Snapped off lug bolt from rotor do I need to replace rotor?
 

I was washing my car this morning and to my shock I noticed that one of the lug nuts off the rear passenger side wheel was missing. After closer inspection I could tell that it was sheard off some how. I plan to take the car to the dealer but wanted some insight from the group if the lug bolt itself can be replaced or am I looking at needing a completely new rotor (Z51) and lastly if a new rotor is required would I need to replace both rear rotors? The car only has 8,000 miles on it.

Thanks

Not sure about the C6, but typically you should be able to just remove the rotor then press or tap out the broken stud. The studs are a mild press fit and usually splined. Install a new stud with a press or use a lug nut with washers built up to pull the new stud into place.

I'm sure someone will chime in with info specific to the C6.

Oh and in the future don't gorilla torque the lug nuts.

:iagree:

Lay off the steroids, Barry!

Rotor against bolt...rotor wins
 

Take rotor off, put in vise with undersize socket, tighten vise, reverse with large deep socket over threaded end of bolt, clamp down.....done deal.....:D :cool: :D

I think you guys are missing something important. The studs are not part of the rotor.

The good news is that they are easy to replace.

:iagree:

I would also want to find out why the stud sheared off, most likely over tightened but could be something else too.

I am sure you know never oil the wheel stud threads. The 100 lb-ft lug nut torque spec is with "dry" threads. If one oiled the threads the resulting clamping load (and tension in the studs) increases exponentially with the torque.

Also, ALWAYS use a qualified torque wrench.

Some people also don't know that the longer the "extension" you use, the more you are multiplying the torque.

Once again I am using the :iagree: sign with one of jschindlers posts

Huh? The length of the extension (from the socket to the wrench) has no effect at all on the torque applied to the lugnut.

Now, if you use a longer wrench, you can apply a higher torque with less hand force, but a torque wrench will "click" at the same torque level, no matter how long the wrench handle.

:iagree: :iagree: :iagree:

Correct. It's a warranty problem, and Mr. Goodwrench won't argue about it. :thumbs:

Thanks guys for info I am glad the stud can just be replaced and I will be asking why it snapped off.

You might as well ask them the meaning of life...they won't know the answer, and if they say anything it will be direct from the "nether regions".

Write it off to "defects in materials or workmanship", and be sure that everyone that changes your wheels in the future torques the lug nuts to 100 ft-lbs. I can't see it being over-torque...it was most likely just a faulty stud. Stuff happens.:thumbs:

Whiskey Tango Foxtrot?

That's what I was taught in school many years ago. I have no way of measuring it, so I'm going by what my auto mechanics teacher taught us.

EDIT- I just did some googling, and it appears my teacher was wrong (or a lot of other people are). Damn, no wonder I went into sales instead of becoming a mechanic :yesnod:

Ah, you were thinking about the hot new chick in school instead of paying attention...he was talking about the length of the wrench handle. :lol:

:iagree: All the cars I ever worked on the wheel studs were pressed into the axle flange, and the rotor simply slid over the studs. April of '06 at the Birthday bash in BG the GM guys took my car to the factory and replaced all four rotos. They never had to mess with the wheel studs. :)

Thanks for jogging my (old) memory. I think you are right, I confused that with the "angle of the dangle, and heat of the meat" theory. That was a long time ago :yesnod:

A radial extension from the socket driver end of the wrench to the nut , such as a crows foot, will increase torque on the nut. Maybe that's what you are remembering your instructor saying?? :cheers:

The studs are pressed into the axle flange, the rotor goes over the flange. The wheel goes on next. The nuts hold it all together. Now... torque is not changed by the length of the extension as long as the extension is from the socket to the torque wrench. The addition of a longer handle on the wrench (Cheater bar) would NOT alter the torque settting although it would make it easier on the user. An extension that offsets the torque wrench centerline however would alter the torque. Mechanics 101, Bedrock City H.S. shop manual.:rofl: :rofl:

Yubba Dubba Dooooooo :lol:

Using an extension will NOT effect a torque wrench, but it can change if you are using an impact wrench.

Almost all broken studs are related to either over or under torquing. If you've had any wheel/tire/suspension work done, I would be extremely suspicious that something was done incorrectly.

On the rear, the stud is blocked by the park brake cover. Quite a bit of dissasembly is required, but you can easily be pressed or tapped out.

Yes, I remember that old theory. Haven't heard it in many moons.

I think it goes like this:

" The angle of the dangle is inversely proportional to the heat of the meat, provided the temperature remains constant"

BTW, it has been proven to be true :D


augydog :cheers:

Torque fundamentals 101
 

Torque is a measure of distance * force. In the American automotive field torque is usually measured using the units feet and pounds or inches and pounds. Given a constant amount of force (how hard you are pushing), increasing the distance (length of cheater bar) will result in a greater amount of torque assuming there is not a limiting mechanism such as that found in a spring type torque wrench. If a cheater bar is added to a plain ratchet wrench, then pushing on the cheater bar with 100 lbs. of force will result in a greater torque than pushing on the ratchet wrench alone with the same 100 lbs. of force.

Since a spring type torque wrench does have a limiting mechanism, a cheater bar will only result in less force being required to push on the wrench in order to achieve the amount of torque the wrench is set for.

As you can see the studs can be pressed out>>
Frnt view
http://i17.photobucket.com/albums/b7...emovedfrnt.jpg
Top view...by rotating the hub to align broken stud there is room on the side area to press out the stud and install a new one
http://i17.photobucket.com/albums/b7...removedtop.jpg

Michael

:iagree: Wonder how it sheared off, though. I've done it on our Grand National when the dip who had rotated the wheels cross threaded it. Easy enough to replace, but still a pita to have to do.

Gents as an update to my initial post it has gotten worse. As of today I have broken off one stud from each of the four wheels.

After inspecting the cracked off stud there was significant rust so they had been cracked for a while before coming off. The last three the were still attacked to the car but just hanging on by a bit and came off when I was cleaning my rims and I noticed some wobble and when I went to tighten low and behold they broke rite off.

My dealer is miffed as to why they are breaking, I do have aftermarket rims and of course they are at the top of the list as far as cluprits go. I don't want to mention names but you can buy more expensive rims than these but I guess there is always a chance that they are an issue. When I called them they mentioned a retaining ring that is a friction fit over the base of the studs left in place after assembly but not required can cause an uneven seating of the rim. I have now ensured that this retaining ring si gone from all the wheel assembelies and I guess we will see what happens next.

If I break another I will be forced to switch back to my factory rims to see if it continues so that we can confirm it is a GM issue or not which I doubt as the odds of it being a chronic issue with GM studs is not that feasable. If I lived closer to to where the rims are manufactured I would ship one back for thier inspection but I don't so I am not at that point yet.

Most of the time I have seen broken studs it has been do to lug nuts being way too loose rather than too tight. Loose nuts cause the wheel to move around slightly and places a significant load on the studs.

Something is not right here. If studs are torqued correctly (everytime), they should not be breaking (unless defective stud). Also, is road salt affecting the studs, I noticed where you are from. Removing the retainer ring should equalize force around the hub for each stud. I find it hard to believe that wheels are affecting studs. Maybe someone along the line, new wheels, balancing, flats, etc., OVER TORQUED the studs. Things are not adding up. Salt and OVER torquing could be your problem. There are alot of Vettes out there with the retainer rings still on them from the factory and not breaking studs.

THIS IS WHAT I WOULD DO: REPLACE ALL STUDS, PROBLEM MOST LIKELY SOLVED.

:iagree: :thumbs:

How are your new wheels centered (hub or lug/wheel centric)?

That is the question I was wondering. I believe the stock C6 wheels are hub centric, in which case a lose lug nut is not going to cause the stud to break. If the new wheels are not hub centric, but rather lug centric, that could be a problem.

:iagree::iagree::iagree:

Incorrect style of lug nuts for your aftermarket wheels ? Some wheels use the standard acorn type nut, some require a nut that has a shoulder that supports the stud all the way through the stud hole in the wheel. If your aftermarket wheels have a larger stud hole, you must use a nut that has a long entension that supports the bore hole and the stud completly or the stud will have bending loads where it pass's through the hole in the wheel with no support in the wheel hole.
This unsupported bending of the stud will cause it to break.
Wrong lug nuts,,,,,, Find a good wheel guy, he will know if this is the problem as soon as he see's it.
just my 2 cents with no bailout backing:flag:
or just a Bubba with a air gun thinking he is the left front tire guy on the 8 car and over torquing the studs. I see few tire shops that use a torque wrench, usually just HAMMER the nuts on with an air gun set at the highest pressure. Not good

Thanks for the info guys a few questions you have asked

1) My car is never winter driven so no chance of salt being the cause

2) I always torque my wheels nuts to 100 ft/lbs and request that the dealer that services my car do the same (by hand not using an air gun). It is possible that either my torque wrence is very out of wack or they are not doing what I ask but I doubt that is the cause.

3) Is there a way to tell if my wheels are hub or lug centric? I will call the rim mauf and ask.

4) I will also ask the rim manuf if there a specific nut that is to be used with my rims. The rims did come with nuts which I used but they look identical to the factory ones from what I remember, I will re-check that when I go home this evening.

Keep us posted:bigears

Yeah, I kind of went...HUH? with that post too.....torque is torque at the point where the wrench meets the nut.......give me a lever and I'll move the world simply does not apply here......

You all must be much younger than I, because I can't even remember High School, no less anything I was taught;)

To the OP, please do keep us posted. What started as a simple thread has become a mystery we want to know the ending too:thumbs:

Good luck, and lets hope we find the answer:cheers:

Great pics...

I just snapped one myself, which I believe was caused by a cross-threaded lug nut :ack:

Michael,

What did you do to your hub so that it isn't rusted? Mine are all rusted out.

Thanks,

Cedric

Something very wrong here....either the rims aren't right or the lug nuts aren't. Do not drive that car hard before you solve that problem. It isn't rust or over tightening...it something else..potentially very dangerous.

good luck and be careful.

I would certainly replace all the studs since the one that broke was most likely overtorqued and stretched. The others were probably overtorqued as well and to be on the safe side and for your own piece of mind, replace all the studs.
Chris

Another reason to avoid using aftermarket rims. Just my 2 cents. I recommend that you engage a micrometer to measure the exact bolt pattern. Some shops sell wheels with a 120 mm pattern; others sell a 4.75 inch pattern. They describe them both as 120 mm when one of them is 120.65 mm. These same businesses will tell you that other GM rims are the same as Chrysler rims. GM uses 115 mm on many vehicles; Chrysler uses 114.3.

Some shops will tell you that Trans Am rims will work on a BMW. Same kind of error-- 120.6 mm vs 120 mm.

What's the deal with years old threads coming back to life?

http://i2.photobucket.com/albums/y14...c/951286cf.jpg

:iagree::thumbs: