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Alternator rebuild - missing a part


rapandi

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Hi Team, 

I have just changed my bearings on my alternator. And cleaned it up etc.

 

When I pulled it all apart I remember there was this “shear key” (not sure of name) missing. It goes in a slot in the shaft of the alternator. 

 

The first pic is my alternator where I am pointing to this shear key slot. The other two are pics I found online of another e30 alternator where they show this so called key. 

 

I don’t have it and was wondering if this can be bought as a separate item? I don’t know it’s purpose but guessing it’s to hold the front end assembly in line with the shaft?
 

43E3A01C-CA48-4CB1-8FB9-9DA4723F5F2B.thumb.jpeg.aeb194a177288a8286e7f97c71f43d92.jpegB73BB3C8-AC67-4E0D-9322-1360F280BB4C.thumb.png.67454b4277fcb6b73790802eab6602ac.png533868F7-C2B5-4809-9868-2B3B321C3324.thumb.png.caec571a9901aed8716ae81d4d046b4f.png

Raj

1972 BMW 2002 Tii - Golf Yellow

 

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8 hours ago, rapandi said:

Hi Team, 

I have just changed my bearings on my alternator. And cleaned it up etc.

 

When I pulled it all apart I remember there was this “shear key” (not sure of name) missing. It goes in a slot in the shaft of the alternator. 

 

The first pic is my alternator where I am pointing to this shear key slot. The other two are pics I found online of another e30 alternator where they show this so called key. 

 

I don’t have it and was wondering if this can be bought as a separate item? I don’t know it’s purpose but guessing it’s to hold the front end assembly in line with the shaft?
 

43E3A01C-CA48-4CB1-8FB9-9DA4723F5F2B.thumb.jpeg.aeb194a177288a8286e7f97c71f43d92.jpegB73BB3C8-AC67-4E0D-9322-1360F280BB4C.thumb.png.67454b4277fcb6b73790802eab6602ac.png533868F7-C2B5-4809-9868-2B3B321C3324.thumb.png.caec571a9901aed8716ae81d4d046b4f.png

 

As you have discovered, once the fastener is tightened, the key isn't necessary. These keys can be critical on certain engine parts due their location of a component like a vibration damper on a crank, where something like timing could be affected by how they're clocked. 

 

On something like an alternator that doesn't have a clocked pulley position, their only useful purpose is to allow you to use the pulley to hold the shaft as you remove or tighten the nut that holds the pulley on. 

 

Like others have suggested, woodruff keys are readily available at the hardware store. My local Ace franchise has a couple bins full of them. 

 

Cheers

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  • 2 weeks later...

So I bought a woodruff key and sorted that problem out. 
 

I torqued down the centre large pulley nut with an impact wrench. Then I spun the fan just to check it spins freely. Yup spins freely! 
 

Then I started slowly tightening the outside 4 long screws which sandwich the two halves of the alternator together. I noticed that by doing so the blades don’t spin freely around. It feels like the rotor is hanging up against the Stator cause the screws are pulling the rotor maybe towards on side? 
 

Not sure what to do? Or if anyone has experienced this. DFE6576A-FED4-4995-9EB3-3F375562F59D.thumb.jpeg.44ef04958127914349338e934238afe6.jpeg

Raj

1972 BMW 2002 Tii - Golf Yellow

 

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17 hours ago, Buckeye said:

Assembled in reverse direction. Fasten two halves first, rotate shaft a few times to ensure there is no binding and then tighten the nut on the pulley. 

Thanks mate. Managed to get it to work. I just slowly tightened each screw equally in several stages. It's good now! Thank you

Raj

1972 BMW 2002 Tii - Golf Yellow

 

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