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[dsn_klr650] harmonics problem with ps spring
Posted: Fri Jun 02, 2000 6:41 pm
by ephilride@aol.com
In a message dated 6/2/00 5:28:41 PM EST, psprague@... writes:
>>
Every system has a "natural frequency" (an infinite number actually). The
natural frequency of the system (your rig) is controlled by its mass and
stiffness (nat. freq = square root of stiffness divided by mass) The
damping (shocks) control the amplitude of vibration, not the frequency. It
appears that you have altered one of the frequencies that is easily excited
by random excitation (traveling down the road). This is a simple explanation
of a very complex phenomena. I would experiment with changing the damping
(increase) since you want to keep the stronger spring. Good luck.
Knot - Whole lotta shakin' goin on.
[dsn_klr650] harmonics problem with ps spring
Posted: Fri Jun 02, 2000 6:53 pm
by Tom Bowman
PSprague wrote:
> To stiffen up the rear suspensionon my KLR 650 A13 I recently
replaced the
> oem shock spring with the PS 500/560 spring. The bike feels
better
> "planted" with no scraping on the panniers but a problem did
develop with
> the new spring: there is now a harmonic or resonnance problem
with the
> bike. Mostly this occurs between 40 and 50 mph, not dependent
on rpms (any
> gear). There is no wobble or weave but like a soft jackhammer,
about 3 to 6
> up and down pulses in the handlebars followed by an equal time
of
> smoothness, then the cycle of jackhammer/smoothness repeats.
Above 50 mph
> there is little or none. .............
>
> I don't want to go back to the oem spring or spend the $$ for
a whole new
> PS shock. Anyone else had this problem? Any ideas???
> >>
And "Ole Knot" answers:
> Every system has a "natural frequency" (an infinite number
actually). The
> natural frequency of the system (your rig) is controlled by
its mass and
> stiffness (nat. freq = square root of stiffness divided by
mass) The
> damping (shocks) control the amplitude of vibration, not the
frequency. It
> appears that you have altered one of the frequencies that is
easily excited
> by random excitation (traveling down the road). This is a
simple explanation
> of a very complex phenomena. I would experiment with changing
the damping
> (increase) since you want to keep the stronger spring. Good
luck.
>
> Knot - Whole lotta shakin' goin on.
Could it be that his bike has some out of round in the rear tire
and the original rear spring/damping setup was so soft that it
masked it? Or that there's some out of balance that was masked?
Tom Bowman
Atlanta
A14 "Olive"
[dsn_klr650] digest number 204
Posted: Sat Jun 03, 2000 6:03 pm
by JSherlockHolmes@aol.com
In a message dated 6/3/00 4:17:02 AM Canada Central Standard Time,
DSN_klr650@egroups.com writes:
>
Hey Tom,
If you need to chat, or do lunch, or something, to help your mind. Or if you
need help with something cuz you are tied up at the hospital, get a hold of
me at my e-mail address. I live in Franklin on South 35th Street and would be
happy to help out a fellow rider.
Jim Sherlock
JSherlockHolmes@...