Motorcycle “Word” of the Week: Damper Assembly

Remember those “Word of the Day” calendars?  They were kind of fun in a nerdy way.  Therefore, I figured I would try something similar here.  Once a week/month, etc., I am going to pick a technical term related to motorcycles and define it for the community. 

For some, these posts might seem ridiculous (“hey, I already know that”), but for others I hope they are educational.  A lot of terminology gets thrown around in motorcycle circles, and there is no shame in admitting when you don’t know something.  HappyWrench is here to help!

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Damper Assembly:  As some of you may know from following me on Facebook, Twitter, or Instagram, I am neck deep in a front-end rebuild of my 1972 Harley-Davidson Shovelhead FLH.  I have completely disassembled both fork legs and besides a big spring, there is also a unit inside there called the damper assembly.  Here is a picture of a damper assembly; numerically, the damper assembly is item #18 in the schematic below.

fork diagram

When everything is all “mushed” together, the damper assembly sits in the bottom of the fork leg, held in place by a nut (item #12 above).  Essentially, the main fork spring, which supports the forward mass of the motorcycle and rider in compression, sits directly on top of the damper assembly. 

There is also another smaller spring that is part of the assembly itself, sometimes referred to as the top-out spring (it’s tiny, but visible in the picture above).  This spring keeps the upper fork slider from banging into the top of the damper assembly when the forks fully extend (essentially preventing the upper fork sliders from falling off the lower legs).

Additionally, there are a series of holes in the rod portion of the damper assembly.  As the front end of the motorcycle is compressed, oil is shoved through these small orifices helping to create a “damping” effect.  Together the main spring, damper assembly, and fork oil, create the compression damping (cushioning when forks are compressed) and rebound damping (cushioning when forks extend) that we feel when we ride.

Anyways, I hope you found this post fun and educational.  Please like on Facebook, tweet on Twitter, or +1 on Google+.

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