Proper Tightening of Differential Pinion Nut


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By alanfreeman - 13 Years Ago
The pinion seal in the rear end of my '54 Mercury has been leaking so I decided to replace it. I marked the parts as outlined in the shop manual so I would reassemble it with the correct pre-load. I went to loosen the nut with a socket and a breaker bar, only to find that the nut was already loose to the point that I could remove it by hand! This is probably why it was leaking in the first place. I removed the parts including the seal and I am ready to re-install everything. The marks I made are obviously useless because the nut was not torqued to the right amount but was loose. How can I get the nut torqued correctly without taking the differential apart? I don't want to mess up the bearing or other parts by torquing the nut incorrectly. Thanks, Alan
By Ted - 13 Years Ago

While I’m not exactly sure which rear end you’re dealing with, you should be dealing with a crush sleeve located between the two pinion bearings.  A new crush sleeve will allow the pinion bearing preload to be set while holding the nut tight.  If reusing the old crush sleeve, there’s a very good chance that once the proper bearing drag is achieved, there‘s still not enough torque on the nut to hold it tight.  That’s due to the used crush sleeve being too short now and not able to hold tension on the nut with the bearing preload where it needs to be.  A side of the road fix for used crush sleeves is to put them over a small pipe and hammer on the outside edge around their circumference so that the sleeve becomes longer.  Not the recommended fix but will at least get you home.

By alanfreeman - 13 Years Ago
Hi Ted and thanks for your response. I don't have the proper tool (as shown in the shop manual) to measure the pre-load on the bearing. I do have a torque wrench. Is there some way I can get the proper bearing pre-load and torqueing of the pinion nut without the gauge? Thanks again, Alan
By glrbird - 13 Years Ago
I had a pick-up  that did the same thing, we replaced the seal and used a braker bar to tighten the pinion nut until it was tight but still able to rotate pinion (wheels off the ground ) with out too much effort. it stayed tight and stoped the rear end noise when you let off the gas at speed.  Other wise you may need to pull it apart and put a new crush sleeve in it, set to the correct settings.
By MarkMontereyBay - 13 Years Ago
I have done this twice on 9 inch rears in the garage with a floor jack and a Snap-on clicker torque wrench after setting the parking brake. Used the floor jack to lift the torque wrench handle end to the spec torque (175 FtLbs for a 65 Galaxie). Since I don't have Barry Bonds performance enhanced biceps to tighten it on the floor under the car. Guess I got lucky both have since covered 50k or more without problems. Not the right way but in a pinch it can be done. 9inch rears are pretty tough, not sure about a stock 54 rear.



Edit: I forgot to say I did this using a new crush sleeve.
By lowrider - 13 Years Ago
I would tigthen it up like Gary suggests. Not too tight though you can destroy the pinion bearings. With todays well built cars thats one of the things the oil change kids look for to generate money for dealerships. They seem to be replacing them without any problems. When you mention crush sleeves & bearing preload you get that "deer in the headlights" look. Same thing from management. With a little common sense you should have no problems.
By Town Vicky - 13 Years Ago
I have had good luck with marking the nut and the housing and counting the turns to remove the nut and then install the nut same number of turn until the marks lineup, never had a problem
By alanfreeman - 13 Years Ago
Job completed and no more leaks. Thanks to everyone who helped! Alan S. Freeman