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[cmichaelo]

And so it happened again, even after I told the same BMW MT Kisco, NY shop to **NOT** over torquing the wheel bolts like they did on an earlier occasion.

But after coming home from the shop I decide to see how much torque it requires to remove the bolts.

On the fronts I could remove them at about 125 lb-ft.

On the rear I needed 160-170 lb-ft.

Only 88 lb-ft is required to tighten the bolts (this is on an E92 M3).

I of course called to complain, and they told me to come in so they can verify which I will tomorrow.

Right now I'm curious though..

At which torque point do the bolt and hub threads start to shread off or the bolt itself weakening?

[Denny347]

The bolts and hubs are a LOT stronger than the 88-89 ft/lbs specs. It has more to do with warping your aluminum wheels than the bolts. Steel wheels don't need to be so careful. I wonder if you are not mistaken about the shop over tightening your wheels. Aluminum wheels and steel bolts heat/cool at different rates and expand/contract differently. That difference could be what is causing the tightness you are experiencing. 88 ft/lbs seems low for such a critical connection between road and vehicle. Maybe engineers recommend the low ft/lbs knowing that with use, the bolts snug up to a tighter spec.

[Ngilbe36]

Just something to keep in mind. The initial torque required to loosen a bolt does not equal the value it was torqued to. Lots of variables at play here like static friction vs. kinetic, differential cooling, etc.

[Scharbag]

Originally Posted by Ngilbe36

Just something to keep in mind. The initial torque required to loosen a bolt does not equal the value it was torqued to. Lots of variables at play here like static friction vs. kinetic, differential cooling, etc.

Very true. One way to check is to use a good torque wrench to tighten to 90 and then see how much torque it takes to remove them in your case. Perhaps you could do that right at the shop using their torque wrench?

Corrosion of the bolt seats and threads will also play a big part. I typically run a thread chaser through my hubs from time to time to knock the swarf out of there. I also make sure that the bolt and wheel seats are clean and smooth. A little brake clean and a rag works wonders. Avoid WD-40...

Happy motoring!

[pbonsalb]

But it does seem odd the OP needed 125 to remove front and 170 for the rear. It does take more to loosen than the tightening spec of 88 but you would think front and rear would loosen with similarly greater torque if tightened to identical 88.

[cmichaelo]

Thanks for the feedback.

I think you're correct that they perhaps didn't [grossly] over torque the bolts. I went back to the shop to complain and demonstrated that on some of the bolts I had to reach 180 lb-ft (on my uncalibrated torque wrench) before the bolt gave way. The shop mgr explained about "break away torque" and "rusty" bolt and that could explain why I needed so much torque.

Now I'm sympathetic to and understand all that. Even so, I've been working on my car and other cars wheels for 25y, and never have I had to use this much force to take a wheel bolt off.

I literally I had to put most of my 175 lbs body weight into making the bolt come loose. So some of these bolts where definitely over torqued.

The good thing is that no damage appears to have been made to even that one bolt that was extra tight. And according to the shop mgr, the lug threads are the first to shred off, i.e. before the hub. So that was a relief.

[ItsGary]

Luckily it wasn't a lock bolt. I broke two keys and the dealership broke two keys from trying to get it off due to an incompetent shop that did a wheel repair after my accident.

[aus]

I change wheels between track wheels and street wheels and always tighten to 90 ft-lbs. I can always loosen the bolts set at 90 ft-lbs using the same torque wrench, just flipped to tighten the other direction.
I know I should use a breaker bar, but it's a $20 Harbor Freight unit so I don't bother.
.

[Richneerd]

I carry a breaker bar and a torque wrench in all my cars. Along with other tools such as a battery jump starter, coil over adjusters, medical emergency pack (I know my E39 and E46 had these under the passenger seat.)

I always torque at 88 lb-ft.

If a shop is putting on my wheels I supervise them. Just a habit of mine, works wonders!

[dparm]

Something to consider is giving the shop a torque stick and telling them to use it. At least that way you will know it's probably fine. Hell, even Discount Tire uses them...

I do something similar -- I give them my plastic-sheathed socket so they don't scratch the wheels. Never gotten any pushback from them.