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      11-03-2011, 05:47 PM   #66
JCtx
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Drives: No BMW yet
Join Date: May 2008
Location: El Paso TX

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Quote:
Originally Posted by aussie2u View Post
I could tell there was slight resistance from him wanting to replace the entire subframe due to the bolt "hollowing out" its mounting point.
What exactly happened to the subframe, and/or differential mounting point??? If bolt just snapped, everything else should be perfect. Something doesn't add up. If something else broke (either differential mount and/or subframe), that could have caused the bolt to snap. We need more information. Any pics man?

Quote:
Originally Posted by aussie2u View Post
He says the probable culprit is the traction control under full power. He feels that the time between the tires wanting to spin and the brakes clamping creates enormous torque that is absorbed by these bolts.
TC only acts on the engine, by cutting timing, or fuel if needed. Brakes are only applied by DSC. What's causing the problem has to be AXLE HOP IMO.

And keep in mind if something else broke besides the bolt, it has to be investigated what failed first. My money is on defective bolts, but could be improper torquing, or even defective subframes and/or differential mounts. In the mean time, can somebody post pics of exactly what's breaking??? Thx.

Quote:
Originally Posted by e92zero View Post
I will check my bolts this weekend and report back if it's lose or not.
Hey, do you have the torque spec those 2 bolts? I want to check mine too just for the hell of it, but I suspect improper torque might not be the most likely cause since it happened to a stock car... but you never know.

As a side comment, to properly check torque, fastener has to be loosened up first, then retightened. But I'll check torque on the fastened nut first. If torque wrench clicks without moving, even if not torqued to spec, it's probably not enough to cause the problem IMO. Hope we hear the real cause of this, although I'm not too concerned, since I never launch my car. And without axle hop, I'm sure my car will never fail like that. But it still shouldn't happen; that's for sure. Good day gang.
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