Pinion nut torque versus bearing preload

[dustyrangers]

It’s probably obvious but why are there two specs for pinions? Is nut torque 170 ft lbs to crush the sleeve and then you set the bearing preload to 18 in lbs?

 

[sgtsandman]

The torque for the nut sets the general pinion depth. The preload fine tunes it and makes sure the bearings are riding properly. Not too loose, not to tight.

 

[dustyrangers]

Does it have it be done in a specific order?

 

[dustyrangers]

That question doesn’t really make sense... of course you do. Sorry

 

[dustyrangers]

Wait I think I had it wrong... responded too quick. What I am reading is you torque the pinion nut to 170+ ft lbs while holding the yoke until you hit 18 in lbs while not holding the yoke?

 

[Bird76Mojo]

The 18 in/lbs is just verifying rotational drag.

 

[dustyrangers]

Ok I got it finally... not sure why that one was so confusing.

 

[ericbphoto]

I think the 170ft-lbs gets you "in the ballpark" then you slowly tighten until you get to the 18in-lbs of "drag" which let's you know the proper bearing preload has been achieved. It's been a while since I did that one, though.

 

[4x4junkie]

170 ft-lbs sounds to me like a figure for a non-crush sleeve (spacer type) pinion setup.

With a crush sleeve, there really is not a set torque value for the nut, it is whatever it happens to take to crush the crush sleeve.
In my experience, crushing the sleeve runs in the range of 250-350ft-lbs on the pinion nut, at least on the 8.8" (it's a little less on the D35).

Continue tightening the nut to crush the sleeve... When the slack between the pinion bearings gets real small, continue tightening only in very small increments (like 1/12th turn at a time) while checking the bearing preload each time, since 18 in-lbs or whatever the bearings call for will come up VERY fast as the bearings make contact with the races (if you exceed the preload, the crush sleeve will be ruined and you'll need to start over with another one).

Also (maybe you already know, but just in case), leave the crush sleeve out while you are setting up your pinion depth, in which case you only need to lightly tighten the nut to set your bearing preload (use an old nut too, not the new one). Once you have a satisfactory contact pattern, then reassemble it using the crush sleeve and a new nut.

Hope that helps.

 

[snoranger]

There's a minimum torque... not an actual torque to spec.