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Broken Lug bolt - dealer parts guy not surprised!

20K views 81 replies 24 participants last post by  Danver 
#1 ·
Really! In all my years of working on my vehicles, accumulated over a million plus miles, and I have NEVER broken a lug. I hand torque to spec. on top of it!

I was removing the lug nuts to rotate the tires and one got stuck. It cross threaded itself and then broke off. WTF? So now trying to het the rotor off the front, which is stuck, to replace the broken lug bolt.

Why is the parts guy not surprised? Are the metals used in Subaru parts sub standard? I have already had both rear hubs replaced due to bearing failure. Fits the substandard metals theory. And it is all not acceptable!:surprise:
 
#50 ·
It's highly unlikely Subaru manufactures stud or nuts. They have/create a spec, and negotiate with manufacturers that produce them to supply the assembly lines. I suspect other car makers probably buy from the same supplier that seems to have improperly plated/treated the inside of the nuts.

I do hope people are registering their safety-related problems at NHTSA.
 
#51 ·
Gorillas playing with air tools set to max torque.
When I request that the gorilla .HAND TORQUE the nuts/studs I get a quizzical look. Then I watch the gorilla wander about to find his 24" torque wrench.
They get paid by the hour or flat rate, speed matters.

I spray a bit of oil on the studs or bolts(German cars) and start the nuts/bolts by hand right up to the wheel.
Torque them in the air, drop the wheel to partially engage the ground, re-torque, fully weight the wheel, check again.
 
#52 ·
I spray a bit of oil on the studs or bolts(German cars) and start the nuts/bolts by hand right up to the wheel.
Torque them in the air, drop the wheel to partially engage the ground, re-torque, fully weight the wheel, check again.
The oil you put on the studs can have an effect on the actual torque that you are ending up with.
 
#60 ·
It's amusing that your very first post on this site is about this lug nut issue and that you're doggedly persistent on it. Is there some backstory here?
 
#64 · (Edited)
I find it hard to believe that rust in the area shown could be responsible for a broken stud.

What would be the mechanism for this? Tires are gonna get rotated regularly, then replaced occasionally. I can't imagine that rust making a bond strong enough to withstand the torque delivered by the emergency wrench or a breaker bar or ????

I do think, as pointed out by someone else some time ago, allowing an impact wrench to 'ride' on the final thread during removal could 'set-up' a scenario leading to cross threading.

no broken studs across my 2 cars. One of them has been to 3 track events.

Not saying people are imagining broken studs. But I see no evidence there is a manufacturing/assembly problem unique to Subaru.
 
#67 ·
Paul, your point about CONTAMINATION is spot on. It may not be that the rust buildup on the end of the stud expanded to impede removal of the nut, but if/when you get dirt or rust inside that nut, it WILL bind up. Often times it will "sing" to ya with a screech as it binds.

Ya gotta inspect and clean up the studs and nuts. boys, and hand start/tighten these nuts as far as possible on the studs before you hit em with the tire iron or air tools.

I recall my Gen 3 OB with aluminum wheels used CAP NUTS instead of open nuts, ditto my '17 Gen 5.
 
#68 ·
I am in the habit of wiping (often wire-brushing) the studs off before I install the wheels but, I doubt many shops take the time to do that. You'd be lucky to see them wipe the studs.

But, after the wiping, are you saying the contamination gets on the threads during nut installation?

Removing the nuts would act as a thread chasing treatment so, I guess the particles would need to drop onto the threads as you approach with the nut? Anyway, I can't see that happening with any great frequency. And then, I spin the nuts on with my fingers - so, this rust particle contamination theory has to allow for that to take place 'without warning'/easily I guess? And then the rust particle seizes everything during/after torqueing?
 
#69 ·
Biggest reason for broken lugs is over-tightening them, plain and simple. Our lugs call for around 90 lbs or torque, not the 120, 130, or more, that most air gun jocks apply when rattling the air-gun on the lug.

That said, my GMC Envoy went through a good 8-10 lugs, during the time I owned her, frequently enough that I bought an entire box of lug nuts (tempered) to have on hand, when I went to rotate the tires. (Factory lugs were really too soft). Haven't had any issues with those on my '12, and I've been rotating the tires myself most times, using my DeWalt 20v Max impact wrench, then final tighten with a torque wrench.
 
#73 ·
Yeah, this seems like a bit of a stretch, not sure it adds up to me. I've read several similar threads here and on other forums and the most probable cause always seems to be careless service people. I've got a combined 300k miles on 2 Subarus and have never had any issues (but I have had obviously over- and under-torqued nuts on a few occasions).
 
#75 ·
@subownerPaul I think your claws are dug too deep in this issue. It is what it is. I've had 4 Subarus and never had a stud break. 1994, 2005, 2011, 2020. If you had 6 studs break I understand the frustration and looking for an explanation, but minor rust inside of a lug nut, not on the threaded portion, I am certain cannot generate enough binding torque to break a wheel stud.

I'm not an engineer but I play one on the internet.🤓
 
#77 ·
In Paul's defense I've seen rust, salt residue, sand, "brown rusty moisture", even Loc-Tight in the threads of some OLDER Subies with steel wheels.

I'm gonna write off all these broken studs to defective materials combined with gorilla torque. I've even had to use heat and a cold chisel on lug nuts(steel wheels), never on a Subie, however.
 
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