Snapping Wheel Bolts

[Panda]

Has anyone had experiences of snapped wheel bolts?

One snapped on me last week (offside front). Bolts were Torqued to 100nm after the bushes were done and were checked a fortnight later. The bolt snapped when taking the wheel off last week.

Had the tracking done today and the front wheels balanced. A nearside bolt snapped when refitting the wheel, the lad was torqueing the nut when it happened (he reckoned it was just as the bolt went tight).

Strange thing is I've got a new bolt from the BMW dealer. He asked me if I would like a black one or a gold coloured one. All mine are silver finished. Just by holding them there is an obvious weight difference between my originals and the new one. I'm guessing that at some point BMW changed the manufacture of the bolts to the lighter black/gold finished type, possibly due to the old style having a problem. Have seached the forum and can find nothing similar though.

Any thoughts?

Now have the arse-ache of extracting a couple of sheared bolts (yep, they sheared flush to flange!!) I'm thinking that maybe I'll get a couple of replacement legs from a scapper/ebay and rebuild with something lowered/uprated. Just the excuse I was looking for......

[BillionPa]

the color is the coating on the bolt, for the type of wheel. cadmium vs oxide.

the bolts have been the same for a long time, and only the coatings have changed. if your bolts are a different weight, they are probably not OE. that said, i have never seen or even heard of a lug nut snapping on a bmw when anti-sieze was used on them. did you use anti-sieze?

[steve0suprem0]

i have a snapped bolt in my rear wheel. the guy at pep boys said i cross threaded the bolt when i put my spare on after i got a flat.

i figured piss on extracting the bolt, i'd bettter just replace the hub. which is 200 bucks from bav auto recycling.

is that part common to any other cars? i know there's some older 7s at the pick n pull...

EDIT: ok, according to real oem, the part (33411134880) is only used on the 525. is this true? wouldn't all 5s have the same side shaft at least, if not another series?

[Panda]

.... i have never seen or even heard of a lug nut snapping on a bmw when anti-sieze was used on them. did you use anti-sieze?

A can of worms could be opened here.......

I didn't use anti sieze/copper slip on the treads. The threads were cleaned with a wire brush though and I put copper slip on the back of the bolt head and the wheel/disc mounting face to prevent corrosion. I was told many years ago to keep threads dry or it will screw the reading on the torque wrench...... and possibly overtighten them.

One snapped bolt I would put down to bad luck but two? Not so sure. Bearing im mind one of them went when being undone and the other was barely tight when it went. Maybe it was a bad batch? I'm pretty sure they are OEM, The car has been in my family for the last 13 years I know they haven't been
changed. The locking wheel nuts are still the originals - I'd expect them to have been replaced before the non-lockers.

[DanDombrowski]

Even if they used different types of steels, you would not notice the weight difference by hand. If one is heavier, it is probably not steel, if not hollow (although that would be obvious when it sheared off).