Bleed brakes with wheels on

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 ..
 
Rucky said:
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 ..
Click to expand...

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 .. :thumbsup:
 
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.
 
enuff_zed said:
Rucky said:
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 ..
Click to expand...

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 .. :thumbsup:
Click to expand...

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!
 
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.
 
ph001 said:
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.
Click to expand...

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.
 
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.
 
ClumUK said:
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
Click to expand...

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?
 
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