godzilladude

I walked into the garage a couple days ago, and as I walked around the Vette, I saw one of my lugnuts lying beside the car, about halfway back. When I picked it up and looked at it, the stud was still inside. Looking at the wheels, it came off the front.

I wonder what caused this? I do take the wheels off and on periodically, to change out the brake pads before and after track days. But I always use a torque wrench, 50 then 100 lbs. I DID recently try out a new little lithium impact wrench, and let it try to load up the lugnuts, but it can't even get to 50 lbs of force. Though maybe the hammering action did it. Maybe just the abuse of running on the track? I drive pretty hard, but its not really set up for racing, nothing hard-core, as one can see in my signature.

And, it was weird that the lugnut was sitting in the garage, 5-6 feet from the front wheel. Like it fell off just as I was pulling in or backing out.

Thoughts? Anyone else seen this? Some kind of heat stress problem from working the brakes hard?

varkwso

It happens pretty often - typically a result of overtorquing at one point or another.

J.R.

It happens pretty often - typically a result of overtorquing at one point or another.

http://images.ibsrv.net/ibsrv/res/sr...ies/iagree.gif

doje

I've seen it a hundred times at the track. By the way, when was the last time you had the calibration checked on your torque wrench? If it's way off, you may overtorque and not even know it. Either way, replace the studs with ARP studs if you are doind track events and regularly pulling wheels. Once and done.

Cloaked323

ARP

racerbob4

Get some high strength studs from Summit or Jeggs. We used to have a crew guy who like to use the torque wrench and before the car went out on the track he would torque the wheels. Even if they hadn't been off the car. So everytime you torque them they get just a little bit tighter and eventually you hit the pont where they are ready to break. That year we had a lot of broken studs before we eventually went to ARP studs. When the crew guy left and we had all the studs replaced with a high strength the problem went away.

davidfarmer

100 ft-lb is too much IMO.........

Cloaked323

I went 100 for over 3 years with the stock studs doing HPDE and finally one broke after I drove all the way to Laguna Seca here's the story Well I'm finally able to get on here and post some video not. But before I do once again I'd like to give a" BIG THANKS" Magstar, John and Roger for making dream drive possible.
11 years ago as I sat in the grandstands watching an ALS race, I said to my good friend Mitchell that someday I'm going to drive this track in a fast car. Well friends it almost didn't happen here’s the story.
While doing my normal track routine, changing from street tires to R-compound track tires etc, I attempted to remove the right front wheel and a stud broke. John noticed that I had some sort of situation and asked what was going on. After a short conversation, me “well looks like I’m going to be a spectator”, John “Easy fix we’ve got time, change the other tires get the car setup you will make the first session”. He was right not only did John and Roger located a dealer who although didn’t have the part in stock, he gave them the stud dimensions and a few possible location in the area that might have required parts for the repair.
Magstar came out of his trailer with a giant sledgehammer and told me to get inside my car, turn the wheel to that left and close my eyes. Magstar was like a dentist getting rid of a bad tooth sorry DH, Magstar knocked out the bad stud it was painless and precise.
Roger with broken stud left LS with John in pursuit of a new stud. They drove to a “Napa auto” where they picked up all the needed parts for the “fix”, new stud nuts and washers. John and Roger returned and in less time than it took to gather the parts John installed the new stud.
Roger and John left for the CC drivers meeting as directed by Dreamin while Magstar finished the job of reinstalling my caliper. I mounted the wheel and headed out just like John said, these guys are great.

edit: correction on involved friends name, Roger not Dan, sometimes I'm a little out of sort

redtopz

Yeah I only go to 90 lbs and have not had a problem yet using oem studs in front and arp studs in back. It is also very common to see people using a torque wrench incorrectly. I see people torque a nut up to the click and continue to pull a bit more. Once it clicks, you have to stop immediately.

mgarfias

Agreed about 100 being too much. I torque to 85. 'course I also use moly. That 85 btw was per ARP when I called them.

Bill Dearborn

I have been torquing my lug nuts to 100 lbs since I started doing HPDEs almost 19 years ago and have never had a lug nut break due to torquing them too much. I suspect when you used your power impact wrench you may have gotten the nut cross threaded and didn't notice when you torqued the nut down with your torque wrench. Since it was cross threaded the nut really wasn't tight and the wheel moved around enough to stress the lug bolt and break it over time. Same thing happens to the NASCAR teams every now and then. Cross threaded lug nut can cause bolt to break.

Bill

Solofast

Good point about the cross threading. Can you spin the stud out of the nut? If it spins out it wasn't a result of junk in the threads or cross threading.

Either way, show us a close up of the broken stud and we can tell you if it was a fatigue fracture or a failure due to overstress.

0Randy@DRM

One thing that I see all the time is the one hand torquing. Using a long wrench is a two hand operation. Right hand on the stick, and the left hand making sure the wrench is turning nice and straight.

I personally learned this, somebody said something to me. I looked up and snap. Hand into ground isn't that much fun.

ARP for the win. They seem to rid these problems.

Randy

waddisme

I haven't broken one yet, but when I had my rear hubs off for pilot bearing replacement, I repl all ten with ARPs. I had to cut them down as I still use the closed end lug nuts for street wheels. No big deal. Seems like we could get a gp together to get ARP to make some stock length ones, then I could do the fronts. Before I went to the ARPs, I bought a tap/die(?) to run over the studs just to keep crud out of the threads.

mgarfias

You don't need a GP to get ARP to do custom work for you, just call them. They'll charge you a small premium to do the work to a stocking part.

redtopz

Good points about cross-threading and using two hands on the torque wrench. You are actually way more likely to break a stud by under-torquing than by over-torquing. As far as getting shorter ARP studs, you can also use a sawzall or hack saw to cut them and then file down the threads on the end when you are done.

froggy47

froggy47

I would buy stock length too. I bet they would sell a lot!!!

godzilladude

Twenty ARP studs have arrived, my weekend project lies before me. I'll cut them down for the closed lug nuts. I've also bought the axle nuts for the rear, might as well address that. Still need to get my loctite and the 33-34mm deep socket. Anyone know where to buy one of these? Sears?

I'll take and post a photo or two of the broken stud, see what folks think.

I know about proper use of the torque wrench, learned the same way others have. I've snapped them off with four-ways before, same issue.

The stud remnant came out easy, so it wasn't cross-threaded.

And, I'll cut down my torque to 85. As long as everything stays in place, I'm a happy camper.

Thanks everyone!

waddisme

Just sent them an email to see how much per set for stock length. Will share when I get an answer.

The axle nut socket is a tool rental from Autozone, so you don't have to buy it. I started to buy one, but you need 33mm to remove and 34mm to repl as new nuts are 34mm IIRC. Have fun with it.