Just me being lazy.

Bringing back to life an 18 year old Audi A8 D2 part 7 - fixing the alternator whine

Ever since part 6 of this project, ever since when I fitted and installed a brand new head unit and amp, I've been plagued by a constant, rpm-dependent whine of the alternator in the speakers.

To fix this I have tried every single 'noise isolator' and adapter known to man, I spent probably £300-400 on them.

I have tried different head units, amps, alternators and everything else you can think of and it made no difference to the whine.

Here's an example of the whine:


After trying everything i could think of, i contacted Gordon at AMP Doctor (https://www.ampdoctor.co.uk/) who suggested fitting a 100000uF 25V capacitor between the alternator and the rest of the car, I got straight onto it:

To my amazement, this reduced the whine by about 80% to this:


Of course 80% wasn't enough for me and with the amp gain turned up a bit it was even louder so i continued looking further.

After research i understood that a D2 alternator regulator is a transistor type one like this:

transistor regulator on the back of a 150A D2 alternator

All the newer generation model cars like from 2003 and up have a new generation of alternators with a mosfet style regulator like below, so i thought why not try it.

So i started by getting a second hand 'new gen' alternator for £28. It fits V8 and V6 D2's as well. Part number is 078903016S.

I completely disassembled it and had the casing vapor blasted.



The 2.8 alternator has a longer rotor shaft to accommodate the one way clutch pulley, but the casing of the 'new gen' alternator is shorter, so to accommodate this the shaft of the 2.8 alternator has to be modified - the thread has to be lengthened towards the center:

I used a good friend in Devon with a lathe:

extended thread can be clearly seen here

Components ready for assembly:

New bearings:

Rectifier being soldered onto the the winding and casing:

The rear positive terminal connection is in a different place on the new gen alternator compared to D2, so i made a bus bar:

Once i knew the dimensions were ok i 3D printed a custom support for it:

bus bar along with the 3d printed support for it

I also managed to find a brand new NOS freewheel pulley from INA:

Checking the runout:

And the alternator was ready for fitting:

original alternator on the left, and my custom one on the right
alternator whilst being fitted

The result? 100% clean audio with no alternator whine.


If any V8 owners are reading this, you just need the 078903016S alternator and the pulley from your original alternator, the pulley bore has to be shortened by about 8mm so that the nut fits on and you have to make a bus bar like I did.

Part 8:

Bringing back to life an 18 year old Audi A8 D2 part 8 - various odd jobs
This post will cover various odd jobs on the car that are too small for their own posts. Starting off with leaking cylinder head, I’ve had this done in part 2 of this project but as you will find out, it was badly bodged.... and paid someone good money for