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Discussion Starter · #1 · (Edited)
I recently had to revisit this and upon taking my spare apart (with c. 80k) I discovered something that I don't think anyone has remarked on, namely...

behind the circlip that maintains the lateral position of the armature is a thin rubber washer and a bronze thrust washer. Then the bearing. So when you drop some oil on the end of the shaft, you are actually doing little to lubricate the bearing! Why Alfa used a rubber washer here instead of one made of absorbent material is a mystery.

Lubrication: You need to pop off the circlip, remove the two washers, then you have access to the outer bearing. ATTENTION! If you pop off the circlip you will have little hope of getting it back on UNLESS you've made a hole in the plastic case on the fan propeller side of the unit (for oiling the inner bearing--described in another BB thread), why? because you need to push the armature out in order to attach the circlip (the armature can move laterally about 1/4")

This leads me to my discovery: as the motor ages, and the thrust washer wears (see photo below), the armature will develop lateral slack, and guess what? the brushes start to move off the commutator. I would estimate that the brushes in my heater motor with 82k have lost about 7 to 10% of their contact.

Probably the best approach bringing the armature back into spec is to add a thin washer to the "stack" and to dispense with the "star" circlip, replacing it with a more secure 2-holed type circlip.

I'm looking into the possibility of adding a hole in the case exactly where you would have access to the commutator to perform a little resurfacing of the commutator surface.

To this point I cannot say unequivocally that what we hear as "bearing chatter" might actually be "brush squeaking". Whatever it is, it's annoying.

look at how worn that bugger is! This is the side that contacts
the bushing, so the bushing is probably worn just as much
IMG_0294.jpg


left: brushes tracking off commutator / right: brushes tracking correctly
heater motor armature.jpg
 

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1991 164L
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Steve I have two spares - new Bosch -108 motors if you need one I can spare one now being down to one BB1 164. I leave on vacation June 17th so let me know soon.
 

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Discussion Starter · #3 ·
Thank you Steve—our savior—I appreciate the offer. For the moment the heater motor is under microscope and under control.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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Interesting. When I attempted to lube the driver's side (exposed shaft end) bushing of the motor in the 91S, the noise did go away. Maybe it was just the thrust washer need lubing at that time. I do suspect though that a thin lube will migrate further along the shaft to get to the bushing. Not terribly sure about that, but seems to have worked for a very long time doing this every couple of years, the motor having maybe 100k miles and a couple of decades of use on it.

Still, it is a cheaply made Bosch motor. Should look for another one one of these days, maybe out of Eastern Europe, where some hard to find parts do show up.
 

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My fan motor has begun 'chirping' when starting on low speed. If I crank the speed up to the second or third speed setting, the chirping will stop, even when reduced back to low speed. How does one lubricate this bearing?

Mark
 

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Discussion Starter · #6 ·
To lubricate the outer bearing (bushing) I'd recommend removing the star circlip (a plastic rivet tool, large end, works well), and remove the rubber washer and thrust washer. Now you will will see the bushing. At this point you can apply some light oil, like sewing machine oil. To force the oil in the gap I took a short piece of clear tubing (1/2" id, 3/4" od), held one end tightly to the bushing, attached my air compressor on one end, and gave it several blasts of air. I repeated this a few times. As I mentioned above you will have difficulty reattaching the star circlip because the armature will move inward. Instead of a star circlip replace it with a clip with 2 holes. The OD of the armature shaft is 7mm so you need a clip that will have a firm grip of c. 6.5mm or less.

The inner bearing can be oiled only after you drill an inspection hole in the case. When I first did this I made the hole very small, but since have enlarged it to about 3/4" diameter. With the help of my spare heater motor it was easy to establish the position of the hole to insert a small wire to let oil dribble in at exactly the spot where the bushing sticks out.

Your description of the noise is dead on, including the weirdness of moving to position 2, and then back to 1 with the noise going away. I also heard the noise on mild acceleration, but it goes away when you let up on the throttle.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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I would still try to dribble an oil such as 3 in 1 to the shaft end. Since it is just a straight shaft and bushing, I think oil will seep by capillary action on the shaft to the bushing inner surface, in contrast to a ball bearing where the oil on the shaft would not get to the balls outside of the inner race. Seemed to work with the motor in my 91S when I had the same noise.

The above is for the motor with the exposed shaft end as built. I haven't seen one with an end cap which would cover the end of the shaft, or does it in some?

The ball bearing at the other end of the motor is much more durable and long lasting.
 
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