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I've never seen a stud break in my life. With cars new up to 15 years old, the tires have been taken off hundreds or even a thousand times.

I went to a car shop in Mexico that said my brake pads need changing, and after changing them I measure the thickness at about 8mm, or way before (5mm of 12mm new left) needing changing.

Then I discovered that 3 studs were broken by them. They replaced them free but while replacing them, the studs keep breaking every time they take off the wheels to put the new ones on.

This has happened about 8 or 9 times. He is tightening the lug nuts by hand, but the first three that broke, must have been tightened by someone else. What is causing this? Should I just pay another mechanic or risk having it done free and keep breaking?

More details, I watched him un-screw it and what happens is while unscrewing the lug nut becomes jammed between two degrees say between 9 and 3 o'clock. He then has to use more force and the stud then breaks.

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  • What car do you have?
    – HandyHowie
    Jun 17 '20 at 8:31
  • Are you saying that even the new studs are snapping?
    – HandyHowie
    Jun 17 '20 at 8:32
  • @HandyHowie That's a great question that I should've asked. If it's only old studs, obviously it isn't this mechanic's fault, it's the one before. The store ran out of studs, so when I go back with the new ones this time I'll find out.
    – user5389726598465
    Jun 17 '20 at 8:45
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    New studs could be much lower strength "hot rolled" steel instead of Q & T low alloy. Also , an improper surface may make them prone to galling . A phosphate treatment is usually applied to prevent galling ( typically flat black color).
    – blacksmith37
    Jun 17 '20 at 19:15

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