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Frequently Asked Questions

Find answers to the most asked questions about your purchase, order or shipping

Used to minimize friction in moving parts. They may also support weight or thrust loads.

This is a collapsible spacer which installs on the pinion and preloads the pinion bearings. Crush sleeves are not reusable and must be replaced if the pinion nut is loosened or removed.

A semi-floating axle rides on an outer bearing, thus supporting the weight of the vehicle. In semi-floating applications the wheel is bolted directly to the axle.

A semi-float axle rides on an outer bearing, thus supporting the weight of the vehicle. In semi-float applications the wheel is bolted directly to the axle. A full-float axle is a housing type in which the axle does not carry the load of the vehicle and does not have the wheel bolt directly to it. Full-float axles bolt to a spindle, which ultimately drives the wheels. They can also be removed with the wheel still on the vehicle.

Get some great insider information from our “How to Identify Your Differential & Axle Type | Differential Tech Tips” video.

How to Identify Your Differential & Axle Type | Differential Tech Tips



Do NOT use bearing grease on your carrier bearings or pinion bearings when setting up your differential. This could cause premature failure from the oil not having the ability to lurbicate the bearings properly. Use clean gear oil only to pre-lubricate your bearings during the install.
A solid spacer replaces the crush sleeve in a differential. It is a solid piece of machined steel which is slightly shorter than a crush sleeve and comes with a variety of shims. The shims are stacked with the solid spacer to achieve different levels of preload on a pinion, the same way as a crush sleeve. The advantage of using a solid spacer and shim set up is that you don’t need to worry about over-tightening the pinion nut, as you do with a crush sleeve. Also, once the preload is set, you never need to worry about adjusting it or replacing anything, like if you have to replace a yoke. When setting preload, you add shims to decrease the amount of preload on the pinion bearings, and remove shims to increase the amount of preload on the bearings.

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.

Universal Joints: Using a grease gun, pump grease into the universal joint until fresh grease can be seen coming out of all four seals. If all four seals do not purge fresh grease, move the driveline to free up the bearings caps and try again until successful.

Slip Yoke & Stub Shaft Assemblies: Coat both the slip yoke and stub shaft thoroughly prior to assembly, and then fully collapse the driveline. Apply grease via the grease fitting until grease begins to come out of the welch plug vent hole. After grease appears in the vent hole, cover it and continue to grease until it begins to show grease in the seal. During re-lubrication it may not be possible to fully collapse the driveshaft. Use the same greasing guidelines as used during initial assembly but be careful not to overfill the driveshaft. Overfilling the driveshaft with grease may cause the welch plug to pop out during use.

Centering Kits: Using a needle nose grease gun, pump grease into the flush mount zerk fitting on the centering kits until fresh grease appears at the ball seal or purge hole. Failure to maintain grease in centering kits can cause failure very rapidly. Worn centering kits will squeak, indicating that greasing is necessary immediately.

No. Once the crush sleeve’s tension between the bearings is released it cannot hold the proper tension again. This is also true if a crush sleeve is over-crushed during installation. It must be discarded and replaced with a new one.
It is nearly impossible to measure the preload on a carrier because it is in contact with the pinion at the time of assembly and therefore is receiving resistance from it as well. A carrier should have to be loaded in with some resistance, such as a few hits from a dead blow hammer. It should not simply load in by hand, and it should not take a huge amount of force to put into place.
Yes. The carrier bearing caps are bored at the factory and are side specific. Mixing up the carrier bearing caps can be a major mistake in rebuilding a differential, especially if it is a design which uses side adjusters. A good practice is to take a punch and mark one of the carrier bearing caps along with the side of the housing it belongs to in order to prevent mistakes during reassembly.

We do all the thinking. Each kit contains all the parts needed to complete the job from start to finish so you know you’re getting all the right stuff the first time. The kits include a ring and pinion and all the bearings, seals, and small parts in one simple part number. Some kits are configured to address one axle, some cover both, and some include a Dura Grip limited-slip differential. A Yukon Pro Kit features a premium Yukon Gear & Axle gear set and uprated hardware to meet the demands of wheeling, off-road racing, track racing, street driving, and performance diesel. USA Quick Kits are affordable, general repair options when stock performance and reliability are the prime concerns.

Yukon Gear & Axle Spin Free Kits replace the failure prone and expensive factory unit bearings with tapered bearings and races. The result is not only a design which is easier and more economical to service, but one that offers significant increases in fuel efficiency because there are fewer rotating parts in the drivetrain for the engine to turn. Less work equals better fuel economy.

Check out our “Yukon Spin Free Kit Installation Walkthrough” video to learn more about these highly effective kits.

Yukon Spin Free Kit Installation Walkthrough

Set-up bearings are bearings which have had their inner diameters machined so they slide on and off a pinion shaft or carrier journal. The advantage to using set-up bearings is that you can quickly install or remove them with different amounts of shims to check both pinion depth and backlash without having to worry about the nice, new bearings you just purchased. Once the correct amount of shim(s) have been found, you simply remove the set-up bearing(s) and install the new bearings with the correct shim.

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

Pinion bearing preload is related to the amount of force the pinion nut exerts on the pinion and its bearings. Axle builders generally measure the pinion’s preload by rotating the pinion gear by its nut with a pound/inch-graduated torque wrench. Crush sleeves or shims are generally used to set pinion preload. The proper torque ratings for new bearings can be found in the front of the installation manual on the Set Up Specifications page or by way of the chart below. Note: Measurements are for the use of new (not used) bearings.