Rearend bearing proload question.

T

Tom Elliott

Senior Member
Just wondering- If you have a differential bearing preload set at 20 in. lbs. and a pinion bearing preload at 20 in. lbs. what would the driveshaft read when turning it with a in. lb. torque wrench? Not factoring in ring and pinion gear contact and the driveshaft roller bearing. Don't know what kind of formula to use to figure that out. Thanks, Tom
 
With a 3.78 ratio you would divide the differential preload by 3.78 and add that to the pinion preload.
I set them up by feel and they work fine.
 
Just curious how much torque it would take to turn the rearend gears with the driveshaft with all the bearing preloads.
 
Not a good question.

Preloads are to ensure proper clearance as everything wears into each other so the loading gets reduced after some use. Then there is the question of what lubricant and what temperature. The oil will have a significant effect on the torque and oil curve can cover a lot of ground. 100 degree oil will be much thinner then 50 degree oil making for more torque need at lower temps.

So in the end, you do the pre-loads right individually and put it together and trust you did it right. Of course, you always have to spin the drive shaft and watch the axles move cause you just built and and you can.
 
Kevin your answer was much better than what I was thinking, but knew there were other factors and If both were correct it would thus be correct.
 
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