From digest.v7.n14 Mon Jul 28 15:48:02 1997
From: <don.mcmahon_at_cis.state.mi.us> (Don McMahon)
Date: Mon, 28 Jul 97 9:22:32 EDT
Subject: soldered alternator pigtails
I recently rebuilt my alternator brushes/rectifier pack with the Bosch
kit from BMW. The kit had a couple of small fittings (copper?) through
which the pigtails are pulled. Sort of like:
/ / / / /
brush spring pigtail stiff-copper-wire fitting
I also had problems getting the factory solder to melt with the iron.
Having only two cars but having three sets of brushes/rectifiers I plowed
ahead. First observe and remember the position of the brushes in the
holders. I ground off the soldered ends, pulled the brushes and springs
out and then filed down smooth the surface of the terminals where the
pigtails would be soldered. Not being good at soldering, I enlisted the
help of a physics lab tech. (He taught me a little trick - putting some
fresh solder on a clean soldering iron tip aids immensely in heat
Using two sets of hands (could have done it with three) we threaded
the first long copper wire and pigtail through the brush holder, (I believe
there is a grove in the graphite brush which must be lined up) and then
through the small copper fitting (bitty tube with flange on the end). The
brush must be pulled through enough to seat the brush springs and yet allow
enough travel in the brushes to make contact with the contacts on the
armature in the alternator. This point seemed to occur when a little of the
pigtail was exposed through the copper fitting.
With the brush seated in the right spot we soldered the outside of the
pigtail to the outside tip of the fitting first, allowing a small amount of
solder to flow down into the fitting. We then soldered the area at the base
of the fitting trying to be careful not to over heat the area causing our
first solder to let go. The second brush was soldered in a similar manner.
The copper wire was the cut off.
The rebuilt brushes at least look as if they will work :-) I have not
put them in a car yet. The rebuilt brushes are in the spare parts kit that
goes on trips. My brushes have stranded me twice on long trips >:-|
I would like to hear feed back from others if they know some better
tricks to rebuilding these brushes.
Don McMahon - BMWCCA #77764 86 535i; 85 535i; 75 3.0Si;
72 911T; 64 VW-Sedan 113 - I don't know when to let go
><snip>I removed the rectifier pack from the rear
[ Help ]
>of the BOSCH alternator on my E28 1986 5'er. The brushes are
>quite short and look as though they have a copper core inset
>into the carbon brush - these hard cores look dangerously
>close to becoming exposed and scoring the amerture.
>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