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I am replacing a leaky pinion seal on my 1937 Packard 120 conv. Does anyone know what the torque spec is?

I don't see a torque spec, but the 1937 120 shop manual cautions that the pinion bearing preload should be readjusted every time the flange nut is removed. Suggest you see Section 160 of the 37/38 shop manual.

You could always try the old standby method of tightening it down until it breaks then back it off 1/4 turn.

I'll ask tonite's dumb question. As I see it a single nut on the universal flange controls all. You tighten that nut until the crush sleeve starts to go and then tighten more until you get the in/lb turn spec whatever the nut torque happens to be and stop-- is that correct?

The 47 manual says when replacing seal to carefully mark the nut, count the turns to remove and then after seal is replaced, put nut back exactly as before and nothing will be changed. Also gives a turn spec but no torque.

51 manual gives a turn spec but also a torque spec of 300-325 ft lbs for the pinion flange nut. No mention of counting the turns but just gives the turn spec upon replacing.

55 manual gives a turn spec but no torque spec and same instructions.

Guess the question is the 51 spec. Is that nut torque amount correct or do you really care what the torque is as long as the turn amount is correct. Apparently I am missing something in the picture because it would seem that you could put things back and have the right turn spec but nut be too loose. All very confusing for my feeble brain cell.

G'day Wayne,

Like to you to PackardInfo. Will be interested in the answers here, as we have a '37 120 diff apart at present.

Going out on a limb here. I believe all are correct and result in the same basic outcome; the crush sleeve compressed and tapered bearings under the correct pressure to prevent radial and axial movement yet run free enough to not burn up with proper lubrication.

I personally go with the method mentioned of marking returning to the prior nut setting by marking the nut, pinion, and flange (yoke). Of course if it was loose prior to seal replacement, it will be loose after making it necessary to tighten further and obtain the proper drag. If the nut was previously grossly over torqued the crush sleeve is over crushed and rendered useless as far as allowing the bearings to be set to the correct preload and the pinion nut under enough torque to hold everything in place under dynamic load.

Ultimately, the 300 - 325 Ft/lbs is fairly typical for initial crush setting with fine tuning being done to get the proper drag. Marking and resetting is typical when everything was fine and a simple seal change is performed, and setting to proper drag if it was loose prior to seal replacement.

My advice in all of this is to clean the nut and pinion and use a liberal amount of red Loctite to ensure the nut doesn't back off. For some reason, this seems to be a universally annoying regardless the make.

Something that I learned recently thanks to Wade by way of Mal was have new gear sets lapped in. Never new of this, and don't think it necessary if the ring and pinion are matched sets, but will definitely look into the service if I install mystery ring and pinion sets in the future. Sure would beat a howling rear end!

Wayne, for including your '37 One Twenty Convertible Coupe in the Packard Owner's Registry.