Subject: Lowering Gear Ratios Facts and
Fiction
Date: Wed, 29 May
2002 22:41:51 -0500
From: "FastVirago" <FastVirago@attbi.com>
Many people have asked about the ability to
lower the highway operating RPM on
the Virago. The problem is this is not
easily done since the gear ratio
change among the motors takes place within
the transmission not the
differential. Specifically the middle
drive gear and the middle driven gear.
Well, here's the facts AND the solution.
All Virago's 700 and up, '84 and up, were shipped
with a 32/11 differential.
32 teeth on the ring gear and 11 on the pinion
gear which makes a performance
oriented 3.43:1 final drive.
As stated earlier the actual ratio change takes
place in the trans not the
differential. Specifically the middle
drive gear assembly is different. The
700 model for example has a middle drive gear
with 49 teeth and a middle
driven gear with 44 teeth. While the
1000 has 45 and 46 respectively. And the
1100 has 47 and 45. You must also take
these numbers into account with the
different 1st - 5th gear ratios which are also
different among the engine
sizes.
Here's the solution. Yamaha is famous
for being a 'parts bin' company. Which
means that many parts are used on a lot of
different models. With that in
mind I've done some investigation. If you wanted
to lower the operating RPM
you can use a differential from the Yamaha
Venture which has a 33/10 ring and
pinion for a 3.03 final drive. Or, to
lower it even further get the one from
a Yamaha VMax with 33/9 for a 2.72 final.
All the differentials have the same
outer housing and bolt pattern just different
internals.
Just remember that lowering the final gear ratio
will not only have an affect
on highway RPM but also, maybe severely, your
acceleration capabilities.
Yours,
FLAASH
A friend made up an excel sheet for the gearing. He checked and recheck
and the
number are right but the only funny thing is for my 750 I must put
in 16.8 for the
tire size to match the stock spec sheets numbers on top speed in each
gear.
You can change gear ratio, engine speed/rpm and tire size.
It is set up for my 750 and the 3.03 gears look good; it would drop
my highway
speeds enough without losing much if any low end. The 2.72 gears look
even
better but I Don't need to be able to do 140. If I can I will and I
don't need to.