How to replace bearings in Beau/UMC capstan motors:

The Beau motors used in ITC cart machines are similar to the Beau motors
made to retrofit Ampex transports.  If your Ampex has a Beau motor with
noisy
bearings, you can easily replace them.  Go to your local bearing house and
order Nachi 608-ZZ -- they cost about $6 per bearing.  This is a
double-shielded bearing, and while it's not a high-grade instrument bearing,
they seem to be quite smooth and quiet (and for this price, you can buy a
bunch and hand-select them).

(BTW, Nachi R6-ZZ is the one that fits the Ampex reel idler assembly; these
are about $4 each.)

Here's how I replace bearings in Beau motors (disclaimer: this has worked
for me but I make no claims as to it being the correct procedure).

1)  Remove the nut on the rear of the capstan shaft (don't remove the
flywheel yet).

2)  With a plastic mallet, GENTLY tap the rear of the capstan shaft.  The
dust shield on the front of the capstan shaft should pop out (nudged by the
retaining clip on the front of the capstan shaft).  Set aside the dust
shield.

3)  At this point, you should be able to press out the capstan shaft by
hand.  Wipe it clean and set aside.

4)  Remove the flywheel.  Be very careful to remove the special aluminum
spacer and wavy washer(s) that go between the rear bearing and the flywheel.
Also, the motor windings are now exposed and EXTREMELY vulnerable.  Be
careful here.

5)  Remove the old bearings.  There is probably a special tool for this
(perhaps adapted from a gear puller), but I haven't found one.  Using the
largest flat-bladed screwdriver that will clear the inside hole of the
bearings, GENTLY tap the inside surface of the bearing opposite the one
facing you.  The idea here is to push out one of the bearing assemblies (it
doesn't matter which one).  Tap gently -- don't use a hammer -- and tap at
different points around the bearing to drive the bearing out straight.  If
it doesn't seem to work, put the screwdriver in from the other bearing and
try driving out the other bearing.  Warning -- this destroys the old
bearings, so don't reuse them.

6)  After removing one bearing, press out the remaining bearing using a very
large nutdriver or wooden stick.  Tap gently.

7)  Wipe the new bearings and carefully press them into the motor.  In my
experience, the Nachi bearings are sized properly and will press into the
motor with hand-pressure only (press on the outer race only).  At this
point, the bearing isn't quite home.

To press the bearing into its final position, you will need to make a tool
from one of the old bearings.  Carefully pry off the dust shields, remove
the balls, the ball cage, and the inner race; this leaves only the outside
"ring" of the old bearing.  Use this "ring" to press home the new bearing.
(The idea here is to avoid any accidental pressure on the inner race.)

8)  Repeat the previous step for the other bearing.

9)  Here's where it can get tricky.  With the Nachi bearings, I have found
that you can slide capstan shaft into the inner bearing races without any
difficulty.  With other bearings I have used, it was more difficult and I
worried about putting excessive side-loads on the bearings, which can damage
them.  Make sure both the inner races and the capstan shaft are wiped clean
before attempting this.

10)  Reinstall the aluminum spacer and wavy washer(s) over the bottom
bearing.  Make sure the aluminum spacer is reinstalled with the "ridged"
side inward, facing the bearing (this is important, since the idea here is
to contact the inner bearing race so that it turns with the capstan shaft).

11)  Carefully reinstall the flywheel.  Make sure you don't dislodge the
wavy washer(s) in the process.

12)  Reinstall the nut and tighten moderately (on some motors, you may have
to grab the top of the capstan shaft with your hand while tightening). Don't
overdo it.  What happens here is that the inner race of the top bearing is
loaded by the spring-clip (near the top end of the capstan shaft) and the
inner race of the lower bearing is loaded by that special aluminum spacer.
You want it tight enough to keep the races turning with the capstan shaft
but not so tight as to unduly load the bearings.  Some finesse is required
:-).

A side issue is whether to use an adhesive to secure the inner races to the
capstan shaft.  With Ashland and Bodine motors, I use one of the Loctite (R)
retaining compounds (use the one specified for bearings; don't use a
permanent thread-locking type).  I have not found this necessary with the
Beau motors since these motors have a threaded capstan which permits secure
loading on the inner races (as described in step 12, above).  Comments?

I should add that I have never had to use force or make special tools to
repair Beau motors.  On the other hand, Ashland and Bodine motors seem to
have much tighter tolerances.  Removing ball-bearings on these motors
generally requires a bearing (gear) puller.  Also, pressing in new bearings
can be difficult (made easier by using inner races from junked bearings to
help tap the new ones into place).

Another nice thing about the Beau motors is that they don't need oiling and
they are very quiet.  I am not sure if they have enough torque for tape
widths larger than 1/4-inch, but I have never tested them.

-Dave Dintenfass, Seattle, Washington 21 July 1998

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