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The R107 uses tapered roller wheel bearings at the front that can be adjusted and repacked. They are simple, but they need correct adjustment and the right grease. A neglected bearing becomes a growl at speed and, at worst, a safety problem.
Symptoms of a bad wheel bearing
- A growl or hum that changes with speed, often louder in a turn
- Play when you rock the wheel top to bottom
- Heat at the hub after a drive
- Uneven brake pad wear or a pulsing pedal caused by excess play
How to check for play
- Raise the front and support it safely.
- Grab the tire at top and bottom and rock it.
- Spin the wheel by hand and listen for roughness or grinding.
- Press the brake to separate bearing play from ball joint play, as explained in ball joints.
How front bearing adjustment works
The front hub sits on two tapered roller bearings. A clamping nut on the spindle sets the preload. The procedure in the factory manual uses a dial indicator to set a very small end play. Many experienced mechanics tighten the nut while spinning the hub to seat the bearings, then back it off and set it to the specified play. Use the procedure and figure in the factory manual for your car.
How to repack
- Remove the caliper and hang it so the hose is not stretched.
- Remove the grease cap, the clamping nut and the outer bearing.
- Pull off the hub and disc together.
- Remove the inner seal and bearing.
- Clean the bearings and races completely with solvent and inspect them. Pitting or blue discoloration means replacement.
- Pack the bearings with high-quality wheel bearing grease, working it into the rollers.
- Fit a new inner seal.
- Reinstall, adjust, and fit the cap.
If you replace a bearing, replace its race too; they wear as a pair.
Grease
Use a quality high-temperature wheel bearing grease. Do not mix greases of unknown type, and do not overfill the cap.
Rear bearings
The rear wheel bearings sit in the rear hub carriers and are not adjusted in the same way. A bad rear bearing usually requires pressing and is often a shop job. A growl from the rear can also be the differential.
Quick answers
- How often should front bearings be repacked? Follow your maintenance booklet; with unknown history, repack and adjust them now.
- Can a loose bearing affect braking? Yes. Play can push the pads back and give a long pedal.
- Is a hum always a bearing? Tire wear patterns also hum. Check the tires first.
- Do I need special tools? A dial indicator helps for precise adjustment.
