Date:         Mon, 4 Jul 2005 21:18:19 -0700
Reply-To:     John Bange <jbange@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Bange <jbange@GMAIL.COM>
Subject:      Final Drive Oil Seal Bushing
Content-Type: text/plain; charset=ISO-8859-1

So I've finally got the engine ready to assemble with the transmission
and put it in. The first step is to put the auto tranny unit and the
final drive together. Auto unit is a fresh rebuild from German
Transaxle. The important part there is to measure the end play between
the oil seal bushing on the final drive and the shoulder of the
reverse planetary ring gear on the transmission (as detailed at 38.5
in the Bentley) in order to shim out the slop. The tranny came from
German Transaxle with the reverse gear offset measurement written on
the instruction envelope: .266 inch. The oil seal bushing depth is
.114 inch. Thus the calculated end play is NEGATIVE .152 inch! That's
more than an eighth of an inch! The guy at German Transaxle said this
means the final drive needs rebuilding, as the pinion shaft bearings
are going. He said to check the pinion shaft for end play and I'll
understand the necessity. Well, I drove out for my weekly Vanagon work
day today and inspected the pinion shaft. No end play whatsoever. So I
pulled the cover plate off and inspected the bearing outer race
therein and the bearing itself in the pinion shaft: race shiny and
smooth as silk, bearing spins smooth and easy. I ran the old
differential oil through filter paper when I drained it to change the
differential pan gasket, and it had not a speck of ANYTHING in it. The
magnet on the pan was likewise perfectly clean. The differential has
clearly been re-done before (the spring washers are missing from under
the five bolts holding the pinion cover plate, and one bolt was only
hand-tight), so maybe some transmission genius did something weird,
like shim the oil seal bushing from behind, to adjust for a badly out
of spec transmission? The guy at German Transaxle said it should take
about 40ft/lbs (!) to turn the pinion shaft against the differential
and mine turns easily by hand. But there's no end play! And all seems
perfect except for the oil seal bushing offset. I am sorely tempted to
pull the bushing off, machine .170 inch off it and pretend nothing
happened! Anyone know if it's possible for the final drive to "fail"
in such a way as to do no more than extend the oil seal bushing but
not harm the bearings? Is the pinion shaft REALLY supposed to take
40ft/lbs to turn?