Gearbox pinion shaft bearing replacement...

[Jim Dupree]

Gerard,
I have done several of these set ups but always with all those fancy special
tools. One thing that I learned early on is that the way Audi (VW & Porsche)
set the ring and pinion is by the noise they make. They set each ring and
pinion gear set in a jig that hold them and run them under load at the
designed engagement depth. They then adjust the engagement depth until the
gear run the quietest, this is the deviation they refer to. The deviation is
marked on the gear set so it can be set up to that spec in a trans. After
doing a few of these (9yrs a dealer, 8yrs at independent) if figured out
that these Germans are pretty damn good a machining and if I was reusing a
gear set I could assemble it with new bearings and all the original shims
and 90% of the time it was exactly correct. The bearings are manufactured to
such consistent tolerances that this worked. I always checked the settings
but I skipped all the many steps setting it up from scratch. On the few that
were off they were only off very slightly. If I was replacing the ring and
pinion gear set I could calculate the change in shims by comparing the
deviation numbers and doing the math. (the math would take me a little while
now but it is not really difficult)
If you reassembled it with new bearings and all the original shims
(undamaged).  Then measure the turning torque when it is assembled, if the
turning torque is with in specs for new bearings the depth is probably
correct. If you do the same with the differential carrier bearings and shims
the ring gear back lash will also probably correct. Obviously there is no
way to guarantee this with out the tools to measure it. The tools to measure
the back lash can be improvised but I don't know how one would improvise the
pinion depth measurement tools.
You don't live near Sacramento CA do you?
Good luck
Jim

----- Original Message ----- 
From: "Gerard" <gerard at 2226.co.za>
To: "Audi Quattro" <quattro at audifans.com>
Sent: Tuesday, August 03, 2004 12:19 PM
Subject: Gearbox pinion shaft bearing replacement...


> I intend to replace the bearings on my 016 tranny differential and on
> the pinion shaft. Don't care if they're "good", they're still 25 years
> old and I am doing all bearings as precaution, blah blah blah.
>
> Thing is, it requires me to measure the actual deviation of the pinion
> shaft in order to calculate the shims I will need. According to Bentley
> I will require some rather fancy looking bar and dial guage setup which
> is centred on the line of the differential and basically takes a reading
> perpendicular to the bar.
>
> Who's done this kind of thing and can suggest methods not required the
> gazillion special tools in the Bentley books?
>
> And, no, I do not wish to send it to the tranny shop 'cos they have
> skills just as bad as mine and they still cost me. :)
>
> G.
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