Trouble after lift! help

I had a 2 inch lift put on my 2001 cherokee sport, 68,000miles
front coils, rear AAL(long) 4 new shocks and new steering damper.
Rides smooth as glass, no vibes, shakes , etc. didn't even have to get it alligned after.
running 30x9.50 futura RVT tires.

my problem is right after the lift, my jeep started making a grind/hum sound only during deceleration, when taking your foot off the gas , and only at certain speeds like 30 , 40 , and 50 ,
accelerates great, quickly stops great , only makes it when coasting or taking foot off gas to decelerate.
?????????
any one have ideals.
one 4x4 shop says ujoints, had them checked and there fine.
one shop said, angle of driveshaft, but when the other shop checked it they said it wasn't off that much and looked fine?
one shop is saying my gearing in the rear diff is bad, opened it up and there is some slight wear on the spider teeth and the pinon bearing gears had alot of play and seemed maybe to be riding high on spider teeth? but no shavings or damaged?
Can someone give me some advise, i don't mind paying to get it fixed right , but don't want to fix the wrong thing. money is tight.
I don't have a tranny drop kit, all the 4x4 shops say it won't help, ?
never had a problem with the diff or this sound ever till the lift?
Thanks guys , any advice is so helpful! i'm at my wits end.
I don't want to keep driving it and thinking i'm tearing something up.

I had noise from my u-joints after putting in my 4" lift. Installed a TC drop kit and it fixed it. At the time I was told that at 3.5" and up, it will be required if you don't change the way the driveshaft connects at the TC.

But since yours is a 2" lift, I'd ask for a second opinion or three before spending the $ on the drop kit.

Money spent on a TC drop kit is going to be very minimal. Go to the hardware store and get longer bolts and a bunch of washers. I did shackles and spacers on an 01 and got vibes.

It's really kind of hard for anyone here to steer you in the right direction. You didn't get an alignment done and you probably should. You have some shops telling you that the angles are OK but we still don't know what those angles are. That would help. I didn't think 2 inches was going to wreak that much havoc on my gals but it did. After an alignment and TC drop...it was good again. 96 and up seem to be more stubborn than previous year models.

Anyway you can measure the angles of the driveline?

i don't have a measurement of the driveshaft angles, but if i drawl a straight line out from the front ujoint and the rear ujoint they are not paralle
the rear seems to point its line so that it does cross the fronts line slightly

I could do the transfer drop kit myself, but i'm not sure what to do about the linkage? how to move or adjust it.
and do you really need to loosen engine mount bolts to do the drop kit.

Often times when a driveshaft u-joint is bad you will only get noise and vibes with decelleration. Nothing on acceleration.

TBCherokee said:

I could do the transfer drop kit myself, but i'm not sure what to do about the linkage? how to move or adjust it.
and do you really need to loosen engine mount bolts to do the drop kit.

Click to expand...

I have 3.5 lift and a 1" Tcase drop and the linkage works perfect, no adjustments were needed there.

read gojeeps page about the t/c drop piece of cake even for a simpleton like me and no didnt mess with engine mounts

Tim_MN said:

I have 3.5 lift and a 1" Tcase drop and the linkage works perfect, no adjustments were needed there.

Click to expand...

I'm sorry for your loss...

(clearance that is)

TBCherokee said:

i don't have a measurement of the driveshaft angles, but if i drawl a straight line out from the front ujoint and the rear ujoint they are not paralle
the rear seems to point its line so that it does cross the fronts line slightly

Click to expand...

You need some axle shims.

How do you shim your axle? is it a simple fix or major take apart project.
and if you put a shim in, how does it change axle position? is it moving it down or up?

shims go in between the leaf pack and the spring perch. Depending on what side of the perch you put them on it will rotate the pinion.

ok dumb question, which side of the perch lowers the joint if pinon needs to come down about an 1/2 inch. ( so if an angled shim small side to which side)?
and what can you make shims out of? what type of metal and how do you measure them.?

TBCherokee said:

ok dumb question, which side of the perch lowers the joint if pinon needs to come down about an 1/2 inch. ( so if an angled shim small side to which side)?
and what can you make shims out of? what type of metal and how do you measure them.?

Click to expand...

Youll have to buy the shims,make sure and get steel.In your case the fat end will go toward the front of the vehicle.

so to shim , i just need to loosen ubolt joints , and hammer in the shims, and retighten? is that it? or am i missing something.?

TBCherokee said:

so to shim , i just need to loosen ubolt joints , and hammer in the shims, and retighten? is that it? or am i missing something.?

Click to expand...

you need to loosen the bolt for the centering pin and make sure the centering pin goes through the shim and into the spring perch. depending on how long your centering pins are, you may need longer ones.

so did anyone have any thoughts on what might be the best or most likely thing that is causing my hum/grr sound , would it really be the diff? or is most thinking angle .

update!
just to let everyone know, i did a 1" tcase drop and the bad sound is gone.
thanks again for all the imput guys!