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BMW 3-Series (E90 E92) Forum
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Broken bolt removal
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02-08-2021, 09:09 PM | #1 |
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Broken bolt removal
I had the unfortunate accident of breaking a aluminum bolt while installing a stress bar on my E90. Any suggestions on how to remove this bolt? Should it be done with a bolt extractor or just drilled out with a smaller titanium drill bit?
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02-11-2021, 11:15 AM | #5 | |
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Steel is very galvanically-reactive with magnesium, which is why it is not used for N52 engine block fasteners. All other fasteners on the E9X are steel. Steel bolts that look like aluminum have a dull, silver anti-corrosion coating. When you say "lubricated well", do you mean you oiled the bolt threads, or used anti-sieze on the bolt. If you did, then that lowers the torque spec for that fastener. Looks like you over torqued the bolt. Last edited by Efthreeoh; 02-11-2021 at 11:22 AM.. |
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cliffschum15.50 |
02-12-2021, 01:24 PM | #6 |
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Interesting. I have a N51 and this bolt definitely looks aluminium to me. I applied penetrating oil on removal to free it, I don't recall anything being used on the way in. It may have been over torqued but not a whole lot. I have a fairly accurate torque wrench.
How much torque should you shave off if applying anti-seize or oil? Like 5lbs? |
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02-12-2021, 06:00 PM | #7 |
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I find that a magnet is useful in reminding myself. Having removed the bolts you show in those photos many times myself, they are definitely steel with an anti-oxidation coating. Strangely enough, the aluminum bolts tend to look less like aluminum than the steel ones do as they are often shiny.
That being said, bolts of all kinds can be threaded into those holes. It may may have been replaced by someone incorrectly at some point. |
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02-13-2021, 11:39 AM | #8 | |
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02-13-2021, 12:47 PM | #9 | |
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But to talk in real terms, home mechanics get caught up in torque specs too seriously. Following torque specs for engine assembly are really important, as are wheel bolts (for safety reasons), but most of the applications in between, you can be close to the spec and it's good enough. Your car is not a spacecraft. Too much torque is worse than too little. It takes practice to learn when the bolt is nearing the torque application spec by "feel", but you eventually learn it. And a lot of home mechanics do not use torque wrenches properly. Many use too big or too small of a wrench and use the wrong type of torque wrench for the application. Too big means the torque wrench is not accurate at the lower and upper limits of the wrench's capacity. Wrong type is beam vs. click. For example, you should only use a 3/8th-drive beam torque wrench on spark plugs.
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A manual transmission can be set to "comfort", "sport", and "track" modes simply by the technique and speed at which you shift it; it doesn't need "modes", modes are for manumatics that try to behave like a real 3-pedal manual transmission. If you can money-shift it, it's a manual transmission. "Yeah, but NO ONE puts an automatic trans shift knob on a manual transmission."
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02-13-2021, 02:03 PM | #10 | |
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The fact it broke says yes, it was over torqued. Period. |
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Efthreeoh17303.00 |
02-13-2021, 02:06 PM | #11 | ||
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02-13-2021, 03:25 PM | #12 |
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Agreed for the tension strut bolt. 73 pd-ft +100 deg. But I was referring to bolts in general; not all are TTY.
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A manual transmission can be set to "comfort", "sport", and "track" modes simply by the technique and speed at which you shift it; it doesn't need "modes", modes are for manumatics that try to behave like a real 3-pedal manual transmission. If you can money-shift it, it's a manual transmission. "Yeah, but NO ONE puts an automatic trans shift knob on a manual transmission."
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02-15-2021, 01:39 PM | #14 | ||
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The Nightman1090.00 |
02-15-2021, 09:57 PM | #15 | |
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I was able to remove it gently using a screw extractor and penetrating oil. |
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