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Cold wheels on a hot hub - What is the right way to set tq?


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So I have had issues now two years in a row at Gingerman where we have broke wheel studs.  Yesterday we changed a tire and hot torqued it to 90 ft lbs is what I was told.  45 minutes later we had two broken wheel studs.

 

We are using the chromoly steel premium wheel studs from Bimmerworld and we are using aluminum wheel lugs as well.  

 

What is the best way to replace a wheel during a race and what should a hot tq be to make sure the wheel will stay on, but not stress the wheel stud?

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6 minutes ago, shutupracing said:

We run same studs and did two tire changes yesterday with hot torque of 90 as well. No issues. 
 

how old were the studs?

 

We replaced them after Gingerman last year so they had Sebring and Nelsons on them. Not too many races. 

 

What lugnuts are you using?

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10 minutes ago, Bremsen said:

If I had to change a wheel during a pit stop, I would drop my torque about 25%.  But, that's with ARP studs and steel nuts.  You're using aluminum lug nuts??

 

Yeah aluminum lug nuts on a steel wheel stud.  I am wondering if I go to a steel lug nut on a steel stud to help with this, but I do not know much about metal and the features. 

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16 minutes ago, E. Tyler Pedersen said:

 

We replaced them after Gingerman last year so they had Sebring and Nelsons on them. Not too many races. 

 

What lugnuts are you using?

Bimmerworld Coated (yellow). 
 

The regular black ones would be fine as well. Both are steel, not aluminum. 

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8 minutes ago, shutupracing said:

Bimmerworld Coated (yellow). 
 

The regular black ones would be fine as well. Both are steel, not aluminum. 

 

That is what I had in my shopping cart so I think I will try that, but wanted to get other opinion of people here on the forum.  A lot of smarter people than me out there when it comes to this type of stuff.

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1 hour ago, E. Tyler Pedersen said:

 

Yeah aluminum lug nuts on a steel wheel stud.  I am wondering if I go to a steel lug nut on a steel stud to help with this, but I do not know much about metal and the features. 

Aluminum lug nuts -ditch those and go to a forged steel lug nut and forged steel studs

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I use the same bimmerworld wheel studs.


I use the bimmerworld black lug nuts, which are not aluminum.

 

I torque to 75 cold and 60 hot.  We check the 1st pit stop after replacing (@ 60ft-lb) and then never worry again.

 

When I broke wheel studs at VIR this year, they were the originals from 2015...  

 

I think 90 is too much.

 

image.thumb.png.f5fd56dc0deb6069944936d71fdbce5c.png

 

From my experience installing so many of these, 60ftlb on the lock nuts has NEVER gotten me to 40ftlbs into the hub.  I almost always have to go closer to 80ft-lb on the nut and even then sometimes barely get to 40 into the hub.  However, with the supplied thread locker and with replacement threadlocker after moving studs into a new hub (wheel bearing replacement), I have never had a stud come off with a lug nut.

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6 minutes ago, Huggy said:

I use the same bimmerworld wheel studs.


I use the bimmerworld black lug nuts, which are not aluminum.

 

I torque to 75 cold and 60 hot.  We check the 1st pit stop after replacing (@ 60ft-lb) and then never worry again.

 

When I broke wheel studs at VIR this year, they were the originals from 2015...  

 

I think 90 is too much.

 

image.thumb.png.f5fd56dc0deb6069944936d71fdbce5c.png

 

From my experience installing so many of these, 60ftlb on the lock nuts has NEVER gotten me to 40ftlbs into the hub.  I almost always have to go closer to 80ft-lb on the nut and even then sometimes barely get to 40 into the hub.  However, with the supplied thread locker and with replacement threadlocker after moving studs into a new hub (wheel bearing replacement), I have never had a stud come off with a lug nut.

 

So if you have to change a wheel/tire during a race where are you torquing to? 60 ft lbs? I already ordered new studs for all my hubs and new steel lug nuts.

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Just now, E. Tyler Pedersen said:

 

So if you have to change a wheel/tire during a race where are you torquing to? 60 ft lbs? I already ordered new studs for all my hubs and new steel lug nuts.

Yes

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29 minutes ago, Huggy said:

I use the same bimmerworld wheel studs.


I use the bimmerworld black lug nuts, which are not aluminum.

 

I torque to 75 cold and 60 hot.  We check the 1st pit stop after replacing (@ 60ft-lb) and then never worry again.

 

When I broke wheel studs at VIR this year, they were the originals from 2015...  

 

I think 90 is too much.

 

image.thumb.png.f5fd56dc0deb6069944936d71fdbce5c.png

 

From my experience installing so many of these, 60ftlb on the lock nuts has NEVER gotten me to 40ftlbs into the hub.  I almost always have to go closer to 80ft-lb on the nut and even then sometimes barely get to 40 into the hub.  However, with the supplied thread locker and with replacement threadlocker after moving studs into a new hub (wheel bearing replacement), I have never had a stud come off with a lug nut.

We are close to the same on all this. Very hard to get to the torque BW recommends on install. We pretty much just do them as tight as we feel they can suffer. 
 

we have issues at only 75lb-ft torque. So we torque to a higher spec. So YMMV @E. Tyler Pedersen
 

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I used the bimmerworld studs for a couple seasons and switched to turner. Much easier to install than the bimmerworld and haven’t had any issues. Cant remember how much time we have on the studs though... it is probably time to change them along with the bearings.

 

Bail on those aluminium lug nuts... I think that’s your issue, not anything to do with torque or stud brand / installation. 

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+1 for bailing on the alum nuts.

 

Not sure why bimmers wear out studs, we have lost one wheel (RF) in 10 yrs and that was my fault for getting heat stroke and forgetting to check torque all day @ Charlotte, it worked loose at hour 12.... Stock infiniti studs

 

Not that it matters while talking bmw but we go 90-100 cold, 85 hot.

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23 minutes ago, Team Infiniti said:

Stock infiniti studs

 

Have you compared the stock studs to the ARP 100-7708 or longer 7713s?  On our z hubs, the knurl is just a few thou larger diameter and the correct length so they press right in.  Changes the thread/pitch to the much more common M12x1.5 so we can use/source BMW/GM lug nuts that are considerably cheaper and easier to find in a pinch (like in the paddock).  All in all a cheaper and stronger setup (win-win).

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4 minutes ago, Bremsen said:

 

Have you compared the stock studs to the ARP 100-7708 or longer 7713s?  On our z hubs, the knurl is just a few thou larger diameter and the correct length so they press right in.  Changes the thread/pitch to the much more common M12x1.5 so we can use/source BMW/GM lug nuts that are considerably cheaper and easier to find in a pinch (like in the paddock).  All in all a cheaper and stronger setup (win-win).

I have not as fixing things not broken does not always have the effect of making it better.

Here, strength has never been issue, also, is there something wrong with 1.25 pitch? We carry our own spares, aside from the one incident @ Charlotte, the only stripped studs have been after impound while carelessly threading after a good race.

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1 minute ago, Team Infiniti said:

is there something wrong with 1.25 pitch?

 

Just not as common.  Not sure who else uses it other than Nissan.  But, it was mostly due to me being cheap, and at only ~$25/corner, I think they were like 1/2 the cost of the standard replacement alternatives when we built the car.  Didn't hurt that they were ARP.

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We have been running ARP 1007715 studs on our car for 4 years (M12 x 1.25).  We have only broken one when it was mistakenly given too many ugga duggas when it was on jack stands the night before just running it up.  We always torque to 80 ft lbs whether it's hot or cold.  I realize that's a little high hot but I just never want to take a chance of coming loose and have never had an issue.  I change studs every couple of years.

 

Thread pitch was mentioned above, that doesn't change torque value that much, maybe 5%.  I have built torque tables in a former life where I actually used math and science instead of mostly psychology as a manager so I have at least had to delve into this subject before, although its been a while.  But, that's getting off subject.  If you want to get a quick a dirty estimate of torque maximum, go to fastenal website they have a torque calculator.  I just went there and used 12mm fine thread and came up with 113 ft-lb dry torque using Din 12.9 which is probably close to what the ARP uses from an ultimate tensile strength.  So 75 or 80 ft-lb dry is well below that so I still think I am good on clamp force since my wheels don't come loose and the studs aren't breaking.  That's really the point in our application, you want them tight enough that they don't come loose, but loose enough that when, for example a cold wheel is tightened on a hot stud when it all comes to same temp the stud stress does not exceed the tensile strength.  

 

Quick and dirty is all you get with a torque wrench, just so everyone remembers that fact.  Even a calibrated one.  We are talking dry torque values here.  On a wheel with varying condition of clamped area.  With varying contamination and condition of the threads.  And varying temperature and expansion coefficients of clamped components.  And a whole bunch of other variables.  I still am not sure what Tyler has going on other than the studs are breaking, possibly from over torquing with a hot stud and cold wheel, that seems like most probable. 

 

Like this article says, torque is the applied force, not the result of the bolt tightness.  It's a quick read on the subject.

 

http://www.heviitech.com/torque-danger/

 

 

 

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I always started 80 cold and then retorqued to 80 hot on stop one.  Finally, after a gazillion races, I had two snap at Sonoma.  I will now heed others in retorquing to 60 on the first stop and then leaving it alone.  We rarely have changed rims during a race, but i would prolly go to 80 on an initial torque.  

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Not using the Bimmerworld studs(motorsports hardware steel nuts and forged studs), but we did have two broken studs after the friday test day at Nelson Ledges.   Replaced two studs and nuts and 80# torque setting.  No other issues but seems the studs can't take the expansion forces as the wheel heats.

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11 hours ago, E. Tyler Pedersen said:

Yeah aluminum lug nuts on a steel wheel stud.  I am wondering if I go to a steel lug nut on a steel stud to help with this, but I do not know much about metal and the features. 

 

Add one more vote to ditching aluminum lugs. The weight saving is not worth the mechanical let down. They stretch and deform with heat, cold, too much torque etc. I tried them one race a long time ago and had one all but seize on to the stud.

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I would think if you were going to use aluminum nuts, which like others say is probably something to avoid, you are going to have to use something to lubricate the threads.  That introduces another variability, but it would deal with any gaulding that might become an issue.  Lubricated threads typically take 25% less torque to get the same clamping force, all other things staying the same, which they don't as I described above.  Even if you use steel nuts, just a little, I mean a little, light oil can keep them working nicely.  Don't put any on the conical face, but a lot of the longer nuts like Muteki like just a little lube to keep them going on and off of long studs without the threat of gaulding.  Works for me.

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13 hours ago, E. Tyler Pedersen said:

 

That is what I had in my shopping cart so I think I will try that, but wanted to get other opinion of people here on the forum.  A lot of smarter people than me out there when it comes to this type of stuff.

Don't trust an old man, he knows nothing 🙂

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