Mid left side engine oil leak

[andrewwynn]

Infinitely reusable bolt solution for stiffening plate:

belmertic.com



Nord-lock are reusable locking washers. The flat washers because the bolt heads are small.

I bought two sets and spares. We sold the one X5 before I installed so I have a spare set of somebody was interested in buying them hit me up.

[EODguy]

Transmission coolant lines and the coolant block.

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[bcredliner]

Just so the other side is represented. I don't reuse the bolts. I am aware they are expensive. And no, I don't blindly believe everything I read. However, BMW clearly states the bolts are not to be reused.

[nick325xit 5spd]

Originally Posted by bcredliner

Just so the other side is represented. I don't reuse the bolts. I am aware they are expensive. And no, I don't blindly believe everything I read. However, BMW clearly states the bolts are not to be reused.

Eh. I reuse them.

Why? Because they are non-critical fasteners. If one of these bolts shears, there's little to no consequence.

I've never had an issue with that, even on a heavily tracked car.

[X5chemist]

I'll take a set! 6 or 7 bolts? PM billing.

[Fifty150hs]

Originally Posted by bcredliner

Just so the other side is represented. I don't reuse the bolts. I am aware they are expensive. And no, I don't blindly believe everything I read. However, BMW clearly states the bolts are not to be reused.

You can save yourself a lot of money and order them from Belmetrics. Waaaaaay cheaper.

[bcredliner]

Originally Posted by nick325xit 5spd

Eh. I reuse them.

Why? Because they are non-critical fasteners. If one of these bolts shears, there's little to no consequence.

I've never had an issue with that, even on a heavily tracked car.

I don't pay much attention to anecdotal information. Not to say you are wrong but even if 100 agree with you it is not enough input to draw a firm conclusion. Extremely easy to make the wrong conclusion. How do you know they are not critical? They hold the reinforcing plate in place. You heavily track an X5?

[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.

[andrewwynn]

Originally Posted by bcredliner

Just so the other side is represented. I don't reuse the bolts. I am aware they are expensive. And no, I don't blindly believe everything I read. However, BMW clearly states the bolts are not to be reused.

Because they are torque to yield by design. It's the very best way to get in there field repeatable clamping force.

Studies show that the torque required to achieve the same clamping force will climb as much as 10% each time a bolt is reused.

There is no way to use a torque level to achieve a repeatable clamping force so it's brilliant to use torque to yield to achieve a precise clamping force. The exact same reason TTY is used for head bolts.

Doing some destructive tests I discovered you could reuse the bolts about 3 times with very little loss of tension but by the 4th time they are shot. 5th or 6th they break in half.

I also discovered you could bump the size up to 12mm (1/2") or upgrade to 12.9 bolts and lubricate during torque and you can achieve a very similar and repeatable clamping force non destructive so you could reuse the bolts an unlimited amount.

So that's the path I took. 12.9 10mm bolts.

With 10.9 bolts dry torqued to 65 N·m you will get about 7500# clamping force but if you reuse the bolt you will need to apply 72-75 N·m to get the same force. (but you won't know How much it takes it changes every time).

So; BMW smartly decided use TTY on those bolts.

Now, you preload to the normal dry torque to get about 7500# then 90° more to stretch the bolt. It will act like a spring and laws of physics take over.

Stretch just to yield and you add 20% to the tension and you get 7500*1.2=9000# (9000*6=54000# total).

Clamping force on a lubricated 12.9 m10 bolt to 60 N·m nets you 8980# of force. It's just too perfect so that's why I decided this option.

Lubricated bolt to reduce the difference each reuse. (the 10% difference is for dry threads).

M11 10.9 standard torque nets you 9400# so that was also a very good option.

I for one appreciate why BMW designed the plate to stiffen the body and recommend keeping the functionality not throwing it away by using any method that drops the clamping force.

[nick325xit 5spd]

Originally Posted by bcredliner

I don't pay much attention to anecdotal information. Not to say you are wrong but even if 100 agree with you it is not enough input to draw a firm conclusion. Extremely easy to make the wrong conclusion. How do you know they are not critical? They hold the reinforcing plate in place. You heavily track an X5?

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.

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.