Can't Get Enough
Join Date: Sep 1999
Location: Cotopaxi, Colorado
Thanked 0 Times in 0 Posts
Re: HOw to set pinion bearing preoad in front Dana 44
The easiest way is to use Dana gears. The reason for this is the pinion depth is marked, which makes a good starting point for the shims. Pinion depth is usually housing specific. Pinion depth is changed by shimming under the large bearing race. If the old pinion had a marking on it that said 0, and the new gear is marked with +2, just remove .002 shims, and the depth should be real close. If you don't have Dana gears, you really should use the special jig for a starting point.
Next, set the pinion preload. This is done by using the smaller shims on the step side of the pinion shaft. The pinion preload is measured in inch lbs. by a method called pinion total torque to rotate. Using a inch lb torque wrench, (a dial type, or beam type wrench, and not a click type) measure the amount of effort it takes to rotate the pinion. Note that this is not the "break force" which is the amount of force it takes to start turning the pinion, but the amount of force it takes to keep the pinion turning. This should be around 30 inch lbs.
These first two steps should be done before any attempt to set backlash and check the pattern. An often overlooked area of setting up a diff is the carrier preload. Carrier preload is set by the total number of shims on both sides of the carrier bearings. The old method of measuring it was with a special tool that slid in the axle and locked it to the carrier. The new method of checking it is by a method known as "total torque to rotate". It is measured just like pinion torque to rotate, but with the ring gear and carrier installed. You take your carrier preload spec, devide it by the ratio, and add it to the pinion preload spec. So if the carrier preload spec was say 40 inch lbs, and the ratio is 4:1, you should add about 10 inch lbs to the pinion total torque to rotate spec, which in this case is about 40 inch lbs.
After the diff is completely set up, with pinion depth, pinion preload, backlash, and carrier preload, diff carrier bearings installed and torqued, you can "paint" the gears with compound to check your work, and make adjustments as necessary.