If an overzealous effort to clean my wheel wells, I ended up removing what I now know to be the factory applied undercoating in one of my wheel arches. I started researching options for re-applying an undercoating using something like this 3M Profession Grade Rubberized Undercoating but am coming across numerous articles/videos explaining that this is a bad idea since it can trap contaminates behind the coating and lead to a huge rusty mess. So I am looking for advice on what to do from here. I don't drive in the rain and salt on the roads isn't an issue here. Is my best bet to just leave it alone?
Removed factory undercoating in wheel well...need advice
- Thread starter TxGlenn
- Start date
First off, rust is not an issue on NSX aluminum body panels. Also, even on a painted steel surface if the surface is clean and dry before you apply the coating I don't think you are going to have a problem.
I use this stuff
https://www.canadiantire.ca/en/pdp/rubberized-rockerguard-undercoating-550-g-0477935p.html
A couple of years after I got the NSX in 2011 I was checking the brake pad thickness and noted that the undercoating was peeling in the rear wheel wells. I peeled off all the loose stuff, cleaned the surface with mineral spirits and after it was dry I touched up the bare areas with 3 or 4 light coats sprayed at about 5 minute intervals. I did not over coat the remaining OEM coating. If parts of the remaining coating were starting to separate from the body, over coating could trap things in the void under the original coating. If you completely remove the OEM coating from the panel surface then a complete respray would be the way to go. My repair looks patchy when clean and the respray texture is slightly different than OEM; but, after a couple hundred kilometers its covered with dust and road crap and not so noticeable. That repair was about 6 years ago and there have not been any issues; however, I was under the car about 1 month ago greasing my clutch slave cylinder plunger and noted that more of the OEM coating is peeling so I need to do some more touch up.
I think the primary benefit to rocker guard is reduction of damage from road debris such as stones / rock chips. It might also provide some minimal damping on the body panels which might result in a small reduction in cabin noise. I use the rocker guard regularly on the rockers and wheel arches of our Honda Pilot (definitely painted steel) specifically to deal with damage from things kicked up by the tires.
I use this stuff
https://www.canadiantire.ca/en/pdp/rubberized-rockerguard-undercoating-550-g-0477935p.html
A couple of years after I got the NSX in 2011 I was checking the brake pad thickness and noted that the undercoating was peeling in the rear wheel wells. I peeled off all the loose stuff, cleaned the surface with mineral spirits and after it was dry I touched up the bare areas with 3 or 4 light coats sprayed at about 5 minute intervals. I did not over coat the remaining OEM coating. If parts of the remaining coating were starting to separate from the body, over coating could trap things in the void under the original coating. If you completely remove the OEM coating from the panel surface then a complete respray would be the way to go. My repair looks patchy when clean and the respray texture is slightly different than OEM; but, after a couple hundred kilometers its covered with dust and road crap and not so noticeable. That repair was about 6 years ago and there have not been any issues; however, I was under the car about 1 month ago greasing my clutch slave cylinder plunger and noted that more of the OEM coating is peeling so I need to do some more touch up.
I think the primary benefit to rocker guard is reduction of damage from road debris such as stones / rock chips. It might also provide some minimal damping on the body panels which might result in a small reduction in cabin noise. I use the rocker guard regularly on the rockers and wheel arches of our Honda Pilot (definitely painted steel) specifically to deal with damage from things kicked up by the tires.
Last edited:
If you have a black car I'd just leave it alone.
However, on any other color than black it bothers me and will just get worse having the body color show through in patches. That's when I'd clean it as best as possible and apply something new.
In the US, I've used Duplicolor, 3M, and Rustoleum Professional (they make two kinds - get the pro version). The 3M is the best, but it's also about 2-3 times more expensive than the next best thing - The Rustoleum pro. I used the Rustoleum pro on my NSX about 3 years and 10k miles ago. It's seen rain, snow, sand/salt mix in that time period and has held up flawlessly so far. Below is a picture of it taken just a few weeks ago. It dries to a nice dark black - some other manufacturers dry to an ugly muddy brown. I bought two cans of the Rustoleum Pro version and used chip brushes to paint it on in multiple coats to avoid the rattle can fumes.
View attachment 162654
