Posted by Scott on May 28, 2009, 11:15 am
My CB900 seems to have developed a new, mild-but-detectable weave/wobble
going through medium- to high-speed turns. It feels like the front end is
seeking a line, but just wanders back and forth without settling down. It's
only there in a turn, no sign of wobble or headshake going straight. What
are the most likely causes of this behavior?
The tires are properly aired, the front is about 50% done with no obvious
cupping or unevenness. The rear is closer to done, starting to square off
some. I've had rear tires that were flatter than this without causing a
wobble, just that funny "step up/step down" feel to entering and leaving
turns.
My list of suspects, in order:
Rear shocks. I probably should have changed these long ago. Now they're
both covered in oil and road dirt, and might not be providing any real
damping anymore. They're the stock adjustable shocks. Last time I checked
they were still available from Honda, but for a pretty penny indeed. I know
that DK sells affordable aftermarket shocks that'll fit. They're
non-adjustable, but since I never carry a passenger I see no problem there.
Swingarm bushings. Anytime I've got the bike on the center stand I give it
a shake to see if they're loose (they aren't), and a frozen swingarm would
be too obvious to miss. I doubt anyone's actually serviced the swingarm
since the bike was built. It's about time for a new chain anyway, and if
I've already got the shocks off, why not do the swingarm too?
Head bearings. Also unserviced since the beginning of time. But I do check
them for play every now and then. I don't wheelie or run over curbs, so
they shouldn't have any notching. Doing an actual service on these is
something I very much do not look forward to.
Wheel bearings. They're the sealed type, and were in good shape when I last
had the wheels off two years (~5,000 mi) ago.
The tires themselves are five years old. Could the rubber age and change in
ways that affect handling like this? It's garaged full time, and I don't
see any cracks or other signs of weathering.
Forks. Unlikely, since I overhauled them two years ago (seals, bushings,
oil). No leaks, air pressure is OK. As air forks they're a little
"sticky", but they've always been. I'll go over the triple tree and
retorque all of the clamp bolts.
Brakes dragging. Shouldn't be, since I put anti-seize on the slide pins,
but I guess they might anyway. That one's easy enough to check.
The last, least likely possibility is that every single sweeper I've ridden
in the past 300 miles is all lumpy and frost-heaved. Not impossible,
considering the DOT in question, but still....
Looks like I've got a few shop days in my future. Anything else I should
look for?
--
'73 CB450K
'82 CB900F (x2)
'04 FSC600 (SWMBO)
Posted by =?ISO-8859-1?Q?=BF?= on May 28, 2009, 1:57 pm
On May 28, 8:15 am, nob...@xmission.com (Scott) wrote:
> My CB900 seems to have developed a new, mild-but-detectable weave/wobble
> going through medium- to high-speed turns. It feels like the front end is
> seeking a line, but just wanders back and forth without settling down. It's
> only there in a turn, no sign of wobble or headshake going straight. What
> are the most likely causes of this behavior?
Your front tire's rubber is probably "dead", and it cannot absorb and
damp out small imperfections in the pavement. A matched set of new
tires will be "cushy" and the extra grip will damp out wobbles and
weaves.
If your rear shocks are worn out and don't damp the up and down action
of the
rear wheel very well, you'll notice a slow speed *wallowing* and the
handlebars will waggle back forth very slowly.
Posted by The Older Gentleman on May 28, 2009, 3:03 pm
>
> Your front tire's rubber is probably "dead",
After five years? No.
> and it cannot absorb and
> damp out small imperfections in the pavement. A matched set of new
> tires will be "cushy" and the extra grip will damp out wobbles and
> weaves.
>
> If your rear shocks are worn out and don't damp the up and down action
> of the
> rear wheel very well, you'll notice a slow speed *wallowing* and the
> handlebars will waggle back forth very slowly.
No, you won't. You'll notice a bouncing of the back end, all spring and
no damping.
Wrong again.
--
BMW K1100LT Ducati 750SS Honda CB400F SH50 Triumph Street Triple
Honda XBR500 MZ TS250/1.
If you don't know what you're doing, don't do it.
chateau dot murray at idnet dot com
Posted by =?ISO-8859-1?Q?=BF?= on May 28, 2009, 5:17 pm
On May 28, 12:03 pm, totallydeadmail...@yahoo.co.uk (Limey Wanna
Cracker?) wrote:
> > Your front tire's rubber is probably "dead",
> After five years? No.
Some rubber compounds can be "dead" in a matter of *hours*, asshole.
> > If your rear shocks are worn out and don't damp the up and down action
> > of the
> > rear wheel very well, you'll notice a slow speed *wallowing* and the
> > handlebars will waggle back forth very slowly.
> No, you won't. You'll notice a bouncing of the back end, all spring and
> no damping.
Don't understand much about hydraulic shock technology, asshole?
Always remember, I'm a cracker. You can eat me.
Posted by The Older Gentleman on May 29, 2009, 2:30 am
> > > Your front tire's rubber is probably "dead",
> >
> > After five years? No.
>
> Some rubber compounds can be "dead" in a matter of *hours*, asshole.
And those include tyres! Wow, imagine the product liability cases.
--
BMW K1100LT Ducati 750SS Honda CB400F SH50 Triumph Street Triple
Honda XBR500 MZ TS250/1.
If you don't know what you're doing, don't do it.
chateau dot murray at idnet dot com
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> going through medium- to high-speed turns. It feels like the front end is
> seeking a line, but just wanders back and forth without settling down. It's
> only there in a turn, no sign of wobble or headshake going straight. What
> are the most likely causes of this behavior?