Quinlan

and so it continues....

Veloce Raptor

..

mark kibort

alright alright
OP, just even out the torques on the wheel and let us know if that solves the rotor vibration problem.

over and out!

Slakker

Interestingly enough, when I found the lugs loose, I tightened them pretty snug and drove for a couple of days until my torque wrench arrived. I then went to tighten them to spec and found them loose again.

I then tightened them to 96 (it's analog, can't hit 95.8 . By torquing them to 96, it became obviously that I had overtorqued quite a bit when doing it without the wrench. So I drove a few more days wondering if they were going to loosen again. I checked them today and they were all snug at a min of 96.

So I guess my question is could over torquing by the tire shop have been the cause of the loose lugs? Seems like a strange concept.

TXE36

How do you know this? If people were reliable "human torque wrenches", then torque wrenches wouldn't exist or be nearly as common.

The most obvious answer is they were under torqued before.

There is actual science to bolt torques but one of the problems with the measurement is that it is indirect. What you are trying to set is the tension on the fastener, since there is no easy way to measure that, the "stand in" is measuring the friction required to turn the threads. In cases where you can measure bolt stretch, connecting rods for example, sometime the tension spec is the actual measured bolt stretch and not torque.

And therein lies the rub - bolt torques are usually specified for new fasteners. Grease or anti-seize on the threads can cause a bolt to be over tight even if torqued to spec (if the spec doesn't call for the lubrication - some do). Thus, when working with used fasteners, I usually under torque a bit by either using the low end of the spec or judgement based on experience.

Case in point, the torque spec for BMW E36 wheel bolts is something like 85-90 ft-lbs. I don't use wheel bolts, I use studs and lug nuts. The spec for the studs is 75 ft-lbs dry. That is the spec I use and have been using since I got the car in 2009. Freshly mounted tires need one re-torque after their first hot session and then they stay at 75 ft-lbs until I take them off. I've observed this behavior for years and I do check them, but after that first re-torque I've never found a loose one.

Over torquing is bad because it can damage the fastener even if it doesn't snap it off. I hate working on vehicles that the previous mechanic monkey torqued everything.

TL;DR Torque the lugs to spec using an actual torque wrench.

-Mike

Slakker

Lol, it's actually pretty easy to determine torque by hand +/- 5lbs if you have a torque wrench for reference. I've tightened lugs on trucks and tires by hand for 25 years and never had an issue, even hauling some pretty big loads. But the demands of a high performance vehicle at a high rate of speed call for 95.8 lbs. So 96lbs it is....

Coochas

Buy a torque wrench. I'm not buying this human torque argument.
Anyone can tighten the lugs on a car/truck so that the wheels don't fall off. Hell, I used to stand on my lug wrench to tighten them when I was young. I'm guessing my torque was way beyond what was prescribed.
On the side of the highway, I agree with the human torque wrench for changing a flat. At the track, do things right and do them the same way every time.

TXE36

$22 HF Torque Wrenches. Repeatable and accurate enough. I've got all of them except for the 3/4". On sale, they are $10. They don't cost much more than breaker bars.

I don't understand the aversion to using the proper tool when it is so stinking cheap. I also don't understand how somebody could properly work with steel bolts into aluminum threads without one.

-Mike

Slakker

Just to clarify, when tightening by hand, I tightened it like I normally do any truck or tailer. Using a breaker bar, tighten all 5 lugs firmly in a star pattern twice. Then repeat a final time adding a little weight to get that last little bit of snugness. My existing torque wrench only went to 80lbs. So when my new one arrived that went to 120 (tekton off Amazon, high quality inexpensive tools), I went to loosen and retighten my lugs to spec. The lugs were loose and came off too easily. I then retightened them to 96lbs and it took a noticeably less amount of effort than I normally use to tighten lugs. Therefore, using anecdotal evidence, I am assuming that I had over tightened them previously and that they had come loose.

As for not buying the human torque wrench argument, try it out for yourself. Tighten a few using a torque wrench, then tighten a few by hand. Recheck the ones by hand and see how close you get. You may be surprised at what the the human body is capable of.

noturavgm

I've done this a few times with a breaker bar for kicks. I can get them all extremely close to one another, but its a crap shoot how close I can get them to the actual torque spec. Precision vs accuracy


There is simply no legitimate argument Against using a torque wrench.

mark kibort

exactly! it is pretty amazing the capabilities of human performance. somethings are even better than tools!
However, this where the discussions here fall apart. i never offered an argument against a torque wrench, i just said that i didnt use one and was very close to spec, always! (and is therefore not dangerous) (not a crap shoot by the way.... craps are less than 50% odds... you want to give me those odds on a range of 90ftlbs to 100ftlbs done by hand? but if you are talking a bet to get right on the spec, you are right! )

mark kibort

This is something ive never heard of happening. especiallly, from an overtorqued nut. possibly, there is an issue with the fit of the lug nut to the wheel that could have changed over time combined with the forces of driving on them. thats why we always check the lugs before we go out each session. not superstition, (as it would seem because i never have seen one loosen) but its about "what if", so we do it anyway because losing a wheel is not pretty... ive seen it a few times on other cars.
what kind of wheels do you have on the car? stock? aftermarket?
using antiseize on the threads?


well, you just havent done the human experiment as others have done. you can get with in 5% very easily and repeatabl

in my case, the only reason for not using one is a reason of my own. its strictly a time thing in the paddock. im just a lot faster doing the job with the 90degree porsche breaker bar. plus, that's what calibrated to use

Slakker

Stock turbo twists, no anti seize. Since it did not happen after tightening to spec with a torque wrench, I'll write it off as an anomaly move on... adding torque wrench to go with the tire gauge and oil in my track bag.

mark kibort

sounds like it would have happened either way. Never hurts to be more accurate thats for sure.

Let us know how the brakes are after the next event. if you never got them hot after the problem, with the even torque on the lugs, you might have to get them hot again for the problem to go away..... that's how i solved it.
again, that was many years ago and it was a one time event. (shop had performed very uneven torques to lugs which i believe caused the vibration like you experienced).

Slakker

Will do. Car control Sat and Autocross Sunday but not sure if that will get them hot enough to find out. Next track days are 5/20 at Hallet and 5/22 at MotorSport Ranch in Cresson, TX.