I just got back from three days at Putnam Park, driving my ITR on the track. On the third day, I ran into a technical problem I had never experienced before, and I'm hoping some of our best mechanical minds can help.

When you use a torque wrench to tighten lug nuts, once you make them snug, it's about another 1/6 turn of the torque wrench before it clicks. And during that 1/6 turn, you can feel the lug nut getting tighter and tighter.

On Sunday, I was swapping tires around, and that's not what happened on the lug nuts on my left front wheel/tire. After snugging them, I did the usual 1/6 turn and it didn't keep tightening, didn't feel as tight as 80 ft-lbs, and didn't click. I'm not a big DIYer but I know what 80 ft-lbs feels like. So during that 1/6 turn it was maybe around 60 ft-lbs (I'm just guessing at that number) for the entire 1/6 turn. I tried it for another, oh, 1/12 turn and it still felt like the same torque and didn't tighten any more. This was not just for one lug nut but all of them. This was right after I came off the track, so the hubs and lug nuts were very, very hot at the time. Also, when I was out on the track, I was feeling a little shimmy in the front end, which I figured may be due to the inability to torque the lugs sufficiently. I brought it in and parked it for the rest of the day. I then drove home, no problems.

Just now, I tried a torque wrench on them and they were fine, no problem getting them to click at 80 ft-lbs.

There was a mechanic at the track, and I asked him about it, and he told me that studs can actually stretch a bit, that it could be that, but it could also be the threads stripping.

My questions are, was this just a function of torquing the wheels when they were so hot? Also, should I have my mechanic go ahead and replace the studs, given this experience?

TIA

 

A visual inspection should reveal any stripped threads, or get a fresh nut (any nut, doesn't have to be a wheel nut) with the same threads and run it on each stud. It should go on smoothly, not loose, not binding. Yes, fasteners stretch when torqued, more so when hot. You will over torque the fasteners when you do them hot, they will either stretch the studs permantly or they could warp the rotors and cause a "shimmy."
<U>Never torque your wheels hot. Wait till they are cool to the touch.</U>
Aluminum wheels will crush a slight bit and small scratches and rust from the rotors will compact a bit into the surface and they will loosen a bit. Aluminum wheels should have the torque re-checked after 200 miles on the street and a session on the track. After they cool of course.

Most people fail to use a torque wrench properly.
1. You must pull gently and stop just when it clicks.
2. Threads should be clean and dry unless torque value specified is for lubricated threads (like ARP headstuds.)
3. Most commonly used torque wrenches are spring type and should not be used to loosen tight fasteners. Also they should always be stored with the setting at minimum value to avoid the spring taking a permanent set and ruining the calibration.
4. For more precise torque, tighten in a pattern that evenly pulls the two items together and start out 10 ft/lbs light, then 5, then recommended torque.

Without seeing the condition of your lugs, it's kinda' hard to tell if you have a problem or what that problem is.

 

I can attest to the torquing of lugs when they are hot. I have a friend who tracks his car quite frequently and he came into this same problem after torquing down his lugs a few times while they were still very hot. Eventually you could see a permanent stretch in them. I would just swap out the lugs if I were you and next time just allow them some more cooldown time. Might consider swapping rotors as well as mentioned above.

 

Does anyone else remember John Meek (Hoochn's Father) specifically mentioning this Monday morning at the EXPO driver's meeting?

I am not a huge tech guy myself, but i do remember him stating to let the car/wheels/studs/lugs cool down before re-torquing them.

 

naturally the metal is softer when it's at a higher temperature. you start putting higher tensile forces on it whilst it's hot and it's going to stretch.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tartje &raquo;</TD></TR><TR><TD CLASS="quote">naturally the metal is softer when it's at a higher temperature. you start putting higher tensile forces on it whilst it's hot and it's going to stretch.</TD></TR></TABLE>

er'yup.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jon D &raquo;</TD></TR><TR><TD CLASS="quote">Does anyone else remember John Meek (Hoochn's Father) specifically mentioning this Monday morning at the EXPO driver's meeting?

I am not a huge tech guy myself, but i do remember him stating to let the car/wheels/studs/lugs cool down before re-torquing them. </TD></TR></TABLE>

Definitely remember that

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Dude &raquo;</TD></TR><TR><TD CLASS="quote"> You will over torque the fasteners when you do them hot, they will either stretch the studs permantly or they could warp the rotors and cause a "shimmy."
</TD></TR></TABLE>
Great post Gary.

I had this very problem of warping rotors happen to me earlier in the month. I was at MAM doing a lapping day. I ran the session just before the lunch break. At the end of the session I was the only car left on track, when I got the checker and came in the pits I was told that if I wanted to I could run a little while longer, so I did. About 15 mins later I get the checker again and bring it for cooldown and some lunch.

15 mins later the next session buzzer goes off and I get up and grab my torque wrench to inspect my lugs. I had a brain fart and kinda forgotten (it was only 15 mins, I know ) how long I had just been on and how soon I was getting back to it. I clicked my right front lugs got to the last stud and I remembered that this was a bad idea so soon and I stopped but the damage was done. Waited that session out, grbbped the next one and as soon as I started the car I could hear the effects of a warped rotor. I realized instantly how and why. Like a trooper, I took the session anyway before I limped it home. I just replaced them all the other day.

 

Thanks for all the advice.

Regarding the rotors, they had been used a while and there are some tiny radial cracks visible, so I will probably be replacing them anyway before the next track event.

 

New rotors, W00t!
I have a big angry Blue Point wire brush and when i have the wheels off, I lightly brush the mounting flanges on the back of the wheel and the rotor where they meet and the stud threads too. Just to knock off any rust or grunge. This needs doing if the car is driven in the rain.

 

Out of curiosity, what were your wheel nuts made of?

I've seen a lot of JDMOMGYO!!11!! kids running aluminium wheel nuts at the track and inevitable they strip them. If you were using aluminium, switch to steel. There is a reason aluminium lug nuts are banned in most race series, no matter what the advertisements on volks website may say. Like others said, let everything cool off before torqueing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KOALA YUMMIES &raquo;</TD></TR><TR><TD CLASS="quote">

Its aluminum btw, not aluminIum.
</TD></TR></TABLE>

haha, only in America

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tartje &raquo;</TD></TR><TR><TD CLASS="quote">naturally the metal is softer when it's at a higher temperature. you start putting higher tensile forces on it whilst it's hot and it's going to stretch.</TD></TR></TABLE>

It would also be safe to say that since the studs and the lug nuts are made of two different metals that the expansion and retraction properties are slightly different. Also the area of the wheel that is in contact with the studs and rotor must be doing a small bit of expanding when hot too.

I would think that if you torqued down hot lug nuts onto hot studs that when they cooled they would be a bit over torqued? Or maybe the stud would be slightly elongated where its threads were not in contact with the threads of the lug nut, over time leading to stud failure?

 

Ken Sachs... all of the track days you have done... and you didn't know/follow this info? Shame on you my friend.

Never ever EVER torque when the wheels are hot. When you just get off track, that is the time for checking tire pressures. Before going out for a session is the time to check torque specs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dave_B &raquo;</TD></TR><TR><TD CLASS="quote"> When you just get off track, that is the time for checking tire pressures. Before going out for a session is the time to check torque specs.

</TD></TR></TABLE>

He has done more track days than most of us combined, i think he knows that midg

That is definitely j00 new name.... Midg, like Donna's hot Mom from That 70's show.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jon D &raquo;</TD></TR><TR><TD CLASS="quote">

He has done more track days than most of us combined, i think he knows that midg

That is definitely j00 new name.... Midg, like Donna's hot Mom from That 70's show. </TD></TR></TABLE>

Then why was it not done, Trunk? (I think Ken does and should know it... could have just been one of those days and wasn't thinking about it)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dave_B &raquo;</TD></TR><TR><TD CLASS="quote">

Then why was it not done, Trunk? (I think Ken does and should know it... could have just been one of those days and wasn't thinking about it)</TD></TR></TABLE>

Trunk was just referring to your second statement... not Ken's mistake of torquing while still hott. Exactly what i quoted, Midg

 

Temperature affects friction. Which is loosely what torque wrenches are based on

That is why for engine assembly, bolt stretch guides, and angle torque gauges are used for more precision.


Modified by neo_ at 2:08 PM 8/26/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jon D &raquo;</TD></TR><TR><TD CLASS="quote">

Trunk was just referring to your second statement... not Ken's mistake of torquing while still hott. Exactly what i quoted, Midg </TD></TR></TABLE>

Correct, I edited my post as to not reflect on Ken himself as I'm sure it was just an oversight (or he's just getting old... )

Trunkz is in reference directly to your abnormally large diameter legs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dave_B &raquo;</TD></TR><TR><TD CLASS="quote">

Trunkz is in reference directly to your abnormally large diameter legs. </TD></TR></TABLE>

FTW

 

i absolutely HATE that feeling you get when you are tightening a nut or bolt, and you KNOW it should be getting harder to turn, and it just keep turning.

this happened to me and Edwin before expo when we were putting his cam caps back on. at least 10 of those cap bolts stretched and they were brand new and just out of the package. first you think to yourself nahhh, just another 1/4 turn. then yer like hmmmm, maybe my torque wrench is fubared. so you dial it back some and give it another 1/4 turn and then you are just like FAWK and throw something or kick your car.

 

Often, you learn something by trying it. And you learn how NOT to do something by trying it the wrong way. As far as I can remember, this is the first time I ever tried torquing my lug nuts when hot. It will be the last time, as well.

The studs and lug nuts are both the original stock steel ones.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy &raquo;</TD></TR><TR><TD CLASS="quote">As far as I can remember, this is the first time I ever tried torquing my lug nuts when hot. It will be the last time, as well.


</TD></TR></TABLE>

I think we all find this absolutely fascinating lol

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RTW DC2R &raquo;</TD></TR><TR><TD CLASS="quote">

I think we all find this absolutely fascinating lol</TD></TR></TABLE>
That Ken might have possibly, just maybe made a mental mistake?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by get RIGHT &raquo;</TD></TR><TR><TD CLASS="quote">
That Ken might have possibly, just maybe made a mental mistake? </TD></TR></TABLE>

Read above... it's that he's finally getting OLDER