Date: Thu, 16 Aug 2012 17:54:50 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: windshield wiper repair
In-Reply-To: <20120816154504.W62C8.1266068.imail@eastrmwml304>
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At 03:45 PM 8/16/2012, mcneely4@cox.net wrote:
>pressable piece that the stud and splines of the shaft fit into has
>stripped. Evidently this requires a new wiper arm, as the damaged
>piece seems not to be replaceable. Is that true?
Usually they are restorable, with some attention to detail. The
biggest factor is how many times it's been done before, as each time
the arm will bed noticeably deeper on the shaft (the exact amount is
the geometry of the spline depth vs angle from the shaft axis).
Short procedure is first to scrape out the metal from between the
splines on the shaft, until it's all clean under a glass. Then
examine whether a second washer will be necessary (likely) so that
the first washer doesn't just end up pulling against the shoulder of
the stud; ditto sufficient clearance behind the arm. Then taking
care not to nip the second washer between shoulder and first washer,
press the arm down by hand onto the exact position desired on the
windshield and while holding it there, add washers and nut and torque
down to the Bentley figure using a beam-type torque wrench (not a
click-type). Again, be certain that the spacing washer slips over
the shoulder while tightening and does not catch on it. If you want
to retain the plastic covers over the mounting hardware this washer
will also have to be small enough to allow that, so you may have to
ream or otherwise enlarge the center hole.
Once the assembly is made, remove the nut and check that the top
washer has not contacted the shoulder; if it has, add a second or
thicker spacer washer and retorque.
>A couple of other questions:
>
>1. Does anyone know for sure that the dash must be pulled in order
>to replace the shaft? Is it possible that it can be reached and
>replaced through the top grill opening? That might be easier to do,
>if indeed it can be done.
It absolutely cannot without cutting through solid metal.
>such a possibility to the shop I consulted in Burlington, Washington
>a couple of weeks ago, and the guy just looked at me as if I was
>kidding, and said, "Never work, not enough metal there to hold
>anything even if you could drill and tap it." GoWesty's page seems
>as if it is something done with some
>regularity: http://www.gowesty.com/library_article.php?id=1512
Decent article except that they forgot to clean out the splines which
will be packed with pot-metal (zinc casting metal, not aluminum I'm
fairly sure) which is the remains of the mating splines formed the
first time the arm was assembled to the shaft.
Drilling and tapping as they say is undoubtedly practical and an
excellent way to save the shaft. However if you're not accustomed to
either accurate drilling or small-diameter hand tapping, I would not
start here. At least do a number of practice ones first - start with
through-holes in brass if that's handy, then through-holes in steel
and finally blind holes. You'll need a plug tap which is easy to
find, and a bottoming tap, not so easy (or drill a deep hole, harder
than you'd think). However you can get two plug taps and very
carefully grind the end off one to make a bottoming tap. Pep Boys
used to sell Vermont-American brand metric plug taps for ~$4 each in
carbon steel, decent quality.
I can tell you (or your chosen mechanic if he's the listening sort) a
good drill size that will be a little bit larger than what you
usually find in tables - this will make it easier to tap and less
likely to break taps or tap teeth, and in steel leads to an
inconsequential reduction in strength. Tap drill size is a fairly
exact science based on thread form and size.
>Given my skills and general lack of patience, this may be something
>I should hire done, but it should be cheaper in that case than
>hiring someone to remove the dash to replace the shaft.
You said a mouthful. Patience is the key.
Yep. Go for it. If you can find a machinist he'll undoubtedly be
expert at this stuff, though he may want to mount your van on his
milling table. I suspect mechanics vary from expert to lousy - but
the worst likely outcome is to wreck the shaft that's already
wrecked. How you divide the sheep from the goats here I can't
say. The more holes I tap the less I'm inclined to trust a random
mechanic until proven otherwise (whereas a machinist or accomplished
model engineer is a pretty good bet).
Yours,
David
