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OK, I'm using the E36 2.5 engine and the Marlin alternator with the donor pulley wedged on the front of it.
It was a quick fix originally to get it up and running but now I realise it's still there and theres a problem. The pulley has just a hole through the middle with no way of locking it onto the alternator shaft.
So it's currently "wedged" on with a little divot(?) and the centre nut being done up really tight but it's going to work loose and it's not centred...
nope - no pix of it at all. The alternator shaft has a groove in it that I can use - just need some way of shrinking the internal diameter of the pulley and a groove in that or a new pulley...
Something like a big washer that you can bolt to the pulley should do it.
If I'm seeing this properly in my head then some metal the inside cut to fit the alternator shaft and groove, the outside big enough to overlap with the pulley. This can then be bolted to the pulley with a set of bolts
The pulley is only an inch or so across so won't be able to bolt to it but may be able to weld a plate like that to it - thats my only thought so far...
You have to be very careful with any modifications to pulleys when you consider how fast they rotate - any slight out of balance will rapidly destroy the bearings of whatever it is attached to and if the pulley fell to bits you could have a good missile exiting through the bonnet!
If Marlin supplied the alternator I guess they would also be the best source for the pulley - they must know what vehicle it came from originally....
Sounds as though you need a 'keyed pulley'. Would filing a slot in the pulley work? You could then make a metal wedge to key the pulley onto the shaft. Something like the following:
