Re-Bushing a Blown-Out Heater Blower Motor

1982911SCTarga · 12:04 PM

If you've owned a later-model 911, 911SC or a 911 Carrera, you've probably seen a heater blower motor with its faceplate worn oblong by wear -- so much so that it can no longer run at all.

I had two motors in that condition. Now, I've only got one.

This weekend I had access to a lathe and some time, so I was able to successfully refurbish a motor. A lathe makes the job easy, but it is possible for a hard-core DIY'er to do something similar using a drill or drill press and a mandrel to hold the bushing stock.

I worked from 1-1/2 inch diameter delrin stock to make the bushing. There are really only three fairly important dimensions to the new bushing: the overall length (I measured from C-clip slot to C-clip slot, you can figure out what you need to do once you've got the old bushing removed), the inside diameter (for the motor shaft) and the outside diameter (which is just slightly more than an inch to fit the diameter of the inner faceplate housing).

To remove the old crap bushing and install the new one, you do have to drill out the three rivets that hold the brush housing to the faceplate. Once this is done, remove the old bushing material, make the new bushing and install it, then re-mount the brush housing (you could use new rivets, tap for screws or something else). I just epoxied the brush housing back in place.

While I had everything apart, I replaced both brushes with replacements I found at the local hardware store. I also chucked the motor's armature in the lathe and polished the commutator with 600 wet/dry sandpaper. These motors are funny things: Everything besides the faceplate-original bushing design are incredibly stout and made to run for years. And years.

Anyway, the first pic shows the worn-oblong faceplate and the new bushing beneath. The screw is there as an anti-rotation pin.

And here's the motor with the squirrel cage re-installed.

This motor runs a treat now.

Brian

5495bb · 5495bb's Garage

Thank for the practical fix. I'm gratefull that my blowers were changed by the PO a few years ago. Looking at the cost I'll be sure to try to fix them myself when they lose the bearing.

1982911SCTarga · 04:48 PM

What got me started on this was post #10 from this thread.

Brian

88911coupe · 01-22-2014, 06:24 AM

Where can you buy bulk delrin? I found a website but the shipping and processing is more that the part. I can't believe theres not someplace that just sells this stuff but I can't think who it might be. Any suggestions? I have replaced the rear blower in my Carrera with the $15 motor and it works pretty well but I'd really like to have the original back in there, just to keep it "original".

Flat Six · Flat Six's Garage

Quote:

Originally Posted by 88911coupe

Where can you buy bulk delrin? I found a website but the shipping and processing is more that the part. I can't believe theres not someplace that just sells this stuff but I can't think who it might be. Any suggestions? I have replaced the rear blower in my Carrera with the $15 motor and it works pretty well but I'd really like to have the original back in there, just to keep it "original".

I usually turn first to McMaster-Carr and Enco, but yes -- shipping on small orders can feel a little out of whack . . .

But if you've got Amazon Prime and buy $50 worth of stuff, you can get free 2-day shipping from Amazon Supply (AmazonSupply.com: The Store for Business & Industry).

HTH

Dale

wwest · wwest's Garage

Were they "keyed" or did you have to mark the housing and faceplate before disassembly in order to reinstall correctly, motor not turn the squirrel cage blower wheel in the wrong direction....low airflow result?

Soak the cotton wadding/bearing, both ends, in 30 weight?

Latter only applies if you keep, or replace "in kind", the OEM porous bronze sleeve bushings/bearings.

http://www.qbcbearings.com/TechInfo/PDF/SinteredMBearings.pdf

88911coupe · 01-22-2014, 12:34 PM

Found this below from MC...now have excuse to buy one of those cheap lathes from Harbor Freight...
McMaster-Carr

Flat Six · Flat Six's Garage

Quote:

Originally Posted by 88911coupe

Found this below from MC...now have excuse to buy one of those cheap lathes from Harbor Freight...
McMaster-Carr

Uh oh . . . I've been down that rabbit hole. Love my 7X12; find all kinds of reasons to over-engineer something just so I can shave some swarf. If you aren't already aware, these are the two best places to start (IMHO) to do your pre-purchase research:

https://littlemachineshop.com/info/minilathe.php

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