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2019 BMW R NineT
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Discussion Starter · #1 · (Edited)
I’ve been looking into sound/thermal insulation to reduce resonance and noise deflection from a skid plate that I love the looks of but keep taking off the bike because it ruins the sonic experience. Best I’ve been able to find so far is a product called hush mat. It purports to work at temps up to 550 degrees, which should be more than enough to handle the heat from the engine and headers. But it seems a bit pricey for my intended application as you have to buy a box of 20 or so sheets for ~$150 USD—and it’s unclear how well it’ll keep being exposed to the elements.

How have those of you with skid plates solved this problem, if at all?

Thanks in advance!
 

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Never noticed any type of noise resonating from the skid plate and my ears are sensitive to strange or noises that should not be occurring. So in short, no problem to solve. I would say ear plugs would be your best bet if engine noise(s) bother you.
 

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2019 BMW R NineT
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Discussion Starter · #3 ·
I do ride with earplugs, heh. Must be a problem that’s particularly bad with this specific plate (Evotech). I absolutely love the looks and fit/finish; it’s a shame it’s so resonant.
 

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You could try roofer aluminum insulation. You can buy it by the roll at HD or Lowes, etc. I used it in my Tintop Samurai cabin and bonnet hood after I pulled the carpet out, it made a difference but not a crazy difference. It's essentially a mm thick layer of glue with aluminum foil backing it. Helps dampen vibrations the same way the expensive branded products do. Insulates the vibrations on the surface of the thing less violent, which makes it less loud.

I think I used Quick Roof. Edit: no it was something else, but it's sold at Home Depot in the roofing supply area.

You could also try insulating the bolts/fasteners that connect the pan to your bike. Wrap the bolts in rubber or something similar that will absorb energy. I had rubber wrapped mirrors on a previous bike (Duke 390) and they had almost no buzz even at high RPMs despite being a highly strung thumper (50hp from a single 400cc, not bad), been tempted to do the same with my R9T's mirrors.
 

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If the sound is from pebbles etc hitting the guard a cheap option might be painting on a coat or three of the rubbery type sound deadening paint that people used to paint car floors with.
 

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2019 BMW R NineT
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Discussion Starter · #6 ·
Definitely not rocks -- it's a persistent metallic resonance, almost like there's a really loud tuning fork attached to the bottom of the engine, which gets louder and more "ringy" with increasing revs. I looked into plasti-dip and it seems people have mixed results with it -- some people have good luck, others have trouble with getting it to adhere to various metals, and others still find that it flakes right off when exposed to the kinds of temps that exist 1 inch from an exhaust header and engine sump.

Thanks all for the comments thus far!
 

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I now make the assumption that your skid plate is an aftermarket? If not and it's a BMW item from a GS Adv I'd suggest removing the plate and check the mounts for any looseness or a broken mount setting up a buzz, really obvious suggestion I know but most vibration/weird noises emanate from looseness, whether it's something unwinding itself or cracked/broken.:cool:
 

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A cheap fix, you could try is installing rubber grommets (looks like a small rubber donut) which provides rubber dampening between the frame and skid plate. You may have to buy longer mounting bolts to compensate for the extra thickness of the rubber grommet.
 

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Discussion Starter · #9 ·
A cheap fix, you could try is installing rubber grommets (looks like a small rubber donut) which provides rubber dampening between the frame and skid plate. You may have to buy longer mounting bolts to compensate for the extra thickness of the rubber grommet.
That’s an interesting thought, not least because it’s a $5 fix rather than my initially-proposed $150 fix.

Would probably have to be a silicone-based rubber to ensure thermal stability, but that’s easy enough to find. They probably wouldn’t even need to be that long to dampen the frequencies I’m having a problem with. Looks like a trip to the hardware store is in my very near future—will report back!
 

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R9teees
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Good thread. I have painted my skid plates with spray on bedliner for years now and have noticed that it does deaden some of that ringing. A mechanic at the bike shop Uses a piece of closed cell foam that he sticks between the oil pan and the plate. I went a step further and doubled up a piece of heat cloth to the between the foam and oil pan. You can spray adhesive the Foam to the bash plate but it’s not needed IMO if snug. The mechanic would do this not so much for noise reduction but to keep any errant stone from finding its way between the bash plate and the oil pan, preventing a puncture if the bash plate takes a really hard knock. I think he learned this from experience. Hope this helps.
 

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I have an SW motech skidplate but never noticed any weird sounds..

I know there's some sprayable rubber kinds for sale.. maybe line the inside with that? Or rubber mats?
 

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I have a set of engine guards on my scrambler and There is a slightly different sound. The skid plate coated with bedliner does Deaden The plate noise.
 
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