Hi all,
Was helping a friend replace his 3rd member, and we had to swap the driveshaft flange (donor was from 79-83 truck). How do we set the pre-load so we don't kill his pinion bearing? The manual does not give a very good description of the process. I've searched the boards, and have some info, but since we swapped flanges, and different 3rd members, counting the # of turns didn't seem to help much.

Any info would be greatly appreciated.
Erik <img src="/forums/images/graemlins/cheers.gif" alt="" />

You don't want the (re-)set the pre-load, as it hopefully should not have been changed. I usually try to torque the pinion bearing down to about 90 ft.lbs. to make it tight, but not affet the crush sleeve and pre-load, which is done at about 130 ft.lbs.

You can't really check the preload properly with the ring gear in the housing. But it's not an option to pull the ring gear at this point, that's more trouble than you need. There isn't enough backlash between the pinion and ring teeth to allow a proper measurement of the bearing preload when it's all together. Since you also can't just put the nut on the same number of turns, the other option I've heard mentioned is to put the nut on and only tighten it to a very low torque, about 10 lb-ft, and then stake the nut. This avoids crushing the crush sleeve any more and creating too much preload. Theoretically, once the bearings are broken in, there really shouldn't be any preload on them anyways.

I've done the low torque technique on one of my diffs when I had to replace a pinion seal, and the gears were still running great two years later when I pulled them out to change ratios.


edit: I suppose if you compare Roger's answer and mine, the clear winner is to just torque the nut to somewhere between 10 and 90 lb-ft and stake it well. <img src="/forums/images/graemlins/lol.gif" alt="" />

Thank you...Sounds like it's fairly easy, and doesn't require as much thought or effort as the book makes out.

I appreciate your help
Erik <img src="/forums/images/graemlins/kewl.gif" alt="" />

I will say a prayer for ya....



Hail Mary full of grace
I don't want to fry the race
let me get this nut just right
as I crank with all my mite.
amen

Amen...