Bearing Inspection, Packing, and Hub Reassembly
- Inspect bearing surfaces and preserve matched cone-and-cup sets.
- Pack bearings with compatible grease and install the seal squarely.
- Complete the documented hub adjustment without confusing seating torque with final adjustment.
- Parts-cleaning pan and brush — Remove old grease with suitable solvent so bearing surfaces can be inspected.
- Lint-free cloth — Dry cleaned bearings without leaving fibers on rolling surfaces.
- Bearing packer — Work fresh, compatible grease through the bearing between the rollers.
- Torque wrench and suitable socket — Apply the initial castle-nut tightening while rotating the hub.
- Clean hardwood block and hammer — Seat the new grease seal squarely with its outer face flush with the seal-bore face.
- Pliers — Remove the old cotter pin and secure the new pin after adjustment.
Remove grease from bearing cones with suitable solvent, dry them with a lint-free cloth, and inspect the rollers and surfaces. Pitting, spalling, corrosion, flat spots, or discoloration make a bearing unsuitable for reuse. Cones and cups must remain matched and be replaced together when defective.
Machine packing is preferred, but hand packing is allowed. For hand packing, push the bearing's wide end into grease held in the palm, working grease between every roller, then lightly coat the race. The grease table specifies lithium-complex grease with NLGI Grade 2, GC-LB certification, and a 500°F dropping point. Remove all old grease before changing grease type and do not mix incompatible lithium, calcium, sodium, or barium complex greases.
Seat the bearing cups fully, install the packed inner bearing, and fit a new grease seal. Apply a light sealant film to the seal's outside rim and use a clean hardwood block to seat it squarely until its outer face is flush with the seal-bore face. After the hub is installed, fit the outer bearing, applicable washer, and spindle nut with its slots outward.
Section 9.8 specifies tightening the castle nut to 50 ft-lbs while rotating the hub, releasing that torque, and then tightening only finger tight. Back the nut off if necessary to align the cotter-pin hole, and secure a new pin. The separate spindle-nut section describes approximately 50 ft-lbs followed by a quarter-turn backoff and finger tightening. The periodic bearing section lists 36,000 miles or 12 months, whichever comes first, while the maintenance checklist separately lists bearing inspection, cleaning, and repacking every 3,000 miles; these are different schedules within the supplied manual.
How It Works
Clean surfaces reveal damage
Remove grease with suitable solvent, dry with a lint-free cloth, and inspect rollers and bearing surfaces for pitting, spalling, corrosion, flat spots, or discoloration; any of these defects makes the bearing unsuitable for reuse. Surface damage interrupts smooth rolling contact and concentrates stress, allowing wear and heat to accelerate. Keep cones and cups matched and replace defective sets together rather than pairing a new component with a worn mating surface.
Lubrication and sealing protect the contact surfaces
Machine packing is preferred; when hand packing, push the bearing's wide end into grease in the palm, work grease between every roller, and lightly coat the race so lubricant reaches the working surfaces rather than merely covering the exterior. Use lithium-complex grease with NLGI Grade 2, GC-LB certification, and a 500°F dropping point; remove all old grease before changing type and do not mix incompatible lithium, calcium, sodium, or barium complex greases. Fully seat the cups, install the packed inner bearing, and fit a new seal with a light sealant film on its outside rim, seating it squarely with a clean hardwood block until its outer face is flush with the seal-bore face.
Distinguish adjustment steps and service schedules
After installing the hub, outer bearing, applicable washer, and spindle nut with its slots outward, follow Section 9.8: tighten to 50 ft-lbs while rotating the hub, release that torque, finger-tighten, and back off only as needed for cotter-pin alignment before securing a new pin. The initial tightening seats the assembly rather than establishing the final nut setting; the separate spindle-nut section describes approximately 50 ft-lbs followed by a quarter-turn backoff and finger tightening, so do not blend its sequence into Section 9.8. The periodic bearing section specifies 36,000 miles or 12 months, whichever comes first, while the maintenance checklist separately calls for inspection, cleaning, and repacking every 3,000 miles; these are different schedules in the supplied manual, not interchangeable intervals.
Step-by-Step Procedure
0/7 doneBearing Service References
| Section 9.8 initial castle-nut tightening | 50 ft-lbs while rotating hub; then release and finger-tighten |
| Specified grease grade and classification | NLGI 2; GC-LB; lithium complex |
| Grease dropping point | 500°F |
| Section 10.2 physical bearing inspection | 36,000 miles or 12 months, whichever comes first |
| Page 52 wheel-bearing checklist | Inspect, clean, and repack every 3,000 miles |
Diagnostic Chart
| Symptom | Check | Spec / Expected | Likely cause & fix |
|---|---|---|---|
| Cleaned bearing shows damaged or discolored surfaces. | Inspect rollers and bearing surfaces after removing grease and drying; confirm the matching cone and cup remain identified together. | Pitting, spalling, corrosion, flat spots, or discoloration makes the bearing unsuitable for reuse. Replace defective cones and cups together. | Bearing surface deterioration; replacing only the visibly damaged component leaves a worn mating component in service. Basis: Bostail 8K Axle Manual |
| Grease history is unknown or replacement grease differs from the grease removed. | Check the replacement grease label and establish whether old grease has been completely removed before changing type. | Lithium-complex grease; NLGI Grade 2; GC-LB certification; 500°F dropping point. Do not mix incompatible lithium, calcium, sodium, or barium complex greases. | Incomplete cleaning or unverified grease selection can leave an incompatible mixture. Basis: Bostail 8K Axle Manual |
| New seal appears tilted or unevenly seated. | Inspect its seating around the bore and verify that a light sealant film was applied to the outside rim. | Install a new seal squarely with its outer face flush with the seal-bore face, using a clean hardwood block. | Uneven installation force or failure to maintain square alignment during seating. Basis: Bostail 8K Axle Manual |
| Hub binds after adjustment or the cotter-pin hole does not align. | Verify that the initial torque was released and the nut returned to finger tight; check that alignment was obtained by backing off rather than further tightening. | Section 9.8: 50 ft-lbs while rotating hub; then release and finger-tighten. Back off if necessary for pin alignment and secure a new pin. | Initial seating torque may have been retained as the final setting, or the nut may have been tightened to force pin alignment. Basis: Bostail 8K Axle Manual |
At the Bay: Diagnose the Case
CASE 1 / 4
Cleaned bearing shows damaged or discolored surfaces.
- Test
- Compare
- Correct
Select the next check
Basis: Bostail 8K Axle Manual. A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.
Common Bay Mistakes
- ✕ Installing a new cone against a defective or mismatched cup.
- ✕ Smearing grease outside the bearing without working it between every roller.
- ✕ Treating the grease dropping point as an allowable operating temperature.
- ✕ Leaving the initial seating torque applied or tightening further to align the cotter pin.
Quick Check
Practice only — not scored.
Plan the Service Sequence
Planning practice only. Follow the applicable manufacturer's instructions, employer safety program and qualified supervision on real equipment.
Plan the first action. Compare the service steps with the bay mistakes.
Hands-on: Shop Test Equipment
Dial Indicator — Bearing End Play
Magnetic-base dial indicator (0.001 in) on the hub face, spindle nut adjustment
🛠 Equip your bay for this test →Symptom: Bearing service — set end play after repack.
Spec limits used
- 0.001–0.010 in — Allowable end play, double-nut wheel end (Dexter 9-15K service manual, p.64)
- 0.008 in — Nev-R-Lube 50 mm max axial end play (Dexter 059-831-00)
- illustrative only — Face runout limit (General shop practice)
Simulated readings for practice. Always follow the manufacturer's procedure and values on a real trailer.
Source: Bostail 8K Axle Manual — 30-35, 52, 60