Carrier Preload

Carrier bearing preload is not specifically measured, but a good tight fit is important in all differential designs. Inadequate carrier bearing preload allows the carrier to move when under load and this can cause the backlash to open up.

Check the backlash by mounting a dial indicator to the housing with the plunger set perpendicular to the ring gear teeth. Hold the pinion yoke and rotate the ring gear back and forth.

The backlash will generally change about 0.007" for each 0.010" that the carrier is moved.

-To decrease the backlash, move the carrier closer to the pinion centerline.

-To increase the backlash, move the carrier away from the pinion centerline.

Screw Adjuster Design: Oil the adjuster threads on both the housing and on the adjusters themselves. While holding the races on the bearings, place the carrier in the housing. Install the carrier caps according to the marks made during disassembly so that the threads are seated evenly on the adjusters. Third member differential designs require a 10 to 12 inch spanner wrench to tighten the adjusters.

Chrysler differential designs require an extension bar and special spanner to access the adjusters through the axle tubes. Tighten both the left and right adjusters evenly by hand until they are fairly tight. If the backlash is too wide, tighten the left adjuster until the backlash is correct. If the backlash is too tight, tighten the right adjuster until the backlash is correct. If necessary, open one adjuster and tighten the other. Both adjusters must be fully hand tightened when acceptable backlash is obtained. The final adjustment should tighten the left adjuster since the ring gear is forced away from the pinion gear while under load.

Shim Design: Some differentials use shims between the carrier bearing races and the housing and some use shims between the carrier bearing and the carrier case. Carrier bearing preload is established by the tightness of the shims. The carrier should be shimmed tight enough that it must be tapped in with a plastic dead blow hammer.

While holding the races on the bearings (and outside shims on the races) start the carrier into the housing and tap it in with the hammer. Install the carrier caps according to the marks made during disassembly.

Check the backlash. If the backlash is too wide, move or add shims to the left side. If the backlash is too tight, move or add shims to the right side. (If the carrier is snug, move and replace the same thickness; if the carrier is too tight or too loose, remove or add shims accordingly.)

source~ http://www.differentials.com/install.html

Nitro Gear

Carrier Bearing Preload – Is simply how tight the carrier fits in the housing and is set simultaneously with backlash.

- On models with shims, carrier bearing preload is increased by adding overall shim thickness.

- On models with adjuster nuts, carrier bearing preload is increased by tightening the adjusters.

Carrier bearing preload is important for a strong setup. If preload is too loose you will be more likely to spin bearings and/or break gear teeth.

Carrier preload tip: If backlash is within spec, but preload is too loose you can add equal amounts of shim thickness to each side of the carrier, or tighten adjuster nuts equally. This will increase preload, while maintaining backlash setting.

Article Written By: Scott Frary