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Hi Packard people

I replaced my rear brake components recently and this entailed removing the brake backing plates and setting the rear wheel bearing end play. Brakes are now good. I inadvertently removed one half shaft and it came out of the splines in the diff. Hope this did not mess up my diff? What is the story with the thrust block?

I also topped up the differential with 80/90 weight gearbox oil. There were very little oil in the diff. I now know that one actually needs 140 weight.

And now the diff is Extremely noisy on the overrun and the oil is leaking out heavily at the pinion seal in front. Obviously the seal is shot.

I have no experience with differentials and cant believe that the wrong weight oil can cause that amount of noise? It starts of as a howling on overrun when the diff is cold and becomes a bad growling noise when the diff gets hot - and it does get hot! Cant drive it like that at all!

Any ideas? I read the procedures in the manual, but I must say I am a bit apprehensive to touch the diff. I also see that parts online is very expensive - for example bearings and seals. Never mind if your gears are buggered then you have to sell your house!

Thanks for any words of encouragement - I this car does not want to be driven anymore!

Regards
Barrie

Hi Barrie,

The nut that holds the flange for the driveshaft on the differential could be loose. That would allow the drive pinion to move back and forth and cause noise as described.
This can be checked by disconnecting the rear u-joint from the rear axle flange and checking to see if the nut is tight. You will need a 1-1/4" socket.

Barrie,

Did you use GL-5 gear oil for the differential? You can use the GL-5 in the manual transmission and differential. You can use a GL-1 gear oil in the transmission, but not in the differential. I hope you problem is a loose pinion shaft nut. Good luck.

(o[]o)

Yes, I hope that the 80/90 Castrol gearbox oil just loosened an iffy pinion nut and that this is what is causing the issue. Will check for correct GL-5 gear oil tomorrow.

Will remove rear u-joint tomorrow to see what nut is up to. I hope that this is the case as the diff was very quiet with no issues before filling with oil - haha! Otherwise I will have to remove the diff tomorrow and go from there.

Thanks for the info. Will keep posting results here for fellows with same issue in future!

Regards

Barrie

I doubt very much that the viscosity of the gear oil was the issue; for many years Packard recommended 90W in the winter, 140 or 160 in the summer.

Remember that the differential uses hypoid gears and unlike the transmission must have a gear oil with "extreme pressure" or EP properties. The EP gear oil is also satisfactory in manual transmissions with the possible exceptions of the very early ones that use yellow metal (bronze, brass) components. But a simple gear oil without EP additive is extremely damaging to a hypoid differential gearset.

Hopefully you'll find the problem is a loose pinion shaft retaining nut or some other simple issue and not the gear teeth face wear from lack of proper lubricant.

Dear africapackard:

Is this a new problem or has the car only recently become roadworthy?

Those pinion seals start to leak when cars sit idle. I don't know why, but it happens to modern cars as well. People who buy modern cars and then stash them hoping to make a mint one day find out that the cars become junk from just sitting.

The real old stuff didn't use seals and they can sit for years with no obvious side effects.

If this is a new problem then recheck the axle end play. You should be able to carefully knock each axle against the thrust block and the get an audible sound when pulling hard on the brake drum. There should be no binding either. Those wheel bearings require grease as well. I made up a special on the car rear wheel bearing packer for cases where I took cars out on test drives and could hear the rear wheel bearings. It was a cheap way to avoid costly breakdowns on cars that saw little use.

Hope this helps

Hi Guys

Removed the UJ this morning and the pinion nut was so loose I could turn it by hand! So obviously this is my issue.

Some questions:

How tight should this be torqued? The manual says 2 to 2.5 foot pounds required to turn the pinion shaft.

How best to keep the nut tight? Locktite presumably. The manual suggests a Hug - Lock nut, and seems to be what I have.

I cant get a new seal locally so will tighten up the nut and put oil and test drive. Just to be sure that I don't have any other issues such as bearings or gears....then order the seal from USA but it will take 6 weeks to get here. The car will be parked for then.

Here is a possible solution for the "wait six weeks" dilemma: Your pinion seal is a pressed steel shell that holds a felt wiper ring and normal commercially available seal. Being cheap and in a hurry on my own cars, I rebuild the seals and put them back:

Carefully pull the old seal with a good seal puller, or by grabbing the nose of the the seal with a pipe wrench and twisting it out. You can now punch out the center section of the pinion seal and replace it with a new one. Use a good sealer and around the new center,and also upon insertion of the assembly into the rear axle.

It will be just about impossible to obtain the drag that Packard specified without taking everything apart but my best suggestion is to keep tightening the nut a little at a time til the bearings take up--that is you can no longer obtain any endplay on the pinionshaft using a dial indicator. I'd probably give it another 1/6 of a turn after that and stake the nut.

The seal you want measures 1.625x 2.437x.50. Over here, that would be a Victor 46281 or Chicago Rawhide 16117.

Barrie,

Excellent advice from Ross.

If there is any doubt about which type of gear oil is in your differential, drain the unit and refill with a brand name EP GL-5 85W-140 gear oil.

I hope the loose pinion shaft nut was the cause. It may not have been, but it must be corrected.

(o[]o)

Barrie, you said that you did an overhaul to the rear breaks by chance did you remove the 7/16-inch vent screw, which holds the brake tube junction to the axle housing at the left side of the housing and clean the vent hole or replace it with an un-vented screw. Many oil leaks at axle shafts and around differential pinion seals have been due to an excessive build-up of pressure in the housing caused by this vent being plugged.