Hi Nick!
While I don't have an FX50, I'm going to try to see if I can give you pointers. Based on what you wrote, you feel the sticking and jumpiness on the steering wheel itself or on the car's body?
Trying to isolate if the issue is on the front end or the back end of the car. You'll feel these types of issues more when the car is stationary or moving slowly because the wheels will be under more tension with the ground when turning than when the car is moving faster. Basically the rack and pinion has to force the tires to break loose of the ground in a shorter distance versus over a longer distance.
I don't think you have a major issue but I'm going to list out a few things to check or see:
- First thing that usually goes bad on all Infiniti's is the lower u-joint that connect the steering wheel to the rack and pinion. You can see this u-joint if you look through the driver side wheel well above the front axle to the back of the shock/strut/coil. You'll see the rack and pinion and then above it immediately is the u-joint. This u-joint is exposed to the elements and causes the ball bearings to corrode/rust and gets to a point where you can feel a rough/hoppy/jumpy/sticky sensation. These aren't expensive, not a lot of work to replace. I'd consider this almost routine maintenance. For reference, part number is 48080-EG000 for the u-joint and
48935-4P00A for the two bolts. Always use fresh bolts. Never mix rusty bolts with new parts. These come pre-greased but there's not that much grease to keep is from going bad again. When I replaced mine, it looked rusty. I was able to confirm it was bad by doing a few things. a) looked rusty. b) while the front end is up on jacks, car not running, hand above u-joint and have someone turn the steering wheel left or right and see if you feel grinding/popping. Or use a stethoscope or strew driver against it and your ear to hear if it's grinding. That will confirm it. There's another u-joint higher up but that's inside the car under the driver side dashboard and those usually don't fail.
- The rear steering is electronic versus hydraulic as the front steering...looking at the part itself, from what I can see it only moves a few degrees of travel. Can the rear active steering be disabled? I believe there are options to disable it. That way you can isolate the rear from the front and see if it keeps happening and if so, then its the front. I still think it's the part above.
- I doubt it's the balljoints on the front upper and lower control arms because those are designed to have a metal ball that works inside teflon. The eventually loosen up and start popping/knocking over bumps, stops, turns. Worth checking..
- One last thing I'm wondering is if the front rack and pinion is slightly shifting on the front subframe. Mine is a 2012 and all 2012 or earlier had this issue eventually. I had it done under warranty at the time. Basically just needs this new upgraded aluminum mounting plate. The plate was upgraded to include a piece of material that stops the plate from shifting. Nothing expensive, easy to swap. May need an alignment after depending how good the mechanic was in keeping the rack in the same spot. Usually how you check if this is the issue, you put the car in park, hold the brakes firmly and turn the steering wheel left to right and listen if there's a pop sound. For reference, part number is 54442-1CA0B from what I can pull up but definitely double check if you need this replaced.
Hopefully this helps!
