wiper blades

[BEast750F@xxxxxxx]

Timothy,

The blades should be of reasonably high quality.  If they were made in China,
you should probably buy better rubber.  The rubber knife edge must be
scrupulously clean.

The rubber insert should slide freely back and forth about 1/8" in the wiper
blade fingers.

The wiper blade should pivot freely on the wiper arm end.

The wiper arm tension spring must exert enough force to hold the arm against
the glass.  Both sides should be equal.

The glass must be clean.  Use Meguiars #2 to rub it clean -- and no it will
not scratch.  #0000 steel wool may be required, but requires restraint and
judgment.  Blow the steel wool dust off with compressed air, lest it mar the
paint with scratches or rust.

With everything in the park position, lift the wiper arm away from the glass
and set it back down carefully.  The rubber insert should contact the glass at
a 90 degree angle to the glass.  Chances are that yours does not.  Thus, the
chattering.  

Adjust this angle of contact by tightening a small crescent wrench against the
flat sides of the wiper arms and twisting carefully until you have bent the
metal into the proper configuration.  After each adjustment lift and lower the
arms to observe the contact angle.

wet the windshield and watch the wipers in action.  At the end of each arc
they will change direction and the rubber edge should deflect in consistently
equal amounts.  In other words, the tested (not parked!) contact angle is 90
degrees, but in action they are being dragged across the screen at maybe 45
degrees.  When they change direction, they should flop over on to the other
side of the knife edge and be dragged back across the screen at the same (but
opposite) angle -- which is 45 degrees in our example.  

If they do not and you have adjusted the resting contact angle to a real 90
degrees, toss the wiper blades and purchase new ones.  Spring for the
expensive ones from Europe if possible, eschew the Chinese models.

DO NOT use the "washers" and wipers in a lazy attempt to clear dirt and/or
bugs from a windshield.  Wash with soap and water, dry with a towel.  The
washers are for already wet windshields, and are most useful when a passing
and filthy truck has just befouled your screen.  No doubt you will clean the
glass at your next stop.

Bill

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