Stiffening plate bolts

[Lambeau]

I don't give a rats-a$$ about winning friends and influencing people. I see so many BMW owners that are scared of performing routine and basic maintenance on their vehicles while they continue to throw money at BMW service centers which enables/encourages them to charge excessive amounts to those who would really need it for a major repair.

Give me one example where there was any level of issue because these bolts were re-used. Got nothing? Thought so.

[ants_oz]

Originally Posted by Lambeau

<snip>
Give me one example where there was any level of issue because these bolts were re-used. Got nothing? Thought so.

PMSL....you make a statement in your post. Then you close it out and think you're a hero, without actually GIVING anyone a chance to respond.

Dude, you are a LEGEND!

LOL

FWIW, I am a qualified mechanic with roughly 25 years experience on the tools. No one touches my vehicles but me, only when I don't have the time to do a specific task. But equally, I don't presume to think I know more than the people who designed and manufactured the vehicle.

Again though, that's only me, and I don't over-estimate my own intelligence or abilities. Unlike some...

[ants_oz]

Specification of fasteners? I'll stick with what the manufacturer says every time. That is MY choice and I make no apologies for it. It is well documented that BMW specify the stiffening plate as a critical chassis component. They also specify the bolts as single use only. I kinda figure that is for a reason, and with neither the skills or equipment to undertake a qualitative analysis of chassis flex with the plate, without the plate, and with new and re-used fasteners, I can't really compete with their data.

So. Who here can? I suspect the list will be short. Zero type short. We're not talking "seat of the pants" analysis here, because that cannot measure chassis axial distortion (for example) in pound-feet per degree of twist. And that is just one measurement that would reasonably be applied to the front-end integrity of the chassis.

Yes, there are plenty of examples on potentially non-critical systems where the vehicle is far less than perfect, and there are improvements available.

Just tell me. Please. How re-using these single-use bolts is NOT a defect. How does it improve the vehicle, or NOT reduce the integrity of the front-end chassis (proof now, not your guess). As someone wanted previously - proof. Evidence. Actual scientific analysis to show that you know more than the manufacturer on this critical matter.

[Lambeau]

I'll continue to wait for one example where re-using these bolts caused any type of issue. I'm reusing the bolts and am getting ready to haul a trailer on a 9,000 mile trip to Alaska & back driving on many miles of rough gravel roads. If my X has issues after that then I'll believe the hype and throw money at BMW for new bolts. Anyone want to bet $ that I'll have issues???

[ants_oz]

I'm guessing you probably won't have problems. Same as probably 99% of people who don't change their brake fluid every 2 years (for example) don't have problems. Same as probably a huge percentage of people with full-coverage insurance never have to use it.

The choice is entirely yours.

[Lambeau]

These 6 bolts are holding a thin aluminum plate. Has anyone else actually held this shield in their hands??? Hard to imagine this thin aluminum shield providing any structural integrity. It would bend so easily in a crash that the bolts would have little if any involvement. If it was a heavy steel plate, the bolts would be more critical.

[admranger]

Originally Posted by Lambeau

These 6 bolts are holding a thin aluminum plate. Has anyone else actually held this shield in their hands??? Hard to imagine this thin aluminum shield providing any structural integrity. It would bend so easily in a crash that the bolts would have little if any involvement. If it was a heavy steel plate, the bolts would be more critical.

Yes. Several times. Same for the one in the 2002 M3. It may be thin (it's likely 3mm), don't be fooled into thinking it's not strong. If you don't believe me, bend yours over you knee. Stamped aluminum of that thickness is incredibly strong, as your emergency room Dr. will see from the results of you trying to bend it over your knee. Don't play materials engineer unless you are one, ok? Your heavy steel plate airplanes won't work, but my aluminum ones will.

FWIW, I haven't changed the bolts on either vehicle. Should I? Yes. Have I? No. However, I do regularly have the vehicles up on my lift. I also use a calibrated torque wrench (just got my favorite back from calibration, fwiw) during installation. They are stretch bolts, but I have not observed any plastic deformation on any of them. Replacing them is on my things to do list. Just need to check the Cal Ranch store to see if they carry them.

Good luck on your drive to Alaska. Having driven from Vegas to DC and back in a 4 month span from hot summer to snowy winter, I can say the X5 is an extremely capable cross country driver.

[Omerta]

Originally Posted by Lambeau

These are very large bolts on a thin aluminum plate. There is no criticality to this application and there is not going to be any negative results by re-using these bolts. The vast majority of BMW owners are clueless when it comes to vehicles and the common sense related to them and will gladly fork out more money to BMW just because they tell you to.

I just changed both differential fluids, transfer case fluid, trans fluid/filter, & diesel fuel filter which means I removed and replaced this aluminum plate and can assure you there is no reason to use new bolts. These bolts are very large and overkill holding on a thin aluminum plate. Common sense isn't a superpower.

Some basic fluid changes and you are now qualified to assure everyone that these engineered bolts are overkill?

A) Its a steel plate on the E53.
B) These bolts fasten the sway bar to the chassis, they also provide lateral support for the undercarriage.
C) Material properties are a real thing. The clamping force will change every time you re-torque those bolts.

Thus it is critical to chassis stiffness in the front. That said, they were designed with factors of safety for performance on the track where under normal conditions its unlikely to cause failures for a garage queen.

Don't share bad advice and call it common sense. If you choose not to replace the bolts, that your prerogative. It is not sound practice to reuse TTY bolts. Period.

[ants_oz]

Originally Posted by Omerta

Some basic fluid changes and you are now qualified to assure everyone that these engineered bolts are overkill?

A) Its a steel plate on the E53.
B) These bolts fasten the sway bar to the chassis, they also provide lateral support for the undercarriage.
C) Material properties are a real thing. The clamping force will change every time you re-torque those bolts.

Thus it is critical to chassis stiffness in the front. That said, they wiere designed with factors of safety for performance on the track where under normal conditions its unlikely to cause failures for a garage queen.

Don't share bad advice and call it common sense. If you choose not to replace the bolts, that your prerogative. It is not sound practice to reuse TTY bolts. Period.

Dunno about your e53 mate, but the stiffening plate under mind is good old aluminium...

[StephenVA]

Guys

The X5 had two different plates under neath our vehicles. The aluminum one used until sometime in 2003 and a steel one used after that point until production ended on the E53. All the 4.8is have a steel one. As far as I can tell all the 4.6is had a aluminum one. The 3.0 models had both but when they changed to steel, I have no personal knowledge.

Bolts: The factory used one time fasteners (nuts and bolts), that are torque to yield. Torque to XXX and then 90 degrees more. These nuts will then change their shape and "lock down" with greater force. Yes, they are expensive. 1 year ago they were $25 for a set. Now Higher. Can you use grade 8 bolts with lock washers and get a solid connection for the bars and structural rigidity? With only a few years of auto engineering education/experience, I would say "yep". But I would also post the "no testing done to confirm acceptability" clause.

Bottom Line: Do not use the old nuts. At least replace them with known good grade 8 and lock washers. Just for safety.

Most of us on the forum, are high maintenance DIY who go above and beyond what the normal owners do to 10 year old cars. A lot of us are not the first owners and have spent $$ to get them "just right" once again. The reason? We want everything to work correctly and not leave us stranded somewhere. I like to believe we are care takers of the things we own, not just "users". Hell, I even weekly wash and detail, Qtrly clay and wax my Minivan!