After installing the 4.57 gears (I have the usual hum attributed to the gear install)
All went well and I like the improvement.
After the Richmond recommended break-in period I have covered 650 miles and decided to change the oil. The oil contained no debris and was slightly greyish as expected on the first change due to the bedding in of the gears.
While underneath I grabbed the drive shafts by the diff flanges and checked for play ( I did not expect to find any) and was surprised that there was approximately 5mm movement in all directions.
The output shaft bearings in the diff were replaced at the same time as the gears were installed and have only covered the same miles.
Ideas please?

 

If it is really 5mm that is too much. Be sure you are moving the shaft at the flange and not the shaft itself (to avoid play in the CV boots). It is more important that the driveshaft have very little play in it. With the rear of the car up, set the brake and leave the car in neutral. Rotate the driveshaft and see how much play there is before the companion flanges (that mount to the driveshafts) move. You should be able to tell by feel when you run out of backlash and start turning the diff. This is more important since the drivshaft drives the pinion against the FD (turning the shafts turns the diff so you are effectively checking diff backlash as well).

 

You mean rotate the propshaft dont you as the drive shafts wont turn as the brake is applied as you suggest
or am I missing something?

 

Drive Shaft = Prop Shaft

What you are calling the drive shafts are really the half axles.

 

Thanks for that, seems like a bit of trans atlantic missunderstanding was happening.
I'll do the check as suggested.

Are you saying then that a slight bit of play is acceptable in the companion flange movement up and down (not the backlash) as it goes through the diff casing?