Frame Prep for Bolt-On Sliders

There is already a bunch of threads on what to coat sliders with, so this post isn't meant to deal with that, at least not directly. My concern is rusting of the portion of the frame that the bolt on sliders interface with.

Since the backing plates on the sliders will create a very small gap between the backside of the plates and the frame, which thanks to the surface tension of water will cause water to be held between the plates and the frame by capillary action for long periods of time, it would seem that this area will be the most critical to address for corrosion protection.

After giving it some thought, my first line of defense will be this stuff:
https://www.buycorrosionx.com/index...xhd90104&sid=7dno42m6xh0d5i91u0383rcioc52k495

I have used this in the past on rust on a vehicle, and it has done a very good job of stopping it from getting worse. It also has a relatively thick and strong film adhesion (much more so than water), even when washing the vehicle (as long as I don't point the power washer directly at it). I plan to completely coat the frame and back side of the slider backing plates with this stuff, let the VOC burn off, and then bolt things up. That should basically displace most of the air voids between the backing plates and frame, preventing water from getting in. Even if the water gets in, it should isolate if from the metal parts. This stuff is sort of like Fluid Film as far as the film strength/thickness goes, but Fluid Film is wax based, and Corrosion X appears to be petroleum based, so the chances of it drying out and cracking should be nil, and as such, be more self healing.

I was also thinking of adding a second line of defense in the form of POR-15 or the like to the frame. However, I am worried that with Corrosion X being petroleum based, that the oil might weaken and break down the water based epoxy. Which brings me to my first question: What type of paint or epoxy coating would hold up to long term exposure to petroleum distillates? I would think a solvent like gasoline is going to be more reactive than say motor oil (I would assume the properties of Corrosion X would be more like the latter), such that what might dissolve in gasoline would be fine in contact with motor oil. Could anyone provide any experience they have had with this situation?

The second question is, for coatings that require a metal prep/acid etch step, would the existing coating on the frame (3rd gen) have to be sanded off to get something like POR-15 to bond to the steel? What about self etching primer or Picklex 20? Has anyone used these products directly on the frame coating with nothing more than a degreaser/acetone rinse prior to application, and had good results with long term bonding? I would prefer to not sand the existing frame coating off before applying primer/paint. I should note that there is very little rust on the frame as of yet, so coatings that bond with rust might not work as well for my situation.

 

POR15 in my mind is a no-go unless you are applying it over a rusty surface. Doesn’t have to be flaking rust, but it needs to have some surface rusting at minimum. It can work over properly etched metal if you go by their prep instructions but it definitely will not work over existing paint.

Idk how CorrosionX will interact or “weaken” the underlying paint but I’ve used it on my truck frame in both the HD and regular form and haven’t had any issues to speak of at this point.

 

I was going to slather RTV on the plates before bolting them to seal out moisture, I haven't yet because I don't want to install them in salt season.

 

Just lithium grease?

 

Preventative maintenance is the best solution. @Chux pulled his sliders after 4 years and it was pretty bad, but not the point of no return. So I would suggest removing them once every year or two and touching up what needs touching up.

Chux also slathered the slider mounting plate in antiseize to try and keep the rust at bay. Time will tell if it works.

 

This is what makes me nervous.. I have sliders on order but living in MA they salt the crap out of the roads.. Guess I'll have to pull them off every year or two and do a little painting.

 

I wonder if some sort of very thin polycarbonate sheet or something glued to a painted slider would help mitigate rust issues, because then you reduce friction and don't have metal vibrating/rubbing against metal.

All it probably take is some fine sand or gravel to get in between the two surfaces and then a few years later you have rust starting either on the frame or slider.

 

I decided to paint the back side of the sliders with POR-15 and spray down the frame with Corrosion X. If grit gets between, the hope is that there won't be much way for corrosion to get out of hand. I guess I'll see in a couple years how this works out.

 

I sprayed outside of the frame and I side of the sliders with a very healthy coat of fluid film. 2 years and no signs of rust..

 

Fluid Film the shit out of it and you'll be gold.

 

I'm putting sliders on my 4runner Saturday. I am planning on going the fluid film route. Does anyone know approximately how many of the aerosol cans I will need? They are 11.75 oz cans.

Can't wait to get them installed!

 

One can is probably enough, get two of you want to go full retard on it.

 

Thank you! Funny coincidence that this thread had such recent replies. This site rules!

 

One will be PLENTY

 

So I have the undercoating on mine done by the company (Autoshine) that the dealer offers. The undercoating itself is the "Auto-Armor" stuff that eventually hardens on. What should I do to prep my frame for the sliders? Should I scrape the stuff off at all the contact points and do fluid film? I'm wondering if it will actually help keep water out of the joints as it ought to create a seal when tightened since it's slightly raised on the frame. Any help/observations appreciated. Cheers!

 

Has anyone pulled the sliders off after fluid film to see if it prevent rust on the truck frame after a few years? Please post pictures of you’ve got them.

 

Weld ons gang!

 

I'm also intertested to know.