R200 problems after replacing pinion seal

[AlexS13]

I recently swapped in a R200 into my 240z and to my surprise it was very smooth and quiet. I did notice the pinion seal leaking quite badly so I decided to replace it. I searched and read multiple posts regarding the pinion nut torque because I was nervous about the bearing preload. I decided to follow the fsm and torque it to 140ft/lbs. Before I took the nut off I marked the nut and the pinion shaft so I can use that as reference when I re-install the nut. I torqued the nut to 140ft/lbs and noticed that the mark i put on the nut was about a 1/4 turn past the mark on the pinion shaft (1/4 turn tighter than it was originally). Now the issue I have is that I'm getting a humming sound from the rear end. It sounds just like a bad wheel bearing. I'm assuming this has to do something with the pinion nut being a 1/4 turn too tight? My understanding from what I have read is that these diff's do not use a crush sleeve to set pinion preload? I'm not too sure what to do from here...replace pinion bearings?

any help would be appreciated.

[EuroDat]

Your problem is that you tightened the worn pinion bearing using the fsm specs. Now the geometry pinion/crownwheel is off causing it to whine. This is always a touchy operation. A lot of people have this problem after changing the pinion seal.

What I have done with succes, 30k km and no noise is as follows:

Mark the position of the old nut before removing it.

Replace the seal

Fit the old nut to original position.

Check the tension on the nut with a tension wrench. Go back and forwards to make sure its right. It will be less than the fsm specs.

Use a new nut and tighten it with tension wrench settings.

Lock the nut by punching in tab.

Hopefully it will be a lot better

You can still do this since you know the position of the nut before you started.

Goodluck

Chas

[AlexS13]

Chas, thank you for that tip. I tried backing off the nut and putting it to it's original position but when I do this the nut is almost loose at it's original position. It almost seems like the bearing has collapsed? I think I'am going to go ahead and replace the pinion bearings. Does anyone have nissan part numbers for the front and rear pinion bearings?

[EuroDat]

These are the numbers for the pinion bearings:

38120-61000

38120-13201

38335-N3200

Its not a job to be taken lightly. I would consider getting it done by a specialist.

Chas

[EuroDat]

I tried backing off the nut and putting it to it's original position but when I do this the nut is almost loose at it's original position. It almost seems like the bearing has collapsed?

When I did mine the tension was a lot less. I cant remember was the tension was exactly, but it was less than half of what the Fsm stated.

If the tension is very low, than the bearings a worn. You could try setting the tension to 30ft/lbs and see if its quiet. Give youself time to work out what to do. Changing the bearings is the easy part. If you dont have the height gauge to determine the shimes for the new bearings you have the adjust it using the crownwheel/pinion contact paterns. Reading and understanding the contact paterns is not easy and if you havent done it before it can take a lot of hit and miss to get it right.

A transmission shop is set up for this. If the bearings are worn to the point that they require replacement, then I would bring it to a shop to get it done.

Chas

[AlexS13]

Thank you very much for the info. I will definetly take it to a shop to get this done.