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Old 01-08-2019, 02:47 PM
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bcredliner bcredliner is offline
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[QUOTE=andrewwynn;1151376]I will have a very helpful case study soon. When I replaced my stiffening plate a while back I used less than grade 8 bolts and definitely not torqued to spec. I just used a good during strong yank on a breaker bar.

The only problem that could be expected if the bolts aren't doing their job is that the plate will slide sideways during a body twist situation.

As I'm well known for tight parallel parking shortcut of driving straight in over the curb about a foot and back onto the road my car gets a very significant "ditch witch" twist test regularly. I need to remove the plate soon to track down an oil leak and will take close looks at all the six mounting points and let everybody know if there is any sign of movement of the stiffening plate.

If there is or isn't the question can soundly be answered.

The primary job of the bolts during normal operations (not a wheel off the ground off-road operations which I'm also no stranger to), is to hold the anti sway bar down.

The sway bar doesn't need half the strength of the bolts used for this job: implication is that the only reason they are overkill bolts is to prevent side slip and that's pretty clear by the name of the part or holds: stiffening plate. It stiffens by preventing the subframe from twisting out of square. (Think of it like a giant "X" under the engine to keep the front left and back right of the engine bay the same distance as the front right and back left. Rather than a couple 1" thick steel bars BMW choose to use a 5mm thick aluminum plate that coincidentally blocks road hazards from the engine, noise and catches drips from messing up people's garage floors (until the foam is saturated and that's usually a second owner problem).

The math I'm sure worked out to "holy shit that's a lot of sideways force" so when they added on the typical 200% to 300% safety factor it landed where it did.

As far as a safety concern by the time you get to where one of these bolts fail there will be 8 things far more risky to your well being and more than likely the bolt failing would improve your chance of survival by decreasing the forces required to crumple the engine bay and reduce the g-forces transferred t

I am not qualified to take a position either way. My bet is you aren't either. All we should do here is offer our opinion and/or advice. Any anecdotal input or experiments we can offer would be, at best, logical rather than standardized industry testing. We can state there are 8 things far more risky to our wellbeing, that it is the typical 200-300% safety factor, sway bar doesn't need half the strength. That reusing them is safer than replacing them. And primary function is holding down the sway bar (would love to hear your basis for that one)--just our layman opinions. FYI- the reinforcement plate on a 2002 4.6 is not 5mm thick.

As far as exactly on topic, that was about the what did you do to your E53 today thread. I thought some members were not aware that the thread is not intended to be used to ask about how to fix a problem, show pictures of what you had for dinner, etc. The only reason is that the majority of members follow that thread and receive post alerts. I think it is a great thread and would not like to see members op out because of so much WAY off topic posts. It's like this irritating debate where some op out or post things like please stop, don't do this again.
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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
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