Well, I just purchased a set of four new tires.

I went with the Hankook V12's. I am skeptical if it is in fact the mismatched tires, but I will find out with these first.

I'll be happy as hell if it is though.

 

Well.. Throwing tires at the problem didn't work.

I have a wonderful new set of Dunlop Star specs which I can't drive on until this is fixed.

It appears to be the left rear bearing. I had previously replaced both already with my mechanic. Funny thing is, I took it back to him last season he torqued the center lug and it seemed to be a non-issue and we didn't replace it.

The nut must've backed off recently and now there is a bit of play without load on the tire, which wasn't there. Can't be sure if there are any other issues, but after tire install the car felt a bit better until the bearing wiggle reared its head.

Why would my car be eating through bearings so quickly?

 

Just fyi if the axle nut comes loose allowing the bearing to separate, it technically wasnt the bearing that failed.

When your mechanic cranked the nut back down, it re-seated the bearing into itself, but likely there was some damage or wear from running in the compromised state, which leads to premature failure of the part.

Your mechanic need to give the nut a really good crank, and make sure the threads are clean and dry.

 

^Well, I am not entirely sure if it wasn't the bearing, or the nut, Initially.

I don't believe that simply tightening the nut will alleviate the issue either, at this point. Is that what you meant?

 

Pretty much cant be 100% sure but I am almost positive your axle nut came loose first.

I personally would never re-use a bearing that has been loaded while not fully seated, but in reality if the bearings and races werent damaged it should technically be fine. The problem is you can never be sure.

The issue is likely a combination of not enough axle nut torque, oily/greasy spindle threads, and off chance a hub that wasn't completely pressed into the bearing (believe it or not the bearing has a specified pre-load...rotating toque less than 17 in/lb at 11,000lbs pre-load). When torquing the nut on the car, it helps to take it to min spec with the torque wrench, then use the impact to take it home. If the splines on the hub or driveshaft are dirty (eg. from left over crusty grease), you may get to min spec but still have some play in the shaft. Thats why I like to use an impact (very liberally) on axle nuts to make sure everything is good. It is also advisable to take a test drive then jack it up and re-torque the nuts in case anything shifted, which your mechanic probably didn't do. This is one area where over-torquing would be quite difficult.

 

I am at a complete loss. The loose bearing was checked visually and spun manually for any hum and no issue according to a local shop today.

The axle nut was retorqued and alignment checked. Rear was ok, but I dont have front camber arms. I dont know if that would be the "floaty" wiggle and instability i am getting?

Bushings checked visually and appear ok. What the hell else can it be?

I need to diagnose and fix this damn thing.

 

Still haven't seen alignment numbers come back.
This rear toe can easily cause an uncomfortable level the back end not feeling planted, especially if you are low enough that the sweep of the toe arm has past the parallel point, and adds toe out as the suspension compresses further.

 

^ I just spoke with the tech and the rear alignment is and overall was in spec. I don't have the actual #'s.

I am thinking it is either a bearing, bushing or shocks.

 

don't take alignments at "face value" always get the numbers, and always watch the tech unless it's someone you know is precision oriented.

I can't tell you how many times i've heard stories of techs cheating the machine by leaning on a corner, and hitting the freeze button.

 

I really don't think the alignment is the issue. Feels more as if something is loose, be it, shocks, bushings, etc..

The axle nut was backed off recently after my tires were put on this weekend which is why it really was wiggling, but I doubt it was that way very long before being discovered.

point is, it ain't the alignment.. Just read through this thread(basically same issue)

https://my350z.com/forum/maintenance...ht-line-3.html

I don't have the car back to test it after retorquing the nut, but we'll see.

 

Op, do you have access to the original wheels/tires? I seem to recall that in earlier part of thread, you said "no issue with the originals" or somesuch.

This is clearly a process of elimination - from our outsider's view because even after all this, I'm not sure I completely understand what you're experiencing.

Only thing I can think to recommend at this point is to take it either a Z specialist or a really competent suspension shop. No one here can do much more besides guess, without driving and/or putting hands on the components.

 

Mic,

Well, I do have the closest thing to the original with the new tires I just purchased. Dunlop Star Specs which is a pretty stiff sidewall tire all around.

I suspect the axle nut/ bearing could be part of the issue. As it had backed off there was play in the left rear wheel and it had been clearly creating movement side to side.

Now that the axle nut has been discovered and retorqued, I am not convinced the bearing isn't damaged or still at issue. There is still a slight unsteadiness to the car at highway speed only if I give it inputs left or right. It is less noticeable now.

I just have to know what to troubleshoot so I can fix it. It's pissing me off, since most common things have been checked. In BMurray's thread above, he went through every suspension part only to come back to the Bearing which was at fault.

Every time I have experienced this wiggle it has been either, a wheel bearing( replaced left and right previously) or the diff mount which also has been replaced.

Do I think that bushings all around, would help, sure, but I don't want to throw money and guess and have wasted effort to have the issue still remain.