twohoos

I just picked up a used AP2 ('07) diff. I trust and believe the seller, who states that it has low mileage (~20K) and was never abused (tracked or launched). However, I just measured the companion flange turning torque and it barely registers on my beam torque wrench -- I get maybe 2-3 inch-lbs. This measurement is of the fully assembled diff, still filled with fluid. There are no signs that the flange was ever removed.

Now, I know that when rebuilding a diff from scratch, the Helm manual calls for 8-12 inch-lbs of turning torque...but then, that's midway through assembly, with only the dry pinion gear in place (i.e. before the LSD unit is fitted and the whole case is sealed up and oiled).

So the question, of course, is whether this apparently low turning torque is anything to worry about?

SpitfireS

Rebuild = with new bearings.
IIRC the manual doesn't spec any turning torque to set for used bearings.
So.. one could say: this is a well broken-in diff
As long as there is absolutely NO axial movement when you push/pull the pinion you're most likely OK.
The thing is, if you start "messing" with the flange nut and tighten it just a little to increase turning torque - and this turns out to be too much and you have to loosen it, all this turning may loosen the nylon locking ring.
Also, broken-in bearings don't wear that much anymore so leaving it a little too tight may damage them.

Use good diff oil and be happy with your fresh diff

Billman250

^

Normal findings. Do not ever disturb the pinion nut of a good working dif, it will affect the tooth contact pattern and it will whine almost immediately.

SouthDakotaS2K

It may also have something to do with the torque wrench. I always use a dial type torque wrench when checking rolling torque while setting pinion and carrier pre-load. The dial wrenches tend to be more precise IMO.