Wheel Bearing - Air Gap Excessive
 

Hi,

I’ve read a few posts on this, but before changing the bearing again, thought I would see if there was any other ways to fix the air gap excessive error?

- I am getting the trio of lights on the dash.
- This is the 2nd bearing I have tried - second one was definitely in the right way and had the magnetic strip for the sensor - brand was Febest and they tell me they have never had this issue for all of their sales
- I have even tried multiple sensors (LHS doesn’t have the issue, but is original bearing still).

A) suggestions please?
B) if I am better changing the bearing again, what brands would you recommend. I was thinking of going genuine, but assuming that would be Meyle or something in an expensive BMW box? I want to stay away from Chinese made as i can’t deal with this a 3rd time.

INPA screenshot attached.

Cheers

Another potential brand I have come across is FAG? Seems German OEM

Not sure if this is a front or rear wheel bearing.

It's pretty near impossible to install a rear bearing incorrectly - it bolts directly to the carrier.

It may be possible to install a front bearing incorrectly. The bearing has a chamfered or rounded edge that must be towards the centre of the car when installed, and the bearing needs to be driven into place correctly (in terms of depth). But once again, it's pretty hard to get this wrong, given it must be installed correctly in order for the circlip retainer to fit.

I guess it might be the wrong bearing? There are two sizes - the very early cars appear to have a slightly smaller front bearing than the later cars.

Or... the ABS module is faulty - the sensor connections inside the module are known to fail.

To confirm the bearing not the problem get about 20' of 2-wire thermostat wire and rig up a temporary swap of left and right sides. Start a new thread for the project I can walk you though the steps.

When you send the left wheel to the right input on the abs module and vice versa you will be able to tell if the problem is in the abs module or in the wheel.

The air gap is pretty finicky and the usual actual problem if you have an "air gap" problem is rust particles in or around the sensor and often cleaning out the port with brake kleen and of course the sensor can solve that issue.

- REAR bearing has 4 bolt holes, possible to install wrong on the hub ---> destroying the brand-new bearing (cannot install in the car that way). There is only one way to install onto the hub.

- FRONT bearings can be easily installed wrong. Use a paper clip to verify which side is the magnetic side and install that side toward the engine side.

- For FRONT bearings ---> BMW 31226783913:

* BMW: $100.
* FAG: $45
* SKF: $65

I highly recommend FAG bc it is the original mfg. I have FAG bearings in my 1998 528i for the last 10 yrs+.

Thanks - it is the front bearing....I forgot that little bit of detail.

@wpoll - definitely not the smaller bearing, as I have one of those too. Will work out and investigate the ABS module

@andrewwynn - will start up a new thread and see how this is done and what can be done to isolate the ABS module. I have cleaned with brake cleaner and a new sensor. The only thing I can think of is using a magnet to see if there is anything that needs collecting from the end of the sensor hole.

@cn90 - if it come down to replacing the bearing again, will look at FAG. It was tested with a paperclip before going in, so the magnets are there.

The only other things I should mention is that running INPA and looking at wheel speed sensors, I seem to get readings on all 4 wheels. Not sure if the airgap with the sensor is sporatic or still gives a reading, but throws the fault as outside of tolerances.

Thanks

Did you check the wheel speed sensor, did you damage it during bearing job?

I have since replaced it twice to see

The alignment is picky. New ≠ fixed. Before doing the more difficult test the first thing to do is swap left and right sensor.

You can try to install with the screw missing so you can slightly misalign the end on purpose but you have to be careful you don't actually rub on the Bearing.