LSD leak

[AlastairA]

I have a 420R with the BMW / Titan LSD and have spotted a small leak - more of a dribble really. During the first service a few months ago, I replaced the oil and fitted a magnetic filler plug. Since then there is a consistent drop or two of oil on the floor  after a drive which seems to be directly below the plug - however the leak is definitely not from the new plug. I have a feeling that it might be from the seal around the Caterham LSD back plate.

I've read a few historical comments about the fact that the diff oil can leak from the seal(s) if the diff is overfilled. Would this be the seal between the back plate and BMW body? Or the seals around the drive shafts?

Probably nothing to be concerned about, but I'd like to get to the bottom of it. Thanks for any advice or experience.

[StevehS3]

How much oil is in the diff? I think the correct amount is 0.8L which is well below overflowing from the fill hole.

[Phil G]

Ditto #2

[ScottR400D]

The book used to say 1.2 L which was close to the fill level. It was changed because of leaks from the drive shafts. It seemed that some diffs never leaked. Some always leaked. 
I've not heard of fill plug leaks nor from the backplate sealant, there's no gasket as such. 
 

Favourite would be a shaft but anything's possible. Unless it's massively overfilled that's unlikely to be the cause. I ran mine with 1.2L for years with no issues.  
 

[AlastairA]

I initially filled with 0.8l but one of the feedback points from PBC was that there was insufficient oil in the diff. CC advised they had topped it up and said that in production they normally use 1l. During the service I managed to extract and replace about 0.8l.

Whilst there is no gasket between the housing and backplate there does seem to be a black sealant that has been used.

I'll check around the drive shafts

[Colin Heseltine]

I changed my diff oil two weeks ago and used the standard USA quart container from redline.  This is 0.98 litre. Drained around 0.78 litre of old oil.  Just been under car after doing over 1700 miles last weeks and no sign of leaks from the oils seals.

Colin

[StevehS3]

Having read the above information I have just topped mine up with the remainder of the bottle. I probably have just over 1L in now. It never leaked with the 1.2L that I had originally. Crikey it is never straightforward! 

[AlastairA]

Thanks All - the car is going into Oakmere this week to be flat-floored and I've asked them to look at the LSD. Will preoort back their findings.