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From: marauder@fluke.UUCP (Bill Landsborough)
Newsgroups: net.cycle
Subject: Re: wabble n roll
Message-ID: <2918@vax4.fluke.UUCP>
Date: Thu, 21-Nov-85 10:45:15 EST
Article-I.D.: vax4.2918
Posted: Thu Nov 21 10:45:15 1985
Date-Received: Sat, 23-Nov-85 05:10:59 EST
References: <1458@decwrl.UUCP>
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 59

In article <1458@decwrl.UUCP> hood@thehut.DEC (Stupid computer tricks) writes:
>
>I've got a wobble.
>
>In March I replaced the stock tires on my bike (84 Honda Nighthawk-S)
>with a pair of Dunlop Sport Elites.  For the entire spring and first
>half of summer, I was convinced that the folks at Honda designed the
>bike around these tires.  Steering, braking, handling, everything improved
>dramatically.
>
>Toward the middle of summer, I started getting a back-and-forth (right-
>to-left) shimmy in the handle bars from about 30 to 45 mph.  Not enough to
>affect the ride at all, but enough to be damned annoying. 
>
>As time went on, the wobble got more pronounced.  It still didn't affect
>handling, but it did get more and more annoying.
>
>I've tried checking fork pressure, wheel balancing, rear shock adjustment,
>and a few other things.  At the suggestion of my mechanic, I increased
>tire pressure from 30psi to about 35.  This cut the wobble quite a bit,
>but still didn't eliminate the problem.  (The mechanic also has a
>Nighthawk-S, on which he put either Metzler or Michelin soft tires,
>and also has a bit of a wobble now.)
>
>I talked about the problem a bit to a guy who runs a motorcycle tire
>store (not where I bought mine) who suggested doing all the things I
>checked, and also recommended against using "aerosol donkey snot" in
>the tires.  He mentioned that sometimes he just gets a bad tire that
>causes wobbles for no apparent reason, but because mine didn't wobble
>until a couple of thousand miles, that it might not be the problem.
>
>The tires aren't showing any signs of unusual wear or anything, and
>everything on the bike seems to be ok.  Any suggestions?
>
>					Tom Hood
>					DEC, Littleton, Mass.
>					via whatever path works

I have had tires which were like that and what I finally found out is
really strange.  The tire was balanced in the round sense of rotation
but was not balanced in the sense of side to side rotation!  For
example, picture sitting on the motorcycle and looking at the front
tire.  The top-left part of the tire is heavy and the bottom-right is
heavy.  Put this tire on a balancer and it will be balanced.  But run
this tire and it will wobble violently (depending on the degree of
unbalance).  I found it by raising up the front wheel and spinning the
tire very fast (about 40mph) with a grinder motor, and then feeling the
handlebars. However that might not be your problem.  Some bikes have a
steeper steering rake than others and they do wiggle, especially when
you let go of the bars at speed.  Also handlebar mounted fairings will
cause a wiggle.

Bill Landsborough
 


"Love is patient and kind; love is not jealous or boastful; it is not 
arrogant or rude... Love bears all things, believes all things, hopes all
things, endures all things."   1 Corinthians 13:4-7