How do I undercoat this?

[avacado11]

I have a gallon of wool wax that’s been sitting for the past 2 months because I haven’t decided the best application plan for my cars.

I have three I need to do. A Pacifica Hybrid, Model Y, and Bolt EV.

Anyways besides the Chevy both the Chrysler and Tesla are heavily dressed up with aero panels. The only thing exposed under them are the ends of the lower control arm, struts, and pinch weld jack points. HV battery components will need to be left bare so this is a majority of the space between the axles.

The Chevy is straight forward. But both the Chrysler and Tesla are giving me a headache due to how they’re covered up. My plan is to:
-drop the rear aero panel and coating the rear sub frame/surrounding body & suspension
-pull all 4 wheel well liners and coat behind them
-coat pinch weld area full length
-coat spots of the exposed front sub frame(mainly where the LCAs attach, leave panels on)

Is this overkill for such a covered up underbody? Should I say screw it and just coat what’s exposed and behind the side skirts? Does the aero covers make that much more of a difference against rust?

I only question this because I’ve rarely ever seen rust behind covers. It usually starts somewhere exposed and works its way back.

 

[Bailes1992]

I've seen plenty of cars rust under covers, usually where dirt has had time to accumulate and traps moisture against the panel.

I use a product called Lanogaurd which is very similar to Woolwax but made in the UK. Every Autmn I strip all the bumpers, sill covers, wheel arch liners, undertrays etc off my cars and go to work. I thoroughly clean everywhere and apply a coat of Lanogaurd using a spray gun. I also use a Sealey SG19 and inject every cavity I can get into.

You can see my process HERE.

 

[eljefino]

This is a great idea. I would just save it for the fall so you don't lose some of the stuff to summer creep.

 

[stevejones]

I remove all the rocker plugs when I do my vehicles; douche the cavity until it starts dripping out the seam. I also pull the wheel liners & trim up any insulators that run from the bottom of the A-pillar to the bottom of the dogleg on the fender. I think it helps avoid this:

And I don't use fluid film. I use Cortec cavity wax, VpCl 368

 

[JoelB]

If salt can get inside a rocker panel it can get around some plastic panels. In my opinion taking off the panels is worth it if you are looking for ultimate protection.

 

[avacado11]

I remove all the rocker plugs when I do my vehicles; douche the cavity until it starts dripping out the seam. I also pull the wheel liners & trim up any insulators that run from the bottom of the A-pillar to the bottom of the dogleg on the fender. I think it helps avoid this:

And I don't use fluid film. I use Cortec cavity wax, VpCl 368

This is what happened to my Accord. Upon a full inspection there was a bad body plug causing water intrusion who knows how long. Driver side rocker had two fist size rot holes behind the side skirt. It was too far gone to be saved so I traded it for the Chrysler. I’m going to apply a healthy dose of undercoat so I don’t see that kind of rot.

 

[JTK]

I've done more than a dozen or so DIY woolwax applications at this point. I have a 5gal pail of it and a few different spray guns / wands. I also have a gal can or two of FF.

If you want to do it right, you will have to drop all the aero panels just like you said. If you want to use WW as a cavity spray, it will work best on a hot day, or you need to keep the product very warm. Other than that FF is the better option for inner cavities. Just a FYI, on a cooler day, with ambient temp WW, trying to crank up the air pressure to your spray gun doesn't help you.

The rattle cans of FF are really nice for getting into the bottoms of doors and really tight spots. Rattle cans are also awesome for quick jobs like putting a shot on battery posts, ground lugs, etc. WW and FF are dielectric, so there's no worries getting it on electrical components.

 

[JoelB]

I've done more than a dozen or so DIY woolwax applications at this point. I have a 5gal pail of it and a few different spray guns / wands. I also have a gal can or two of FF.

If you want to do it right, you will have to drop all the aero panels just like you said. If you want to use WW as a cavity spray, it will work best on a hot day, or you need to keep the product very warm. Other than that FF is the better option for inner cavities. Just a FYI, on a cooler day, with ambient temp WW, trying to crank up the air pressure to your spray gun doesn't help you.

The rattle cans of FF are really nice for getting into the bottoms of doors and really tight spots. Rattle cans are also awesome for quick jobs like putting a shot on battery posts, ground lugs, etc. WW and FF are dielectric, so there's no worries getting it on electrical components.

I've found putting the aerosol cans in hot water for about 10 minutes before using them really makes it flow nicely. Before I was seeing issues with the fluid film squeezing out from under the spray nozzle when using a long wand attachment.