Wheel bearing adjustment question.

Wheel bearing adjustment question. - Printable Version

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- APXD 30 - 12-13-2006

I was just looking through the Zone 2 tech form for March and would like to understand part of this excerpt pertaining to wheel bearings:

"Tires must have sufficient tread and be in good condition. Tires with cracks from the heat or dry-rot are not acceptable no mater how much tread is left on them. Lug nuts must be torqued to factory specifications and the front wheel bearings must be adequately adjusted. You are responsible for maintaining appropriate tire pressures."

What adjustments can be made to the wheel bearings? I had one fail on a new, FWD car. Was it/could it have been adjusted when the shop installed the Eibach sport suspension?

- Brian Minkin - 12-13-2006

What they are hunting for is loose wheel bearings which is a sign of impending bearing failure. Bearing failure which will build up extreme heat could lead to a wheel departing the car while it is in motion. A loose wheel bearing also will effect the handling of the car in cornering. There is a static test for loose (worn out ) wheel bearings which is to raise the car on a lift and push and pull on the tires with your hands at a 12 and 6 position. If you find a click or more movement your bearings are worn and should be replaced. Acceptable movement is no more than 2mm. Simply tightening bearings that are loose will further push the bearings under preload into a worn out race and will still fail. You can also diagnose a worn out bearing from noise (a grinding sound when you rotate the wheels) and even perhaps a rumble feeling in the steering wheel.

Once bearings show movement they are worn out and need replacement. Repacking will not help as the hard metal of the race is worn and pitted and the softer metal of the bearing cup will not hold up to the pressures placed on it. If inspection of the races during repacking shows a darkening of the metal surface even if no pitting is evident and no play was found this is also a sign of a worn out bearing.

Reasons for bearing failure are :

1. the lubricant has washed away or broken down due to failure of the seals

2. An outside contaminent has entered the bearing and scored or pitted the race.

3. A bad ground strap has caused static electricity arcing across the bearings and this has destroyed the race through electrolysis.

4. Miles and age

When I tech a car for RTR tech inspection I always check for bearing play and rotate the wheels to be sure there is no crunching sound coming from the bearings. Our tech form ask the inspector if the bearings are in good condition and have no play.

- ccm911 - 12-28-2006

OK. Good stuff on bearings.

Now. How do you remove the old races? Can I do this myself, or do I need a press? I have changed my bearings twice, but never replaced the races. It is time to do so with this next change.

Any ideas?

- Mike Andrews - 12-28-2006

Actually what I think they are talking about is the older cars that require an adjustment of the front wheels bearings....

You would do that by running the spindle nut up to the wheel bearing washer until a drag is felt as you try and move the washer under the nut. Too much free play resulted in a wheel with too much movement and too tight risked damage to the bearing as they expanded due to heat.

The races can be removed with a good drift (punch) and a big hammer. Take the rotor and hub off of the car, clean all of the old grease out of the hub and knock the race out from the opposite side. Once you get the grease cleaned off you will notice a nice ridge that you will engage with the drift to knock it out. It's a three beer job at most Big Grin

- Larry Herman - 12-29-2006

ccm911 wrote:

Quote:How do you remove the old races? Can I do this myself, or do I need a press? I have changed my bearings twice, but never replaced the races.

You're not the first person who wondered why they packaged the bearings in those nicely machined holders!