[DeTomaso] Spinning wheel stud

Tue Jul 17 19:43:42 EDT 2018

Yes, bolt stretch is directly proportional to clamping force if the fastener is uniform in dimensions. In the Coyote engine I’m rebuilding, many critical fasteners are torque to yield, which means you torque to a small value and then turn the fastener to a specified angle. The friction of rotation is then removed from being variable and causing variable clamping loads. Variable clamping loads aren’t your friend in a uniformly clamped-together assembly. 

On the Coyote connecting rods I’m just about to assemble, I already directly measured bolt stretch vs torque and calibrated my final torque needs. I’ll also measure stretch as I assemble it to double check the torque gave me the correct stretch. 

In the structural steel world, you can pre-tension (provide clamping load) a high-strength bolt assembly by the turn-of-the-nut method, which is sufficient to get the right clamping load. The method is just as it seems: you turn it a set amount  regardless of the torque needed to do this. The caveat is that you must calibrate this in a special machine. The method is like torque-to-yield stuff and the principle is what Joseph is describing. 

Corey

> On Jul 17, 2018, at 4:43 PM, Joseph F. Byrd, Jr. <byrdjf at embarqmail.com> wrote:
> 
> The nut rotation is what causes the stud to stretch
> To rotate the nut, you must exceed the friction between the threads and under the head
> That friction is the torque you measure when rotating the nut
> 
> When I Assisted with fasteners on precision heavy equipment, torque was rarely a specification with stretch being the primary objective.  When the actual elongation of the bold could not be measure, or just didn't want to...nut rotation was an acceptable method to specify.
> 
> The reason for stretching is to provide a known compression or clamping force.  a rule of thumb for most bolts was a 45Kpsi compression was achieved with a bolt stretch 0.0015"/per inch of bolt.
> 
> Using a wheel stud  is extreme overkill, but...
> Given the stud active length is 1.5" the stretch would be 1.5 X 1.5 = 0.00225"
> The thread pitch being 1.5mm (about 0.06" per rotation)
> There will be deformation of the threads as the nut is loaded, the rule of thumb is us 70% of pitch, so one would expect 0.040" stretch per revolution.
> Assuming all the thread deformation would have from just had tight, that 0.02" could be as much as 33% rotation, about 2 flats,  So from hard snug to full  elongation would be another 0.00225/0.040 = 5% rotation , about 1/3 of a flat on the nut.
> 
> 
> -----Original Message-----
> From: DeTomaso [mailto:detomaso-bounces at server.detomasolist.com] On Behalf Of Pantdino via DeTomaso
> Sent: Tuesday, July 17, 2018 16:46 PM
> To: kenn_green at yahoo.com
> Cc: detomaso at server.detomasolist.com
> Subject: Re: [DeTomaso] Spinning wheel stud
> 
> I think torque is what causes the stretch and the amount of torque determines the amount of stretch. 
> 
> A lubricated thread has less friction than a non-lubricated one , so you have to decrease the amount of torque applied. The friction in the thread is part of what you are overcoming with your torque wrench  
> 
> But Jack is the real expert here. Maybe he’ll chime in. 
> 
> Jim
> 
> Sent from AOL Mobile Mail
> 
> On Tuesday, July 17, 2018, Ken Green <kenn_green at yahoo.com> wrote:
> 
> I recall that stretch is more accurate then torque.  I wonder if there is a reliable way to compare turn after contact with stretch?  I guess that's a stretch?
> 
> Ken
> 
> 
> From: Pantdino via DeTomaso <detomaso at server.detomasolist.com>
> To: larrys at panteraparts.com
> Cc: detomaso at server.detomasolist.com
> Sent: Tuesday, July 17, 2018 11:45 AM
> Subject: Re: [DeTomaso] Spinning wheel stud
> 
>  But keep in mind that anti-seize is acting like a lubricant as you
>  tighten the nut, so you need to subtract maybe 10% from the torque
>  applied. Certainly donat exceed it.
> 
>  Jim
>  Sent from AOL Mobile Mail
>  On Monday, July 16, 2018, Larry Stock <larrys at panteraparts.com> wrote:
> 
>    Dear Sean, and all Pantera Owners, please liberally use anti-seize
>    on all
>    your wheel studs each time you take off a lug nut to avoid this
>    situation.
>    What Sean will need to properly fix this is typically a new $700+
>    billet
>    axle & Bearing installation to properly cure his problem. Please
>    take a
>    little more care and prevent the dilemma that Sean has endured.
>    Larry Stock
> 
>  On 7/16/18, 5:26 PM, "DeTomaso on behalf of sean mundy"
>  <detomaso-[1]bounces at server.detomasolist.com on behalf of
>  [2]seanmundy at hotmail.com> wrote:
>> I tried all the suggestions with no luck. The jack idea did put
>> pressure on the wheel but I was nervous to really apply a lot of
>  force.
>> I've already screwed up enough. I just drilled out the stud and was
>> able to get the last lug nut off and remove the wheel.
>> Only took about 10min using three different drill bit sizes.
>> Now the hard part begins taking the rest of the hub apart. And
>  spending
>> $$$
>> From: [1]sean mundy
>> Sent: Monday, July 16, 2018 2:57 PM
>> To: [2][3]detomaso at server.detomasolist.com,
>  [3][4]larry at ohiotimecorp.com
>> You are using the jack between the bottom of the wheels and pushing
>> them against each other??
>> From: [5]larry at ohiotimecorp.com<[6]mailto:larry at ohiotimecorp.com>
>> Sent: Monday, July 16, 2018 2:33 PM
>> To:
>> 
>  [7]detomaso at server.detomasolist.com<[8]mailto:detomaso at server.detomasol
>  ist.co
>> m>
>> I'm with Jeff on this one. Pressure baby pressure.
>> I have had to do this a time or two. I have two 4" X 4" with about a
>  6"
>> X 6" plywood screwed to the ends. The plywood goes on
>> the inside of each rim, for protection. You then place a scissor jack
>> in the center to apply pressure against the rim. Not too
>> much pressure, just enough pressure.
>> Make sure the spinning stud is down on the bottom to get most of the
>> pressure. Youse your electric impact to give it a good
>> shot.
>> Larry (worked for me) - Cleveland
>> Sean:
>> Since the other three lugs came off, try prying the wheel away from
>  the
>> hub cocking the wheel a bit. You'll probably need a
>> piece of wood or something that won't damage the wheel. The idea is
>  to
>> put enough load on the studs that the hat on the back
>> of the stud will bind against the axle flange "freezing" the stud and
>> then the impact wrench will loosen the nut. This might
>> take a bit of force and finesse, and several sets of hands.
>> It's been some time since I've had mine apart, but if you can get the
>> wheel off, you might be able to get a wire-feed or stick
>> welder in there far enough to spot weld the stud and hold it in place
>> until you want to change the studs.
>> Good luck and don't swear too much!!
>> Jeff 2467
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