Rear pinion seal leaking, question on diff play

[fastfalcon94]

My 94 vr4 has 64k miles on it right now. Last year I put on a 1 piece cf driveshaft and poly rear diff/subframe bushings. I drove it around some, ran it at the track. This year I drove it some. I brought it to the track a few weeks ago and ran 11.5 @ 126mph. Then a few days later I drove it 6 hours round trip to a car thing in NH. When I got back i noticed some fluid on my rear bumper. I believe it's the pinion seal so I ordered a seal from Ninja performance. I disconnected the driveshaft today and my rear diff seems like it has some rotational play in it. As in it moves a little bit clockwise/counterclockwise before it catches and the tires spin. I have another diff (unknown mileage) and it doesn't seem to move as much (granted it doesn't have axles or anything in it, not sure if that would make a difference. It doesn't have any in/out or side to side play.

Here is a video of what I am talking about. Should I replace the seal and see how it goes? Swap in the other diff? I do get some vibration issues at 120 mph. At the track though I just kept going. I was thinking of rotating the driveshaft 180 degrees to see if that helped.

Thanks - Charlie

http://i1192.photobucket.com/albums/aa327/fastfalcon94/th_VID_20150926_123312114_zpsa2i9wg1l.mp4 (http://i1192.photobucket.com/albums/aa327/fastfalcon94/VID_20150926_123312114_zpsa2i9wg1l.mp4)

[Chris@Rvengeperformance]

I haven't checked that recently, but it does seem excessive.

[fastfalcon94]

I think the manual said something about 5mm of play max if you lock up the ebrake and rotate the driveshaft underneath the car. My car doesn't have that much. when everything is connected. With the driveshaft disconnected it has 4.89mm of play. Hopefully more people chime in. I'm debating just putting the seal in, topping off the fluid and trying it. It was never clunking or anything like that.

[box]

I wouldn't be touching it if it's within spec, you're just going to open up a can of worms. Replace seal with an OEM unit, call it a day.

[RealMcCoy]

The one on the bench, you are able to distinguish by feel where the carrier starts to turn, and limit the turning torque to just feeling the backlash. In the car, you are feeling the backlash of the ring and pinion, as well as the spider gear backlash, and the axle splines...

[Jimvr4]

Leaving this here http://www.3sgto.org/transmission-suspension-drivetrain/6361-rear-differential-pinion-seal-leaking.html

[fastfalcon94]

I read through that page the other day. With the driveshaft connected i only have about 2mm of play max. I just replaced the seal last night, torqued it down, and filled it with fluid. I couldn't find anything wrong with the old seal. No tears or anything. My turbo oil return lines were also leaking where they mate up against the oil pan. I put on some new gaskets and put some rtv on the bolt heads/thread. Tonight I'll test everything out. I'm a little skeptical.