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From digest.v7.n38 Sat Aug 2 16:28:03 1997
From: Pearson-Franks Family <>
Date: Fri, 1 Aug 1997 21:29:40 -0700 (PDT)
Subject: BOSCH Alternator/Generator Brush replacement

>From: Richard Cartledge <>
>Date: 25 Jul 97 15:46:52 +0100
>Subject: BOSCH Alternator/Generator Brush replacement?

>Richard writes: <snipped>

>The brushes are quite short and look as though they have a copper core
>inset >into the carbon brush - Anyway the brushes look as though they have
>a soldered >pig-tail and I have obtained some replacements from a BOSCH
>retailer for 3.5 >UK. Has anyone ever changed these - the solder doesn't
>seem to melt with a >soldering iron and if I am scared to use a blow-torch
>in case the plastic >moulding melts.

>Any advice from people who've done this would be very nice.


I have replaced the brushes in a number of Bosch alternators in my E12's and E28's. I have used pn 12 31 1 727 756 which I purchase from Bavarian Autosport for US$5.50. (No fudiciary affiliation, even when I passed the $12,000 mark purchasing parts!) The only complication that occurs to me is that the lead goes through a cone-shaped punch in the regulator assembly, which is crimped and then soldered. I heat the assembly, use a "Soldapullet" to suck off the liquid solder, then snip the end of the crimped cone off with wire cutters. The brush assembly will then pull right out. I then drill a very small hole in the crimped cone to pass the wire on the new brush assembly through. The finely-stranded wire is connected to a longish (4 cm) stiff bit of wire to make it easy to lead it through the crimped cone.

A purist would have the commutator turned, but I never have, and have put 50K miles on top of 120K to 160K alternators a number of times.

Hope this helps (even if late!)

Larry Franks
Issaquah, Washington
'86 535i
'86 528e
'79 528i
'77 530i
'83 245 GLT (Swedish iron)

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