Alternator Rebuild Information

Alternator Rebuild Information

Alternators should be considered a maintenance item. Alternator brushes and slip rings wear out and must be replaced. On older American alternators I usually replace the brushes at 100,000 miles for a few dollars and get another 100,000 miles out of the alternator. On Bosch alternators the slip rings wear out with the brushes and must be replaced also. This is not an easy DIY project. The least expensive way to have this maintenance done is to remove it and take it to your local auto electrical shop and have it rebuilt. The brushes and regulator on the Bosch alternators are one assembly and must be replaced together, and the slip rings must be replaced also, so it is more expensive to rebuild than other alternators. My local shop charged me $110 for my '88. The frequency for this maintenance is approximately 100,000
miles. I don't know if the amount of air conditioning use affects this figure but if you live in a hot climate maybe you should do it at 80,000 miles.

One of the symptoms of worn brushes and slip rings are "voltage spikes" that destroy the regulator. This sounds OK since the regulator is replaced during the rebuild anyway, but are these "voltage spikes" responsible for some of our fuel injection "brain" failures? Rebuilding the alternator may be good preventative maintenance for the fuel injection "brain" also. It may be good for your sanity as well, since it will keep you from being stranded with a dead battery when the brushes wear out. I don't have experience with the earlier Paris Rohne alternators but I would think that the 100,000 mile frequency would hold true. YMMV.

Earl Gillstrom '88 S4 5 Speed

I have had great success with Wagner Alternator in Chino, California. Their address is 13352 Elliot Ave, Chino, CA 91710. (909) 465-1950.

For me they have pretty much made it a DIY item, but you can get your starter motor or alternator checked, maintained, or repaired while you wait. Their prices and quality of workmanship are excellent. I've dealt with them since the mid-eighties. They ship and receive from all over.
Daniel Shapiro
'82 928 5 speed Chiffon/Brown
Borla exhaust, JB Weld radiator
powered by Wagner

I have used the Bosch alternator on my 1983S for about 7 years and 70K miles now without a back cover or cooling gig, and without any problems. I went to the Bosch alternator because I went through 2 of the Paris-Rhone rebuilds in 2 years--even with the cover and cooling stuff installed. The rebuild (? yeh, right ) quality clearly sucked on these gizmos and they were not cheap either (both crapped out about 1 month after 1 year warranty period) . I sourced the re-builds locally (DC area), so the big three (who I did not use/know at the time) may have a better rebuilder I sourced the Bosch unit from an independent rebuilding shop (Arlington Armature in Springfield VA) who I now swear by and not at (as was the case with the auto-parts store rebuilds). I now always have my own alternator rebuilt, and do not do the swap thing.

I am now running MDS (jet hot coated) headers (since last fall) and still have no problems with the Bosch alternator even though I have no cooling cover at all.

While I prefer German alternators, I still strongly prefer France for my food and wine.

But as Ed always says: YMMV,

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