Quote:
Originally Posted by cn90
oldskewel is correct,
I have removed the bolt many times and compare it against a brand-new bolt.
There is no deformity of the old bolt from repeated tightening and loosening.
In other words, the old bolt does not lengthen when compared with a brand-new bolt.
The fact that a bolt is angle-tightened does not mean it is a "use-once-and-discard" type of bolt.
This has been a funny thread, especially if read by BMW or indy mechanics, as they do not replace these bolts.
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This will only be the case if the bolt was never fully tightened. The bolts i've taken out and measured are ALL longer than they started and grew each time I tightened. (it will not look longer it's only 0.08mm longer per cycle or so). The picture i took above shows clearly that the bolt is 36.25mm long in the thread count that should be 36.00.
Tightening to spec 4 times plus an unknown times it was done on the vehicle took the bolt to internal failure and one more time broke it in half.
It will not distort below maybe 70-80 N·m which will net you about 2/3 of the design clamping force. Clearly that is enough to not cause cars to suddenly start flipping over, but it also is a lot less than design.
When i reused my bolts i looked up the advised torque for M10 class 10.9 and would have set them to something close to that (67 N·m spec).
Torque'd to normal spec should be ok in my humble opinion, but until somebody actually does the research to determine for sure nobody knows. if the plate moves a tiny bit under certain suspension dynamics that will affect performance to some extent. Is it something anybody will ever notice, that's clearly up for debate.
I like the idea of maintaining the design clamp force but not have to replace the bolts so i'm upgrading to 12.9 bolts to achieve that.
measure the torque it takes to remove your 'seat of pants' tightening, i would be curious; when i removed my wife's they ranged from 68 down to about 20 ft·lb, which I would regard as not nearly ok. (one was 45, also not ok).