Bleed brakes with wheels on

[Rockhopper]

I always do the same.

[Smartbear]

It is common practice to not lubricate wheel nuts.
I personlly disagree and have always lubricated wheel nuts.
Clean Oil and Grease on the Lock nut especially.
Never had a whell come off or loosen, always check after tyre changes.
Also put a film of grease on the alloy wheel where it meets the hub unless you have those plastic shims that go between.
I shall probably be shot down in flames now.

The problem with lubricating wheel nuts is that they no longer receive the correct tightening torque
Rob

[domsz4]

i would guess that many garages use a pneumatic system to bleed brakes and change fluid. i have one called a gunsen easy bleed that works very well.

[Jasonn]

I've always used a thin smear of copperslip on the threads

[enuff_zed]

I've always used a thin smear of copperslip on the threads

Ok, so given that the torque setting is reached when the resistance to turning of the stud equals the setting on the torque wrench, the stud will stop at a particular point. Now, add a lubricant which makes it easier for the stud to turn. Therefore it will move much further before the resistance equals the torque wrench setting.
Imagine how much extra force you would need to apply to get the stud to move that far without lubrication. Quite a bit.
Therefore, although it could be argued that the torque setting is still the same, the stud must be further in to the thread in the hub, which means it is applying much more force to the seat in the wheel and equally, the stud itself is under much more tension.
Although the turning force applied has effectively been the same amount, the gripping force of the stud holding the wheel is much higher.
In conclusion, I'm with Smartbear and will leave the studs dry, but ensure they are correctly torqued up.

[Rucky]

Having spent a career in aero engine / aircraft manufacture operation and repair, Iit is standard practice to lubricate all clean nut and bolt threads with clean engine oil or assembly specific lubricants during assembly to achieve correct and consistent torquing -unless they are operating at high temp, are specially coated or sometimes single use.
Commonly to prevent Galling caused by metal on metal contact at high load.
Its a hard habit to break
I agree with your comments regarding resistance to torque , hence the oil for consistency.
I agree that it is equally common practice to assemble un lubricated wheel nuts and studs.
I was just responding to the issue of "I'm just trying to identify which idiot overtightened my locking wheel nuts costing me £100 to get them welded off and replaced today"

Dry nuts and an impact driver incorrectly used do not bode well.


But each to their own ..

[enuff_zed]

Having spent a career in aero engine / aircraft manufacture operation and repair, Iit is standard practice to lubricate all clean nut and bolt threads with clean engine oil or assembly specific lubricants during assembly to achieve correct and consistent torquing -unless they are operating at high temp, are specially coated or sometimes single use.
Commonly to prevent Galling caused by metal on metal contact at high load.
Its a hard habit to break
I agree with your comments regarding resistance to torque , hence the oil for consistency.
I agree that it is equally common practice to assemble un lubricated wheel nuts and studs.
I was just responding to the issue of "I'm just trying to identify which idiot overtightened my locking wheel nuts costing me £100 to get them welded off and replaced today"

Dry nuts and an impact driver incorrectly used do not bode well.


But each to their own ..

Having spent a career in Military aero engine / aircraft operation and repair, it was standard practice to NOT lubricate all clean nut and bolt threads with clean engine oil or assembly specific lubricants during assembly to achieve correct and consistent torquing. Our approach was to replace the fastener if there was the slightest doubt, and assemble it dry.

But each to their own ..

[Jasonn]

I think I got into the habit of a thin amount of copperslip when I had to change the wheel on my hillman imp - imagine 4 spotty 17 year olds trying to loosen the damn wheel nuts which finally gave with a horrible squeal/screech as each one gave.

After that experience I always applied a very thin smear right at the end of the stud (or bolt depending on the vehicle) just to act as a preventative measure. Its probably psychological and has no scientific basis, but each to their own.

[BadgerDog]

Having spent a career in aero engine / aircraft manufacture operation and repair, Iit is standard practice to lubricate all clean nut and bolt threads with clean engine oil or assembly specific lubricants during assembly to achieve correct and consistent torquing -unless they are operating at high temp, are specially coated or sometimes single use.
Commonly to prevent Galling caused by metal on metal contact at high load.
Its a hard habit to break
I agree with your comments regarding resistance to torque , hence the oil for consistency.
I agree that it is equally common practice to assemble un lubricated wheel nuts and studs.
I was just responding to the issue of "I'm just trying to identify which idiot overtightened my locking wheel nuts costing me £100 to get them welded off and replaced today"

Dry nuts and an impact driver incorrectly used do not bode well.


But each to their own ..

Having spent a career in Military aero engine / aircraft operation and repair, it was standard practice to NOT lubricate all clean nut and bolt threads with clean engine oil or assembly specific lubricants during assembly to achieve correct and consistent torquing. Our approach was to replace the fastener if there was the slightest doubt, and assemble it dry.

But each to their own ..

In either case the take away should be: know the proper procedure for the equipment you are working on and use it, otherwise the torque setting will be incorrect. Lubricating is perfectly fine... if the specified torque settings take that into account, and vice versa.

I do not have any source as to whether or not BMW publishes torque specs expecting lubricated bolts, but I am gunna go ahead and assume NOT since most folks and shops don't and they know it (and not lubricating when the spec assumes lube is more dangerous than the opposite as you end up under tightening).

So in conclusion: do what the manufacturer expects!

[ph001]

Also from an engineering background... I routinely apply a light coating of copperslip to the wheel bolt threads but NEVER to the chamfer on wheel bolt head. It is the friction between the bolt head and the recess on the alloy that results in an accurate torque setting.

[BadgerDog]

Also from an engineering background... I routinely apply a light coating of copperslip to the wheel bolt threads but NEVER to the chamfer on wheel bolt head. It is the friction between the bolt head and the recess on the alloy that results in an accurate torque setting.

What type of engineering (electrical / mech / etc)? I dont think thats correct, but Im not 100% sure. ALL friction sources should contribute to the torque required to move the bolt incrementally. If you reduce any one of them the others have to "work harder" to make up the difference and you will still over tighten. At least thats my take, but Im an electrical / software engineer so while I have the general background its not my specialty.

[Jasonn]

I only use a thin smear on the threads and the only reason is to prevent them rusting/corroding, which was a real PITA when I had a puncture many years ago (now have breakdown cover as well) but old habits die hard.

[ph001]

What type of engineering (electrical / mech / etc)?

Electronics! So nothing really to do with the subject matter

[BadgerDog]

What type of engineering (electrical / mech / etc)?

Electronics! So nothing really to do with the subject matter

Fair enough! I wasnt trying to call you out, just curious.

[Pbondar]

Quick question for you guys, 35is with 19" wheels, can the brakes be bled with the wheels left on? And if so, would a garage choose to do it this way when carrying out a brake fluid change as part of a service?

Cheers

To come back to the original post...surely you would like to check the pads etc to coincide with a fluid change and a general check of linkages / suspension etc?

Logically you would normally group similar activities together?

It’s not a personal criticism more just good maintenance practice?