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  #21  
Old 09-09-2020, 06:20 AM
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Quote:
Originally Posted by aureliusmax View Post
From a practical engineering standpoint, I don't see any proof of that actually occurring. Given the size of the frame, materials, etc and a number of other manufacturers that don't have this plate.

I can see it acting as a stiffening brace and a skid plate from off road debris, but if that thin plate is not there having the front frame crack in half is just preposterous.

You may notice that the cars that don't have the plate often have diagonal braces over the top of the engine. You are correct about the car won't likely break at the seams without the plate however it's definitely not impossible. Fatigue failure at a weld is absolutely a solid possibility with the stiffening plate removed. It might take a couple years but with the additional twisting at every pothole it's a definite possibility.

As far as comparing other cars that don't have it, that's not a valid comparison, the valid comparison would be to remove the cross brace over the engine on an E90 etc. The X5 is absolutely designed to utilize the stiffening plate and does so on every single bump.
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  #22  
Old 09-09-2020, 08:36 AM
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Well said and expertly backed up, Andrew. Thanks for informing us with your knowledge and your own experience!

CN90 said in another post that “head bolts, when you compare old vs new, are different. The old ones are longer from stretch. The stiffening plate bolts, they are big and fat, very much like a wheel lug. They don’t elongate with tightening. They will never break if you torque them properly.”

Any truth to his post?
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  #23  
Old 09-09-2020, 08:45 AM
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Quote:
Originally Posted by aureliusmax View Post
I don't see any issue with doing so. Can always upgrade to industrial 8.8 or 12.9 grade metric bolts if your old have stretched.

Also I have been driving without the reinforcement plate, so I can chase and repair leaks. Really it's more of a skid plate, I found no difference in performance driving.
Do you have the exact spec for the 12.9 grade metric bolts? Where can I find some?
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  #24  
Old 09-09-2020, 09:50 AM
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Part number for the Reinforcement Plate Bolts

Quote:
Originally Posted by Maruzo View Post
Well said and expertly backed up, Andrew. Thanks for informing us with your knowledge and your own experience!

CN90 said in another post that head bolts, when you compare old vs new, are different. The old ones are longer from stretch. The stiffening plate bolts, they are big and fat, very much like a wheel lug. They dont elongate with tightening. They will never break if you torque them properly.

Any truth to his post?

Stiffening plate bolts use a nearly identical method to tension the bolt as head bolts and by definition will be longer afterwards. They are torque to yield installed meaning literally torque until they start to stretch past the point they will return to normal.

So the phrase about not elongating is patently incorrect. If they didn't stretch they weren't torqued to spec. (Also why they will absolutely snap in half after about five operations).

SP bolts are 10mm exactly the same as the head bolt on M54. Not sure if the same on M62, but on the ones I installed they didn't seem any different diameter than M10.

BMW wanted a way to get a consistent clamping force and since even using torque doesn't do a good job they choose stretch the bolt which achieves a very reliable amount of clamping force because when the bolt stretches it's fairly simple math of the yield strength of the metal and the cross section of the bolt.

When torquing to spec the clamping force will vary 10-20%, and if adding lubrication, maybe 40-50%.

Using TTY it won't matter if dry or oily because it's not turned by force but by angle, just has to be enough pre tension to get into the yield zone during the 90 part. It's a kind of fascinating method to get the job done really. They wanted 60,000# of force on the plate, not 35,000 20,000 which is what would be achieved with torque wrench method.

When doing the destructive tests it becomes very obvious how it works by the 3-4th test as the torque to turn steps rising as you turn farther. Torque would rise to about 100 Nm until 40-50 and then just stay at 100 Nm as I turned the last half I could definitely feel that the bolt lost its ability to fight back and on the last time the bolt snapped before turning 45 into the 90 part of the tension routine.
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Last edited by andrewwynn; 09-09-2020 at 10:07 AM.
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  #25  
Old 09-09-2020, 10:47 AM
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There you go Maruzo. I'm one of those who reuse and torque to spec and then do 45 degrees instead of 90. I don't drive the truck for performance and so don't notice any jiggly feeling Andrew describes.

Will follow x5only's lead and order from FCP eventually, but will wait until all maintenance that requires the plate to be removed is complete. FCP banks on people not keeping their cars long enough for repeat failures of the parts purchased and as x5only pointed out, with enough volume of sales, hopefully their losses are covered many times over so the lifetime guarantee sticks around for a long time.
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  #26  
Old 09-09-2020, 01:14 PM
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Search for M10-50 12.9 bolts you may find some for sale. They can be 1.0 or 1.5 pitch. Double check the length I'm only 95% on the 50mm.

I'm on board with the 45 concept and plan to test the effectiveness of that when I replace my plate (coming soon. Oil pan gasket soon to be replaced).

My spidey sense tells me you'll get 70-80% of the clamping force which should be effective at torsional control. Anybody that's tried it should be able to tell as there would be a telltale run on the aluminum if it moves even 1mm during twisty maneuvers.
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  #27  
Old 09-09-2020, 01:23 PM
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Great info again. Thanks Andrew and Crystal!

By the way, what is a good replacement bolt that is cheap enough to stomach? You guys keep mentioning 12.9mm. Where can I get my hands on some?

I bought a intake manifold for a Benz R350 from FCP and wanted to return it. I had to buy another intake manifold from them first before I can return the first one.

I had the first one taken off and the 2nd one installed. I still haven't return the first one yet!

LOL

You can never get a live person to do the return so the first manifold is still in my warehouse.
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  #28  
Old 09-09-2020, 01:35 PM
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That's how it works. Procedure is to buy your replacement part, fill out their return form, send back your worn out/damaged part, and within a few days of them getting it back you'll get the refund on your replacement part order. No need to speak to anyone on the phone.
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2010 X5 35d Build 02/10
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  #29  
Old 09-09-2020, 11:37 PM
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Quote:
Originally Posted by Maruzo View Post
Thanks! Price is now $19 each for the bolt! I'm probably just gonna reuse the factory bolts for now.
You had to go and say it! Now we'll be down the reuse or don't reuse the stiffening plate bolts rabbit hole.
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  #30  
Old 09-09-2020, 11:43 PM
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Quote:
Originally Posted by Maruzo View Post
Great info again. Thanks Andrew and Crystal!



By the way, what is a good replacement bolt that is cheap enough to stomach? You guys keep mentioning 12.9mm. Where can I get my hands on some?



I bought a intake manifold for a Benz R350 from FCP and wanted to return it. I had to buy another intake manifold from them first before I can return the first one.



I had the first one taken off and the 2nd one installed. I still haven't return the first one yet!



LOL



You can never get a live person to do the return so the first manifold is still in my warehouse.


I called FCP twice to do returns. Got a live person within minutes.


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