Rear diff noise

[Cisco82]

Hi guy,
after abut 500 miles on roads today i noticed a problem on my rear diff : when i accelerate i hear heavy noise , it seems a soft of knocking into rear differential. I lift the rear wheeles nad i tried to move the rear wheels and when i move a wheel i feel , i'd say a big backlash and then the noise when the grears "start workins" , i m not sure i was able to explain the situation... I suppose the diff is gone ... any idea or test i could do to confirm this idea? Or do you think it could be something else?

The axles and U joints are well greased and i can see just a little leak under diff but nothing big.

Thanks

[rickf]

With both wheels in the air you will be feeling the backlash of the combined spider gears, both axles and the ring gear. The best way to check it is with it sitting on the ground, wheel chocked and in neutral. Then try turning the driveshaft back and forth and see how much play you have, should be very little. 1/8 turn or less. Also try pushing the shaft up and down where it goes into the differential. This checks the pinion bearing. What you describe sounds like a pinion bearing symptom. The pinion bearing in these is huge so I doubt it but anything is possible if it ever ran out of oil. The race for the two bearings is one piece and is getting kind of hard, and expensive, to find. You can always swap the differential with the front one to see if the noise goes away.

[Cisco82]

Thanks Rick, au usual your advice is useful. I did as you suggest and i likely found the problem , chepear than expected: one of the differential bolt was a bit loose so , under accetaration , the torque moment transferred by drive shaft made the differential housing "knocking" on the chassis.

Problem fixed easly , thanks again.

Francesco

[rickf]

Cheap and easy is always a gift You may want to take those bolts out one at a tie and spray the bolt and hole with brake cleaner and then put blue Locktite on the bolts to prevent them from coming loose again. Do not use the red locktite since heat is usually needed to break them loose again in the future.

[lpcoating]

I think it's a good habit to check bolt torques throughout the driving season on the drivetrain and suspension.

Guy

[Mark]

Yes I agree, 1 time I checked the u joints nuts on the drive shaft, some were loose, so I took the driveshafts off, got them balanced at the driveline shop, yes they were out of balance.Got the shafts balanced, no more loose nuts

[Cisco82]

Thanx guys I think the mutt has a problem with vibrations so i was thinking to add a counter nut in order to keep the diff fixed since I can't avoid vibrations.

I appreciate the suggestion to use loctite but if it possible i like to avoid it if not strictly necessary.

See you on the road


Thanks


Francesco