DIY Change Wheels
04-18-2019, 08:11 PM
#31
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If you loosen them they why bother retorquing? It seems you would be doing the same thing every 100 miles. Not trying to be wise, just curious.
04-18-2019, 09:02 PM
#33
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The theory is that it takes almost 50% more torque to move a torqued fastener. Therefore, if you torque down a tightened faster you will not apply enough torque to tighten. No better example than the manual from PAG to torque center locks. I am paraphrasing but >> After reaching desired torque, loosen 90 degrees and retorque>>" Also, everything I have ever read indicates the same thing "never try to torque a fastener without releasing first" . Hope this helps.
04-18-2019, 09:51 PM
#35
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http://www.privacylives.com/wp-conte...0-002-tpms.pdf
04-18-2019, 09:59 PM
#36
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The theory is that it takes almost 50% more torque to move a torqued fastener. Therefore, if you torque down a tightened faster you will not apply enough torque to tighten. No better example than the manual from PAG to torque center locks. I am paraphrasing but >> After reaching desired torque, loosen 90 degrees and retorque>>" Also, everything I have ever read indicates the same thing "never try to torque a fastener without releasing first" . Hope this helps.
https://www.scsconcept.com/residual-...ady-tightened/
04-18-2019, 10:06 PM
#37
Racer
The point of checking the torque of the lug bolts after 100 (to 250) miles is to make sure the bolts are still at spec. If you torqued them correctly to begin with, usually they have loosened only a little bit, if at all. I'm not entirely sure why this happens, but especially with alloy wheels the metal may have compressed a little, heating/cooling cycling may have loosened things a little, the wheel may have snugged up to the hub, or the threads may have stretched a little since the bolts were torqued. The only time I would loosen a bolt when doing this check is if I discovered it had been over-tightened.
Also, the computer knows when you've changed wheels because it no longer receives radio signals from the TPM sensors and the car is in motion. When you enter the info about new wheels, it searches for the new wheels' TPM sensors.
Also, the computer knows when you've changed wheels because it no longer receives radio signals from the TPM sensors and the car is in motion. When you enter the info about new wheels, it searches for the new wheels' TPM sensors.
04-18-2019, 11:12 PM
#38
Three Wheelin'
Perhaps based on distance vs revolutions New tires rotate less for a given distance compared to old worn out tires. There might be a number of ways to derive at the same result that other manufacturer uses. ABS is a good example because wheel slip is sensed by the sensor and than it triggers the computer to interpret which wheel and which brake to activate or pump and release. ABS works flawlessly and will out-brake any F1 driver. It was developed for jet-liners and then F1 and then trickled down to passenger cars.
04-19-2019, 12:10 AM
#39
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Perhaps based on distance vs revolutions New tires rotate less for a given distance compared to old worn out tires. There might be a number of ways to derive at the same result that other manufacturer uses. ABS is a good example because wheel slip is sensed by the sensor and than it triggers the computer to interpret which wheel and which brake to activate or pump and release. ABS works flawlessly and will out-brake any F1 driver. It was developed for jet-liners and then F1 and then trickled down to passenger cars.
04-19-2019, 12:19 AM
#40
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This is overkill.
--^
Two or three stages is fine, but it is just as effective to progressively, in a star pattern tighten the lug bolts/nuts 'by feel' until you get close to the required torque and then break out the torque wrench (or attempt, in earnest, to achieve the spec torque.)
Right. There are a least two reasons to progressively tighten the wheel lugs:
1) This ensures that the wheel is flat on the wheel hub. If the interface (flanges on modern Porsches, rings on others, etc.) between the wheel and the hub is 'tight' it's possible to have the wheel 'cocked' on the hub. If you 'choose unwisely' and torque-to-spec one lug, torquing the other lugs to spec may not cause the rest of the wheel to seat flat against the hub. Or, IOWs, you just torqued the wheel so that it can't seat flat on the hub.
2) If you just go from finger-tight to full-torque-spec in one go, the first lug you torqued will be over-torqued when you're done.
Right.
Impact wrenches are just plain risky for tightening any fastener unless you have invested in high-dollar calibrated equipment like automotive assembly factories do or you've done some closed-loop calibration of your air wrench and your compressed air system.
Impact wrenches are for loosening fasteners. And then only sparingly.
Air impact wrenches - power tools in general - remove any 'feel' from the process of fastening or unfastening. It's a good way to not notice that threads are damaged when you remove a fastener and a better way to damage threads or over-torque a fastener on the way back in.
Tightening a steel fastener in an aluminum hole with a power tool is a big no-no. The torque spec is usually a 'any more than a little tighter than this and you strip the aluminum threads' spec.
I always torque wheels to spec with the suspension unloaded. I use a wheel chock to keep a wheel from turning. This further ensures that the wheel stays flatly seated on the hub.
Your lug bolts are likely way-over 90-100 ft/lbs after you apply your air wrench unless you a) have a week-a$$ed wrench or weak air or b) you've figured out which setting to use on your air wrench that has torque adjustments and have a torque wrench that reads torque when loosening a fastener to make sure.
When you use a torque wrench, if you don't see the fastener turn at all *before* the wrench clicks/beeps/vibrates that's an indication that you may have exceeded the torque spec.
For steel-on-steel exceeding the torque spec even by a large margin isn't usually a serious problem. For steel-on-aluminum exceeding the spec by a not-large margin often results in thread damage. This will usually only become apparent the 'next time' when the hole won't take the torque.
Hopefully, wheel hubs on modern Porsches are still steel and not aluminum. It's well known that the hub carrier is aluminum and why frequent brake pad changes result in stripped carriers.
--^
Two or three stages is fine, but it is just as effective to progressively, in a star pattern tighten the lug bolts/nuts 'by feel' until you get close to the required torque and then break out the torque wrench (or attempt, in earnest, to achieve the spec torque.)
Right. There are a least two reasons to progressively tighten the wheel lugs:
1) This ensures that the wheel is flat on the wheel hub. If the interface (flanges on modern Porsches, rings on others, etc.) between the wheel and the hub is 'tight' it's possible to have the wheel 'cocked' on the hub. If you 'choose unwisely' and torque-to-spec one lug, torquing the other lugs to spec may not cause the rest of the wheel to seat flat against the hub. Or, IOWs, you just torqued the wheel so that it can't seat flat on the hub.
2) If you just go from finger-tight to full-torque-spec in one go, the first lug you torqued will be over-torqued when you're done.
Right.
Impact wrenches are just plain risky for tightening any fastener unless you have invested in high-dollar calibrated equipment like automotive assembly factories do or you've done some closed-loop calibration of your air wrench and your compressed air system.
Impact wrenches are for loosening fasteners. And then only sparingly.
Air impact wrenches - power tools in general - remove any 'feel' from the process of fastening or unfastening. It's a good way to not notice that threads are damaged when you remove a fastener and a better way to damage threads or over-torque a fastener on the way back in.
Tightening a steel fastener in an aluminum hole with a power tool is a big no-no. The torque spec is usually a 'any more than a little tighter than this and you strip the aluminum threads' spec.
I always torque wheels to spec with the suspension unloaded. I use a wheel chock to keep a wheel from turning. This further ensures that the wheel stays flatly seated on the hub.
Your lug bolts are likely way-over 90-100 ft/lbs after you apply your air wrench unless you a) have a week-a$$ed wrench or weak air or b) you've figured out which setting to use on your air wrench that has torque adjustments and have a torque wrench that reads torque when loosening a fastener to make sure.
When you use a torque wrench, if you don't see the fastener turn at all *before* the wrench clicks/beeps/vibrates that's an indication that you may have exceeded the torque spec.
For steel-on-steel exceeding the torque spec even by a large margin isn't usually a serious problem. For steel-on-aluminum exceeding the spec by a not-large margin often results in thread damage. This will usually only become apparent the 'next time' when the hole won't take the torque.
Hopefully, wheel hubs on modern Porsches are still steel and not aluminum. It's well known that the hub carrier is aluminum and why frequent brake pad changes result in stripped carriers.
- Use an impact air gun to remove wheel bolts.
- Pull wheels and put on new ones, using 2 pins.
- Finger tighten each bolt for about 5-10 turns to make sure it is properly threaded.
- In a star pattern, use my impact air gun at it's "low" setting to tighten wheel bolts. This does NOT get them to 118 ft/lbs. How do I know? See step 5.
- In a star pattern, with a hand torque wrench set to 118, torque down each bolt. Every time I've done this, each bolt has at least 1 full turn before the wrench clicks.
- After a few drives, re-torque as in step 5.
04-19-2019, 12:41 AM
#41
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In a star pattern, use my impact air gun at it's "low" setting to tighten wheel bolts. This does NOT get them to 118 ft/lbs. How do I know? See step 5.
In a star pattern, with a hand torque wrench set to 118, torque down each bolt. Every time I've done this, each bolt has at least 1 full turn before the wrench clicks
In a star pattern, with a hand torque wrench set to 118, torque down each bolt. Every time I've done this, each bolt has at least 1 full turn before the wrench clicks
With observation of the bolt turning before the spec is reached you know that static friction is overcome and the wrench is reading the dynamic force.
* Last century, one of the cars I leased, had lugs drilled-out and front wheel hubs replaced under warranty. Twice. The second time, I sat the SM down, pointed this out and suggested might want to do something about procedures. Of course, now, knowing more about 'operations' I suspect he knew exactly what was happening, was adding to the bottom line, and was just playing the odds that the parent company wouldn't mine the stats and start refusing warranty reimbursement.
After a few drives, re-torque as in step 5.
04-19-2019, 12:57 AM
#42
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Interesting. I often find that when I do it a couple lugs take 1/4 turn or so.
04-19-2019, 09:57 AM
#43
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Interesting. I wonder if I have the PDI checklist sitting around and if re-torquing the lugs is on it. ‘cause you know that the factory doesn’t and with all the suspension packers folks find after months of driving it’s apparent that it would be hit-and-miss at PDI. So, we should be seeing some wheels falling off...
04-19-2019, 10:36 AM
#44
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Interesting. I wonder if I have the PDI checklist sitting around and if re-torquing the lugs is on it. ‘cause you know that the factory doesn’t and with all the suspension packers folks find after months of driving it’s apparent that it would be hit-and-miss at PDI. So, we should be seeing some wheels falling off...
I've done this swap a lot. Do lug bolts ever wear out and need replacement?
