Completed my Valeo to Bosch alternator conversion - Bimmerfest - BMW Forums

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Old 01-24-2004, 08:55 AM
Forced Induction
Location: Meridian, Idaho, USA
Join Date: Jan 2004
Posts: 4
Mein Auto: 98 M3 supercharged
Completed my Valeo to Bosch alternator conversion

Recently, my alternator was showing signs of death. So, after much research on a few BMW forums I found that a few folks have converted their Valeo alternator to the Bosch unit. I even found part #'s for the conversion.

The Bosch, as is, did not fit properly due to the length of the pulley being just a bit too long. However, there is a pulley conversion one can buy to gain the proper pulley offset.

Since I'm nursing a broken leg and torn up knee, I could not complete this conversion myself and had to pay someone to do it (I hate admitting that...). With my Dinan supercharger in place, it took extra time to complete and ultimately, more money.

Most folks might not find it necessary to do as extensive parts replacement as I did, but due to the space my supercharger takes up I didn't want to have to go in there again.

Here are the dealer part #'s:
Bosch 140A alternator 12-31-1-744-567
Pulley for Bosch alternator 12-31-1-432-988
Belt 11-28-1-469-266
Tensioner 11-28-1-717-188

Prior to the replacement, I could only get 13.9V during cold idle, and a little lower during warm idle. With the new alternator, the reading is 14.6V at cold idle. A definite improvement!

The plug-in for the 2 alternator's are identical and required no modification. IF you have a supercharger, a small amount of grinding on the alternator will be necessary for clearance. ONLY if you have a Dinan supercharger.

Finally, I no longer have to deal with the fear of the Valeo alternator leaving me stranded on the side of the road because it decided to die at that time, or replace my battery because I wasn't getting the proper charge to it.

I'm a firm believer in getting information available for other's that might need it, so I hope this helps someone in the future.


03 M3 SMG
98 M3 supercharged
91 300ZX TT
06 Dodge CTD Megacab
93/95 Honda CBR900RR

Last edited by MOTRSPRT; 01-24-2004 at 09:50 PM.
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