Hi,


I have a grinding noise that's road speed dependant It sounds like it's coming from the front of my '03 R53. I looked that the front wheels while I was changing the transmission fluid this weekend.


I spun both front wheels I heard a little rubbing from the pads against the disks, but nothing that really sounded unusual. I did notice that the front rotors have a VERY pronounced ridge where the pads don't cover them. I've read that this can cause a squeal, but this isn't a squeal.


About the time that it occurred I also got the warning light trifecta. A couple years ago I would get it sometimes in very hard left hand cornering, but hadn't had it in a while. Previously it would go out, now it's staying on.

I changed the front pads a year or two ago, but left the rotors alone. The pads all seem to have plenty of material left. At any rate, I've ordered new rotors and a couple wheel speed sensors. Any thing else I should look at? I wish I'd spun the back wheels as well when I had all four wheels off the ground to change the transmission fluid.

 

Could be a wheel bearing, slalom left to right while driving at speed, if it's in fact a failing wheel bearing you will hear the noise more prominently when that bearing is loaded vs unloaded.

 

Sounds like you're on a good start with the rotors and the speed sensors. A wheel bearing could inhibit some strange noises while moving forward. Most of the time you'd hear a very pronounced grinding noise when turning and putting load onto a specific wheel. I've had a bad wheel bearing cause some really strange symptoms before. Make sure the dust plate isn't making contact with your rotor. If you can, maybe take a video and post it up. Sometimes noises that a failing or bad part make are easily identified with people who have experienced them. It might help.

 

I've seen a youtube video of diagnosing wheel bearings back jacking up one wheel at a time and letting the engine idle in gear with one wheel in the air. The guy demonstrating it said it was potentially dangerous but worked pretty well as long as you had an open diff. Any way to tell if my R53 has an LSD?

 

Apparently it doesn't have an LSD. I gently let the clutch out and everything stayed put. I did find out the left front wheel bearing was bad.

 

You can input your vin at this site HERE and it'll tell you what you have from factory. You can check for a noisy wheel bearing with the vehicle stationary too. Jack the front of your vehicle and rotate the front wheel; while rotating, place your hand on the front coil spring. You should be able to pick up a vibration in the spring. There may also be free-play in the bearing. You can try to check for free-play by jacking the front of your vehicle and wiggling the wheel up and down.

Bearings here - http://www.pelicanparts.com/catalog/...pg4.htm#item13

 

I changed the left front bearing and the front disks. I probably didn't really need to change the disks the noise has gone away. I also changed the left front wheel speed sensor but I'm still getting the trifecta. Does anyone know how to determine which wheel sensor is bad other than substitution? I bought another wheel speed sensor. I was guessing the right front would be the next one to try.

 

To find out which sensor is faulty you would need to scan it. Unfortunately regular OBD scanners won't do, you would need access to one that reads ABS codes. Have you driven the car yet? My lights went off after the first 200 meters or so of driving after replacing the sensor.

 

I pulled the right front sensor and it was pretty obvious that was the problem, it was pretty chewed up. I also noticed the piece that appears to a sort of dust cap for the wheel bearings was tweaked a bit. I initially thought maybe I messed the dustcap up pulling out the old bearing, but now I think that it was probably a piece of the old bearing that did that and the wheel speed sensor.


I put the old sensor from the left side in the right side, since replacing it didn't change the trifecta. I have one new sensor left, but I wanted to make sure that whatever tore up the old right side sensor didn't mess up the new one. So far the sensor looks unscathed on the right side. This did cause the trifecta to go away for a while.


Everything went perfectly for a few miles then the car started acting like a wheel was slipping under pretty moderate acceleration and even more scarily when under moderate braking. I turned off DSC and everything seemed okay, but then the trifecta came back.


The speed sensors seem okay, I checked the connections to both and they seemed good although the locking tabs on both of them broke when separating them, so now only zip ties are really keeping them together.


I'm thinking about putting my remaining new speed sensor on the right side, but I'm also wondering if whatever the right speed sensor is supposed to "see" is bent. Hopefully it's not that dust shield piece that's on the end of the outboard CV joint. I tried spraying contact cleaner down in the hole the speed sensor goes into last night to clean whatever the speed sensor points to off, but it didn't help. I thought usually there was kind of a serrated surface the axle that the ABS sensor detects, but didn't see anything like that.


I'm getting a trifecta now when I start it up. Any ideas?


-Eric

 

Its the wheel bearing and the ABS sensor was broken due to the rust back side of the wheel bearing rubbing into the head of the sensor. Check both sensors on each side.

https://www.northamericanmotoring.co...ed-sensor.html







When they are new its fine , when the wheel bearings are much older the seals flares out from the rust and rubs the ABS senor head down till it fails. Mine did this when I replaced it at 190K.

 

I replaced the sensor on the left side with a new one. That didn't fix the problem so I put the sensor that was on the left side on the right side, where I'd had the bad wheel bearing. The sensor that had been on the right side was apparently messed up as you describe.


The ABS, Traction control, etc. worked well for a few miles then it started acting like the wheels were slipping. I could get around this by turning off traction control, but eventually I got a trifecta, which seems to mean that it can't sense a wheel rotating.


I have one more unused sensor that I was going to try installing on the right side. Do you know what the wheel speed sensor senses? The sensors looks like they could be some kind of hall effect sensor, like some bicycle speedometer and electronic ignitions use. I don't see any rotating magnets for it to sense.


I checked the connections on both wheel speed sensors and they looked okay. I've looked at the right side sensor, where the wheel bearing died, after it's been installed a while and didn't see any new damage to it.


-Eric

 

I think I figured out that the back of the bearing seemed to have a pattern to it that I think the sensor senses. I figured out what happened with the recurring trifecta was that the wire of the used sensor that I installed on the right side had rubbed against the crank pulley.


I installed my remaining new sensor and made sure to tuck it up a little further away from the pulley. The zip ties for the sensor plugs have a little piece that appears to be intended to lock into a hole to hold them in place. Neither one of mine seemed to be attached to anything. Anybody know what they're supposed to attach to?

 

Its reads off the back of the wheel bearing pattern much like a hall sensor. It has to be close enough to read, the heads get damaged from the rusted out back of the bearing and it cannot read it right or the heads crack ( in the axle carrier slot ) in the slot from bearing pushed by the rusted bearing.

The ABS sensor on the driver side follows the brake pad sensor and gets hooked on that. The ABS sensor on the passenger side, hooks on the peg near the strut then goes under the wheel well plastic and into a clip holder that holds the whole plug head.