How to Troubleshoot a Four Wheel Drive With Manually Locking Front Hubs
The manual four-wheel drive locking hub functions as a direct link between the front axles and the wheels. When in the unlocked position, the wheels can drive over hard surfaces, like highway asphalt and roads. The locking hubs can be turned by hand outside the vehicle to engage or lock the front axles for application in off-road conditions, such as mud, sand or dirt. Although simple in design and function, the locking hub components can take a lot of stress and torque. Troubleshooting locking hubs requires some dis-assembly and inspection.
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Things You'll Need
- Owner's repair manual
- Butter knife
- Tire iron
- Floor jack
- Jack stands
- Allen-head wrenches
- Socket set
- Snap ring pliers
- Carburetor cleaner
- Rags
- Machine oil
- Torque wrench
Instructions
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1
Lock both manual hubs in the engaged position and test drive the vehicle over a soft surface, like dirt or sand. Place the selector in low or first gear. Make a short rapid acceleration. Get out of your vehicle, after placing it in park or neutral and setting the brake, and inspect the tire prints. Hubs that have fully engaged will leave four gouges in the dirt, rather than only two rear depressions. If the hubs engaged properly, the vehicle will also give an abrupt lurch.
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2
Place the vehicle in park or neutral, for an automatic or manual transmission type. Set the emergency brake firmly. Go to the front wheels and inspect the hub dial levers. Try locking and unlocking both wheels. If the dial levers do not turn, look for wood or gravel stuck in the outside seam of the dial mechanism. Pick all debris out with a butter knife. Try the levers again.
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3
Place the vehicle in park or neutral, depending upon your transmission type. Set the emergency brake. Use a tire iron to loosen the front wheel lug nuts on both sides. Do not remove the lug nuts. Lift the front of the vehicle and place to jack stands under the chassis. Finish removing the wheels with the tire iron. Use a Allen wrench to remove the lock dial case. Try not to damage the underlying gasket.
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Use a socket to remove the six bolts that hold the hub body. Pull the hub body off. Use a pair snap ring pliers to remove the C-ring on the axle shaft. If the C-ring has broken or appears missing, you will have to replace it, since the hub will not function without it. Use a large socket to remove the hub shaft nut, by turning it counterclockwise. Pull the hub assembly out, making sure to keep all ring spacers in order, as well as the hub spline sleeve and the spring within it.
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5
Clean all the parts with carburetor cleaner and a rag. Look for damage and wear on the axle shaft splines and on the inside of the hub splines. Replace such parts, if they show stripped splines. If your hub has a plastic inner cam, wipe it clean and examine the edges. The edges should be sharp, and not rounded. Replace the plastic cam if it shows any deformity. There should be no grease on any of the the parts.
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6
Wet a rag with machine oil and wipe down each individual part. Refer to your owner's repair manual for the proper sequence of reassembly. Install the spring underneath the two locking hub cams. Press the hub mechanism between your palms and twist it. If it does not move, it means the engagement gears work properly. Place the hub gear back on the shaft. Install the axle nut and torque it to specifications with a torque wrench.
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7
Use the snap ring pliers to install the C-ring over the nut. Replace the hub body over the studs and tighten the six nuts with a socket and wrench. Place the dial case back on and tighten the Allen-head screws with the Allen wrench. Perform this operation on the opposite wheel hub assembly.
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Replace both wheels. Tighten the wheel lug nuts with a tire iron. Use the floor jack to raise the front end and remove the jack stands. Finish tightening the front wheel lug nuts with a torque wrench, according to specifications.
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Tips & Warnings
There should be no impacted grease inside the hub case. It must be clean, and allowed to turn freely. Lubricate all the hub assembly parts with light machine oil or automatic transmission fluid only.
References
- Photo Credit off-road image by Dariusz Kopestynski from Fotolia.com
