Stiffening plate bolts

[TiAgX5]

I remember a DIYer posting here a few years ago, had a chronic front end creak after re-using the OE bolts/nuts (torque+90deg, as specified). Replacing fasteners resolved the issue.

[lo_jack]

Originally Posted by Omerta

No, the supplied bolt grade is 10.9. Using a 9.8 grade bolt is 15% weaker...

12.9 would be the way to go in that direction. Won't have the TTY properties but has a higher tensile strength which will increase its high cycle fatigue life. New torque spec would be 62 lbs-ft for a 12.9 grade M10x1.5.

Thanks for the clarification.

[TiAgX5]

It's possible a stronger bolt and higher torque could exceed the deformation pressure of the aluminium plate.

[bcredliner]

Sometimes it is actually better to read, and, follow instructions.

This is not unique to the E53. It is across many models and years and in other applications unconnected with BMW or even motor vehicles. Since I wasn't on the X5 design team and the full dealer cost is about $25 dollars, I see no reason to even consider not replacing the bolts.

[StephenVA]

Originally Posted by bcredliner

Sometimes it is actually better to read, and, follow instructions.

This is not unique to the E53. It is across many models and years and in other applications unconnected with BMW or even motor vehicles. Since I wasn't on the X5 design team and the full dealer cost is about $25 dollars, I see no reason to even consider not replacing the bolts.

The parts are cheap insurance. Net at the Dealer was $25. McDonald's money.

[TiAgX5]

When it comes to fasteners, I've always look at what the designers did and follow suit.

No need to re-invent the wheel.

[Omerta]

Originally Posted by TiAgX5

It's possible a stronger bolt and higher torque could exceed the deformation pressure of the aluminium plate.

I'm sure that plate is steel based off the weight when I removed it. The clamping forces are basically the same for the higher strength fastener. The difference is that the bolt is not yielded which impacts its preload and high cycle fatigue characteristics.

The TTY connection specification is 64 ft-lbs (43 ft-lbs+90*) for the 10.9...

[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.

[bcredliner]

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.

How to win friends and influence people.

[ants_oz]

Originally Posted by bcredliner

How to win friends and influence people.

He must have been on the BMW e53chassis design team. I wish I was that good.