there doesn't seem to be any shims on the outer surface used to position the axles...

without opening up the centre, is there any way i can locate the thrust block?

one other thing - in the middle of the centre where the axles meet, there seems to be a washer with roughly the same diameter of the axle spline. it was just floating around in there, so when i tapped one axle in, i seated it properly, then tapped the other axle in. any idea of what this washer is/does? i dont think its meant to be loose like that!

That sounds like the thrust block. They are located with a circlip on earlier R200's but I am not sure on the later ones.

Did your original centre have a washer/disc in between the axles?

no the original centre was just striaght through...

this mechanical centre has a washer in the middle... its only about 1inch in diameter. its just floating around.

It should be easy to remove if like the long nose R200. All you do is locate the side with the circlip and give it a short sharp punch with a brass drift and it comes out. I am not sure about this one but i would say thats the sources of your problem noise most likely.

I cant say any more for sure without looking at it. Sorry.

your talking about removing the washer in the middle? its only about a 1mm thick, and about an inch in diameter

I cant see what its function would be ?

Non of my nismo or nissan cataogues show a washer there so I am at a loss.
It is a Nismo centre and not Kaaz or HKS etc?

i think its a nismo...

Must be a newer model than 2002 as thats my last nismo full catalogue.

If it looks all OK and like its meant to be there it probably is.

hmm... any chance the type of oil has anything to do with it?

im using Penrite Limslip 90... would it be advisable to use the 85w140 type? there is also the LSD additive for the oil, but i havn't put it in because i thought it was already blended in the Limslip.

Drop the oil out after a fast tight run and some tight turns. Look for any metal particles glinting under a strong light! Also check the magnet in the base plug.

The sound you describe does sound like the energising plates or something is making metal to metal contact.

Did this diff come new or used. Do you have any paperwork?