Bobcat 753 Front and Rear Tire Hub Assembly with Exploded View Diagram

For precise repair or replacement, locate the axle-end assembly drawing in the equipment’s service manual–section 4, pages 45-48. The exploded view breaks down each part, listing OEM numbers: bearing pair (PN 654123), seal (PN 789456), and retaining ring (PN 321654). Cross-reference these with the parts catalog if working with aftermarket alternatives.

Inspect the spindle taper before installation–clean it with 120-grit emery cloth and degreaser. Apply Loctite 243 to the bearing threads to prevent loosening under vibration. Torque values for the hub mounting bolts are critical: 120 ft-lbs for M16 fasteners, 90 ft-lbs for M12. Over-tightening risks distorting the housing bore.

When disassembling, use a press or bearing puller–hammer strikes will damage the race seating. Replace seals if wear exceeds 0.005″ on the lip edge. Pack bearings with NLGI #2 grease; avoid mixing brands, as incompatibility causes premature failure. For off-highway use, upgrade to synthetic grease with a -40°F rating.

Verify wheel offset alignment during reassembly. Misalignment by even 2mm accelerates tire wear and increases rolling resistance. Use a dial indicator to check runout–limit is 0.008″. If reinstalling existing fasteners, test for thread integrity; M12 bolts with worn threads should be discarded.

Understanding Wheel Bearing Assembly Layouts for Compact Loaders

Begin troubleshooting by locating the spindle nut behind the wheel cover. This component secures the bearing preload and must be torqued to 120-140 ft-lbs after reassembly. Use a calibrated torque wrench to avoid uneven wear on the tapered roller elements.

Inspect the seal positioned between the outer bearing race and the drum. The double-lip design (part #6511646) prevents contaminants while retaining SAE 90 gear oil. Replace if cracks or deformation exceed 0.3mm in depth during visual examination.

Follow the spindle’s inward taper to identify the inner bearing (NSK 32005-X). Its cage spacing should match the manufacturer’s 12-ball arrangement–deviation indicates improper installation or damage from previous overloading. Verify radial clearance with a dial indicator before proceeding.

Trace the hydraulic brake lines connecting to the backing plate. Ensure the wheel cylinder (right-side units require 24mm bore, left-side 22mm) aligns with the pushrod actuators. Misalignment causes uneven pad wear and leaking at the bleed valve after 80-100 operating hours.

Check the ABS tone ring teeth count–this model uses 48 pulses per revolution. Missing or chipped teeth trigger false wheel-speed sensor codes. Clean the magnetic pickup with isopropyl alcohol and calibrate using a diagnostic tool set to 0.5V threshold.

When disassembling, mark the rotor-to-hub interface at three equidistant points. Improper indexing during reassembly induces lateral runout exceeding 0.002 inches, leading to pulsation during braking. Use a machinists’ blue dye for precision alignment.

Replace the stub axle gasket (Fel-Pro 13282) if oil seepage appears near the spindle-to-knuckle joint. Apply Molybdenum Disulfide grease to the splines before mating components to prevent fretting corrosion after 1,200 operating cycles.

Finding the Compact Loader Wheel Bearing Housing Components

Begin by checking the official service manual for the compact loader’s wheel assembly–section 3-5 or Chapter 6 typically lists bearing housing parts. Manual part numbers 6737019 (left side) and 6737020 (right side) correspond to the spindle assemblies, while 6503524 identifies the bearing kit. If the manual is unavailable, reference the VIN plate: decode the 17-digit identifier using an OEM parts catalog–this filters results to model-specific components.

Part Description	OEM Reference	Aftermarket Equivalent
Spindle housing (left)	6737019	RHK-4125L
Spindle housing (right)	6737020	RHK-4125R
Bearing & seal set	6503524	BSK-2213
Axle shaft	6549171	AX-8914

Local dealers may stock fewer than five identical units–order direct from the manufacturer if stock levels are low. Third-party suppliers like Napa or Ridgid often cross-reference OEM numbers; verify the part’s compatibility with the loader’s serial range (e.g., S/N 52300000+). For older models, dismantle a non-critical wheel assembly to inspect stampings–visible casting numbers like 2E-7541 correlate to specific revisions.

Step-by-Step Breakdown of Compact Loader Wheel Bearing Housing Removal

Park the machine on level ground and engage the parking brake to prevent unexpected movement. Use wheel chocks on opposite wheels to stabilize the unit. Release hydraulic pressure by lowering attachments, then shut off the engine and remove the key. This eliminates stored energy in hydraulic circuits that could cause sudden shifts during disassembly.

Loosen the lug nuts in a star pattern before raising the wheel. Position a floor jack beneath the designated lifting point–typically the reinforced frame near the axle housing–then elevate the assembly just enough to clear the ground. Remove the lug nuts entirely and set them aside in a labeled container. The wheel should now slide off the spindle with minor effort; if resistance occurs, check for corrosion or dirt buildup where the wheel mates to the bearing surface.

Inspect the exposed axle flange for signs of grease leakage or wear. Remove the outer dust cap by tapping gently with a plastic mallet, working around its circumference to avoid deforming the seal. Beneath it lies the retaining nut and washer, secured by a cotter pin. Straighten the pin’s legs with pliers, then pull it free. Rotate the nut counterclockwise using a 1 1/8-inch socket, applying steady torque–it may require significant force due to factory preload.

Slide the thrust washer off the spindle, followed by the bearing cone and rollers. Note their orientation for reassembly; the tapered side must face inward toward the axle housing. If the bearing does not slide freely, tap the inner race lightly with a brass drift to avoid damaging the hardened steel. Clean all components with brake cleaner, then inspect the races for pitting, scoring, or discoloration indicating heat damage.

Examine the spindle threads and splines for deformation. Run your fingernail across them to detect burrs–these can cause premature seal failure if not removed with a fine file or deburring tool. Apply a light coat of molybdenum disulfide grease to the new bearing races before installation. This reduces initial friction during reassembly and extends component life. Ensure the spindle O-ring groove is free of debris before fitting the new seal assembly.

Reinstall components in reverse order, torquing the retaining nut to 120-150 ft-lbs while rotating the wheel to seat the bearing evenly. Insert a new cotter pin, bending its legs outward to secure the nut. Verify proper preload by checking wheel rotation–it should spin freely with minimal resistance. Refit the dust cap, pressing it evenly to avoid distorting the lip seal. Lower the machine, torque lug nuts to 90-110 ft-lbs in a cross pattern, then perform a final operational test before returning the unit to service.

Key Wear Points in Compact Loader Wheel Assembly Bearings

Inspect the inner raceway for spalling–often the first sign of fatigue. Look for flaking or pitting along the load zone, typically a 60–90° arc where the rollers transfer force under operation. Replace components if material loss exceeds 0.5 mm in depth or covers more than 20% of the race surface.

Check outer raceways for brinelling, identifiable by shallow depressions or grooves. These occur when impact loads surpass design limits, particularly in rough terrain or during abrupt starts. Measure wear depth: grooves deeper than 0.3 mm indicate compromised integrity and mandate bearing replacement.

Roller elements require examination for uneven wear patterns. Ideal rollers maintain a uniform cylindrical profile; deviations such as tapered ends or hourglass shapes signal misalignment or inadequate lubrication. Use a micrometer to measure diameter variations–deviations over 0.05 mm warrant immediate attention.

Cage integrity is critical. Look for cracks, distortion, or broken segments–common in nylon cages exposed to excessive heat or contaminants. A damaged cage accelerates roller skew, leading to catastrophic failure. Replace if any deformation or fragmentation is visible.

Seals must remain pliable and intact. Hardened, cracked, or displaced seals allow ingress of dirt and moisture, drastically reducing bearing life. Press-fit seals should sit flush; bulging or misaligned seals require reseating or replacement. Verify seal lip tension by gentle tug–resistance indicates proper function.

Grease condition provides direct insight into bearing health. Fresh grease appears smooth and translucent; degraded grease turns dark, gritty, or waterlogged. Perform a blot test: spread grease on paper–contaminants appear as irregular specks. Relubricate if contamination exceeds 5% by volume or if consistency changes.

Axial and radial play must stay within specified tolerances. Mount a dial indicator to the spindle; apply 10 kg load radially and axially. Movement beyond 0.1 mm radial or 0.15 mm axial play confirms bearing wear. Exceeding these limits necessitates full assembly replacement to prevent further damage.

Essential Gear for Servicing Compact Loader Front Axle Assemblies

Start by securing a 1-inch drive torque wrench calibrated to 150–200 ft-lbs for tightening wheel fastening nuts; models with a digital display reduce guesswork during final torque verification. Without precise tightening, bearing preload shifts, causing premature race damage or catastrophic spindle failure.

A set of snap ring pliers–internal and external jaws–is non-negotiable. The axle housing retains the bearing cartridge via a thick snap ring that often corrodes in place; specialized pliers prevent deforming or breaking the ring groove during extraction. Standard pliers slip, risking injury and extended downtime.

Mechanical Disassembly & Reassembly Kit

• 8 mm to 24 mm combined metric socket set with 1/2″ and 3/8″ drives
• Breaker bar (minimum 18″ length) for seized spindle nuts
• Brass drift punch (6–8 mm tip) and dead-blow hammer for bearing race removal without damaging aluminum hub surfaces
• Feeler gauges (0.001″–0.020″ range) for verifying bearing preload clearance
• Micrometer or digital caliper (0.0005″ resolution) to measure spindle diameter and detect wear patterns
• Thread chaser set (M12x1.75, M16x2.0) for cleaning corroded drive flange bolt holes

Lubrication demands include a high-temperature bearing grease compatible with lithium complex thickeners–NLGI GC-LB certified–to ensure resistance against 250°F operating temperatures. Applying a 1/4″ bead around each roller cage prevents dry starts and reduces bearing noise under radial load. A grease gun with a 90° coupler simplifies relubrication under tight spaces.

Final checks require a dial indicator mounted on a magnetic base; sweep the rotor flange face while rotating the wheel assembly to confirm runout does not exceed 0.003″. Excessive runout indicates uneven wear or bearing misalignment, necessitating shim adjustment beneath the bearing cartridge. Replace seals with OEM-spec polyacrylate seals to prevent contamination ingress–aftermarket rubber compounds degrade within 500 hours when exposed to petroleum distillates.