Rebuilding the alternator
 

I found myself with enough parts laying around to put together a rebuilt alternator. I knew that front bearing was noisy so set out to replace the bearings and other "while you are in there" parts.

I was inspired by Homeoboxter’s project starting in post #66 here:
https://986forum.com/forums/show-tell-gallery/73917-blue-boxster-resurrection-project-4.html

This video helped me realise that the drive pulley was defective… it was frozen solid.
https://www.youtube.com/@WestronicsIrl

To remove the my pulley I bought a 33T Alternator Removal Socket and a 10mm triple-square bit. It took considerable force to loosen it.

This video is for Volvo alternator, but most of it applies to the Porsche unit. It is very detailed.
https://www.youtube.com/watch?v=05ZMnrtTFzE
NB - the rear bearing holder on my alternator is black and must be placed before installing the back cover. I have not found a video that shows this step clearly.

I also had to drill out the bearing holder screws. They are M4x.7 and 16mm long would be enough. I bought 25mm and cut the excess off.

Since I don’t have a press I used a bearing puller on the front bearing,
In effect I was pulling the alternator case off the bearing.
At first I reinstalled the pulley, with a piece of metal to prevent the bolt of the puller contacting the end of the shaft (in this case the steam valve of an old pressure cooker). The pulley was not screwed all the way down so it would not immediately contact the alternator case. As the bearing started to move I screwed the pulley out to provide more clearance. Here is my installation.
http://986forum.com/forums/uploads02...1768507972.jpg

It would perhaps be easier to use a 30mm socket instead of the pulley.
http://986forum.com/forums/uploads02...1768508039.jpg

I used my dremel clone to cut the slip ring and it broke off easily.
http://986forum.com/forums/uploads02...1768508081.jpg

I had intended to change the brushes in the voltage regulator, but the regulator was not designed to make replacing the brushes easy. The grounding tab that is supposed to be just to the right of the brushes is broken off... I will have to find a way to replace it.
http://986forum.com/forums/uploads02...1768508128.jpg

According to this video the brushes can be changed... with difficulty.
https://www.youtube.com/watch?v=b-ZRpGTVdSQ
Since my brushes still have some life in them I decided to reinstall the regulator as is.

Given this is a spare alternator I don’t plan on buying a pulley right away, they are a bit pricey. The parts kits with bearings, a new slip ring and new brushes are readily available.
http://986forum.com/forums/uploads02...1768508273.jpg

Other videos if you want to watch more…
Front bearing removal was explained here:
https://www.youtube.com/watch?v=sTTfemu_gcY&t=797s
The rear bearing and slip ring:
https://www.youtube.com/watch?v=DhjT6qKUOBc

I followed the Volvo alternator video mentioned in the first post. A few notes on my experience.
The front bearing went into the front casing easily after I heated the front casing and put the bearing in the freezer. Then, after installing the bearing holder, I put the rotor in the freezer and heated the bearing and was able to install the rotor into the casing.
I was worried about tapping the slip ring on with those skinny legs between the rings and the base, but it is the top, under the slip rings, that you are forcing on to the shaft splines so there is very little force transmitted by the "legs".
Aftter soldering the wires onto the slip ring base (those wires are more resistant than they look) I installed the rear bearing (using the freezer and heating again).
Next the rear bearing holder is inserted in the rear cover, tabs fit into grooves to properly align it. It was tight enough that I had to tap it into place.

http://986forum.com/forums/uploads02...1769004246.jpg
(sorry for the fuzzy photo)

Next the front and rear covers where assembled. I used a rubber hammer and a large C clamp to get them close enough together to insert the four screws... then the screws pulled it tight. Make sure the covers are properly aligned and not cocked on way or the other.

I installed the regulator and now I have to test it.

Nice and easy project! When you replace the slip ring and resolder the terminals to the ends of the coil, make sure you use a small amount of soldering iron but try to build it up to last. The pulley is about 3-times smaller in diameter relative to the one on the crankshaft, meaning it can spin well over 10.000 rpm, on average! I had to redo the soldering on mine when it snapped after a few thousand miles during acceleration :D. :cheers: