Undercoating recommendations needed

[SteelGreyM]

Hey everyone,

Got my subframe reinforced a little while back but unfortunately I scratched some off while replacing the rear diff bolts. Can anyone recommend an undercoating for me? Everyone seems to like the 3m black stuff. Bonus points if the coating is grey. Thanks

Edit: I dont think I was specific enough in my description. Im looking for a rubberized type of undercoating. Ive circled a photo of stuff similar to what im talking about. Also attached is a photo from my subframe reinforcement. You can see they sprayed it everywhere and it dries to a protective rubberized texture. Thanks!

Edit 2: I think I found the same product used on my car. 3M 08889. I'm going to order it and will update with how things turn out. And because i'm crazy, i'm going to put some Por 15 underneath the undercoating.

Additionally, I have a few scratches in my engine bay. the engine bay is matte but touch up dries glossy. Whats the best way to touch up an engine bay scratch?

[Rich022]

"Undercoating": -if you mean the underside of the body, i went with with Wurth Self Etch Primer Grey and SEM EZ Coat Light Green #62233; this is pretty darn close to our factory color underbody coating. Also used Wurth Brushable Seam Sealer for weld seam areas first. As for engine bay, Maybe BMW has colors available for engine bay.

[Jersey_M3]

3m Professional is great stuff. I have a few extra cans in my garage if youre looking for some on the cheap

[SteelGreyM]

"Undercoating": -if you mean the underside of the body, i went with with Wurth Self Etch Primer Grey and SEM EZ Coat Light Green #62233; this is pretty darn close to our factory color underbody coating. Also used Wurth Brushable Seam Sealer for weld seam areas first. As for engine bay, Maybe BMW has colors available for engine bay.

Hey thanks for the recommendation! That looks pretty close to factory color. Im gonna the spot with a wire wheel first juuuuuust in case some microscopic rust formed in the meantime. Then primer and undercoat. Thank you!

Edit: This seems to be just the paint. I was looking for a rubberized undercoating to prevent rust.

[SteelGreyM]

3m Professional is great stuff. I have a few extra cans in my garage if youre looking for some on the cheap

Hey. Is it the rubberized stuff. What color? Can you link it?

[Jersey_M3]

Hey. Is it the rubberized stuff. What color? Can you link it?

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Professional-Grade-Rubberized-Undercoating/?N=5002385+3292638249&rt=rud

[SteelGreyM]

https://www.3m.com/3M/en_US/company-...2638249&rt=rud

You've gotta be super careful with that stuff. If you trap any moisture underneath it then it will rust faster and worse.Be sure you've properly and extensively prepped the surface before spraying it. If not, it will peel and trap moisture.

[Jersey_M3]

You've gotta be super careful with that stuff. If you trap any moisture underneath it then it will rust faster and worse.Be sure you've properly and extensively prepped the surface before spraying it. If not, it will peel and trap moisture.

I used 2k epoxy before using it, my Instagram page shows the work done. Jersey_M3

[SteelGreyM]

I used 2k epoxy before using it, my Instagram page shows the work done. Jersey_M3

Great work! Looks like a quality job!

[Rich022]

the Worth Self Etch Primer is color Grey If I forgot to mention the color)

The 'rubberized stuff': should be SEM #39793 "HEAVY TEXTURE CHIP GUARD" Opaque. I can't believe all the different paints etc were required when i did my subframe reinforcement 5 yrs ago. BTW all the undercoating sprays, sealers etc. I've used have held up very well.

[Rich022]

If i recall, the order: seam sealer the welds etc, then self etch primer. I THINK I applied the Light Green 62233, and last the Chip Guard. Reddish has a video on this. I followed their recommendation.

[Maxima SE]

When I did my RACP replacement 5 years ago, the consensus was to go with WURTH products. I cant recall if this was based on redish motorsport videos or forum member advice. Looking through my pictures, it looks like I used the following:

https://www.wurthusa.com/Chemical-Product/Underbody/Stone-Guard-Grey/p/8890972

https://www.wurthusa.com/Chemical-Product/Adhesive-and-Bonding/Seam-Sealer/Brushable/Brushable-Seam-Sealer-1-Quart-Can/p/08901021

https://www.wurthusa.com/Chemical-Product/Primers/Zinc-Weld-Thru-Primer-13-53-Fl-Oz/p/0893109

pricey but this is the part where You don't want to cut corners.... last thing you want is rust down there

[mscott7426]

I used 2k epoxy before using it, my Instagram page shows the work done. Jersey_M3

What'd you use for the primer? It looks like it matches the OE stuff pretty well

[SteelGreyM]

3M Rocker Panel Coating, 08889, Gray, 23 oz Net Wt (650 g) https://www.amazon.com/dp/B000L9VXHE...ing=UTF8&psc=1

Btw guys I ended up buying this stuff. Matches very closely and looks great. High quality stuff. I can recommend it.

[Jersey_M3]

What'd you use for the primer? It looks like it matches the OE stuff pretty well

It’s not the right color but it appears to be a great product. From Amazon:
1 of SprayMax, 2K Epoxy Rust-Cure Primer, Gray, Aerosol (1)