Jake-n-bake

Hey guys, thanks for reading. I'll try and keep this short.

Okay, there is a grinding noise originating from (as best as I can tell) under the pedals/drivers seat. When I had my radiator replaced I recieved a note on my reciept saying "Grinding noise heard on test drive, need wheel bearings replaced". So I swapped those bearings for some Timkens with my bare hands and so help me it didn't fix it.

So, I grabbed the axel shafts and tried to get some "play" out of the u-joints; nothin. My genius uncle who's a guru with car mechanics suggested it could be the bearings inside the axle housing itself.

The Jeep is a 2000, has 163,000 miles, and it is the original axle (check my pics to the left!). The noise seems to be coming from the axle than other places (sorry for being so vague, I have to travel at least 10mph to get the noise so precision is hard).


Here are some symptoms that may help with your hypothesis:

- the noise is directly tied with the tire's RPM; faster the wheel turns, faster the noise pulses.
- Does not get louder or quieter upon turning.
- Loudest at about 15 mph
- fairly certain my differential fluid is fine
- I removed the 4x4 axle and it still made the noise

Well, there it is. What could be the source of the noise? Could my u-joints still be the culprit? Any easy tests to eliminate some sources? Thanks again for reading!

Basshark7

I guess first thing is first, How old is she and how many miles? Original or swapped Axle? If you had to say is it closer to the seat or the pedals? Are you saying it is on the driver's side and definitely not the passenger's side? I'm not going to be much help but the other guys/gals will want this information.

Jake-n-bake

Thanks dude! I appreciate it. I edited the original post from your suggestions.

HudsonN

Have you checked to make sure your backing plate is not rubbing on your rotor?

Sounds too simple, i know, but it's worth a look.

Jake-n-bake

Hey HudsonN, I'm not too sure which backing plate you're referring to. Could you clarify?

Basshark7

I am fairly certain that HudsonN means the backing plate associated with your brake rotor. Take the wheel off and feel just above or below the brake caliper (it has a cut out in it for the caliper) there is a thin metal plate that hangs out back there and covers the inside of the rotor without touching it. I don't know its exact purpose but I have to believe it is to prevent dust from the brakes getting into other mechanical parts.

Jake-n-bake

Hmm anything could be the culprit I guess! However this noise has persisted for over 25,000 and I've changed calipers since then and no change to the noise...I'll keep my eyes and ears peeled though

Jooman07

Is anything felt in the steering wheel when it's making the noise?

mr white

Pop that diff cover and check those bearings and then fill it back up with New fluid. The differential is right in front of the pedal assembly basically so it's possible those bearings are shot. Or the pinon bearing.

Knucklebuster

Has the transfer case fluid been checked? There's a chain in there which if stretched (worn) could be slapping against the inside of the case. There is also bearings in there which could be growling for lack of lubrication. Don't remove the drain plug first. If the fill plug can't be removed, you're stuck with an empty case with no way to fill it. (No, Don't ask me how i know). Search "transfer case service" for details.

Jake-n-bake

Good job mr white and knucklebuster! You seem to have guessed it. Front pinion bearing; plain as day. I finally found the answer in the 2000 Cherokee Service Manual. Here is what it says about bearings in the front axle...the red section is where I found my answer.

BEARING NOISE



The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.

Pinion bearings have a constant–pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differential.
If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
source.

Worn or damaged differential bearings usually produce
a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differential
bearing noise is also constant and varies only
with vehicle speed.

Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.


Hope this stuff can help somebody! Now to pay to get it fixed :/