Alternator drive parts - wear?

[pdg]

So I replaced the driving dog, rubbers and cup after it all decided to chew itself to bits. I thought I'd check on it yesterday so I dropped out the alternator again for an inspection.

There was what I consider a surprising amount of rubber 'dust' in there...





That's after just under 200 miles. The rubbers are a little bit scuffed in places but otherwise structurally ok, the cup and dog appear to be just fine. The dog is quite rough though, as it was when I bought it (brand new BMW OEM from a dealer).

I cleaned it all up and refitted it - working fine so I think I'll add 'drop alternator for inspection' to a service schedule...

Normal or the beginnings of a concern? Worth taking the dog out and running the rotozip over it to smooth it off?

Cheers guys.

[Grim]

Is the alternator seating correctly? Mine didnt look that bad at 47,000.

[pdg]

I think so, going in flat and square, shaft spins without any wobble on the cup.

I'll be checking it in another 'some' hundred miles - if it's still doing the same thing I'll polish up the driving dog to make it smooth.

Considering the cost of the rubbers compared to the metal parts it's no real trouble to keep replacing them. Plus, it only takes about half an hour to remove, inspect and replace the alternator.

[Grim]

I wonder if the rubber is degrading.

 Did you use any sort of lubricant on it?

 Mine was kind of tough to reassemble and I ended up using some silicon based tire/vinyl dressing to get it to slip together. Now you got me worried. I ran mine 150 miles today. Maybe I need to pull it and check.

[pdg]

I used a silicone lube on it... Stuff designed for 'o' rings.

The rubbers don't look or feel degraded at all, the only apparent wear on them is where they contact the face of the driving dog. There is moulding marks and 'flash' on the rubbers from manufacture, it's still soft and pliable.

Before I fitted any of the parts I tried putting the dog, rubbers and cup together 'dry' and it wasn't happening - I didn't want to put that much force onto onto the alternator flange etc. to assemble them. If nothing else, the distortion of the rubber this would have caused would surely accelerate wear...

If you do drop yours off, any chance of a photo of your driving dog part? Wouldn't mind comparing the 'finish'...

[pdg]

So, thought I'd drag this one up.

I've now done another ~700 or so miles, took off the alternator for inspection and everything is fine......

No more residue than before, no apparent degredation (a little 'polishing' on the contact points) to the rubbers, cup and dog look fine.

Guess it was just bedding in.