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Heater Blower Motor Hybrid

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Click
Posts: 63
Joined: Jul 08, 2014 12:48 PM
Location: Reading, PA

Heater Blower Motor Hybrid

Post by Click »

I have a Sofica car and had the classic squealing blower motor. I pulled it, oiled it with sewing machine oil and reinstalled. Squealed within a week. Removed it again, oiled it with turbine oil and it lasted a month before it started squealing again. Re oiled it and it lasted approximately a week before it started smoking whenever it was used. Bought a "good" used motor off the board here only to have that one start squeaking within a week as well!! Needless to say I've gotten quite tired of pulling the firewall cover in the cold weather and I want to fix it for good. I can buy a new Sofica assembly for ~$190 but there's that Bosch motor staring at me in the face for the low low price of $70.

My question is can I swap Sofica cages onto the Bosch motor? I've done quite a bit of searching and I've heard of people using bosch assemblies in sofica cars using the "newspaper trick" as apparently the Bosch motor housing is a bit smaller and lengthening the blower covers since the bosch assembly is 1/2" longer. In my searching however I found no results on mixing parts.

If the shaft diameters are the same, and the bosch cages are the part that makes the bosch assembly longer, I could put sofica cages on a new bosch motor and machine some delrin spacers to make up for the motor diameter difference and have an "almost new" sofica assembly that would drop in for $100 cheaper....



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Shawn D.
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Location: Alpharetta, GA
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Re: Heater Blower Motor Hybrid

Post by Shawn D. »

Yes, you can put the Sofica cages onto the Bosch shafts -- I have done so. Space them to match the Sofica spacing. I don't recall anything about the motor body being smaller, but that's an easy thing to take care of.
Click
Posts: 63
Joined: Jul 08, 2014 12:48 PM
Location: Reading, PA

Re: Heater Blower Motor Hybrid

Post by Click »

To update this thread

So the Bosch shaft is quite a bit thicker. I carefully drilled out the sofica cages on a drill press but the one didn't come out perfect. There is a noticable vibration at speed 2 and at speed 3 it's ready to consume the car. If anyone is interested in a basically new bosch blower motor let me know haha

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demetk
Posts: 8431
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Heater Blower Motor Hybrid

Post by demetk »

Maybe it's easier to file down the shafts. I would do that by just turning on the motor and laying a file on the shaft. Polish up with emery cloth.
Mike W.
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Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Heater Blower Motor Hybrid

Post by Mike W. »

demetk wrote:Maybe it's easier to file down the shafts. I would do that by just turning on the motor and laying a file on the shaft. Polish up with emery cloth.
Naw, you'd need a lathe. I'm not sure what technique Click used, but I'd use a batter bit/spade bit, maybe tapered a little, at very high drill speed with a slow hand feed. Plastic, especially hard plastic, is odd to drill, almost counter intuitive, but you do not want a twist bit that tries to pull itself in.

Click, you might find it easier/cheaper to buy a junk Bosch assy and swap the blower wheels, then try to mount that. :dunno:
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