Just after the 4.5" RRO lift I started hearing a grinding noise from the rear diff (standard 5.12:1) at speeds over 85km/h and mostly when I release the throttle pedal.

I made then 2 thoughts. 1) that the bearing was worn, but know with the lift the problem showed up, so I changed it and I also put a LSD. The problem continued. So I stuck to my second thought that the RRO lift doesn't possition correctly the axle and that's why I have that noise.

So I kept thinking that when I will install the calmini 3", everything's gonna be fine, but I was wrong that grinding noise still remains.

So I would like to ask if anyone of you had ever had this problem and how did you solved it

Can you list what steps you have taken?

1. Installed RRO 4.5" Lift  =  Grinding rear noise

2. Replaced rear bearings and installed LSD.   (All bearings?  Pinion Carrier and axle?)

3. Replaced RRO lift with Cal Mini?



I know it too simple, but Have you checked the dust guard on the rear brake drum?  Often times they get bent while working on the Kicks and make a grinding noise.

Have you checked the U-joints?  No red dust / dry needles, Good free motion each direction. 

I had something very similar and it turned out to be the rear pinion angle.

check your pinion angle on the calmini kit.

RRO 4.5 kit....not sure there.  I am running it and no grinding noises.. so my theory may be debunked..

Put it simply:

1) Before RRO no grinding noise.
2) Just after RRO grinding noise.
3) I replaced the pinion bearing and I also instaled the LSD. grinding noise continued
4) with calmini 3" again grinding noise.

As for the rear u-joints: With RRO I had a homemade axle spacer, which was out of balance and I was blowing  Ujoints twice a year. Now with the calmini I also changed the u joints and I also replaced the home made spacer with the calmini spacer.

Do  you believe that the problem is wrong rear  pinion angle? and if yes is it adjusted from inside the diff (during the setup), or you adjust it from the adjustable rear A-arm that calmini has?

I have the same noise from mine after the calmini 3" lift, you can adjust the rear A-arm to make less noise but it just the angle of the tailshalf.
When I put some weight in the back the noise disappears.
Turning up the radio also helps to get rid of the noise.