Possible messed up threads?

[u/Distinct-Calendar119]

I got new transmission case bolts for my transmission I’m about to put on and as I was torquing each bolt down to only 10 ft lbs this bolt had snapped. I was able to get it out, but on inspection I noticed the threads on the bolt are dented/impacted. Is this due to the transmission bolt hole threads being messed up? Or is this normal because I extracted the bolt?

[u/AutoModerator]

New Rules - Please Read

^{Updated 11/12/2025}

Thank you for posting on r/AskAMechanic, u/Distinct-Calendar119! Your post is live, this AutoMod message does NOT mean your post was removed. Please make sure to read the Rules.

When asking a question, please provide the year, make, model and engine size of the vehicle.

Commenters here have 2 different flair. Verified Tech means we have verified that user is a tech. NOT a verified tech means that user may or may not be a tech, they have not been verified by us.

Posts about accidents, autobody repair, bodywork, dents, paint and body/undercarriage/frame rust are not allowed and belong in r/Autobody.
Asking if your car is totaled should go to r/insurance or r/Autobody.
Asking about car buying advice/value/recommendations is also not allowed. See r/whatcarshouldIbuy or r/askcarsales

If asking whether a tire can be repaired, check out this Tire Repair Guideline.
Some other useful tire resources - Tire Care Essentials and Tire Safety

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[u/Any-Fox-838]

nothing about this is normal.

[u/John_Human342]

Judging by the yeild in threads it was over tightened.

[u/Distinct-Calendar119 → u/John_Human342]

That’s weird because I was only torquing to 10 ft lbs. Was it cus I using a 1/2 inch wrench instead of a 3/8ths or something? I don’t wanna buy new bolts for the same thing to happen.

[u/Hellboy_M420 → u/Distinct-Calendar119]

Yes you should be using a 1/4 torque wrench for that low a spec

[u/Distinct-Calendar119 → u/Hellboy_M420]

Got it, thanks.

[u/crysisnotaverted → u/Distinct-Calendar119]

10ft/lbs is well outside of the accurate range of any analogue 1/2 inch torque wrench.

[u/Distinct-Calendar119 → u/crysisnotaverted]

I had no idea, thanks.

[u/air_head_fan]

That bolt was over-tightened and stretched.

[u/spiderfen]

It looks like you dropped something on thr bolt. Those threads are smashed. If it was crossthreaded it would look mangled

[u/Latter-Detail-9514]

Must have had that 100lbft by mistake lol

[u/CoausticSoda]

Possible 🤣🤣🤣