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I previously asked this question as my passenger side wheel fell off with a broken stud. What can cause a wheel to fall off/hub to break?

After repairing it the mechanic checked the other wheels and said he found the driver side stud had snapped as well(though the wheel hadn't fallen off). He said he recommends I should replace all 3 hubs or all the studs on the other hubs.

1) What would have caused the passenger side stud to snap too, would it again have been loose nuts(none of which have fallen off as far as I could see) or would the impact from the car falling to one side cause the driver side stud to snap too? what would have caused it?

2) Is the mechanic right in telling me to change all studs rather than just the snapped ones, I think he is suggesting the may have rusted away but I don't remember seeing any rust or maybe he is saying they could the accident could have impacted all the studs?

3) Shouldn't the mechanic have checked all studs and further damages before fixing the first hub or, given the situation, is it normal to unravel things as you go?

Thanks

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    Re 3) No, he was probably asked to fix one thing - so carrying out a full inspection of every nut and bolt on the suspension just because he was told to fix one stud / hub and he won’t be given the time for that and you would not want to pay for it either. How does “you asked us to do X, and while we had it we did Y and Z so now your bill is A... – Solar Mike Aug 17 '18 at 17:36
  • @SolarMike well I did ask him to check all studs in light of what happened however he repaired one first then looked at others, so I was wondering if that would be considered normal practice considering the situation. – James Wilson Aug 18 '18 at 0:49
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If you have 2 snapped studs then the last tire tech working on your car over torqued all your wheel nuts. The ones not snapped are probably stretched. They stretch and then fail. I'd replace them. And use a torque wrench in the future, not an impact gun.

  • Are you saying I need to change all studs on the two wheels which had broken studs or all 4 wheels since they may have worn studs. You say it was the last tech but could it be the last tech torqued properly but it was a previous tech that didn't torque properly. Relating to this i'd be grateful if you could answer this question: mechanics.stackexchange.com/questions/58038/… thanks. – James Wilson Aug 18 '18 at 3:10
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If the fracture is relatively flat across the stud, it was very likely caused by loose nuts which led to fatigue failures. I would replace all studs on the affected wheels because they may have also started to fatigue .And the additional cost of replacing 4 instead of one should be a modest increase. A proper inspection for small fatigue cracks would cost more than the studs ,and a local garage could not likely do it. Rust has nothing to do with it.

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I've previously replaced studs on a Mini when changing from steel to Dunlop D1 alloy wheels. I needed a slightly longer stud.

If I remember rightly, I bought a bag of 20 new studs for a very nominal amount of money and fitting them didn't take long at all.

Could you replace just the broken studs? Yes. Would this be acceptable for the UK MOT? Yes. Will another stud break in the future? It's impossible to be sure.

I'd suggest checking the price difference between changing just the broken stud and changing them all and making your decision after that.

I'm not sure why he'd recommend changing the hubs themselves.

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