What this is
A 3D reference for the ring and pinion of a Dana 44 type rear axle. The model shows where each part and each shim pack sits. The Setup tab shows what each pack moves, and how backlash, preload and the contact pattern respond. It gives no procedure, tool sizes or figures. Those come from the instructions supplied with a gear set and from the service manual for the vehicle.
The four settings
- Pinion depth. How far the head of the pinion sits from the centerline of the ring gear. Set by the depth shims. Read from the contact pattern.
- Pinion bearing preload. How hard the two pinion bearings are squeezed together. Set by the preload shims. Read as the torque it takes to turn the pinion on its own.
- Backlash. The free play between the teeth of the ring gear and the pinion. Set by how the carrier shims are split between the two sides. Read with a dial indicator on a ring gear tooth.
- Carrier bearing preload. How tightly the carrier is held between its bearings. Set by the total of the two carrier packs.
Reading a tooth
Each ring gear tooth has a toe at its inner end and a heel at its outer end, a top land along its crest and a root at its base. On this axle the convex flank is the drive side, loaded when the vehicle is driven forward, and the concave flank is the coast side. Marking compound painted on a few teeth is wiped away where the pinion touches, and that mark is the contact pattern.
Before working on an axle
A gear set that is set up wrongly can fail quickly, and a failed gear set can lock the axle while the vehicle is moving. The parts are heavy, the bearings are pressed on, and the vehicle has to be supported securely with the axle unloaded. A driveline shop sets gears every week; if the tools or the experience are not to hand, that is the place for the job.
About this model
This is a schematic, built from the general layout and the headline published dimensions of this axle family. It is not an engineering drawing, and no dimension should be taken from it. The gear teeth are drawn to look right, not to mesh exactly. The shim packs, and the movements they cause, are drawn three times life size so that they can be seen.
It follows the traditional layout: depth shims behind the cup of the inner pinion bearing, pinion preload set by shims, and carrier shims between each bearing and the carrier. Versions of this axle differ. Some set pinion preload with a crush sleeve, some carry their carrier shims outside the bearing cups, the ring gear bolts changed size, and the larger 8.9 in version is a different design.
The name Dana 44 is used only to identify the axle. This app is not affiliated with or endorsed by the maker of the axle or of any vehicle.
Notes and privacy
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This edition