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[John_Clayton]

The pinion bearing on my diff. has collapsed. The car - a 2.5 V6 Tourer - has only done 115,000 miles so I'm very surprised it's happened. I did get some warning in the form of a loud whine on the over-run. Anyway, I'm after advice on replacing it myself. I already have the diff. out of the car and have removed all the damaged bearing parts from inside. Are there any pitfalls to be aware of when replacing the bearing, i.e. getting the correct pre-load etc.? Or is it a job best left to a specialist? Incidentally, the Haynes manual said to lever the driveshafts out of the diff. I wasn't able to do that in situ so have removed them still attached to the diff. Again, any tips on that task? Thanks in anticipation.

[Matchless]

Given the likely cost of quality bearings and the difficulties in setting pre-load I would be looking for a replacement diff from a breakers.

To remove the drive shafts, use a pair of stout screwdrivers or pry bars, either side of the shaft. Apply a little load then jerk the levers to surprise the spring ring.

[Big_Roger]

Hi,
I had this problem on a Senator that I had some years ago and considered replacement bearings as I used to work in a precision engineering shop. I decided eventually on a s/h unit.
From the look of them the Senator and Omega diff units are very similar.

The biggest problem is that the collapsing bearing will have mixed minute particles almost like grinding paste, of the duff bearing into the oil and spread them everywhere inside the diff unit and thus into the diff carrier bearings which will also soon fail, as will any new bearing you replace.

Even if you could clean it all out, you will need various shim thickness  washers, and a replacement collapsible collar to set pre load on the pinnion bearing.

Ideally you would need a setting gauge for the pinnion height, but with a great deal of inginuity and patience and lots of engineers marking blue, you might get the pinnion mesh approx where it was originally.

I think I have said enough, it's not worth the hassle ! Go and get s/h diff unit from scrapper. you should get at least 90 days warranty.

Roger

[John_Clayton]

Thanks for the advice. The driveshafts came out fine, using 2 lengths of 3 mm thick steel. (Only a thin screwdriver would fit in the gap and it wouldn't be much good for screwing afterwards!) A local breaker has a 1996 Omega Automatic Saloon. The Haynes manual says it's the same ratio - 3.7 (changing to 3.9 from 1998) but I'd like someone to confirm that if possible. Haynes manuals have been known to contain errors! Obviously I'll do a tooth count before purchase, to be certain.

John Clayton

[Matchless]

Pre '98

Manual
2.0 : 3.9, 2.5D : 3.45, 2.5 : 3.7, 3.0 : 3.9

Auto
2.0 : 3.9, 2.5D : 3.45, 2.5 : 3.9, 3.0 : 3.9

Upto mid 95 the 3.0 may have had 3.7 diff.