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Discussion Starter · #1 ·
I need to replace the brushes on the alternator and I have a question for any electrically minded people out there.

The alternator is 80 amp and I have a spare unused set of brushes (ie brushes & regulator assembly) but from a 70 amp alternator.

Everything is Bosch and the spare unit is the same size physically. Can I use it, or will fitting it cause any damage?

Any advice would be appreciated. Cheers.
 

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As long as the brushes are the same physical size on both units, there should be no problems. I would only replace the conductive inner of the brushes that wears though as the tensioners may be different strengths.
 

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Discussion Starter · #3 ·
That was quick! Thanks very much.

Actually, I was intending switching the complete brushholder assembly but you're right, I could just change the brushes themselves.

I'm not sure if the holder assembly ( the thing that actually screws into the alternator) is simply just that, a brush holder, or if it does something else.

It has a little green electrical thingy on it (diode? resistor?)Anyone know what that does?
 

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It has a little green electrical thingy  on it (diode? resistor?)Anyone know what that does?  [/b]
Green? hmmm without seeing it not too sure But it is probably the diode pack you are explaining and that is the Power diode and the Field exiter diode.
You can get Suppresion capacitors and Surge protection diode's on alternators but can't ever remember seeing them on a bosch alternator.
 

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I have not specifically examined the type of Bosch alternators fitted to Saabs, but all the Bosch alternators that I have examined have the voltage regulator and the brushes in the easily removable bit. The diodes and other relatively esoteric bits are tucked away within. Presumably the brushes and the voltage regulator are the bits that need to be replaced most often.

I'd just replace the whole unit as one piece. It should not make any difference whether it's a 70 or 80 Ampere unit.

'Phone you nearest Bosch dealer or Robert Bosch themselves (himself?) in Denham, Bucks 01895 834466. They are usually pretty helpful. You could of course see if the part numbers are the same.
 

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Originally posted by DaveS:
[qb]It has a little green electrical thingy     on it (diode? resistor?)Anyone know what that does? [/qb][/b]
Not having seen one myself, I nevertheles suspect if it's a small 10mm dia disc it might be a wee capacitor to help surpression of electrical noise...
 
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