The arm is soft metal (that will crack) so it strips before the shaft or the motor gears do.  It's best to get new arms, but if you are adventurous (or just cheap like me), use some bits of drywall sanding mesh to repair the slipping arms.  Put it into the arm socket so it just fits snugly to the shaft. 

This trick has bought me years of extra service on these wiper arms. Both my '84 and '85 had and still have the original (formerly loose) wiper arms.  And, they will still slip if overloaded as long as you use the right amount of mesh--just enough to work, but not so much you lock them to the shaft!  Test that they will slip with some reasonable amount of force when held before you drive off.

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Neil N
Sent: Thursday, February 27, 2014 11:16 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Idea to Re-use Worn Wiper Arm?

Hi all.

The wiper arm metal is soft (pot metal?) so I assume it's prone to cracking, but if one compressed the portion of metal on wiper arm that contacts the wiper arm shaft, would this reduce the ID of the hole on arm and enable the arm to better re-knurl to the wiper arm shaft?

After repairing my '81 Westy yesterday, finally pulled my head out of the engine bay to see that snow load had forced a wiper arm on the '88 to drop. I measured the length from shoulder of wiper arm shaft (below
splines) to end of splines and length of portion of wiper arm that slides over the shaft. I saw just over 1 mm difference. The shaft is shorter. This gave me cause to file a **very, very ** small amount of metal off the shoulder of shaft to see if that would help the arm seat further down. It seemed to help wiper re-knurl, but all that spawned the above question.

Neil.

--
Neil n

Blog: tubaneil.blogspot.ca

'88 Westy http://tinyurl.com/c8rlw6p

'81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/

Vanagon VAG *Gas* inline-VR Engine Swap Group:

http://tinyurl.com/d7gd5ej