grinding noise in front end above 35MPH

I have a 99 XJ with 93K miles, bought it 3 weeks ago. Replaced all fluilds and filters, including front rotors/calipers/pads.

I have a light 'wirring' (sounds like brakes dragging - but don't seem to be) sound that seems to come from the left front wheel. I replaced the calipers/rotors/pads (semi-metallic) when I bought it. When I had the wheel off to replace the rotor/caliper i checked the hub (but did not remove it) and it rotates freely, there is no play when grabbing the tire and trying to rock it.

I jacked up all 4 wheels and engaged 4WD to see if I could isolate the noise - no luck.

I swapped tires off my '85 XJ, the noise is still there.

The noise becomes noticable at about 35MPH and above. It only varies with road speed, engine speed makes no difference, neither does being in 2WD or 4WD Hi or Lo. Shifting into netural while moving makes no difference. I have tried to load each wheel by veering sharply side to side, but it makes no difference. Only when coming out of a large dip, when the suspension is unloaded does the sound go away, but only for a instant.

The sound is low, but noticable. Could it be a hub starting to fail or...? Any other checkes I can do?

Also, when I jacked up the rear diff, if you grabbed one rearwheel and rotated it there was quite a bit of slack, and a fairly loud clunck in the driveline, quite a bit more than the front. I don't have another to compare it to, to determine if it is normal.

I switched hubs from side to side, hoping that the noise would move as well. When I had the hubs off, they felt fine, with the drivers side (the side my noise is coming from) a little bit tighter when rotating it, than the passenger side.

The axle shafts are in good condition, splines ok, u-joints are free, not binding.

The noise did not move, and stayed the same.

So, running out of options, I removed the front driveshaft. Drove around and the noise is still there (audible at 35mph and above).

What to do next!?!?

I am now reaching for straws....I am thinking about removing the drivers side caliper or pads and see if the noise goes away (I replaced the calipers, rotors and pads, semi-metallic, shortly after I bought the Jeep).

Any ideas on securing the caliper out of the way or removing the pads so I could safely test drive it?

Any other things to check? The*big* item is the front axle. I just changed fluid (75W-140 Redline Synthetic) and there was some material on the magnet. The ring/pinion/side gears looks fine (i.e. no unusual wear noticable, not overheated, no missing teeth, etc) The fluid was clear and clean. Any quick checks I can do on the ring/pinion/bearings?

Thanks for any suggestions?

P.S. I take it this noise is not supposed to be there, is it?

Thanks.

My guess is hub.

Just some straws, make sure the backing plate is far enough away from the rotor, it could be close to the rotor then catch wind and start rubbing same with the inner fender it could blow out and hit the tire once your at speed.

Same deal, starts around 20-30, goes away around 10mph, im thinking hubs/hub bearing. My mechanic was clueless and he apparently works on jeeps all day long.


http://www.naxja.org/forum/showthread.php?t=73073

My 98 does the exact same thing.......i just kinda learned to ignore it but i sure would like to fix it if i knew what was wrong.

Sounds like your wheel bearings are going bad. Try this: When you hear the noise @ 35 mph, turn the wheel sharply right and left. If the noise goes away while the wheel is turned, it's probably the bearings.

The extra load put on the bearings while the wheel is turned will usually stop the vibration from the bad bearings.

I learned this from a local mechanic who diagnosed bad bearings on an XJ I was thinking about buying. I heard the noise, took it to him, and he diagnosed like I described above. I bought a different XJ (thankfully).

I'd guess bearing noise too if you're sure it's not tire noise. Probably the reason they sold it.

If you can, jack it up on all four corners, run it at idle in high gear 4WDHI and carefully poke around with a mechanic's stethoscope until you find the sound you've been hearing.

There are a lot of things in a Jeep that can make funny noises, mostly harmless. But a noisy bearing is failing. Probably not too bad yet if you don't feel it turning the rotor by hand while off the ground, so It may run a long time like that, or it may crumble into a wad of blue metal pulp tomorrow. Better to fix it now before you get collateral damage.
I don't think they are particularly difficult or expensive to replace (may be wrong about that :dunno: ).

also ... if it's a wheel bearing, you should be able to feel some play in the wheel when you have the vehicle jacked up. Put your hands on the jacked up wheel in the 12 and 6 oclock positions and push-pull hard and fast. You should feel a little play in there.

Check all the U-joints I just thought my front wheel hub had crapped the bed, bought it, had a bunch of other junk installed, called 1-2 hrs before it was suppossed to be done and the mechanic said the front wheel (outer) u-joint was crap, got it too him and saved 100$.