3:23 Sure Grip...why is only driver side wheel spinning?

[TylerCharger69]

   I bought this rear as a complete sealed unit. It's a 489 case 3:23 Sure Grip.  No vibrations, no noises.....very smooth. Question is, why is only my driver side wheel spinning? I know I need to check it, but is it possible it's simply low on fluid? There is absolutely no evidence of a leak on it anywhere. And...I'm not sure how long the rear end was on the shelf.

[TylerCharger69]

  Oh!  And....it's good to be back! Missed this place!!

[myk]

There's a test for that I think.  Put the rear end off of the ground and try to turn one wheel by hand.  If you encounter a lot of resistance and can't turn the wheel the differential should be good. If the wheel spins freely then something is wrong. If I'm wrong about this someone please correct me...

[TylerCharger69]

Yeah...it won't turn unless both wheels are in the air.

[c00nhunterjoe]

Sounds like its 45 years old and wore out..... fwiw, i have a VERY nice 742 pumpkin with 4.30's i would like to get rid of. Fresh and solid.
Birthday burnout: http://youtu.be/x86OGyvN-6A
General lee, by joe: http://youtu.be/YQiFd0aZ-00

[TylerCharger69]

But could the fluid level be a possibility?

[justcruisin]

If it's a cone type - probably is, it is most likely worn out. The cones bottom out and don't provide enough bite on the side of the cone. Trying to turn one wheel while the other is on the ground is not a definitive test as to the condition of the center section. If the problem you are having is only at light load it could be weak preload springs, but if you nail it and only one wheel drives then it needs to come apart. The cones can be machined and shimmed. Checking oil level is pretty easy (pull the bung and stick you finger in to feel for oil) but it is unlikely to be your problem if it runs quiet.

[Kern Dog]

But could the fluid level be a possibility?

Uhhh... No.
The '489 case leads me to believe that it has a CONE type Sure Grip unit. Their design is such that they work for awhile then slowly wear until the internal walls of the case wear away and it essentially functions like a one legger design. The standard practice is to replace the unit instead of trying to "rebuild" it. Fluid makes no difference in your case. Often it is the opposite: Low on gear oil or the appropriate friction modifier results in the unit locking or grabbing too much and NOT slipping in turns like it is supposed to.

The test my axle guy told me is such: place the 3rd member in a vise. Place a splined rod in one end, fixed so it cannot move. Place another splined rod in the other side with a torque wrench. A new unit should require 120 ft/lbs to break away. A serviceable unit should hold 80 ft/lbs or more. Below that number, replacement is suggested. I once took a 4.30 CONE type in and found it held 30 ft/lbs. Yeah...I sold it at a swap meet to a guy that wanted the housing and gears. He didn't care about the worn diff.

[moparnation74]

I suggest rebuilding the 3rd member.