Mid left side engine oil leak

[nick325xit 5spd]

Originally Posted by andrewwynn

If the bolts are not tight you will lose three structure of the plate's design. Clearly it's meant to be structural and will change the dynamic of the suspension.

I've driven plenty with the plate off completely and the body wiggles reminds me of my convertible z28 when the top was down.

The clamping force is about 8000# per bolt when properly torqued.

When people just "snug" the bolts to reuse them they are converting the stiffening plate into a underbelly guard losing the body stiffness of the design.

Like I mentioned I've driven plenty with the plate off but it for sure makes a difference.

I agree that it's structural, but the very fact that you've "driven plenty with the plate off completely" reinforces my point that the plate is non-critical. Of course it feels shitty with the plate off.

[bcredliner]

Originally Posted by nick325xit 5spd

One can draw some conclusions based on the fact that people have been reusing the bolts for two decades. And as for the reinforcement plate itself, well, that's a piece that BMW added to make the cars stiffer. Older BMWs didn't have them at all, and modern BMW subframes are a lot stronger than the flexible pieces that they used to use.

Note, however, that I am NOT advocating retorquing in the same manner. If you keep stretching the bolt it will fail. What method to reach torque specs do you use?

So yeah, if these were difficult to get to, or actually holding in a critical component, I'd say replace them. But the reinforcement plate is not a critical component. You can take it off entirely and drive the car.

You can only assume that two decades of anecdotal evidence are proof. How many X5s owners do you know about that reuse the bolts? Whether the plate wasn't used on older or isn't on newer X5s doesn't matter. Didn't the first year of the X5 have the plate? Regardless, neither is applicable other than to reinforce the importance of the plate, bolts included.

I suspect the primary reason the bolts are reused and supporters are so adamant is the cost. And rather than pay the price some look for supporting input to justify not replacing them. I thought about reusing the bolts the first time I removed them but decided I didn't know as much as BMW about the reason they chose the not to reuse bolts.

[Fifty150hs]

Originally Posted by nick325xit 5spd

I agree that it's structural, but the very fact that you've "driven plenty with the plate off completely" reinforces my point that the plate is non-critical. Of course it feels shitty with the plate off.

I wouldn't want to get in wreck without that plate in place, especially if someone was injured or killed. BMW says not to operate the vehicle without it in place. They don't suggest it they flat out say not to do it and that doing so is dangerous. A lawyer would love to see no plate in place in a collision.

[nick325xit 5spd]

Originally Posted by bcredliner

You can only assume that two decades of anecdotal evidence are proof. How many X5s owners do you know about that reuse the bolts? Whether the plate wasn't used on older or isn't on newer X5s doesn't matter. Didn't the first year of the X5 have the plate? Regardless, neither is applicable other than to reinforce the importance of the plate, bolts included.

I suspect the primary reason the bolts are reused and supporters are so adamant is the cost. And rather than pay the price some look for supporting input to justify not replacing them. I thought about reusing the bolts the first time I removed them but decided I didn't know as much as BMW about the reason they chose the not to reuse bolts.

My point, as andrew demonstrated above by regularly driving with the plate removed entirely, is that the plate is not critical to safety. Therefore you can comfortably and reasonably cut corners on it.

Yeah, sure, new bolts are better. But at this point, it's pretty clear that new bolts are not necessary.

And I said older BMWs, not older X5s. IIRC, BMW started using a stiffening plate on all their cars around the time when the X5 was introduced.

[nick325xit 5spd]

Originally Posted by Fifty150hs

I wouldn't want to get in wreck without that plate in place, especially if someone was injured or killed. BMW says not to operate the vehicle without it in place. They don't suggest it they flat out say not to do it and that doing so is dangerous. A lawyer would love to see no plate in place in a collision.

You're extrapolating pretty far out from what I've actually said here.

[andrewwynn]

Actually the car would be safer in a crash without the plate. Seems a main purpose of the plate is to keep the car rectangular in a crash.

A little simple math: hit something firm on a front corner and the 6000# hammer roughly 2.5' off center with a relatively minor crash can be 10g or 60,000# times 2.5 or 60*2.5=150k ft·lb.

That torque will be applied to twist the body into a parallelogram with the main component resisting that being the stiffening plate.

Without the plate the car will flex and make the g-force less on the humans inside sacrificing the the car by crumpling.

There are long term concerns about fatigue failure so I would not recommend driving all that long without the plate

I also would not recommend turning the plate into a dust shield by loose application of the bolts (anything under 65 N·m is effectively hand tight and won't be helping much in an offset minor crash that would turn a fender bender into a total wreck).

Look at the non frame of the car. There is really very little diagonal structure save the stiffening plate and that is apparently it's primary job. (hence why it's clamped with 54,000# of force. Also why it's so thick so it can do the job of cross bracing.

[bcredliner]

Originally Posted by nick325xit 5spd

My point, as andrew demonstrated above by regularly driving with the plate removed entirely, is that the plate is not critical to safety. Therefore you can comfortably and reasonably cut corners on it.

Yeah, sure, new bolts are better. But at this point, it's pretty clear that new bolts are not necessary.

And I said older BMWs, not older X5s. IIRC, BMW started using a stiffening plate on all their cars around the time when the X5 was introduced.

Why are new bolts better if they are not necessary? Is cutting corners ever a good thing, especially concerning safety?

I really value Andrew's contributions to the forum and this has no reflection as to the extent of his knowledge. That said, Andrew did not design the plate or determine what bolts should be used. IMO regular driving results are interesting but a good test would be in max conditions not regular driving that would not include max breaking, emergency lane changes, going to the handling limits, driving twice the speed limit down a pothole filled road etc.

Assuming you are correct about older BMW having a similar plate, why would they spend so much money on something that is not important or necessary?

Yes, I was pretty sure when I asked your point was not about E53 X5s only. That's the issue. It should be about only E53 X5s.


.

[andrewwynn]

Originally Posted by Fifty150hs

I wouldn't want to get in wreck without that plate in place, especially if someone was injured or killed. BMW says not to operate the vehicle without it in place. They don't suggest it they flat out say not to do it and that doing so is dangerous. A lawyer would love to see no plate in place in a collision.

The plate will protect the car in a crash. It will be softer on the people without the plate. The crumple zone will be much softer without the plate that will take 100s of 1000s of pounds to bend. It will also hold the engine up rather than allow it to submarine below the firewall in a straight on collision.

Definitely not "less safe" from any significant point of view. Any less control due to the extra body flex will be at limits of control that will put the failure mode on something else like hitting 4 pebbles.

[nick325xit 5spd]

Originally Posted by bcredliner

Why are new bolts better if they are not necessary? Is cutting corners ever a good thing, especially concerning safety?

I really value Andrew's contributions to the forum and this has no reflection as to the extent of his knowledge. That said, Andrew did not design the plate or determine what bolts should be used. IMO regular driving results are interesting but a good test would be in max conditions not regular driving that would not include max breaking, emergency lane changes, going to the handling limits, driving twice the speed limit down a pothole filled road etc.

Assuming you are correct about older BMW having a similar plate, why would they spend so much money on something that is not important or necessary?

Yes, I was pretty sure when I asked your point was not about E53 X5s only. That's the issue. It should be about only E53 X5s.


.

Do you replace your tires as soon as the compound starts to fall off and grip declines? Or do you run them down to the wear bars? Any tire below about 50% tread, or a few years old has lost a significant amount of grip. If you keep running them, are you not cutting corners with regards to safety? Do you run the optimum compound tire for every season of the year?

Everything is a trade off vs. cost. The question is whether or not you’re giving up anything meaningful.

[andrewwynn]

It's a different thing when talking about torque to yield bolts.

There is good reason to follow the rules and use new bolts in a TTY situation. The stiffening plate is not a "mission critical" part like the head so you can absolutely get away with reusing bolts to some extent even without losing strength a couple times.

It's not remotely similar to "half worn tires" a better analog would be torquing lug bolts.

@bc definitely is "Fringe" regarding keeping things as close as possible to perfection and that's a commendable goal.

I am far far closer to the "within reason" crowd (I'm willing to bet @bc wouldn't drive without stiffening plate while working out where is the oil leaking). It's not a significant risk I will stand by that but I also have a 3.0 not a 4.8 or X5m. It does matter.