2006 M45S Wheel studs breaking

[Court]

To all,
I have a 2006 M45 Sport with 155k, stock rims. I have had wheel studs break on all 4 tires within the last 20k miles. I have replaced all of them on the entire vehicle, as most looked old and rusted out (One rear wheel, the first time this happened, had 3 that sheared off and luckily I was at a low speed and felt the wheel bobbing crazily). I also replaced all the lug nuts. Even after replacing them, and using a torque wrench to exactly 90lbs, I just removed one of the rear wheels, after no problems for 6 months, and two studs broke as I took them off (with a wrench, not using any air tools). The other lug nuts came off easy with little effort, leading me to believe that they had come loose from the 90 ft lbs that I set them at last February. Weird ?

When the problem began to occur, I thought it might be shock/strut related, thus I replaced all of them. I have also replaced rotors with slotted/drilled and new brakes. I don't feel any shimmies, even at high speeds, from any of the wheels. I have measured the rotors and they are an EXACT match down to the mm of stock.

So, I remain perplexed. ANY idea what is causing this ?? Bad tires, bad wheels ?? Anyone else experience this problem??? Driving me crazy.

Any help and your time is much appreciated.

[bicsintegra]

I just replaced broken studs at about 90k miles, then at about 125k miles I got new front hubs and have not had a problem since. but then again that was only 3.4k miles ago. is your car lowered?

[kmiles]

I didn't have any problems with my wheel studs until I started buying tires from Discount Tire - their air wrenches were cranked so high that they were cracking multiple studs off on my M35x. I switched back to Costco Tire and haven't had a single broken stud since then.

[amc49]

When you change studs you MUST ensure they are the correct ones, some in the catalogs will seem to fit but that last .010" of pilot OD will NOT go into the holes with the correct pressfit. Then they will always be loose and tend to break over and over............you need a total of around .005" interference fit to go in right and still last.

I say that after changing studs on 200 mph race cars with zero issues.

[steve_c]

When you change studs you MUST ensure they are the correct ones, some in the catalogs will seem to fit but that last .010" of pilot OD will NOT go into the holes with the correct pressfit. Then they will always be loose and tend to break over and over............you need a total of around .005" interference fit to go in right and still last.

I say that after changing studs on 200 mph race cars with zero issues.

I agree with amc, you need to check that you are using correct studs & nuts, in both fitment & quality.
I would go straight to Infiniti to purchase these items.

One clue you gave is you stated you broke a stud while removing.
Only a few possibilities for that occurring, among them over torquing.
Was the stud stretched or the nut stripped from over torque?
Maybe the torque applied was OK, but the stud/nut was of inferior quality & could not accept the torque applied?
How is your torque wrench, what type is it, how old is it?
Torque wrenches are precision tools, maybe yours is not calibrated correctly!
A few other possibilities, (amc covered correct studs & nuts) so if it were my problem, I would start with correct OEM nuts & studs, followed by proper torquing with known good accurate T/wrench.
In any event, you have a serious issue at hand, so stay on top of it!

[Court]

Wow, that is great news. I totally think that may be the issue. Maybe just a discrepancy between those lugs and studs. I have not experienced any appearance of the studs stretching or any stripping. They look brand new, as they are. I have noted that the stud holes on my wheel appear to be a bit tattered..which is a clue to the possibility of some play and movement that may be putting extra pressure on the studs. I feel like I've got a good torque wrench, as I've done most of the work on this veh myself..shocks, struts, brakes, starter-- (never again by the way..don't attempt this!.suks) but that is worth checking too. I always check discount tire as they are prone for over torqueing ..they have put my lug nuts at 110 before.

Nope, car is not lowered, it's all stock and I'm an old man, not a drifter. Nothing outrageous going on, but a lot of fast freeway driving.

Really appreciate everyone's input. I will head to Infiniti, get correct studs and lug nuts and probably replace one or two rims as I said, the stud holes may have been slightly bored out due to the breakages. Hope that fixes it. Weird that I went 130k+ with no issues. This has been quite the weird problem.