If you should one day find yourself sitting in front of a differential, ready to get to work on the pinion bearing when you realize that you have forgotten your torque wrench. You begin to wonder- can I, and how can I, set the pinion bearing preload without a torque wrench?
The short answer is yes, you can, and there are a few ways you can manage this task. One of the following methods should work for you.
Setting the Pinion Bearing Preload Minus a Torque Wrench
You can adjust or set the pinion bearing preload by turning the pinion nut to tighten or shorten the spacer. This collapsible space is generally used to get a more precise pressure on the bearing preload. You want to get as close as possible to the correct amount of pressure, which is where a torque wrench comes in handy. If you are fresh out of torque wrenches, you can try some of the following methods instead:
While you most likely have a variety of zip ties lying around the garage, you will need a very large one for this job. If you do have one, wrap the zip tie around the pinion nut as tightly as possible. Holding onto the tail end of the zip tie, pull it in the direction you want the pinion nut to go so you either tighten or loosen the nut.
Save yourself a little headache and decide which direction you need to turn the pinion nut BEFORE you wrap on the zip tie. This will prevent you from having to do this job twice.
Old Fashioned Duct Tape and Rope
If you talk to an old-timer, they will tell you that they didn’t need a torque wrench to set the preload, they simply used good old-fashioned duct tape!
Now you might need some heavy-duty tape and not the stuff your wife has been using in the kitchen, but a strong piece of duct tape can actually do the trick!
Cut off an exceptionally large piece of duct tape. Find an equally long piece of strong rope and wrap the duct tape around the rope. Position the rope around the pinion nut so you can pull on it to either tighten or loosen the nut, as required.
It might not be fancy, but it will get the job done.
Nuts and Bolts
Now, this is a sure-fire method, however, the trick is finding a nut that is large enough.
Attach a nut to a bolt and put it on the pinion nut so that you can either tighten or loosen it, whichever you need. This acts as a makeshift wrench. Be sure to have the pinion nut on tightly between the two nuts of your makeshift wrench.
One of the easiest ways to get your pinion preload correct is to use the notch method. Using a small file, simply make a notch in the pinion, the flange, and the old nut anywhere that these parts meet. Take note also of how many threads are sticking out past the nut.
You can now put these items right back where they were before. When screwing them on, you continue to tighten until all the notches line up again. This should give you the same preload as before, assuming the preload was proper before you started.
Noise Elimination Method
If the preload is too loose, you will absolutely hear it. There is a distinctive whining noise that will come from the differential, especially on deceleration.
This is a pain in the behind, but this usually only needs to be done once or twice before the problem is solved.
If you hear the whining noise, tighten the pinion nut a ½ a turn tighter and see if the whining sound disappears. If it still is not completely gone, tighten the nut another ½ turn.
This is time-consuming and annoying, but it often works after the first ½ turn. Some people feel that the pinion nut shouldn’t be messed with more than once or twice, but the fact remains that a loose nut will prevent the pinion from working properly.
The Bottom Line
Regardless of the method you have chosen, be certain that you don’t over tighten the pinion nut. A loose nut may make noise and not allow the pinion to work as it should, but an overly tight pinion nut will wear out the bearing prematurely.
It is best to tighten the nut slowly and in small increments, such as ½ or ¼ turn maximum.
Setting a pinion bearing preload when you do not have a torque wrench can be quite a bit of work for the inexperienced, but if you are comfortable with doing these types of repairs, you should have very little problem getting this job done correctly.