?Fork oil - Page 4

 

On Sat, 12 Jun 2010 10:15:30 -0500, "frogliver"


In those days, ATF could mean several things. Usually, it
meant a Dezron spec which was formulated to the specs of
several automakers.  Dexron was the successor to the old
Type A designation .  General Motors was the primary but,
Chrysler had used Type A from the early sixties and went
along with GM adding their own spec reference as do Ford
starting with the 1976 model year.  Somewhere in the early
seventies, the Dexron designation replaced the Type A
designation.  If you test samples from various makers of
Dexron or any of the others, you will find rather large
variations in the viscosity which is a primary consideration
in motorcycle fork oils.  In 1979, a reference to "ATF"
would usually have meant Dexron or Dexron II since it was by
far the most common.  Type F spec'd for older Ford products
would not have been used since it has a friction modifier to
help the trans clutches get a bite at lower pressures.

I have had several seventies machines on which I replaced
the fork oil during maintenance.  By far, the best thing to
do and save yourself much consternation, swearing and time
is start with a name brand fork oil since the viscosity is
well controlled within brand lines.  The same viscosity in a
different brand may perform differently.  My personal
favorite is Bel-Ray - there are several other excellent
brands.  They are all available in various weights as well
as multi-grades.

My own preference for fork oil in all street/highway riding
is determined by ride quality and handling.  An oil too
light allows the fork to compress or rebound too quickly and
possibly bottom out on sudden hard braking and allows too
much nose dive for me.  Too viscous and you will find your
teeth rattling on rumble bars.  You can tune the fork to
your preferences.  At 240 lb, I am sure the forks require a
different oil for me than a lighter rider for similar
results.

Bottom line, pick your brand and weight of fork oil as a
starting point.  Measure the oil level and quantity very
carefully.  On my bike, the manual gives an oil level as
measured from the top of the fork tube with the spring
installed.  To get this, I use either a piece of wooden
dowel stock readily available at places like Home Depot or a
piece of small diemeter pvc or cpvc marked with a sharpie
for the correct oil level.  For best results and least
hassle, just forget the "ATF" and go with a good fork oil
unless you like to work for giggles instead of results.  You
will be pleased with the result.

Lugnut