Hoping for a little insight. Recently purchased a 10 AE FC3S project car. The PO told me that one of the rear calipers was hanging up when I bought it. They seem to be working fine though. After removing the caliper, I noticed that the brake rotor was difficult to turn by hand. So I disconnected the drive axle to find that the issue was somewhere in the rear end. Next, I disconnected the half axles at the diff. The axles seem to turn fine by hand, eliminating the wheel bearings. When trying to turn the diff, it seems harder to turn than it should. I can turn it by hand though.

My questions are:
How much effort should it take to turn the axle stubs with the drive shaft and axles disconnected?
What is the likely cause of this? Other than tearing it apart, how do I tell if I need to order a rebuild kit? Could it just be something simple? Apparently the car sat for a while. It had temp plates on it, dated 2012.
When I originally pinpointed the issue as the diff, I started shopping diffs. I found a great deal on a FD Torsen on Ebay, so I jumped on it. Now that I have had time to do some more research, I am wondering if a Torsen would be better than the clutch type? Once tuned, I am thinking I will be in the 400-450whp range. The car will be streeted a little, mostly to and from autocross events. I am willing to give up comfort for a better autocross car. After looking at several threads, it sounds like there are pros and cons to both types of diffs. Has anyone run both that can offer a side by side comparison?

Thanks for your inputs.

 

To turn one axle in the direction opposite the other, it should take a minimum of 40ft-lb to initiate movement ("break away" torque) and it will lessen slightly once moving. Good diffs are 80ft-lb and up.

Anything other than that is not a diff problem. It should take about 10ish inch-pounds of torque to turn the pinion if you remove the differential/ring gear assembly, slightly more with everything in place. It should be a lot harder to backdrive the pinion by turning the axle stubs but not significantly so.

 

Thanks for the reply peejay. That helps. I haven't dropped the diff yet, so I think that I will test it with a inch/lb torque wrench at the drive shaft connection to make sure that it is above the 10ish inch/lbs. I have a gut feeling that something inside has started corroding from sitting so long. Who knows, though. There's a high probability that I will have to drop the diff and learn how to tear it apart and/or learn how to rebuild one. Should be interesting.