120 Amp Audi Alternator Install

[ranahan@charter.net (John Erickson)]

I installed an Audi 120 amp alternator on my 16v over the weekend and 
thought I'd pass on what little tech info I gleaned from the experience.

First of all, you may ask, "Why?"  You don't -need- a 120 amp 
alternator.  Well, 'cause it was cheap ($50) and it only had 200 miles or 
so on it.   That's the cheapest replacement I found anywhere.  Besides, it 
-looks- cool.

The installation is basically "plug-and-play" with a couple notes:

- The mounting bracket on my engine had too much material outboard of the 
rear mounting bolt hole.  It hit the case on the alternator prohibiting 
proper bolt alignment.  A couple minutes with a Dremel fixed that problem.

- The adjustment bolt on the Audi unit has a larger diameter than the one 
on the stock alternator.  I widened the slot in the adjustment bracket to 
compensate.  I have read that others just put a long bolt all the through 
the bracket and bolt hole and put a nut on it (No thanks.  That means you 
need two hands to tighten the bolt.  One hand is usually busy holding 
tension on the belt.).

- The back of the Audi alternator is black plastic and has a fitting for a 
two inch ventilation duct.  The fitting will hit the radiator if left in 
place.  The Dremel took care of that problem as well.

- You need to swap pulleys, but do that on the car.  Its nice to have the 
alternator held in place while you are wrenching on it.  Besides, the belt 
is easier to deal with if you just pull off the pulley.  The stock 
alternator pulley is keyed, but the Audi alternator is not.  I stuck a long 
rod into the alternator to keep the armature on the Audi unit from turning.

The old pulley on the Audi alternator lines up perfectly with the pulley 
that drives it (AC compressor).  I was quite pleased to get a nice 14v out 
of the alternator when I fired it up.  All-in-all, I probably spent two 
hours on the swap.