I have a rear whining, believe it is the 3.65 gears, 4x4 5.9. I paid a transmission shop to replace the rear in December, but it still whined some. The mechanic said you just can't get all the whine out of some chrysler rears. About a month ago, it started leaking at the pinion bearing, so he replaced bearings and gears. It is quiter now, but still has some whine to it, and he says he made several attemps at adjusting it and it is done right, but he can't get all the whine out.

Its not so loud as to be noisy, but after warmup, it is enough to make you think its not right. With the rear cold, it doesn't make hardly any noise.

So, do I have a mechanic that doesn't know what he is doing, or is true that some rears are going to whine no matter what. He has a good reputation for rebuilding transmissions, and did go back and and rebuild it a second time without having to get ugly about it.

 

first thing is first, we need to know which rear you have (8.25 or 9.25), double check the gearing, these trucks were sold with 3.55 or 3.92 gears, and how many miles on the truck?

but this whining is not normal to my knowledge, it might not be the rear, but it is NOT NORMAL, my truck doesnt make any whining noise, at all

and the obvious 'whiney' parts have been replaced already imo

 

I have an 01 with 3.55 diff. Mine would whine while making right and left turns. Added a couple of ounces of Royal Purple Friction Modifier and have been whine free for over two years.

 

Adding Royal Purple Friction Modifier will not help unless you have a limited slip diff. The noise that the OP is hearing is most likely that the pinion depth was not set up correctly. Sounds like it is towards the tight side to me.

 

It is the 9.25 with 3.55 gears, it is not limited slip.

Thanks

 

Like I said before, if he replaced bearings and gears, he has the pinion gear depth not adjusted right. It is too tight against the ring gear, that is why you hear the noise only after the rear heats up and do not hear it when it is cold. Diff. fluid is very thick when cold and thins out to a degree when hot. The transfer case can also whine but you would notice that more towards the center/front of the vehicle. I still am leaning towards pinion gear depth not set correctly.

 

im going to have to go with pete on this it sounds like the pinion is adjusted too tight

 

Thanks sharp, you made my day because I had a rough day today.

 

It has about 1,000 miles on it, should it be reset at this point?
I was told by another mechanic that once the gears have run a few miles and mated, that the whine is there even if the gears are corrected.

 

That other mechanic is wrong. You can still readjust the pinion depth and get the whine out with the proper settings. Only way there could possibly still be a whine left afterwards is if there is too much bearing wear on the pinion from being preloaded too much. My advice would be to take it back to the original mechanic and tell him to adjust the pinion depth per specs. If and only if you still get a whine, take it back to him and tell him to REDO the rear end with new gears and bearings because he is the one who screwed it up to begin with. If he does not know what he is doing, take it to a reputable shop that does and then give the bill to the original mechanic who screwed it up.