HOW TO .... Replace a Front Wheel Bearing
When a wheel bearing goes you'll notice. A bad bearing starts to make it's presence known by producing a whine or drone at high speeds and is more pronounced on sweeping bends when the load comes on that wheel (ie. on left bends the load is on the right wheel and vice versa). As the bearing deteriorates the noise gets louder and louder 'til finally you can't hear the stereo and the car sounds like it's just about to explode, unless you're happy to drive around at 20 miles per hour in which case you might get another 2 months out of it. If on the other hand you'd rather change it it's a fairly simple procedure.
|The front wheel bearings on the MX5 - Eunos Roadster come as part of the front hub assembly and while it's probably possible to get the bearings seperately and press them out, it's easier just to replace the lot.|
1. - Start by parking the car on a level surface, engage the handbrake, and loosen the nuts on the relevant wheel. Raise the car and remove the wheel. At the centre of the hub is a cap which covers the hubnut. Place a screwdriver or chisel behind the lip and tap this out, leaving the hubnut and shaft exposed. The shaft itself is keyed or slotted and the outer rim of the nut is bent into the slot to prevent the nut from loosening. Use a punch to tap the bent section clear of the shaft, allowing the nut to be loosened.
|2. - If your wheel has a hole in the centre, result. This is going to be an easy job. Loosely refit the wheel, lower the car and using a 29mm or 1 1/8" socket loosen the hub nut, and smile to yourself as you skip step 3.|
|3. - So your wheel hasn't got a hole in it and none of your friends will lend you theirs. Dont panic all is not lost. Start by getting a friend (if you have one) to stand on the brakes while you try to loosen the nut. If there's no one available or this doesn't work place a crowbar between the wheel studs to lock the hub in place. Don't worry about damaging the studs as the entire hub is being replaced anyway.|
4. - Use a 14mm spanner to loosen the lower caliper sliding bolt, and tilt upwards to slide the brake pads up out of the way. Use the same spanner to loosen the upper and lower caliper mounting bolts and remove the caliper. Tap the brake disc with a rubber or hide mallet to remove it, and remove the hub nut.
5. - The hub is now exposed and ready to be removed. Spray the area liberally with WD40. If you have a 2 or 3 leg puller or a 2 bolt puller simply attach it to the hub and remove it and smile again as you skip step 6.
6. - If not, measure the distance between the 2 threaded holes in the hub and drill two corresponding holes in a flat piece of fairly heavy steel using a 9mm drill bit. Place the centre of the steel over the shaft and place two M8x50 bolts with flat washers through the holes you've drilled and screw them into the hub. Gradually tighten alternating sides, and the hub should slide off the shaft. I say should because I have a pullers and didn't need to do this.
|7. - If, as in my case, the inner bearing race remains on the shaft while the hub comes off, tap it with a hammer and chisel taking care not to damage the shaft. If you need to remove the backplate simply undo the three 12mm bolts.|
8. - Slide the new hub onto the shaft and tighten the hubnut to press it home. Refit the disc and the caliper. I recommend using threadlock on the two mounting bolts before refitting them, and while the lower caliper sliding bolt is out smear some copper grease on it.
9. - The hubnut should be tightened to 190-205Nm so a good torque wrench will be required. If you have access through the wheel, simply refit the wheel and lower the car. If not, either use an assistant to press the brake pedal or lock the hub using a large filter wrench, or worst case scenario the crowbar on the studs method making sure that you refit the wheel nuts first so as not to damage the studs, and taking care not to bend them.
10. - Refit the cap, and the wheel. Pack away your tools and go for a nice drive without that irritating noise.