When spinning rear wheel by hand...

[PLAPELLO]

Hello,

Question: When spinning rear wheel by hand, should it be as smooth as doing the same thing to a front wheel? Or should you be able to feel the gears within the differential?

To clarify, I have a 2001 Sport 4x4, but I do not have it engaged and I have it set to Neutral.

So the front wheel spins freely, I do not feel anything due to being in 2wd mode. When I spin the rear wheels, it sounds fine, but I do feel some kind of, um, like a tap tap tap tap tap in both wheels. I do know the differential and the gears are still all touching and moving.

I am just wondering if it is normal to actually feel something like the gears moving and touching as the tires spin?

As always, I thank you for the wisdom.

 

[PLAPELLO]

I recently changed the fluid in my rear diff, changed the wheel bearings and seals.

I did not however change the carrier bearings or pinion bearings. Nothing felt like it had any play, I rotated everything by hand and it all felt smooth, I rotated the drive shaft by hand and it felt smooth, I put it all back together and it moves still and nothing exploded which I think is a huge plus.

The old fluid was nasty, and it did have tiny grains of metal, but it has 185,000 miles and I think original fluid. I am just wondering if that feeling from rear wheels is OK, or if I should have more work done to the differential gears, bearings, etc.

 

[zpn_by]

At that kind of miles, particularly as you said there were small bits of metal in the fluid, you would expect there to be some play. Were both rear wheels off the ground when you were spinning them? Keep in mind too, that even though your axle shafts are supported by the inner and outer bearings, they will experience gravity loading and you'll be able to feel the bearings (even new ones) just a little with the weight of the wheel and tire on them, vs. spinning everything by hand when the axle is partly disassembled. Now that you have it back together, do you have any noise from the back end? One other question - I don't know if it was available on the Sports, but do you have the Traction-Lok rear axle? You could be feeling some action on the clutch plates if that's the case. If you have the TL, did you use the friction modifier when you reassembled?

Being as far into the axle as you were, it may have been a good idea to do the bearings that you passed on, but of course we don't know what your time or $ budgets were like when doing the maintenance. I'd say if you don't have noise, keep going for now, and wait until there's something you can identify...

 

[PLAPELLO]

Hello,

Thank you for the reply. I have an open differential.

I just did a drive on the highway and I can hear a noise from my back end, and the truck has one too. ba da ching.
Anyways, one thing I will have to test is to see if the noise is coming from my newly replaced parking brake pads. Possible they need to be dialed back a little.

The main reason I did the outer wheel bearing and seals was I had a very noticeable puddle of diff oil on the ground coming from an axle seal which left a nice trail to follow up.

I will have to keep an eye on it, or an ear I suppose and do some more research. I am trying to find more info to see how difficult it will be to align everything back up after taking it out. That was the part that made me a bit nervous to pull everything out.

 

[Robman]

I had an explorer with a "whining" noise coming from the rear end.. I just slapped a whole different rear end under it .. from a higher mileage explorer with the same gearing. The one I installed has alittle play in the pinion but no whining noise and slight drag so it was a good enough trade off. Not sure what you mean by lining everything back up... you might mean internal stuff, but in the case of taking the whole axle in and out there are pegs where the springs sit under the axle making lining the axle up a no-brainer. Also I used Synthetic Lucas oil as my "friction modifier" that has to be added to the rear end with full synthetic gear oil.