Hi, I am new here and I’m from Spain so I apologize before for my bad English 😂

I bought a G37s 2012 not very common here like a year ago and I always had vibration in my steering wheel from left to right, I bough new rims JAPAN RACING JR20, 20”, 10 at the back and 8,5 at front, with 225/35/20 and 255/35/20. I also got HR springs on it and got my car alligned after that . Got my car with crazy vibrations even more than before... after balance my wheel lot of times where I bought the wheel and still the same I took it to another place and they told me the back wheels where bad from factory... I got that fixed and it got better I still have vibration in the steering wheel from 110km/h and I feel vibration in the car in my seat, pedals, and the car in general. It’s really frustrating I check wheel bearing and they look fine.
I even put back the OEM wheels and still the same... anybody with the same problem and got it solved? Thank you

 

Was the driveshaft removed at some point in time? It has to bolt to the differential in one particular orientation.

 

Not totally remove , when I got it I got a click y noise when I go slow, and I seen here how to fix it it just need a bit of special grease in the part of the wheel not inside, I’m sorry I don’t know how it’s called in English 😂😂But it went , it’s possible I put it back wrong?? I didn’t pull it totally out

 

I had to replace my differential a few years back. so in the process, I changed the drive shaft out to a one piece aluminum one, and all the differential pushing to solid ones. installed the Z1 inserts into the subframe bushings. I end up with a high speed vibration that ruined all the positive effects. I researched driveshaft Pinion angle and found mine to be out of spec. I end up shimming the front differential mount about 3/8" and it corrected the problem. I have this car well over 100 mph plenty of time and haven't had any vibration. I noticed you never took your drive shaft out.
In this process I found there is a specific side of the universal joint that the nuts have to be on to seat properly. Mine were not . I have a theory that had something to do with my differential going bad in the first place . to long of story.
Now when I am checking for vibration after wheel balance and drive shaft balance I check driveshaft pinion angle also.