GeorgeCo

I was installing new wheel studs today and got to thinking (always dangerous) if the nut will be torqued to 96 ft-lbs, why doesn't the bolt back out since its only tightened to a fraction of that? Even considering the effect of using thread locker, it seems like the bolt would spin. Can someone explain what's going on from an engineering/physics perspective?

996_C4S

I'm clueless but have the exact same question ... looking at the set of studs I ordered last month, and wondering about torque on the back of the stud. English major here.

Heima996C4S

What did you torque the studs to?

996_C4S

I haven't yet. The studs need to be tightened with a hex wrench; I guess I'll need an adapter/similar for my 1/2" torque wrench drive.

Seems like I'd want at least as much torque on the studs as on my lug nuts (94 lb.), right? I'm thinking there's less danger of over-tightening the studs since there's no aluminum - ?

Macster

Been a long time since I dealt with wheel studs but when I did the portion that fit in the hub/wheel was splined.

The stud when tightened down the first time the spline section was drawn into the hole and its splines cut mating splines in the hole of the wheel/hub. These splines kept the stud from turning when the nut was tightened or loosened.

fpb111

It depends on what the studs bottom out on, if anything. The studs are not clamping any thing until you mount a wheel. I would bet not much more than finger tight with threadlocker/locktite. Does the supplier spec a value for the studs?

When you torque the lugs (bolts or nuts) you are applying clamping force on the wheel not twisting force on the stud. When you are just replacing lug bolts with studs you are not clamping anything until you mount the wheels with the nuts.

Macster not sure what type of studs they are using. Normally they would have splines and a head to tighten against the flange, as you indicate. But if these have an internal hex (allen) then it sounds like they are screwed in from the outside like a large set screw.

acadian_dad

Is this for track ?

If these are the track studs that I've used previously, they have shoulders that bottom the stud onto the hub flange. No splines. Not needed.

http://www.track-studs.com/ProductInfo/stud_install.cfm

You can use red thread locker but the heat from the brakes is going to break that down anyway.

If they are the ones with an Allen key head - don't torque with that - its just for ease of initial install - torque with the locked nuts. And it's only to 15-20 ftlbs.

The torque on the nut when you install wheels is still 95 ftlbs. Torque just loosely translates to a linear preload tension in the fastener. Don't worry about the stud initial torque.

996_C4S

Acadian - thanks very much!

acadian_dad

Glad I could help - do check them on a regular basis - just don't torque them when hot.

There are a number of threads on the GT3 forums about the pluses and minuses. I've never had problems with mine but a couple of guys I know have had studs snap while driving on track.

Play safe !

GeorgeCo

Fpb111: your answer makes sense. I had been thinking of the force being applied as a twisting force rather than a clamping force as the nut tightens. The stud was tightened until it bottomed out using thread locker and only torqued to 15-18 ft-lbs, wheel nuts torqued to 96 ft-lbs

fpb111

As Acadian says, keep an eye on them to make sure they don't partially back out while changing to your track tires.