skid plate resonance?

[Eville Rich]

I have an Altrider skid plate on my 2016 S10. I get what I think is a resonance from the skid plate, most obvious between 3k and 4k rpm in 4th through 6th gears and in the first half of throttle. It's there at other times, just most obvious in those conditions. While I'm pretty sure it's just the skid plate, I want to make sure I might not be overlooking something else, like something in the clutch. I ride with earplugs and it's still pretty loud.

I've been able to ignore it, but this morning was a little overboard. It also helped me hone in on the skid plate as the likely offender. I was following a dump truck at a reasonable distance for about 5 miles. I could "hear" the changes in the dump truck's speed via the resonance. There's not too much else on the S10 that would vibrate like that, other than the skid plate. My guess is that the low-frequency rumble was getting picked up.

I see that folks have used Dynamat and maybe other materials to reduce skid plate resonance. Any other tips for the Altrider skid plate? I'm going to check all the connections, but it felt solid after my commute. On my WR250R I improved things a lot by adding rubber washers to the connectors, but that is a totally different setup to the S10, and I don't think a viable solution.

Thanks much,
Eville Rich
2016 S10
2015 WR250R

 

[AVGeek]

I think the resonant damping material is the way to go. Everything has a harmonic frequency, so changing the mass will change that frequency, usually to one below our audible threshold.

 

[Sierra1]

I'm thinking it may be a combination of the skid plate, and something else....tires? I have that skid plate, and Battle Wings, but no noise. AVGeek is right about EVERYTHING having a harmonic frequency, but there are a bunch of Teneres with Altrider skid plates without the buzz. Logic would indicate there must be something, however minor, different with yours. Good luck.

 

[WJBertrand]

I think the resonant damping material is the way to go. Everything has a harmonic frequency, so changing the mass will change that frequency, usually to one below our audible threshold.

Agreed. I lined the inside of my skid plate with Dynamat and it really quieted it down. I think a lot of noise is just reflected engine noise. Besides a quieter ride, I think the presence of the Dynamat material will help cushion the sump a little should there ever be a large enough impact to force the plate into contact with the engine.

All of these bash plates seem to be made of large, flat pieces of featureless material, this is bound to act like a sounding board. I think a ribbed design would not only be quieter but potentially stronger as well.

 

[Ironhand]

I had the same complaint about my Altrider. I stuck a strip of neoprene padding intended for race bike seats on the inside of mine and solved the problem. A Dynamat-like product should do the trick.

 

[DryRider]

I had the same issue...I went to O'Reilly auto parts store and bought a pack of sound deadening stuff for car stereo speaker installs for 15-20 bucks and that did it. I just took the plate off and this stuff has a thick black aluminum front sicky back side and put it all over the bottom of the inside of the pan. I Liked it because it would not absorb anything or catch fire...looked easy to clean it. Made the sound go away. Those harmonic distortions can be hard to find. It was also complicated by how and whenever the plate came off to change oil the sound could change. Happy to have found others had a fix here and that did it.

 

[Propsoto]

Different skid plate, but same problem. As others have said, Dynamat or similar.