had my wheels off today and when I re-installed them, I thought I would test emergency tightening process. first the threshold torque of 100nm or 75 ft. lbs. marked the arrow then continued with the 443lbs of wheel torque. came up pretty short of the stop mark. anybody tried this. Gordon

 

Come on RL's. My interest is in the accuracy of my P.I. Torque wrench. Anybody? Gordon

 

Interesting. I've read about the emergency torque process, but never tried to do it. I'll have to re-read try it out for myself next time.

 

I can imagine the actual torque applied based on the marking would be a bit dependent on temperature. They probably based the marking on worst-case with a bit extra for safety.

 

Temperature, friction and condition of the grease, etc...

 

I'm interested in other peoples physical results doing the same test. Gordon

 

Carry the PI torque wrench in the frunk for road trips...then you won't have to worry about the emergency procedure to remove and install the wheel in an emergency. Better yet, It's worth carrying a tire plug kit....for punctures. It will get you home or to the dealer...and you won't need to remove the wheel and carry a wrench.

 

To be honest, this method is just meant as a stopgap until the wheel can be torqued properly - it certainly won't say anything about the calibration of your torque wrench.

 

https://rennlist.com/forums/attachme...g-img_0883.jpg
The locking mechanism appears not to be fully engaged in the photo i.e. not in the fully out ~flush position. If so, hopefully you adjusted it outwards after proper torque and before driving.

 

Of course I set the locks properly. Still waiting for others to post test results. I can't believe I'm the only one to check this, maybe, as I am a 40 year Porsche mechanic.

 

I actually have experminted with this procedure on couple of occasions just for curiosity. I had similar experience to you. The specified torque of 443 ft.lbs moved the mark I made after the initial threshold of 100 nm to 7 ticks out of 9, (where 9 marks the stop point). Of course I got curious to learn more about this, so I repeated this process several times and depending on the amount of anti-sieze compound you use on the threads, the Marked point final position ranged from 6th to almost 8th tick on the scale shown on wheel. Then I decieded to increase the torque setting on my torque wrench by 20 additional ft.lbs increments over the specified 443 ft.lbs and repeat the process to find out the needed torque to bring the marked point to stop location (9th tick on the scale). Again depending on the amount of anti seize compound you use on the threads, the torque ranged from 480 ft.lbs to 550 ft.lbs to bring the marked point made after initial 100 n.m. to the stop point.
This was really interesting and indicates that the emergency procedure will alway ensure you exceed the specified torque of 443 ft.lbs.
Only concern if any of course would be the Negative impact of over torquing the bolt & nut. Well the preload to cause permenant damage to the bolt or nut is quite high. The preload can be taken safely all the way up to 90% of proof load (which is 85% of yield strength). I have ran a quick calculation, and it appears you have to be higher than 1000 ft.lbs before you can damage the bolt or nut permenantly, assuming the wheel seating area can withstand the resultant compressive stresses. Regardless it is pretty safe to assume that 600 ft.lbs would not cause any permanent damage.
Discussing this further with my local Porsche service, they confirmed that they are more concerned with under torquing the central locking nut rather than over torquing it by an additional 30%. So if you are caught in an emergency situation and have no access to a large torque wrench, you can safely use the Porsche procedure without worrying about the wheel coming off or causing any permanent damage to the wheel or centeral locking mechanism. Of course you can certainly re-torque the wheel once you have access to proper tools, but you are safe to drive your car until such time. Mark

 

^ Great info. Thanks Mark! We're heading on a road trip down to CA tomorrow, and it's good to know about this in a pinch.

 

That's great information Mark. Aren't the wheel nuts a couple different metals though?

If you were using that procedure would you run it up to the stop or just short?

 

Thanks for sharing your experiment results. But for the emergency procedure, don't you still need a torque wrench to apply the initial 100 N*m?? So this is an emergency procedure for when you have a 3/4" socket wrench, and a torque wrench capable of 100 N*m, but not 443 ft*lbs? Seems odd.

 

I might pick up a 3/8 to 3/4 drive adaptor to keep in the car just in case.