Lug studs too tight - PeachParts Mercedes-Benz Forum

dlssmith · #1 04-03-2007, 10:47 PM

I torqued my lug studs properly and carefully, and with never sieze and now can barely get them off. The mechanic broke one the other day and it had to be drilled out.

Do the threads stretch? Should I just replace all of them? This is on the 210.

log673 · #2 04-03-2007, 11:08 PM

Just find a way to extend your ratchet, and it should come off. I had a problem like that once. I just took this two piece kayak paddle that I had, and attached one end to to my ratchet and got the bolt to turn.

300SD81 · #3 04-03-2007, 11:19 PM

Broke 2 ratchets taking mine off after going to a tire place... Breaker bar and 8ft metal pole got it off

#4 04-03-2007, 11:28 PM

The never-sieze reduced the friction on the threads enough so that you torqued the wheels to a much higher foot pounds or NM value than what your toque wrech was set at. That's why you should never use never sieze on lug bolts, or any other bolts without calculating a lower torque figure.

Heat is going to be your friend, along with a long breaker bar. Do not let anyone use a impact wrech to try and remove them, just be patient and try doing it with the car on the ground and the parking brake set firmly.

log673 · #5 04-03-2007, 11:40 PM

I read some quote somewhere that went something like this, "Give me a bar/rod/lever long enough and I can move the world." Just remember that. If it doesn't move, then make your extension longer.

Ferdman · #6 04-04-2007, 05:08 AM

John, I always use Never Seize on lug bolts when I torque them and they loosen easily with a lug wrench when I need to rotate wheels or replace brake pads. Our indy applies a thin coat of white grease on all lug bolt threads to avoid rust issues. Have you experienced firsthand a specific problem with Never Seize on lug bolts, or is it something you have always heard? Consider that torquing lug bolts without Never Seize and rough threads you're achieving the torque value due to increased thread friction and not necessarily providing the proper clamping force to secure the wheel to the hub.

Hirnbeiss · #7 04-04-2007, 06:50 AM

The problem is probably Northern Iowa with its winter and salt having conspired to corrode the lug bolts.

Hatterasguy · #8 04-04-2007, 10:18 AM

Quote:

Originally Posted by Hirnbeiss

The problem is probably Northern Iowa with its winter and salt having conspired to corrode the lug bolts.

Bingo I think thats it.

I have been using never seize for years on various lug bolts on various MB's and have never had a problem.

Matt L · #9 04-04-2007, 10:24 AM

I third the recommendation for anti-seize on the lug bolts or nuts. I have *always* applied this and used a torque wrench to tighten them, and have never lost one.

It is atypical for a torque to be given for a dry surface. The engineer would have absolutely no idea how much friction would be given by the threads, and thus wouldn't know how tight the bolt was for a given torque.

We don't rely on friction alone to keep our fasteners tight. The torque values are computed to give a bit of elastic deformation to the metal. That's what keeps things together.

lkchris · #10 04-04-2007, 10:30 AM

Lubricating the wheel mount bolts creates erroneous torque readings and they get overtorqued.

Mercedes prohibits this.

BTW, 110nm = 80 ft-lb.

Best defense might be regular tire rotation.

Those living in snow/salt areas might consider "exercising" wheel bolts as just another thing you have to do to fight the rot.

Matt L · #11 04-04-2007, 10:35 AM

AP40.10-P-4050Z

"The round contact shoulders on the lug bolts must be free of oil and grease. Bolts with damaged threads, worn zinc plating on the radius seat or corroded radius seat must be replaced, otherwise they may shear off."

Hatterasguy · #12 04-04-2007, 10:39 AM

I suspect the more important reading with lug bolts is stretch, because after all that tensions your wheels.

Would anti seize affect the stretch reading? I have to say no, I have always used a 1/2 drive torqe wrench to tighten the bolts, and an 18in breaker to pop them, never had an issue.

#13 04-04-2007, 10:57 AM

Quote:

Originally Posted by Ferdman

John, I always use Never Seize on lug bolts when I torque them and they loosen easily with a lug wrench when I need to rotate wheels or replace brake pads. Our indy applies a thin coat of white grease on all lug bolt threads to avoid rust issues. Have you experienced firsthand a specific problem with Never Seize on lug bolts, or is it something you have always heard? Consider that torquing lug bolts without Never Seize and rough threads you're achieving the torque value due to increased thread friction and not necessarily providing the proper clamping force to secure the wheel to the hub.

Lug nuts have a manufacturer's recommended torque that is given for a DRY thread. There is a reason for this. The following chart represents the torque required to produce a given bolt (or stud) elongation:

Effect of Lubrication on Torque
Torque Rating in Foot/Pounds
Lubricant on a ½-13 thread/inch bolt
NO LUBE, steel 121
Plated & cleaned 90 (26%)
SAE 20 oil 87 (28%)
SAE 40 oil 83 (31%)
Plated & SAE 30 79 (35%)
White grease 79 (35%)
Dry Moly film 66 (45%)
Graphite $ oil 62 (49%)

Something like 80% of the torque goes to overcome friction. So, if you lubed the threads and torqued the nuts to "dry" specs, you would be overtightening the fastener to some extreme....probably past the elastic limit.

One should NEVER use anti-seize on lug nuts. Anti-seize naturally reduces the friction between threads and can lead to vibration induced torque relaxation. Not a good thing. I believe most any wheel manufacturer will say the same thing. I know that Centerline states that in their assembly instructions.

softconsult · #14 04-04-2007, 10:58 AM

I am not an Engineer, but I did work as a sheet metal mechanic at Boeing aircraft years and years ago. In the basic training class they definitively explained that the main contributing factor in torquing fasteners was the surface area under the bolt head. They said that this area was far more of a friction contributor than the threads. This was with new fasteners, but I suspect the relationship is true for lug bolts.

I don't recall ever having a lug bolt being that tight. I don't us anti-sieze, and never have a problem. Frankly the 80 NM doesn't seem like that much torque when I tighten the lug nuts with my torque wrench. I would think you really would want to use anti-sieze sparingly and never get it on the contact surface between the bolt and the wheel.

Steve

Ferdman · #15 04-04-2007, 11:14 AM

Matt, I agree that no lubricant should be applied to the shoulder of lug bolts. I apply a thin layer of Never Seize with a cloth to the last 1/2" of threads on each lug bolt. My experience is the same as yours ... have never had any problems loosening lug bolts torqued to 80ft/lbs. On the other hand I've sheared off a 1/2" to 3/8" reducer trying to loosen lug bolts that a MB dealer tightened with an impact gun. Now when I go to the dealer for PA State Inspection I request that they inspect brake pad thickness without removing the wheels.