The short version
- Only serviceable tapered sets can be repacked. A sealed hub cannot, and no trick makes it possible.
- Grease goes through the cage, not around the outside. If it did not come out the top, it is not packed.
- The adjustment is a procedure, not a torque. Aim for 0.001 to 0.005 inches of end play.
- Mixing two incompatible greases can turn both to liquid. Match the thickener or clean it all out.
Most modern cars have nothing to repack wheel bearings on, though a 4×4 with locking hubs is the exception. The bearing is a sealed cartridge and the only maintenance is replacement.
But trailers, older rear-wheel-drive front hubs and many light truck applications still use serviceable tapered sets. Paying someone else has its own price. On those, knowing how to repack wheel bearings properly is the difference between a component that lasts decades and one that fails on a highway shoulder.
Do you actually have serviceable bearings?
Take the dust cap off. What you find settles it.
| What you see | What it is | Serviceable? |
|---|---|---|
| A castle nut and a cotter pin | Adjustable tapered set | Yes |
| A large staked or single use nut | Sealed hub or cartridge | No |
| A spring loaded grease cap | Trailer hub with a pressure cap | Yes |
| No cap at all, just a bolted flange | Bolt-on hub unit | No |
The distinction matters more than it sounds. Where the two designs came from, and why the industry moved, is on the bearing versus hub assembly page. Front and rear corners often differ too, as the front and rear comparison shows.
What is inside
A tapered set is five parts and they are all separate.
Two cone assemblies, inner and outer, each with tapered rollers in a cage. Two cups, which are the hardened outer races pressed into the hub. And a grease seal at the back.
The cones are the parts you clean and repack. The cups stay in the hub unless damaged. If they are, they get driven out and replaced as a matched pair with their cones.
A cone and its cup wear together into a matched pair. Fit a new cone against an old cup and you have a new part running on a used wear pattern. It fails far sooner than either would alone.
Getting them out and clean
Pull the dust cap, straighten and remove the cotter pin, then take the castle nut and the flat washer off.
Rock the hub gently and the outer cone will fall into your hand. Support it, because dropping a bearing on concrete damages it.
Slide the hub off the spindle. The inner cone stays behind the seal, so lever the seal out and remove it. Plan on a new seal every time, since they rarely survive removal.
Clean everything in solvent until no old grease remains anywhere, including inside the cage. Then dry it properly.
It is a common sight and it does real damage. Air can spin an unloaded, dry bearing far beyond its rated speed, scoring the rollers and races. It is also dangerous if a roller lets go.
Inspection before grease
This is the point of the whole exercise, and it takes two minutes.
Look at the roller surfaces and the cup faces under good light. Pitting, flaking, discoloration and dull gray banding are what you are looking for.
Blue or straw coloring means the bearing overheated. That is heat damage to the hardened surface, and no amount of fresh grease reverses it.
Run a fingernail across the cup. It should feel like glass. Any ridge, groove or roughness means the set is finished.
Packing them properly
Smearing grease over the outside does nothing. It has to be forced through the cage, filling the space between every roller and the cone.
- Put a generous blob of grease in the palm of one hand.
- Hold the cone with its wide side down and push the edge of that side into the grease.
- Push firmly enough that grease appears at the top, between the rollers.
- Rotate the cone a little and repeat, working around until grease has emerged everywhere.
- Finish with a light coat on the outside and a smear in the hub cavity.
A cone packing tool does the same job with less mess and works well. What does not work is any method where grease never appears at the top. That means the inside is still empty.
Roughly a third to half full is right. Packing the cavity solid does not help and can hurt. Grease that cannot move gets churned, and churning generates heat.
The grease compatibility trap
Grease is oil held in a thickener, and the thickeners do not all get along.
Mix a lithium complex grease with a polyurea grease and the two thickener systems can break each other down. The oil separates out, and what is left runs from the bearing as a thin liquid.
The bearing then runs effectively dry while the cap still looks full. This is a real and documented failure mode, not a myth.
Either use the same grease already in there, or clean every trace of the old product out first. Topping up with whatever is on the shelf is the gamble.
Look for the NLGI GC-LB certification mark. That is the wheel bearing and chassis rating. It means the product was tested for this duty rather than just labeled for it.
The adjustment, which is where people go wrong
A tapered set is not tightened to a torque figure. It is adjusted to a clearance, and the sequence exists to seat everything first. Getting this right is most of what it means to repack wheel bearings well.
- Fit the hub, washer and nut. Tighten to 15 to 25 pound feet while rotating the hub. This seats the rollers against the cups.
- Back the nut off completely, until it is fully loose. Everything is now seated with no preload.
- Retighten to finger tight only, around 5 pound feet.
- Back off to the nearest cotter pin hole. Never tighten forward to reach one.
- Fit a new cotter pin and check the result.
Done correctly you should feel a barely perceptible amount of play, roughly 0.001 to 0.005 inches. On a dial indicator the needle only just moves. By hand it is a hub that turns freely with the faintest trace of movement.
Too tight is the more common mistake and the faster killer. A preloaded tapered set generates heat immediately, cooks the grease and fails quickly.
Too loose lets the rollers skid rather than roll, and every bump becomes an impact load. The result is the same dents as a bad installation.
The instinct to make it snug is exactly wrong here and worth resisting deliberately. It is the opposite of the sealed hub axle nut, where a specific high torque is correct, as the torque page explains.
Trailers, and the boat trailer problem
Trailer bearings work harder than most people think, and boat trailers face something no road vehicle does.
Tow to the ramp and the hubs reach running temperature, perhaps 80 degrees Celsius. Then reverse into the water and they are quenched to lake temperature in seconds.
The air sealed inside the hub cavity contracts as it cools, by around 18 percent over that temperature drop. Something has to fill the space. The nearest available material is the water outside the seal.
On a hub with a few hundred milliliters of air space, that contraction can draw fifty milliliters or more of water past the seal. Water displaces grease and rusts the rollers. It happens in a single dunk.
The fix is a pressurized or spring loaded grease cap. It keeps the cavity slightly above ambient pressure, so any flow is outward. That is what those caps are actually for.
Even with one fitted, an annual strip and repack is accepted practice for a trailer that goes in the water. For a road only trailer, once a year or every 12,000 miles is the usual interval.
How often on a vehicle
Where serviceable bearings still exist on a car or light truck, 30,000 miles is a common recommendation. Many manuals tie the interval to brake service.
That is convenient rather than arbitrary. The hub is already off when the rotors come off, so the extra work is small.
Signs it is overdue are the same as any bearing problem. A hum that rises with speed, or play at the top and bottom of the wheel. Both are covered on the play and vibration page.
The cap is a seal rather than a cover, and removing one without wrecking it is worth getting right.
Quantity trips people up more than technique. How much actually goes in covers the cavity as well as the bearing.
Repack before storage rather than after, for reasons on the sitting page.
Setting that adjustment to a number rather than a feel needs a dial indicator.
Getting the old grease out first is covered under cleaning the bearings, and whether to buy a tool for the packing step is on the packer page.
New bearings out of the box are not ready to fit, which is on the new bearings page.
The adjustment step has its own procedure and its own measured target, set out on the adjustment page.
Common questions
How do you repack wheel bearings?
Strip, clean and inspect the cones. Force grease through the cage from the wide side until it emerges at the top. Refit with a new seal and adjust to 0.001 to 0.005 inches of end play.
Can I repack a sealed wheel bearing?
No. There is no way in, and drilling one creates a contamination path without repairing the worn surfaces making the noise.
How tight should the spindle nut be?
Not tight at all in the final position. Seat at 15 to 25 pound feet while rotating, back off fully, retighten finger tight, then back off to the nearest cotter pin hole.
What grease should I use?
One carrying the NLGI GC-LB mark, and ideally the same thickener type as the grease already in the hub. Mixing incompatible thickeners can liquefy both.
How often should trailer bearings be repacked?
Once a year or every 12,000 miles for a road trailer. Annually as a minimum for a boat trailer, because launching draws water past the seals.
Do I need new races if I fit new bearings?
Yes. Cones and cups wear as a matched pair, so a new cone on an old cup fails early. They are sold together for that reason.
Is repacking still worth doing?
On a serviceable set, very much so. Choosing to repack wheel bearings on schedule is genuine preventive maintenance, unlike anything attempted on a sealed unit. The replacement overview covers that distinction.