Akcelr8 N VA

I had the misfortune of shearing all 5 wheel studs (stock studs) on the left rear going into the Snake at VIR turning a routine turn-in into a very thrilling spin!! I'm now running ARP long studs. How often to you guys change out your wheel studs? Annually? I figure, because we remove and install wheels so much at the track, that all the repetitive torquing fatigues the studs causing failure at some point.

Woods

Damn!!! that sucks. I replace mine with the ARP long studs from Summit racing immediately. Only because I saw this happen to Rich Raymor at Summit about 10 years ago. Front are a piece of cake the rears are a bit harder on the C4.

Akcelr8 N VA

I was very lucky...I had just passed a car in the short straight after NASCAR bend and was chasing Mike into the Snake. Studs let go, rear rotor dropped to the track, disinigrated, and the wheel and tire went under the car and out the rear... no body damage. I ended up spinning 3 times in the dirt. I thought I cut a tire until the dust settled and I saw the tire and wheel roll in front of me all the way to the guardrail!

I found a way to get the long studs in the rear hub without pulling the hub. I file a "flat" on 1/4th of the stud head and filed a small flat on the seam of the spindle at about the 9:00 o'clock position. This gives just enough clearance to get the stud in without compromising the integrity of the stud or the spindle.

How often do you change out your ARP studs?

Woods

Never have replace the ARP bolts. But I don't change wheels that often. You should really press the bolt in to the hub. If you pull it on use plenty of antiseize on the stud and nut.

Check you PM

Cobra4B

Not sure... I just had them installed a few weeks back after have 3 stockers have the threads mangled after 4 years of on/off.

yellow01

Glad you are OK!!!!

BrianCunningham

Yes, yes they do fatique.

I'm glad your OK

I recently snapped a couple, and had to replace them before bringing my car out. Thanks to Gary Hoffman for helping me out on that.

The front's are a piece of cake. The standard length studs can be replaced in the back w/o taking the bearing off. So it's not that bad.

Cobra4B

^ Not on a C5... fronts are easy, but rear requires removoing the parking brake shoe which really requires removing the hub to get the retainer spring back on.

Aardwolf

A wheel bearing wears out and a new one comes with new studs, that's how I have been replacing them.

Akcelr8 N VA

Yes, I replaced my rear wheel bearings the end of last season. The bearings are still fine but the studs, however, didn't last that long!!

Solofast

A properly torqued stud won't fatigue.

If you don't have sufficient torque on the stud the cyclic loading will cause fatigue and will snap them off in a few minutes.

Suggest that you check the lug nut torque before each session and make sure they are properly tightened. Some folks have mentioned that they are lubing studs (as noted in the other topic nearby), and I find that they can loosen up if lubed. At any rate, we torque the lug nuts after putting on track tires, and then again, after the car has been driven a bit. Sometimes we find they have loosened up a lot.

Akcelr8 N VA

Solofast, good suggestion on checking the torque after each session. I have to admit to getting lazy in the past and only checking in the morning and again before the afternoon sessions. Since the incident I check the torque after everything cools down between each session.

It seems to me, however, that everytime you torque a bolt or stud that you're stretching it a bit and over time that causes fatigue and eventual failure. Am I right???

To Brian and Jonathan, thanks for the "well wishes". If it happened almost anywhere else on the track I would have either taken out other cars or the spindle would have dug into uneven runoff and possibly flipped the car. I'm counting my blessings on that one hoping this post will cause others to check their studs, and trying to learn from my mistake!!!

AU N EGL

Wheel bearings and ARP wheel studs should be part of your annual winter maintenance program

63Corvette

In 2005, I broke 4 of the five studs on my right rear wheel in the carousel at Sears Point. The right rear wheel jumped up and down, so I backed off. The next turn (7) is a double right hander, so the rear wheel was unloaded and I felt nothing. However, going down the back "straight" and into turn 10 the right rear moved up and down several inches, so I just shut off and entered the pits. I was able to borrow studs from my competitors (Tom Saki's Sunbeam Tiger) and continue the next practice without any damage...but I was very lucky. I knew that something was wrong, but not what nor how bad. I feel sure my experience was caused by lug nuts insufficiently tightened, so now we torque before each practice or race.

Cobra4B

^ That depends on how many track events you run during the year.

kelp

I have noticed alot of grunge and metalic shreds building up on my lug bolts, more than other cars I've raced. I put kan-o-kroil on them and discard any that give me any resistance in removing or installing them. I go through lug nuts like water. But, haven't had any problems so far. If anyone tollerates lug nuts that don't just zip right on, this might be one area where zero tollerance saves trouble.

AU N EGL

The stock studs and bearings are not really meant for the lateral forces we put on them from consistent high speed corning. The stock studs are not very strong. When you change the bearings put in new ARP studs at the same time.

Also look at some hardened open ended lug nuts for track or auto-x duty.

fatbillybob

on a similar note I have seen guys use studs that were clearly too long like 2" extra on race cars. Why do people do this? It looks funny and adds unsprung weight. I see it on a few vettes and many 911 porsches. There has got to be a reason.

UstaB-GS549

I really think the stock studs are fine if you torque the lug nuts to 100 ft-lb.

If the lug nut is properly torqued, the stud only sees a static load due to the torque. Fatigue is defined as more than 10,000 stress cycles. I can't imagine anyone changing wheels that many times. Anything less is considered a ductile failure.

If your lugs are loose, the stud will see one stress cycle for every revolution of the wheel. Now you are doing something to the stud that can approach fatigue damage. The damage is cumulative and its effect will depend on how hard you corner and accelerate. You may break the stud some time in the future while torquing the nut.

If the stud doesn't break when you tighten it to torque, it should not break when loaded on the track unless it was never tight to begin with.

I had a discussion once with a fellow driver about his three broken studs on his rear wheel. He was black flagged for spitting lug nuts at corner workers. His theory was that the engine torque broke them because he had a highly modified motor. It turned out that the 17 remaining nuts were loose when he checked the torque a short while later.

Your wheel torque should not change. If your lugs are loose after a few laps, either they were never tight or their was something between the wheel and hub that was compressible. I have been doing this for 20 years now, and have never found a loose lug nut on a wheel that has been torqued. That's not to say that I have not forgotten to tighten the nuts after changing wheels. I did once & got lucky.

The M12x1.5 studs from ARP are 8740 HT with a tensile strength of 190,000 psi. If the stock studs are Class 12.9 they would have a tensile strength of 174,000 psi and the improvement in strength would be about 9%.

Torque values are usually based on a value that loads the fastener to 80-90% of proof or yield. I don't know what the yield strength is for the ARP studs, but unless it is higher than the stock studs and you torque the nuts to more than 100 ft-lbs, I doubt that you have really gained that much.

I don't see much benefit in hardened lug nuts. Nuts are usually matched to the stud bolt material and are softer so the threads deform and share the load. Maybe harder to cross thread when installing? Maybe the real benefit of using ARP studs is that the nose makes them harder to cross thread when you are in a hurry.

Just my opinion on causes of wheel stud problems:

1. Over torquing wheel studs with impact tools.
2. Lubricating studs and not reducing torque value.
3. Cross threading by starting nut with power tools.
4. Forgetting to torque one or more nuts.
5. Getting junk in threads and using excessive torque to remove nut.

davidfarmer

I've only seen it happen when over or undertorquing. In theory, torquing to 90-95ft-lbs should NOT be enough to permanantly deform steel studs, and especially if you are using anti-seize.

I had a friend that would adjust his torque wrench, torque to the "click" then give it just a little "extra". I warned him, but he continued. After about 6 events, he started braking studs. He didn't seem to understand that he was defeating the entire purpose of using a torque wrench when he "over-clicked" it.