Best DIY undercoating

Hey all,

I checked around the forum and cant really find any solid info of what DIY (done at home) undercoating that you guys have tried. My frame is showing some minor rust and I will sandblast it and spray it.

I used this on my last truck and it was o.k. but I was wondering if you guys have used anything that is better and stronger. I can apply with a spray gun as well.

Used last time
https://www.ebay.com/p/Automotive-C...ust-Oleum-6-pack/25016957631?iid=292493115309

 

Lots of info in here on general rust prevention:

https://www.tacomaworld.com/threads/rust-prevention-treatment-consolidation-thread.355928/

I’m of the train of thought that it’s better to just coat the frame in a nice protectant like fluid film or other good choices out there. Forces you to do touch up/maintenance and allows you to see any problem areas rather than hiding it. Any areas that start to rust get wire wheeled to bare metal then recoated.

Unless you are about to recoat the whole frame due to bad rust, then that’s a different story. I’ve ventured to some restoration forums and they don’t usually like rubberized undercoat or even por15.

 

cool thanks. I will check it out.

 

Fluid film

 

https://www.youtube.com/watch?v=o1InzXNp7Pw

seams like possibly a good product?

 

I used something like that about 20 years ago on my first truck back when I live in Michigan. I had similar results to that video, but it didn't last long, probably because I didn't paint a protective coating over it.

 

The problem with the "repair" shown in that video is that none of the "rust converter" products out there is intended as the "final solution." All of them require some type of finish paint / coating to be applied after the rust converter has cured. In fact he even says so in the first video only to not do it and sees exactly the results that were predicted. BTW, neither undercoating nor Fluid Film (and I have used both) are really a final solution either. Both need follow up attention to be effective.

If you really want to protect an already rusted frame from further damage, one needs to descale and clean the rusted area, convert it, paint it, then FF or undercoat it.

 

The best coating for rusted metal is POR-15. It does not require any topcoat unless it is subjected to UV. It makes a super hard black coating and stops rust dead.

The best rubberized undercoating I have used is Transtar:

$94 TRANSTAR (4361-F) Quick Dry Rubberized Undercoating - 1 Gallon

https://www.amazon.com/TRANSTAR-436...coding=UTF8&psc=1&refRID=DV32DEQ9S6VVV7RW7FY5

 

Black Star is suitable for use as a final coating.

 

This undercoating is crap

 

No its definitely not, better than any rubber style for sure. Its not very good for lazy people though if they dont want to touh it up with a spray can a few times each winter. The stuff works amazing and can be literally sprayed on everything unlike rubberized coatings

 

I'm not sure of your year, but you might want to check with your local dealer about the frame tsb. Mine was checked "OK" and is currently in the shop getting a coating by Toyota. I'm not exactly sure of what they are applying, but I can ask today when I pick it up. It sounds like a permanent solution. Might be worth a shot for you.

 

I posted this in another thread:

I bought a 2006 Tacoma a little over a year back that already had the frame and LCA's replaced, but everything else under there looked kind of crusty to me. So here is the approach I took (mainly based on another member's post), not cheap and took alot of time (mostly my 17 year old son's lol since I bought the truck for him) but IMO it's as comprehensive as you can get:

-Use an air scaler to remove any surface rust: -Prep / De-grease / Clean Everything then Paint Everything with POR15 (2 Coats):

POR-15 Semi-gloss Black 3 Gallon Rust Preventative Paint Kit

https://www.amazon.com/Por-15-Semi-gloss-Black-Gallon-Preventative/dp/B00ODCYL42/ref=sr_1_1?s=automotive&ie=UTF8&qid=1518616975&sr=1-1&keywords=POR-15+Cleaner+Degreaser+%2F+Metal+Prep+%2F+Semi+Gloss+Black+-+3+Gallon+Kit

-Paint Inside of Frame Rails:

Eastwood 12515Z Internal Frame Coating Rust Prevention with Spray Nozzle, Green, Pack of 1

https://www.amazon.com/Eastwood-125...eywords=Eastwood+Internal+Frame+Coating+Green

-Spray Everything with Rubberized Undercoating:

$37 Automotive Spray-On Rubberized Undercoating Material, 1-Gallon RUS-1020F6

https://www.amazon.com/Automotive-R...16925&sr=8-9&keywords=rubberized+undercoating

-Spray Gun used:

$35 TCP Global Air Undercoating Spray Gun with Suction Feed Cup - Apply Sprayable Truck Bed Liner Coating, Rubberized Undercoat, Rust Proofing, Chip Guard Paint - Pneumatic Automotive Application Sprayer

https://www.amazon.com/TCP-Global-P...518617176&sr=8-13&keywords=spray+undercoating

-Make sure to use a Respirator with that POR15 stuff, very toxic smelling:
https://www.amazon.com/3M-Paint-Pro...18617779&sr=1-2&keywords=full+face+respirator

 

Dealership did mine, but couldn't tell you what they used or the quality of the undercoating, and unfortunately the quality of the work itself.

 

on My old tacoma that had slight rust in the rear I did the rust removal by hand with wire wheel and an assortment of tools, primed and painted. It was time consuming and impossible to get in all the nooks and crannies. Rust came back in some areas. When I got the 2015, did FF with compressor and undercoating gun. It’s not only easier but the FF creeps into areas hard to reach. It only takes me 20min. One a yr. in the fall.

 

To clarify, Fluid Film is not the same as classic undercoating. Undercoating is generally an asphalt / bitumen based coating, sometimes rubberized, that goes on wet and dries. Some undercoating products dry harder than others. (Ziebart for instance is pretty soft.) It is intended to prevent corrosion from starting and does little to inhibit / stop corrosion once it starts.

Fluid Film goes on wet and "dries" to a gel like substance. That said, it's never really "dry" and can get wiped or worn off. That's why you may have to re-apply it in locations where it is likely to get removed over time. That's also why it's kind of messy and some folks don't like it. The big difference with FF is that it does contain corrosion inhibitors so it will slow corrosion that has already started. (It will not totally stop rust that has already started though.) One advantage of FF over undercoating is that it will "flow" into tight areas and thus protect them better than undercoating.

I will add that the effectiveness of both products is highly dependent on who applies them and how well they apply them.

 

There really is no one product that works in every situation. I use a combination of rubberized product, POR-15 and FF type products depending on what I'm trying to accomplish.

 

Got my truck back from the dealership this morning, they did a lot more than I expected. Entire frame, cross member, and LCA's. Looks descent to me? They gave me a loaner all week that got 37mpg, and it was all free. Service guy claimed this was a permanent solution to the frame rusting issue, time will tell.

 

I see a few more mentions of por15. I used the stuff to recoat the inside of my steelies, going 100% by the instructions and using all of their prep products to do it. This way if I have an issue I can blame the product given I’ve used everything they said to and how they said to, short of perfect humidity levels. So far it is doing fantastic, however I read a lot of heresay on other forums stating it does have its downsides, one being if you prep wrong then it won’t fare much better than undercoat in the long term. Or that it will eventually peel off like electric tape even on properly prepped metal, basically becoming a rust motel. Which is why I plan to check my wheels in 6 months and see if the heresay holds up or if the product is working like it should. You can’t trust anyone properly prepped on the internet, so most outcomes are just anecdotal.

Their 3 step process is basically just a degreaser (smells just like simple green) then basically a phosphate conversion solution that I guess accomplishes the same thing as corroseal or Ospho or whatever popular one you can find, then finally coating with the por15.

Biggest drawback is you MUST topcoat this stuff within the directed timeframe or you are going to have a fun time roughing it up with sandpaper to get a topcoat to stick. The coat is not UV stable, but what I read is that the coat itself isn’t compromised, it just fades and looks like crap on sun exposed areas.

I read a lot of good things about it on a lot of off-road forums but when I went to do my own research elsewhere, I found a lot of bad experiences too.

Just food for thought. I ended up using it and liked it.

I don’t think I’d use it on a frame however.

 

Very bad design, for many many years that's for sure. I'll definitely keep an eye on it, regardless. Thank you for the info, it's very much appreciated.