Frequently Asked Questions

The carrier, or carrier case, is the unit which the ring gear bolts to and axles slide into. The carrier case transfers power from the ring gear to the axles.

This is a hardened shaft which installs into the case and keeps the spiders securely in place. In semi-float applications, it also prevents the axles from sliding inward into the carrier case.

A limited slip differential is a type of carrier case where the spider gears are preloaded and prevented from turning easily via a friction surface. Once enough power has been applied to the spiders, which is called a breakaway point, the spiders can turn. The preload and friction can sometimes cause noise or “chatter” when negotiating a turn.

Pinion preload is the amount of resistance or “drag” measured when attempting to turn the pinion without the carrier installed.

The spider gears are a set of four to six gears which install into the carrier. The rotation of the spider gears allows one axle to spin faster or slower than the other.

Spider gears are also known as satellite gears, they rotate around the side gears in the differential carrier. Side gears may also be referred to as axle gears or planetary gears. The spider gears are the ones with the cross-pin shaft going through them. This array of spider and side gears take the rotational energy from the driveshaft and help redirect it outwards to the axles and on to the wheels. They also play a key role in allowing the wheels to rotate at different speeds when the vehicle is turning.

For a more in-depth look, view this installation video from our Resource Center.

Spider Gears Video

When traveling in a straight line where wheel speeds are identical on both sides, all LSDs continuously provide equal traction to both tires. The difference between LSD types has to do with how this occurs and what happens when additional traction is needed.

In a clutch-type unit, the spring array applies pressure to the side gears which puts pressure on the clutch packs in the outer part of the carrier. Both axles get equal pressure and both tires get equal traction. When a tire starts slipping, the clutch packs are engaged with different resistance. The clutches work to maintain synchronization between the tires, transferring more torque to the tire that has the best grip while reducing torque transfer to the tire that has less grip.

A gear-type LSD has no frictional surfaces to initiate torque transfer. It uses floating helical-cut worm gears that operate in pockets and mesh together. Under normal driving conditions this type of LSD acts like an open diff. When acceleration or wheel slippage occurs, axial and radial thrust is applied to the helical gear pinions in their pockets. Under these loads, more torque is transferred to the tire with the best traction in a progressive manner as torque is withheld from the tire that is slipping.

It’s the point where the numeric increase in gear ratio necessitates a new/different carrier be used. The act of increasing the numerical ratio of a gear set results in the diameter of the pinion gear becoming smaller. To maintain proper contact, the thickness of the ring gear can be increased. The point at which thickening is no longer viable is known as the Carrier Break, which necessitates the move to a larger carrier with a taller deck height.

To see the Carrier Break points of popular differentials, check out this article from our Resource Center.

Carrier Break Points

The term “thick gears” refers to a ring gear that is thicker than stock to maintain proper meshing in a carrier that is being upgraded with a numerically higher gear ratio. When increasing gear ratio, a smaller diameter pinion gear is employed and the thicker ring gear makes up the difference by moving the gear teeth ‘higher’ so the two gears mesh properly.

Get more info on Yukon ring and pinion gears by watching our “Unboxing Yukon Ring and Pinions” video.

Unboxing Yukon Ring and Pinions

The pattern refers to how the ring gear and pinion gears mesh. There is a process used when reassembling a differential that optimizes ring gear and pinion tooth contact. The procedure involves changing the pinion position via shims in the carrier and repositioning the carrier. Dialing in the tolerance between the gears will ensure a smooth-running, long-lasting differential.

For more info on reading gear tooth patterns, check out this video from our Resource Center.

Reading Gear Teeth

Whirring noise only while decelerating at any or all speeds is most likely caused by bad pinion bearings or loose pinion bearing preload, and almost never by bad ring and pinion gears.

A howl or whine during acceleration over a small or large speed range is usually caused by worn ring and pinion gears or improper gear set up.

Rumbling or whirring at speeds over about 20 mph can be caused by worn carrier bearings. The noise may change while turning.

Regular clunking every few feet may indicate broken ring or pinion gears.

Banging or clunking only on corners can be caused by broken spider gears, lack of sufficient positraction lubrication, or worn positraction clutches.

Rumble while turning may indicate bad wheel bearings.

A steady vibration that increases with the vehicle’s speed can be caused by worn u-joints or an out of balance driveshaft.

Clunking only when starting to move or getting on and off the gas might be loose yokes, bad u-joints or worn transfer case or transmission parts.

Size, as it relates to strength and ease of installation. The smaller Spartan Locker, also known as a lunchbox locker or an insert-type unit, is easier to install because it replaces the spider gears. Since the Spartan Locker is installed in the carrier it relies on said carrier for strength. The Grizzly Locker, sometimes called a mechanical locker or automatic locker, is bigger and significantly stronger. It replaces the entire carrier assembly and has more clamping force, forged internals, and a forged 8620 low-nickel alloy steel case that is much more robust than the OE carrier it replaces.

Gain more insight into lockers by checking out our “Installing a Spartan Locker,” “Unboxing a Spartan Locker,” and “Yukon Grizzly Locker” videos.

Installing a Spartan Locker

Unboxing a Spartan Locker

Yukon Grizzly Locker

It is the measurement from the base of the housing to the gear teeth. This mounting surface within the housing changes to accommodate the smaller pinion gears that are used when swapping to numerically higher gear ratios. A taller deck height maintains proper contact between the ring and pinion gear teeth by moving the ring gear farther ‘up’ in the housing.

These kits are for shops and builders who have shims on-hand and are looking to save money over a Master Overhaul Kit. They include carrier bearings and races, pinion bearings and races, a pinion seal, marking compound, and a brush.

Yes. There is an order to the madness. There is a prerequisite method involved where have one parameter dialed in leads to the next step.

1. Pinion Depth

2. Pinion-Bearing Preload

3. Backlash

4. Carrier-Bearing Preload