Noise after replacing tires

[rookieTJ]

Fix one thing, and something else starts to happen.

Recently upgraded my tires from some crappy 32 inch mud tires, to a set of 33x12.5x15 BF Goodrich K02s. Had them mounted and balanced. Fixed my front steering to ZJ conversion all is good.

Now I am getting a noise from I think the rear end, sounds like a low-pitch whining of some sort, the noise only occurs when I am in gear, decelerating. Noise goes away when I depress the clutch or when im in neutral. This happened shortly after getting tires put on. Happens in every gear, at any speed over 15 mph. I don't remember this noise when the 32s where on the car.

As far as I have read on other threads, could it be the rear pinon and bearing? I'm guessing it's not okay to drive it like this? Any help would be great...

01' TJ Sport - 87k miles, 5spd m/t

 

[pagrey]

Your old tires just drowned out the noise, they are most likely unrelated.

 

[Steel City 06]

Start by pulling the rear driveshaft and driving around in 4WD (essentially front wheel drive). If the noise goes away, you know it's either the driveshaft or something connected to it. You can repeat the test by removing the front driveshaft and installing the rear to eliminate the possibility of issues with the front.

While you have it off, check the pinion yoke and the transfer case flange for any play.

Note that whenever you have the rear shaft removed, you must use the parking brake. If the car is in 2WD and park, there is nothing stopping the rear wheels from spinning other than the parking brake. Especially use it any time you're underneath messing with the shafts.

 

[rookieTJ]

Start by pulling the rear driveshaft and driving around in 4WD (essentially front wheel drive). If the noise goes away, you know it's either the driveshaft or something connected to it. You can repeat the test by removing the front driveshaft and installing the rear to eliminate the possibility of issues with the front.

While you have it off, check the pinion yoke and the transfer case flange for any play.

Note that whenever you have the rear shaft removed, you must use the parking brake. If the car is in 2WD and park, there is nothing stopping the rear wheels from spinning other than the parking brake. Especially use it any time you're underneath messing with the shafts.

Would low fluid level cause these issues? Just took notice both diffs are leaking fluid. Here’s some pics.

 

[Steel City 06]

Would low fluid level cause these issues? Just took notice both diffs are leaking fluid. Here’s some pics.

View attachment 186348

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View attachment 186351

Yes, it could, especially if the pinion is dry. I would open the differential covers, make a new seal with Permatex or a pre-cut gasket, and fill with new lube. If you get less than about 2 quarts or so coming out, it was probably low.

While you have them open, take a look at all the internals and look for any odd wear or damage. Take pictures and post them if you're unsure.

 

[Goatman]

As the fluid drains be sure to look for any debris or grit in the bottom of the diff housing. Any chunks or shavings and it's a pretty good bet the diff will need a rebuild. Look for any wear on the gear teeth. Some wear is ok, but any chipping or odd wear pattern is bad too.

 

[cpwolf]

If it’s leaking, I would open the fill hole before pulling it apart. Put your pinky in and see if you can feel fluid. How far down is it? Not scientific like measuring as others suggested, but it will tell you if the fluid is below and possibly way below.

 

[rookieTJ]

If it’s leaking, I would open the fill hole before pulling it apart. Put your pinky in and see if you can feel fluid. How far down is it? Not scientific like measuring as others suggested, but it will tell you if the fluid is below and possibly way below.

As the fluid drains be sure to look for any debris or grit in the bottom of the diff housing. Any chunks or shavings and it's a pretty good bet the diff will need a rebuild. Look for any wear on the gear teeth. Some wear is ok, but any chipping or odd wear pattern is bad too.

Yes, it could, especially if the pinion is dry. I would open the differential covers, make a new seal with Permatex or a pre-cut gasket, and fill with new lube. If you get less than about 2 quarts or so coming out, it was probably low.

While you have them open, take a look at all the internals and look for any odd wear or damage. Take pictures and post them if you're unsure.

Okay, I ordered new lube lock gaskets on amazon, front arrived today, rear will be here Sunday. I opened the little fill black rubber Grommet on the rear diff, and my finger could feel fluid, doesn’t seem low, but I didn’t do a true measurement, waiting for this weekend to get covers off. But definitely fluid in there just very dirty, see photos attached. I’m not 100% sure but diff fluid shouldn’t be this dirty should it?

 

[Jim Byrne]

I just installed a set of BFG 31" mud-terrains and at over 70 MPH I have a noise like driving on the speed bumps on the side of the lane.