[kenhumphrey]

I picked up a 99 Dakota Club Cab Sport 4X4 (5.2, auto) a few months ago as a tow and trail truck. Recently I've noticed an occasional noise from what seems to be the left front wheel area when turning or backing up at slow speed. The noise might best be described as a high-frequency, low-pitch grinding sound that can be felt slightly through the brake pedal and floorboard. When the noise occurs, it will stop if I apply the brakes. I recently replaced the front pads and had the rotors turned; rechecking the work didn't show anything obviously wrong. I understand that there's a TSB for early (97-99) 4WD Dakota's front hubs, but the posts I've seen on it seem to involve higher drving speeds and a clicking or popping noise from the front end when stopping. I don't think the noise was there before the brake job, but I can't swear to it. I didn't think it was pad noise, since there's a vibration that can be felt. Any thought on the matter? Thanks for any help!

 

[ImperialCrown]

Any silver metal dust from metal-to-metal grinding on the left, front brake area when you did the job? Is there now? There may be an obvious interference problem that you can easily see and remedy, like a mis-positioned clip or backing plate. The rotor may have to come back off for the inspection.
If you grasp the wheel firmly on either side with the truck jacked off the ground and rock it, do you notice any play? This may indicate a worn wheel bearing.

 

[kenhumphrey]

Thanks for the suggestions; I checked out both sides today and didn't see anything contacting or scraping on the left or right sides. The calipers do flex a bit on both, but since the caliper bolts go through rubber insolators I'm assuming some flex is inevitable. The wheels don't wobble at all and when I had the rotors off, the hubs turned smoothly with no apparent roughness, catching, grinding sounds or the like. Possibly the hub doesn't make any noise unless there's weight on it? It has started making the noise at times when driving straight but, like when backing up or turning, the noise will go away as soon as the brakes are applied. Another person riding in the truck agrees that the noise is coming from the left front wheel area.
Some additional information, if it would be of help: this Dakota has the heavy-duty suspension (skid plates, about an inch higher ride height, 31-10.50x15 tires; kind of like the Jeep UpCountry Suspension package) and when the wheel is turned to the limit, the inner leading edge of the tires will contact the frame rail lightly but the noise isn't dependent upon tire contact. There's no binding or popping when turning, so I don't think the front axle is engaging. 4 wheel drive will engage and disengage smoothly. When it was making the noise when I was driving down the street at about 30 MPH, I engaged the 4WD on a straight section and the noise stopped, like when the brakes are applied. At this point, do you think replacing the left front hub would be worthwhile? Thanks for your help.

 

[ImperialCrown]

If there is no bearing free-play or bearing growl in the LF hub, I wouldn't think that it has failed.
If the noise goes away when braking, something is being held still or being neutralized with braking force.
If the noise started after the front brake job, let's concentrate on that.
If the rotors were turned, could there be a rough finish spot on the left one? If you swap the left and right side rotors, does the noise now sound like it is on the right side?
Make sure that the pad contact surfaces and where they rest on the mounts is clean and greased and without wear 'ditches' from past pad contact wear. These can be ground a little to help make them flat.
Usually I will replace rotors instead of turn them. Turning removes more metal that is already down to a bare minimum for good heat dissipation in the interest of weight saving and factory material costs. Machining rotors can introduce brake noises.
New 'white box' rotors are usually fairly inexpensive to replace compared to the labor to machine them on a brake lathe. I prefer to start fresh with new pads and new rotors.

 

[kenhumphrey]

Thanks for the idea- I did as you suggested; it appears that there was a problem with that rotor. Although it was flat and smooth, something on it was causing noise. I installed a pair of replacements from Auto Zone and the noise is taken care of. Thanks for your advice!

 

[ImperialCrown]

Good deal.