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Alternator Nut Issue

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I have a newer alternator on my 1970 2002. It was on the car when I purchased it. I noticed that my alternator pulley was not as tight as it should be after replacing my alternator bushings. It seemed like the pulley was slipping on the post and the metal fan blades were making some noise. I popped off the nut and bought two different sizes of woodruff keys before realizing that there was no way for one to fit. So, I decided to put it all back together and simply put more tension on the nut to hold everything tighter. I stripped the nut that holds the pulley. I have been to 2 different screw specialty places to find a replacement with no luck. The dealer is shipping one in from Germany and I'm hoping it will work. Has anyone else had this issue? Is friction really the only way to get the pulley to not slip? Any advice appreciated. Thank you.

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So, the pulley is just resting on the alternator shaft? It probably does cinch up against a shoulder on the shaft near the body of the alt. Unfortunately, not much of a shelf to work with.

There was no provision for a woodruff key?

A couple of ideas-

Use a dremel tool and make your own slot for a woodruff key.

Or-

Grind down a flat section of the alternator shaft so that it is D shaped. Fabricate a washer with the same D shaped opening. Make a 90 degree bend at one end of the washer and grind it down into a small pin shape. Drill a shallow hole in the pulley for this lock pin to catch on to.

Or-

Drill a hole through the end of the alternator shaft for a roll pin to fit through. Drill below the threads. Use a dremel tool to cut a slot in the face of the pulley. Put the pulley in place, put the roll pin through, then the washer and nut on the alternator shaft will cinch down onto the pin and into the slot on the pulley.

Or-

Just wait for the correct parts to arrive.

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Take alternator to local Starter/Alternator shop and see if they have the size you need and have them put it on for you, they will use Air wrench. This will hold it!

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Take alternator to local Starter/Alternator shop and see if they have the size you need and have them put it on for you, they will use Air wrench. This will hold it!

That is what I did and it worked for me.

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Are you sure the nut is not bottoming out on the shaft. And if it is, another washer should cure it. I also have a late Alt with no woodruff key, my pulley is snug as a bug in a rug... Anyplace near you that rebuilds Alt's should have plenty of left over nuts and washers to choose from...

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There is some variation in shaft and pulley styles among alternators. You do need a Woodruff key as SteveJ described, but maybe your pulley does not match the shaft. I've run into that when substituting a Bosch alternator from another BMW model. I second ifayeoh's suggestion to take it to an alternator shop.

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