H190 Differential Gunk and Pinion Nut Torque

[Ron1200]

I'm replacing the U-Joints and Pinion seal on my '79 620 KC and have a few questions. First a shout out to Mike for the U-Joint How To.  It's been 40 years since I last changed one, so I did need to read up on it.

 

In prep for the pinion seal replacement, I drained the differential oil and found this. Is it bad or normal? The point of the pick is resting on the top of the magnet for reference. 

 

 

My Chilton manual was of no help for changing the pinion seal, but I managed to pry the old seal out and get the new one seated without issue. My question is regarding the torque on the pinion seal nut.  I read that it should be torqued to 100-120 ft. lbs. However, the nut was really easy to remove at maybe 40 ft. lbs. of torque.  Given that the nut was not at the proper torque and their was no rear end noise, should I tighten it to spec? Will the higher torque move the pinion in relationship to the ring gear? As a compromise, I marked and counted the number of turns needed to remove the nut and reinstalled it using the exact same (9 1/2). I have not reinstalled the drive shaft yet.

 

This is where I got the torque info: Differential Pinion Seal and Drive shaft problem

 

The drive shaft does not need balancing unless repaired or shortened. I've removed several flanges by steadily tapping (not hammering) forward on the back side with a 4 pound mallet. The pinion nut needs 100-120 ft. lbs. torque to tighten it.

 

 

BTW... I have a gallon each of Sta-Lube GL-4 (trans) & GL-5 (diff) on the way from Amazon.

 

Thanks

Ron 

 

[flatcat19]

Your plug/diff is fine. That's really normal for the magnet to look like that.

 

 

Run your finger through it to make sure there are no huge chunks.

[Ron1200]

Thanks Flatcat! One less thing to worry about!

 

I'm inclined to torque the pinion to spec, but don't wish to cause other problems.

[datzenmike]

Clean the magnet so you have a reference next time you inspect. A black paste with fine filings is normal.

 

40 pounds isn't much, maybe the seal was replaced before some time ago? It would have been 100+ set at the factory. If rebuilt it would have been done properly and set again. I don't see any harm in setting it properly. If you return it to 40 I would keep an eye on it for a while just to be safe.

[G-Duax]

Not enough torque, it will just loosen up more if you do that.

Finding a loose nut on removal means that the crush sleeve has relaxed, maybe from hard use like clutch dumps, big power, etc..

The reason I never use a crush sleeve on any of my diff rebuilds anymore.

I always go to solid pinion spacers, which take more work setting up, but will never loosen.

 

But if I have to go with a crush sleeve, like on a customer's diff, I always take it down to factory torque figures.

[Ron1200]

Thanks Mike and G-Duax!  I'll torque it to spec (100-120 ft. lbs.).

I'm glad I decided to service the drive-line... I'm replacing seals on the transmission output and pinion to stop the drips, discovered the loose pinion nut and the loose driveshaft flange bolts (two of which were less than finger tight and none were very tight). Four fixes... a home run!

[Foxx60]

Did you index the parts of your drive line before taking it apart if no then rebalancing is in order replacing u-joints does fall under the repair catagory unless you put it back the same as it was

[Stoffregen Motorsports]

Unless he took the slip yoke out of the driveshaft, there shouldn't be any vibrations to worry about.

[Ron1200]

Got the GL-5 in the differential and took it for a test drive today.  The 620 is running sweet and smooth (just like Woodford reserve :thumbup:  ).

 

I did have to remove and re-index one of the yokes.  Thanks to Mike for the the hammer tap u-joint removal technique.  I was able to remove it - move it 180 deg - reinstall it.