Vibration found

[pester]

After months of searching for a foot peg vibration at 4000 rpm's I found today that it is the shock. I stretched a bungee around it - pulled it tight - and no more vibes. I'm assuming the normal engine vibes at 4000 is being amplified through the shock vibrating the spring or shock body. So now what? Ohlins?

 

[TigerDude]

I'd try re-torquing it in first.

 

[pester]

Thanks TigerDude. I should have gone into a little more depth ... sorry. Every bolt and nut has been retorqued...Some several times.

 

[L.B.S.]

Thanks TigerDude. I should have gone into a little more depth ... sorry. Every bolt and nut has been retorqued...Some several times.

What about tweaking the preload a wee bit? If you prefer the ride height/static sag as it is, I'm sure a 1/4 or 1/2 turn of the preload ring won't be too obtrusive. Maybe that might be just enough to change the resonance. If that doesn't work, then at least you haven't spent any money prior to a better shock purchase.

 

[pester]

Good idea L.B.S. I measured the sag. 1 5/8 inch. A bit more preload couldn't hurt. Trying to understand this problem I've also noticed the coiled spring isn't equidistant from the shock body all the way around.

 

[Fred]

The NC, especially the DCT model in D mode, produces a low frequency vibration when it is lugging. I noticed yesterday when on a particular road that the engine vibrations initiated a strong sympathetic resonance in the front suspension which wasn't there before the addition of Race Tech Gold valves. It only seems to occur in D mode and only on specific rural roads which tend to have a little corduroy surface.( I used to be in the vibration diagnostic business in a previous lifetime), and it is not uncommon to have an engine or drive train set up a very annoying sympathetic vibration in structures or specific sheet metal and plastic that is really enhanced when it finds a willing recipient for the engine's vibration energy. Springs love to vibrate like tuning forks so you may be on to something. You can attempt to raise or lower the frequency of the vibrating spring and it may go away.... only to re- emerge at a different engine speed!!!!

 

[pester]

Well problem solved. I intended to add preload but instead found that the preload adjustment was bottomed out. This tilted the spring into the shock body causing it to rub. The vibration of the spring was transferred to the shock.