Check backlash between the crown wheel and pinion

[Kjetil]

Hi

How to check the backlash between the crown wheel and pinion on the rear axle differential transmission?

According to repair manual it shall be between 0.004 to 0.018 in.

I have the hydraulic top off, and wan't to check.

I have no idea where to stick the feeler gauge.

Thanks for any help


Kjetil

[Billy26F5]

You want to have it as close to 0.004" as possible, I don't know what feeler you have, but i would think this check should be made on the inner portion due to lack of access to the outside (Ford say nothing about this, unless it's in something I don't have). Don't know if you've got the axle completely off, but if not don't adjust the preload, just fit what came off (both bull pinion carriers, arranged to get the backlash right). If you do have it off then remove the pinion (six bolts holding the bearing cups, not the big nuts controlling the pinion preload which in this situation you should check too) and see how the diff spins, if it seems heavy (unlikely) add a shim, if it feels loose remove one. Ford specify a total of shims but under the assumption that the bearings are new. Old bearings will likely feel a bit loose like that. Once that's done refit the pinion and check everything the normal way. On final assembly remember to seal both sides of each shim, otherwise you'll have a very irritating leak there.
Sandy

[Kjetil]

Hi

I found an interesting instruction:

https://www.euroricambigroup.com/sites/ ... Euro_0.pdf

[Billy26F5]

Very interesting details, I'll see what their formulae do for the Major. The dial gauge does allow free choice for the measuring point but not the Ford way. By the way, no depth of mesh adjustment on Major's, so a few odd wear patterns will be around on teeth.
Sandy

[Kjetil]

Hi

I did a check on the NPSM.

D = 304 mm and 35 teeth, giving M = 8.69 and a backlash between 0.254 and 0.330

Fordson specifies 0.004 to 0.018 in equal to 0.1 to 0.5 mm

I have measured a backlash of 0.2 mm.

Kjetil

[Billy26F5]

Looks like you're fine then, did you measure it on the inside?
Sandy

[Kjetil]

Hi


Not sure what you mean by inside.

I used a dial gauge, like shown in the link above.


Kjetil

[Billy26F5]

So you did it on the outside then (this is referring to the position relative to the gear teeth). Not possible with a feeler gauge, too tight to get access. Hope you can get this axle done soon now.
Sandy