[Vwdiesel] "W" alternator

adamo robison adamanderr at hotmail.com
Sun Feb 1 08:15:02 PST 2009

so did  you ever sort out the number problem. it synced up witht he 80 gauge. could a different gear be put in the tach gauge itself like different speedo gearing. Im also interested in the 90 dash in a mk1. how did you make that work?very  interested in that.
i tried wikipediaing pulse divider directly before passing out last night so i didn't find much. anyone mind explaining that to me.
thanks again

From: tonyandlillie1 at earthlink.net
To: adamanderr at hotmail.com; vwdiesel at vwfans.com
Subject: Re: [Vwdiesel] "W" alternator
Date: Sun, 1 Feb 2009 08:20:54 -0600

yes, it "worked". As in, it did register a reading. 
however, at idle it reads 4000RPM. That's 6 times the real idle on my car. As 
explained, a gas 4-cyl tach takes a square wave form with four pulses, divides 
it by four, and figures the RPM there. The "W" terminal on the back of the 
alternator (it was there on my Bosch) that is not normally used, off to the 
side from the regular plug.  
As Loren expalined, the Alternator puts out 24 plulses per 
engine revolution, so you can see why the tach reads way too high.
In my car, which is a 1982 1.6 N/A Jetta, I have a 1995 
Audi 90 dash with a 4-cyl 1989 80 instrument cluster. The 80 had a 4-cyl also. 
But, you can use a GTI instrument cluster fohe MK1 dashes. None of 
the MK1 Diesels came with a tach that I'm aware of.
 r most of t
One other thing to consider is, the alternator slips a bit 
on the belt, so it won't be 100% accurate. Although, it's really close. There 
are other alternatives as well. Here is one:
Tony Hoffman

  ----- Original Message ----- 
  To: tonyandlillie1 at earthlink.net ; 
  vwdiesel at vwfans.com 
  Sent: Sunday, February 01, 2009 1:23 
  Subject: RE: [Vwdiesel] "W" 
did it work? what is the "W" all about, does anyone have a part 

didn't any mk1s come with tachs and why wouldnt a gas one 

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