/298136/tilt+a+car-flips-your-car-on-its-side-for-easy-access