Some rather exciting footage from our friend Christina's recent Sebring outing:
Some rather exciting footage from our friend Christina's recent Sebring outing:
I feel like the only times I've seen wheel studs shear off are either 1) someone forgot to tighten the lugs enough or 2) major impact with a pothole (I saw a Corvette pitted next to us at a Summit Point enduro years ago shear a few studs from a pothole way off the line that had developed.
Seems unlikely they'd all just shear at once from stress failure. I mean, even if one goes, what are the chances of all 5 going immediately like that?
That said, makes me think it's time to change studs on the rally car. They've been on there for like 5 years lol..
In reply to irish44j :
I have seen wheel studs shear off several times. Usually it is only one, after the other three/four lug nuts fell off. Never all four/five.
In any kind of motorsports, EVERYTHING is a maintenance item on a long enough timeline, tho!
Who's kids was just saying something about all those missing wheels in the magazine?
Only way I can think to have a bunch of studs shear either at once or close together is if they were over-torqued and stretched. That would make it easier for them to start failing. Might not go all at once, but once the first 1 or 2 fail, the others might not be able to take the increased load and could just let go.
irish44j said:I feel like the only times I've seen wheel studs shear off are either 1) someone forgot to tighten the lugs enough or 2) major impact with a pothole (I saw a Corvette pitted next to us at a Summit Point enduro years ago shear a few studs from a pothole way off the line that had developed.
Seems unlikely they'd all just shear at once from stress failure. I mean, even if one goes, what are the chances of all 5 going immediately like that?
That said, makes me think it's time to change studs on the rally car. They've been on there for like 5 years lol..
I suspect I lost one stud first. Three of the four holes on the wheel were oblong. There was a slight vibration coming from that one corner. I assumed it was a bent wheel or I had thrown the weights. It seemed fine as I was still turning the fastest times of the weekend. The vibration continued for a good 30 minutes before it suddenly got reaalllyyy bad going into T1 and then finally sheared the other three studs.
Not my car, so I don't know the replacement interval that the owner had. She's going to look at her records and let me know. On my M3, I replace them every season. I put mine through a lot of wheel changes during a race weekend. Even with the annual replacement, I had a wheel stud break halfway through the season at WGI last year. Preventative maintenance is my favorite thing. One less thing to worry or wonder about when the green flag drops.
I've seen it happen with brand new aluminum wheels that were powder coated from the factory. There was powder on the lug seats, which plastically deformed under load, effectively leading to an undertorqued condition on the lugs. This leads to cyclic loading of the studs and failure of all four in pretty rapid succession until the wheel departs the car.
I've had that happen, only not on track, not in a race car, and it was because I fogot to tighten the lug nuts.
I’ve seen it happen several times when guys used impact wrenches to tighten the lugs. I discussed it with them and told them it was the wrong tool and to only use a torque wrench and they defended it, saying the impact works for them. Well clearly not, I said, and they got pissed.
dculberson said:I’ve seen it happen several times when guys used impact wrenches to tighten the lugs. I discussed it with them and told them it was the wrong tool and to only use a torque wrench and they defended it, saying the impact works for them. Well clearly not, I said, and they got pissed.
They do make torque sticks, which you can put on your inpact to limit its torque. Basically an extension that is designed to be somewhat elastic. They do work.
The bigger problem is torquing and then assuming you are good. I have learned to torque, drive around a bit, and then retorque.
How do I know all of this? I have lost 2 wheels on different occasions and almost lost two more. I may be a slow learner.
In reply to Robbie :
No they weren’t using a torque stick. And this is three different people all used impact wrenches to install lugs, all lost a wheel, and all defended the use of an impact - again without a torque stick - to torque wheels. Bizarre. (And yes they are all Lemons racers.)
I sometimes give Dennis, our Chump chief, abuse about retorquing the wheels every two hours, but I know I'm wrong. This seems like proof.
David S. Wallens said:Some rather exciting footage from our friend Christina's recent Sebring outing:
Good wheels,but certainly not great wheels.
3 years ago with the previous chassis we were using with the dirt late models here in Edmonton we weren’t able to take the as the right rear wheel was trying to come off during the pace lap and he pulled into the infield. Now all the wheels were tightened with a tourque wrench but what happened was it was tearing up around one wheel nut,the wheel stayed on.
Now 3 weeks later a local sprint car driver had this happen to him going into turn 4 at Castrol raceway in a b main. Thankfully he was able to bring it to a safe half in the middle of 3 and 4.
We recheck lug torque at every driver change, you can tell when they are starting to go. So far we have had two broken studs and no lost wheels. We did notice one driver torquing them with a breaker bar before one of them broke so maybe just one real failure. After one broke we just ran with three for the last two hours with no problems.
akylekoz said:We did notice one driver torquing them with a breaker bar before one of them broke so maybe just one real failure.
"Hey, something's wrong with the torque wrench, it's not clicking!"
And +1 to everyone who checks lug torque at every pit in.
Another common cause of wheel loss is running new wheel attachment hardware for the first time. Here's me trying out some new wheel studs:
They didn't fail all at once either, you can even see one fly off if you play the video at minimum speed from the 25sec mark. In the last few corners before the wheel let go I thought I had a soft tire on that corner, but it was because the wheel was only hanging on by 1 or 2 lugs.
Here's that RX7 that was on the cover of GRM once trying out some new lug nuts, after driving to the track on them all torqued up:
Turns out the thread specifications weren't exactly right.
By the Damage It Looks/ Sounds as If 3 weren't Tightened , But Stuff Happens, repair, check other parts for Structure Damage and Start Getting ready for the Next Show.
AngryCorvair said:I've seen it happen with brand new aluminum wheels that were powder coated from the factory. There was powder on the lug seats, which plastically deformed under load, effectively leading to an undertorqued condition on the lugs. This leads to cyclic loading of the studs and failure of all four in pretty rapid succession until the wheel departs the car.
We had that with a batch of wheels at work. Made for some exciting times.
Hahhah I saw this on facebook. I had the same thought... who yielded the studs? Glad neither her nor the car were damaged.
I was lucky at my second ever track day (After a couple of autocrosses) back in 1995. I had my 94 Mustang (hot E36 M3 at the time) on BFG R1's. Entering turn 3 at Gratton an off camber down hill left hander. After turning in three wheel studs broke on the rear right, luckily there is an access road there that goes right off the outside of the apex back to the pits, I just wobbled down there and came to a stop. When I got back to the pits everyone else was 'Why are you still on stock studs, they're not up to it. I was a newbe and didn't' know any better. I always used a torque wrench, but the wheels and been on and off dozens of times on the stock studs.
I managed to borrow a stud off someone else and drove home slowly on four out of five studs and ordered 20 uprated ones the next day.
I lost a wheel once at Laguna Seca. Hub failure, not stud failure. I had just installed some upgraded units that apparently had a design flaw. You really don't have a lot of options when it happens.
Scary stuff, but glad it happened in a fairly controllable/safe space with room to stop!
I run the Bimmerworld race studs on my E36 and replace every two years per their recommendation. Cordless impact has been fine to get the nuts on but I don't slam it all the way tight - then torque wrench to spec. Never lost a stud although my friend cross-threaded a lug nut on accident which required an emergency stud swap.
AngryCorvair said:I've seen it happen with brand new aluminum wheels that were powder coated from the factory. There was powder on the lug seats, which plastically deformed under load, effectively leading to an undertorqued condition on the lugs. This leads to cyclic loading of the studs and failure of all four in pretty rapid succession until the wheel departs the car.
I had that happen after powder-coating the brake calipers. They looked great, but as the powder melted from the heat, the entire assemblies became loose.
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