Long post about fasteners.

The plate is being pressed to the mounting frame in 6 locations. The pinch force needs to exceed the lateral force potentially generated, or it would 'work' the fasteners, putting them into a shear loading.

All fasteners act on an elastic concept. I cannot say why the BMW engineers spec'd TTY hardware. But really, all they arw doing is giving a clamping load for pinching the metal parts together.

Any fastener that has sufficient tensile and shear strength, that meets or exceeds the originals, should be ok.

My old Mack dump truck, occasionally breaks wheel studs on the front. They're about 1.5" diameter. 550ft lbs. Tq spec. They must be getting fatigued from a shearing force, that crystallizes the shank, and eventually a fault line is created...then you have a nut and 1/2 stud cruising down the road, sans vehicle...and me changing out 3 new hard to source studs.

I don't doubt that the sheer panel ads rigidity. If not tightened enough, there may be movement at the contact points, and noise may be a symptom. Doesn't seem to be too common, only 1 complaint in the whole thread.

I suspect, I'll source some good 12.9 bolts after I have a look at the panel, and how it affixes to the 4.6. I'm not keen on an open nut system, but it's the easiest and most reliable...and works in a pinch.

Carroll Smith's book... Nuts Bolts Fasteners and Plumbing is a great resource.

https://www.goodreads.com/book/show/...mbing_Handbook


BMW engineers, are still beholden to the laws of physics. They have not always made the best calls. But they've had some great wins as well.

I only wish I could have a GM LS engine, 302ci, with a 3" stroke singing at 8000, in a BMW fit and finish vehicle...Best of both worlds.