I have read many accounts, both here and on the Volvo 'brickboard' site, that attribute warped brake rotors to improper tightening of the lug bolts/nuts. Initially I bought this, but the more thought I give to it the harder it is for me to accept. I took a degree in mechanical engineering (ok, a long time ago) but never practiced it, and have worked in construction management since graduation. So granted, I have lots of years away from theory and lots of time spent in another area, but here I go. The wheel's mounting surface is flat against the 'hat' section of the rotor, which is flat against the axle's flange, and the 3 flat surfaces are bolted together in 4 or 5 locations. If the torque on each of these bolts varies, then I assume only the immediate areas of wheel, the 'hat' section, and the flange adjacent to the bolt hole experience different stress. At this point if I'm wrong, then I should stop. However, assuming I'm correct, then how do these extremely localized different stresses contribute to warping the rotor? Also, if the force is insufficient to stress the material beyond it's elastic limit, and I assume this is so since visual inspection shows no deformation, then the material will return to it's original shape when the force is removed and the vibration caused by 'warped rotors' during braking will disappear. However, this does not appear to be the case in my experience with warped rotors.

So, I'm at the end of my reasoning, and looking someone(s) to explain how this works.
regards,
Mark

I do know that European cars tend to have less meaty, thinner rotors that are not turnable (less unsprung weight).

I was impressed at a tire shop in Atlanta where there were no pneumatic wrenches in the tire installation area. The manager told me that they had to buy a Jaguar owner four new rotors ($$$$ at the time) because of warping caused by overtorquing of the lug bolts. This is why I remove and mount my tires myself here.

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

Thanks, but this is more of the same that perpetuates the 'theory' that overtightening the lugs warps the rotors. I am asking for engineering facts, not the factual story of a business owner deciding to spend a few ($$$$) dollars to satisfy a customer. By the way I am easily convinced by facts, and if my reasoning is faulty then I will welcome the truth.
regards,
Mark

Here's a credible source that argues that there is no such thing as a warped brake rotor:

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

so it's all a lie?

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1994|040|W124.036|E500
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Could it be that on these extremely localized areas of increased stress, lateral forces due to streering, uneven road surfaces, and constant heat expansion and contraction multiply the amount of stress on the given area?

Of course, I don't know what I'm talking about.