beefychicken

Just want to put up a quick review - no pictures though, sorry –

Installed the Z1 rear subframe collars on a 2014 Q60/G37, Sport, AWD

Going into this I already had the Bell Raceworks diff brace installed and FWIW, i did Motervate's blown diff bushing repair.

Purchase and shipping;
Bought straight from Z1’s website with no issues (except that the collars went on sale for 20% off one month after I ordered.) Shipping was quick, 3 days if I recall. Collars arrived well packaged with no missing pieces or damage. Overall, it was a good experience, would give 5 of 5, but will drop it to 4 because I missed the sale.

Install;
Z1 has a very detailed video which I highly recommend watching before going to the text instructions. Z1 says to drop the axle back portion of the exhaust. I did not need to do this as the Invidia Gemini I have installed allows adequate access to slip the collars in. Other exhaust systems including stock may have to be removed, not sure.
Removed both rear wheels – I highly recommend this – then removed the rear W brace and the two forward braces (I think the front braces are associated with the AWD – similar to the convertibles).
Loosened the four bolts and lowered the subframe enough to slip the top collars in.
The top collars were simple. The bottom collars were a tough fit. I ended up spraying them with WD-40 and used the floor jack to push them into the bushing.
I noticed that the rear top collars have notches for the bottom collar, so I made sure all of that was aligned before tightening anything.
Buttoned everything up, torqued per the instructions, lowered the car and put away the extra pieces for a future project : )

Driving;
As expected NVH was increased, especially with the differential brace, since everything is solidly coupled to the frame.
Overall not too bad for the first 20 or so miles, then the metal to metal creaking started. This noise was a bridge too far, so I had to do something.Traced the source of the noise to the rear collars creaking against the W brace mounts. Tried some grease, worked for about 15 miles, then it came back with a vengeance.
Final solution was to cut out some super thin foam padding (1/16’) and inserted the foam between the W brace and the rear collars and between the frame and forward upper collars. So far so good, 100+ miles and no more creaking, still some NVH related to drive train vibrations and noises, but nothing is a deal breaker.

Follow on effects:
Torque transfer to the wheels is so much better now. Some of the acceleration lag is gone, even though the 7AT is still the 7AT, but the solid connection between the drive train and the car is a huge improvement in getting my measly stock power to the wheels.
Handling is improved also. The AWD already has a huge front sway bar and I installed the 370Z Nismo bar in the rear. So all that plus the coilovers and teflon bushings associated with the front UCAs and rear camber arms made me think I was good to go suspension wise. But these collars made a noticeable difference, You can definitely tell the rear part of the car is tracking tight in turns and body roll has decreased noticeably.

Overall, for the price and ease of installation, I would recommend this for anyone as a quick, easy, cheap mod with great results. Only shortcoming is a little bit more driveline NVH and the metal to metal creaking and the creaking can easily be remedied during installation.

Have a great Infiniti day and feel free to ask questions!