abbylind Posted February 18, 2015 Report Share Posted February 18, 2015 My 77 620 started making noises in the drive train. Namely a rattle on acceleration and a sharp clang occasionally. The clang had a sharp ping and sounded like someone banging on the drive shaft. I examined the drive shaft and noticed it had some slop. The rear dif had a leak which had sprayed grease around the front seal. I removed the dive shaft and found the u joints were loose. The carrier bearing was OK but after 100K miles I elected to replace it and balance the drive shaft. The diff seal is fairly easy to replace. Remove the nut that holds the dive shaft linkage and pull the linkage with a gear puller. The seal covers the face of the diff. I used a small pry bar to pull the seal out. Reverse the process and put a small amount of grease om the new seal edge and use a board with a hammer to seat the seal. The drive shaft should be re installed in the same position rotationally to maintain the balance. Hope this helps other Ratsunners.. Ive got my 77 in my shop for some other improvements and replacements....More to come and pics too 2 Quote Link to comment
Draker Posted February 18, 2015 Report Share Posted February 18, 2015 Not a bad post.. one thing that could make it better though.. a few pictures! 1 Quote Link to comment
abbylind Posted February 18, 2015 Author Report Share Posted February 18, 2015 Also the pinion diff seal that is listed by Autozone is incorrect. It looks like an axle seal not a pinion seal. I ordered the correct one from Rockauto 1 Quote Link to comment
datzenmike Posted February 18, 2015 Report Share Posted February 18, 2015 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. 1 Quote Link to comment
abbylind Posted February 18, 2015 Author Report Share Posted February 18, 2015 The balancing was included with the u joint and carrier bearing replacement..Thats what the driveshaft exchange I use does They replaced u joints and rebalanced the driveshaft on my M1008 military truck in the past...what a monster! I used my air ratchet and wedged a large prybar against the driveshart bolts to remove the pinion flange. Came off pretty easy 1 Quote Link to comment
abbylind Posted February 18, 2015 Author Report Share Posted February 18, 2015 Heres the drive shaft and differential prior to removal....nice gear oil deposit 2 Quote Link to comment
abbylind Posted February 19, 2015 Author Report Share Posted February 19, 2015 This is the drive shaft removed and the pinion seal pulled out 1 Quote Link to comment
abbylind Posted February 19, 2015 Author Report Share Posted February 19, 2015 The actual part number for the pinion seal is 1979 at Autozone and OReillys and Rockauto 1 Quote Link to comment
abbylind Posted February 20, 2015 Author Report Share Posted February 20, 2015 New u joints,carrier bearing, and new pinion seal.... drive shaft installed 1 Quote Link to comment
abbylind Posted February 20, 2015 Author Report Share Posted February 20, 2015 After seeing the pinion seal leak it was apparent that something had caused it. I checked the differential axle vent and found it was clogged with dirt and grease. I cleaned the vent and reinstalled. Hopefully that will prevent another seal blowout 1 Quote Link to comment
datzenmike Posted February 20, 2015 Report Share Posted February 20, 2015 Time to replace the oil. With a new seal you can probably get away with a synthetic now. 1 Quote Link to comment
abbylind Posted February 20, 2015 Author Report Share Posted February 20, 2015 Done and done sir! Drained and refilled...Tranny is next.. 1 Quote Link to comment
abbylind Posted February 20, 2015 Author Report Share Posted February 20, 2015 After everything is done I plan on power washing the underside 1 Quote Link to comment
datzenmike Posted February 20, 2015 Report Share Posted February 20, 2015 GL-5 for the diff and GL-4 for the transmission. Don't spray near the diff or the transmission vents. 1 Quote Link to comment
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