You can only really test it under normal pressure when props/VCU are fitted. Turning it by hand for fault finding is ok but testing in anger is the only way to know it's ok. It's the only way to find vibrations and squeels.Half of them i have looked at buying have rear prop removed. I know why .... VCU usually. But how can I then check IRD is working properly ?
You would have to check the rear pinion for play. There will be an amount on rotary movement - but there shouldn't be any lateral play at all. You'd then have to drain the oil, if it comes out grey, then that's the bearings ground to a pulp and suspended in the oil. If it comes out looking like oil, then its either OK or they have replaced the oil since removing the propshaft! Then you'd have to remove the rear pinion and examine the teeth on the crown and pinion gears - if there's much (any?) signs of wear, then that's abuse from bad tyres/VCU that would result in an IRD not suitable for putting back to 4WD.Half of them i have looked at buying have rear prop removed. I know why .... VCU usually. But how can I then check IRD is working properly ?
You can get a rough idea how much bearing wear has taken place by the amount of backlash in the rear prop output flange. It should be no more than 3mm or so.But how can I then check IRD is working properly ?