Grrrrr BMW rant

[AlanJ]

Phoned BMW this morning to complain...........

BMW UK or your local dealer - if so who?

 

[sars]

Phoned BMW this morning to complain...........

BMW UK or your local dealer - if so who?

Dick Lovett, Bristol, it is impossible to prove that they have not removed the wheels before, however Stratton, Hull stated that at brake fluid change the bolts should have been checked for the correct torque settings.

I feel a written rant to BMW UK is in order, item should not have failed, yes if I was tightening the bolts, but not to loosen them.

Anyway all four wheels now on.....pictures once I have cleaned the car.....they do look awesome though

 

[Garvin]

As for adding copper slip to the threads, not sure about that one. It depends on how the bolted connection was designed, by adding a lubricant you reduced the stress on the bolt (through the drop in friction on the head and thread), which is no bad thing, however you need a certain amount of pre-stress on the bolt to make a good connection, and that's one of the reasons for torque values. By adding copper slip you reduce the desired pre stress when given the same torque setting and thus reducing the quality of the connection.

I'm not going to argue with the technical analysis, but I've not had a problem with any wheel on any of my cars Ms in over 20 years - and they've nearly all been used on track and covered 20k+ miles a year

Copperslip etc is not really a lubricant as such, it's an anti-sieze product. Believe it or not it has pretty much the same 'friction' as steel and, as such, has little effect on the clamping forces for given torque so can be used with confidence on wheel bolts. Grease or oil on the other hand are to be avoided!

 

[Maniac]

Copperslip etc is not really a lubricant as such, it's an anti-sieze product. Believe it or not it has pretty much the same 'friction' as steel and, as such, has little effect on the clamping forces for given torque so can be used with confidence on wheel bolts. Grease or oil on the other hand are to be avoided!

lol for a minute, I thought that read ANTI-SLEAZE lol... too many newspaper stories on TV at the moment clearly...

 

[TitanTim]

Tempting as it may be never put copper grease on the wheel bolt threads as this will give a false torque reading if using as wrench.

Tim.

 

[Garvin]

Tempting as it may be never put copper grease on the wheel bolt threads as this will give a false torque reading if using as wrench.

Tim.

No it won't. If you use a torque wrench then the bolt will be tightened to the same torque no matter what lubrication is used. The clamping force will change though! For oil and normal grease the clamping force for a given torque can increase hugely, which is why such lubrication shouldn't be used. Copper grease can result in an increase in clamping force for untreated steel bolts into a steel hub but it's not that significant. If the bolts are plated in any way then this usually reduces friction and copper grease makes hardly any difference at all.

Wheel bolt torques and, hence, pre-loads are pretty low compared to the size of the bolts and so, even using normal oil/grease you would be hard pressed to generate a clamping force, for the torque specified, that would damage the bolt or hub threads. But this is not the real problem, the real problem is generating too high a clamping force which can damage the alloy wheel and cause splits in the rims (which is why I always ensure that tyre fitters never, ever use an air gun on my wheel bolts). As copper grease doesn't affect the clamping force significantly it's not really a problem for wheel bolts.