this is not funny !

[cortexx]

http://www.youtube.com/watch?v=bg5NPJ0_iEk&NR=1

for some reason i cant stop watching and laughing at it How does this happen ?

[Skym]

Not tightening the nuts????

One of the comments mentioned that the owner said on TV that there was not enough thread, half an inch (usually only happens with spacers and I think Nismo sell longer, stronger studs for Skylines to prevent this problem from happening). Also I gather the nuts came off one by one when each wheel became unbalanced.

[cortexx]

I can only imagine the embaressment level of the guy in the car

[MarusGTR]

Not tightening the nuts????

One of the comments mentioned that the owner said on TV that there was not enough thread, half an inch (usually only happens with spacers and I think Nismo sell longer, stronger studs for Skylines to prevent this problem from happening). Also I gather the nuts came off one by one when each wheel became unbalanced.

Owner: "Hellaflush, man!"

[frankiman]

actually someone mentionned on another forum that he used different nuts for the track wheels, and those nuts had a different thread (M12x1,25 vs M12x1,5) and because of that e could only tighten the nuts about 1 rotation or something

[MarusGTR]

actually someone mentionned on another forum that he used different nuts for the track wheels, and those nuts had a different thread (M12x1,25 vs M12x1,5) and because of that e could only tighten the nuts about 1 rotation or something

Effectively cutting the safety factor by half, nice.

[frankiman]

Effectively cutting the safety factor by half, nice.

much more than that lol

[MarusGTR]

much more than that lol

Half the thread pitch so half the shear, half the load, BUT you're right, If he torqued to the same spec he probably put too much load on wathever thread he was engaging so it's way more. Let's say ball park 1/4 if the thread is still elastic (or 0 SF if the thread is plastic, which is probably in this case).

[Oakville]

one frame there looks like the actual studs are missing...or am I just seeing things.

rear left

[amnash]

what a moron! lol

[Snake556]

I've seen this a few times. I lawl'd. Then I think about how bad that guy must feel lol

[Skym]

actually someone mentioned on another forum that he used different nuts for the track wheels, and those nuts had a different thread (M12x1,25 vs M12x1,5) and because of that he could only tighten the nuts about 1 rotation or something

That makes more sense.

Half the thread pitch so half the shear, half the load. BUT you're right, if he torqued to the same spec he probably put too much load on whatever thread he was engaging so it's way more. Let's say ball park 1/4 if the thread is still elastic (or 0 SF if the thread is plastic, which is probably in this case).

So your saying the thread on nut should have been taller (also thicker??), so it touches the base (thicker part) of thread on stud, which is what you mean by elastic. But in this case it was plastic because thread on nut was at the top of thread (thinner part) on bolt and with the same amount of torque that was meant for the base of thread + weight, stresses of drifting car, etc caused the failure of thread?

[MarusGTR]

That makes more sense.



So your saying the thread on nut should have been taller (also thicker??), so it touches the base (thicker part) of thread on stud, which is what you mean by elastic. But in this case it was plastic because thread on nut was at the top of thread (thinner part) on bolt and with the same amount of torque that was meant for the base of thread + weight, stresses of drifting car, etc caused the failure of thread?

Hmmm yeeees and no. What I meant is that what makes the bolt applies pressure to the rim is through energy transfer; the nut shears the surface of the thread through torquing and that energy is transfered to the axial strain of the bolt, stretching it. Both the thread and bolt are deformed in their elastic linear domain of Hooke's Law. What's making the bolt lock is the surface friction between the thread that can counter the axial force exerted by the rim. If you run a nut with twice the pitch of the bolt, you effectively run half that force, so it takes 1/2 the amount of energy to make the bolt unscrew itself. This would be the case if the guy just torqued it to a same angle as he would with the right pitch (e.g. tight and 1/16 of a turn for both).

As for my second comment, if he would of torqued the bolt to spec, he would of applied energy to a weak structure. While the bolt is flat on the rim, torquing the bolt would cause the threads to stretch along the pitch so that it can still turn on it's axe, increasing the pressure applied axially. Since you run twice the pitch in the nut, you have to exert twice the shear and bending on the affected thread to run the same torque. This would probably cause them to go easily beyong their ultimate strength and start deforming plastically (which is, from an energetic point of view, a point of no return) and they'd flat out fail on load or fail by fatigue.

Think it like this. Say you have to run 100lbs of pressure on the bolt with an ultimate yield safety factor of 1.25 (80% ultimate strength). With the right pitch you can, no problem. If you run a nut with twice the pitch of the bolt, effectively going past the 1.25 SF to 160% ultimate strength, and you try to torque it to that spec, you never be able to have that pressure; you'll only end up with considerably less pressure or you'll break the bolt while torquing.

Edit: Ive just realised I was thinking that he was running twice the pitch but it was only 1.2 times (1.5/1.25). Still applies. I guess I was really tired. Still am, didn't sleep last night lol.

[cortexx]

Well ... i'll say this ,- I didn't realise there was such a science to stopping the wheels fall off your car.

But I did go check the torque on the lugs for all of my vehicles this afternoon..

[Tony-R32]

i've seen this before, but unlike most of you i can't help but cringe.

I would probably cry if that happened to a car i care about lmao!