Catalytic converter protection: Auto Defender vs. Cat Shield?

Thank you for purchasing one of our shields! I wouldn't worry too much about galvanic corrosion on the 4th gen model due to the fact you don't drill into the frame. The gen 4 shield is a complete bolt on using existing holes in the car, and the steel underneath the car is coated. The galvanic corrosion issue is mainly with the any model prius that needs to be drilled in the subframe. When you expose the drilled carbon steel to the aluminum shield, those two dissimilar metals will cause the galvanic corrosion. But since we use zinc coated rivet nuts whenever you have to drill, we don't expose the steel frame directly to our shield thereby preventing galvanic corrosion. In your case if you are worried about any dissimilar metals touching, its best to use nylon washers anywhere dissimilar metals touch. You could add nylon washers in-between the frame and the shield, thereby preventing the two metals from ever touching. As for any discounts, we can talk in pm.

 

The electrostatically applied anti corrosion coating on the bare metal of the chassis rails in exceptionally thin. After that, the underside is painted with the car's outer color. While the clear top coat is applied to the body panels, none is applied to the undersides. While this provides a degree of corrosion protection, it is not optimal.

Whether using an aluminum or stainless shield cat shield, to assure additional corrosion protection, I'd spray the contact area between the shield and the chassis with a rustproofing compound like this.

The thin plating on the steel rivet nuts offer very little protection against rusting when in contact with the drilled bare steel of the rails. For added protection, I applied JB Weld epoxy to mine before setting them. This offers an optimal level of corrosion protection by eliminating any "air space" between the rivet nut and the exposed metal. Less effect would be applying rustproofing to the drilled hole when installing the rivet nut. Any seam sealer compound could also be used.

To eliminate contact between the stainless steel screws and the plate, either aluminum or stainless steel, I used #14 neoprene backed stainless steel washers. The rubber washers eliminate contact between the shield and the screws.

 

I had my Millercat shield installed by Toyota. When I picked up the car, there was a smell, so I assume that they treated something with some sort of spray or rustproofing. (It smelled to my untrained nose like rustproofing, or WD40, or similar. The smell did not last.) Do you know what Toyota uses when they install the shield?

 

There is still a gap between the plate and the frame rails where dust, dirt an salt bearing moisture can accumulate.

The can comes with a very narrow straw like a WD40 can, The gaps can easily be reached without jacking up the car and the spray can takes no more than a couple of minutes to apply.

Definitely worth the time and cost.

 

Your pictures aren't showing up.

 

Georgina! Can you spell out your suggestion for a spray against corrosion? Your link does not show up.

Also, MillerCat now sends along 3 strips of adhesive foam to distance the shield from the frame and cat, so there's bound to be significant separation all around. The spray idea ... what is it?... gets better and better. I do have some spray that's black undercoating that is a rust preventive...perhaps that would be appropriate? It is a rather thick spray.

 

Not undercoating which is useless and traps water that is conducive to promoting rust underneath like plastic panel and maybe the plastic foam.

You want a rustproofing compound. You apparently have some kind of internet spam blocker.

Search for:
CRC 06026 Heavy Duty Corrosion Inhibitor, 10 Wt Oz
on Amazon.com

 

Thanks. Got it, it is coming from Amazon.
No doubt about probable ad blockers...I'll take em' all.

 

Thanks for the tip! How often would you recommend spraying this? I've got the aluminum Cat Security with stainless steel screws on my Prime. We don't need to salt the roads up here very often in Seattle so I don't think corrosion is as bad as it is in the East Coast.

 

In your case, you can spray it one and it will likely last the life of the car.

 

I can not help but think that an alarm, and a shotgun, would be the best prevention......

 

Don’t let the inciting violence police prius chat members find your statement, you’ll be poop poo’d on like the feller who goes by the initials of etcss.

 

I just installed the Auto Defender with the aluminum panel touching the frame. On right hand turns, I can hear a rattle sometimes. I probably need to remove the panel and install some foam or rubber barrier in between to silence the noise. Guess I'll have to break out the drill and grinder to remove the rivets/security screws...

 

You could try using a shim to wedge between the frame and aluminum.
Probably one of the rivets/screws aren't quite tight enough?

 

The same happened to me. All I did was to grab the center edge and pulled it down. The span was flexible enough that it bent down to provide additional clearance. That was 6 months ago. Still, no rattle.

 

I didn’t realize that there was another vendor that offers cat theft prevention

 

Violence vs. pacifism debates aside, I'm a bit busy to be hanging around the parking lot 24/7, staring at my car with an eagle eye. You may have more free time on your hands though, lol.

 

Did you grab the area I circled in Red? I'll give it a try. And I'll try a shim first as well on the frame, before I drill/grind. Thanks for the ideas!

 

YES.

 

I installed 2 MillerCat shields. One for our 2007 and one for our 2013. Pretty easy install and no noise at all! Knocked both out in just a few hours.