diff measurement pitfall

[frank rabbets]

When measuring your diff play at the flange circumference on vehicle be sure you have at least one wheel of the other axle off the ground so that it does not restrict the reading. Otherwise if the diff you are measuring has more play than the other that other diff you will not be able to turn the flange fully. I got a bit confused today? Answer on a postcard Jon.

Incidentally the rear diff has 2mm at flange. The front one is a little harder to measure as there is additional play in the driveshafts. From what I can feel there is 2mm for the pinion backlash and a total of 7mm before the front wheels turn. Within limits?

Frank

 

[Jon Wildsmith]

I've never measured it like that but 2mm sounds reasonable but I don't know about the 7mm without going and doing mine. Are you just checking up on things or looking for the cause of a problem?

 

[frank rabbets]

Not tracing a problem Jon. Just paranoid as usual; but I'll be alright now for a few days! Must change the oil; in fact I havn't checked the level yet.

Frank

 

[nathanrobo]

Frank

Did I set a hare off on this? Well I'm paranoid too (as Jon will tell you)!

You mentioned to get one the opposite wheel off the ground before measuring, I'm assuming this is on the same axle - right?

 

[frank rabbets]

Nathan,
If you want to measure say the front diff play by rotating the propshaft round and back again until you feel it stop, it maybe the rear diff with perhaps less play is stopping you turning the front shaft rather than the crown wheel and pinion teeth hitting. This is because they are geared together through the centre diff. So if you jack up one rear wheel this fully releases the rear diff effect. This happened to me yesterday. I checked the front and found 2mm play at flange circumference. I thought this felt too tight because I could not feel the front half shafts being locked up. So I jacked up one rear wheel and the front prop turned 7mm.

So my theory is that if you measure diff play with all 4 wheels on the ground you will get a reading equating to the play in the tightest diff [assuming no play in props or centre diff].

Is that more obsessional than you or about the same.

Frank