Locking wheel bolts too tight

[190]

On the basis that there is no point carrying a spare wheel if you can't undo the wheel bolts with the tools carried in the car, I decided to remove all the wheel nuts and tighten them again at something less than gorilla tight. Managed all of the normal wheel bolts and one of the locking bolts. The other 3 are so tight I decided a strategic withdrawal and some thought was needed before the locking bolt key got damaged.

In terms of the locking key surviving intact would it be safer to get a garage to undo them with a rattle gun ?

Any thoughts on whether the threads should be dry or lubricated in order to prevent future problems ?

I've always greased wheel bolts and never had a wheel fall off in 40 years.

 

[andy27168]

Wheel bolt threads should not be greased, though a very slight smear of suitable grease on the bolt taper seat would stop it binding on the opposite taper on the wheel.
I would use a power bar and attempt the locking wheel bolts first before the other bolts on the wheel, I wouldn't use an impact gun on a locking wheel nut.

 

[John]

I had this issue recently, ironically with the wheels that Andy ^^^ now has on his car.

Locking bolt sheered straight off and left some in the hub, so you couldn't get the wheel off, and some in the locking wheel bolt key.

Useful.

 

[AMGeed]

As Andy, I too would use a long bar to release your locking wheel bolts. It wouldn't hurt to soak them with a bit of WD40 beforehand either.

 

[WG M-B]

The old style locking wheel bolts can be removed with a special socket.
The later types with an anti tamper collar are a pita.
I try to spin the collars off then use the removal tool on the bolt. If not then drill them, which is great fun when you're trying not to damage the wheel

 

[190]

Thanks guys.

I'll give it another try.

 

[martyz]

I always smear a little bit of copper slip on the threads,never had a bolt come loose or
not manage to remove am I wrong?

 

[Hawkwind]

As previous post, try the locking bolts first, before removing the other bolts.

Refit the non-locking bolts good and tight, then try the lockers again.

 

[hotrodder]

I always smear a little bit of copper slip on the threads,never had a bolt come loose or
not manage to remove am I wrong?

There's a long thread on the subject here http://www.mbclub.co.uk/forums/wheels-tyres-brakes-suspension/178560-copper-grease.html

Cliff notes (basic facts without heresay) version is that a properly tightened fastener stretches a tiny amount elastically which results in a wedging action that prevents it loosening.
Upto around 80% of the torque required to preload the fastener sufficiently for this to occur is needed to overcome friction. In other words if the threads are dirty/manky there'll be more friction and the fastener will be preloaded less for X torque, lube it and it'll be stretched more for a given torque than if it was clean & dry
The elastic range for metals is relatively tiny. Stretch them beyond the yield strength and they behave plasically i.e. specific 'stretch bolts' aside over tighten a fastener until it yields and it won't be preloaded properly. It's scrap
The MB torque figure for wheel bolts is for dry, clean bolts and it's around mid way between 'generic' torque figures for dry and lubed fasteners of the same strength class (10.9)

If wheel bolts are lubed and torqued to MB figures they'll be overtightened some. Most likely not enough to damage things. If a tyre monkey runs up your oiled or greased bolts with his rattle gun they could be harder to undo than if they were overtightened dry. This is because the tyre monkey is more likely to tighten them beyond yield and permantly stretch the threads if the friction is lower due to lubricants. Note that some tyre monkeys use a nut gun to spin them up and then "check" them with a torque wrench While this can be done if the rattle gun is set low enough it's probably more often done as a 'show' i.e. the torque wrench will click at any figure over what it's set to
Lubing the bolt seat (nutface friction in bolt speak) generally has a bigger effect on torque than the threads. I posted a pie chart that illustrates in the copper grease thread

 

[190]

hotrodder,

Thanks for the pointer to the previous thread - it was an informative thread.

I do understand that the threads should be dry but I also wonder where that would get me if it means I can't remove a wheel at the side of the road. The normal wheel bolts are not the problem as you can jump on them to apply the 200ftlbs it might take to shift them. It's the locking bolts that are the problem as they are just not engineered to take that force that dry removal requires especially when the supplied wheel wrench is not an appropriate tool to apply the force squarely. Perhaps the solution is to ditch the locking bolts altogether, assuming I ever get them out in one piece. I feel strongly inclined to do that.

I take on board your point that there might be a problem if someone else uses standard torque on lubricated threads and I could buy the dry thread approach if the bolts were not in a corrosive environment. It's clearly the correct theoretical approach but I still wonder if it's the best practical approach. I hear about people having difficulty removing wheels but I don't hear of wheels falling off because the threads were lubed.

On lubricated threads in general I do always subtract 20% from torque values when threads are other than bone dry. I have a classic BMW motorcycle and the same debate takes place on forums about anti-seize or not on spark plugs. I have always taken the pragmatic approach and used copper grease with a reduction in torque value. If the threads in the head have lasted 40 years I don't want to be the one to strip them if a plug seizes in. I wonder that isn't a problem with modern cars that now have very long plug replacement intervals.

 

[Hawkwind]

I doubt very much if your average tyre monkey uses any other torque setting than maximum.

 

[Bellow]

Any thoughts on whether the threads should be dry or lubricated in order to prevent future problems ?

I've always greased wheel bolts and never had a wheel fall off in 40 years.

As demonstrated below, the stress falls slightly at the yield point.

Stress = Force/Area. For the stress to fall either the area must increase (impossible) or the force lessen. The force lessens - and is detectable by hand. I torque to recommended level with the bolt coated in water resistant grease and have never reached the yield point on a wheel bolt - ever. Neither have I ever had a bolt work loose. My bolts are removable at the same torque they were fastened to - no matter what they have been subjected to. Dry bolts and salted roads? No thanks.

edit PS. I would reduce slightly the applied torque for an alloy wheel.

 

[hotrodder]

Breakaway torque (whether loosening or tightening) is always higher because static friction (stiction) is nearly always higher than dynamic/kinetic friction

hotrodder,

Thanks for the pointer to the previous thread - it was an informative thread.

I do understand that the threads should be dry but I also wonder where that would get me if it means I can't remove a wheel at the side of the road. The normal wheel bolts are not the problem as you can jump on them to apply the 200ftlbs it might take to shift them. It's the locking bolts that are the problem as they are just not engineered to take that force that dry removal requires especially when the supplied wheel wrench is not an appropriate tool to apply the force squarely. Perhaps the solution is to ditch the locking bolts altogether, assuming I ever get them out in one piece. I feel strongly inclined to do that.

I take on board your point that there might be a problem if someone else uses standard torque on lubricated threads and I could buy the dry thread approach if the bolts were not in a corrosive environment. It's clearly the correct theoretical approach but I still wonder if it's the best practical approach. I hear about people having difficulty removing wheels but I don't hear of wheels falling off because the threads were lubed.

On lubricated threads in general I do always subtract 20% from torque values when threads are other than bone dry. I have a classic BMW motorcycle and the same debate takes place on forums about anti-seize or not on spark plugs. I have always taken the pragmatic approach and used copper grease with a reduction in torque value. If the threads in the head have lasted 40 years I don't want to be the one to strip them if a plug seizes in. I wonder that isn't a problem with modern cars that now have very long plug replacement intervals.

Cheers. My take would be to throw the standard wheel brace away and replace it with something better... telescopic wheel braces don't take up any more room but give a chunk more leverage, a 3/8 breaker bar is even better IMO as the shape at the business end makes it a lot easier to apply pressure with one hand (to reduce 'cam-out' effect with locking wheel bolts) while heaving on the other

Obviously your current problem is getting the locking keys out/loosened. As well as the suggestion to tighten the other bolts first i'd give the head of the locking bolts a few sharp blows with a hammer i.e. fit the key, socket and a short extension and hit that. Ideally with a big dead blow or copper/hide faced mallet rather than a regular hammer so you can hit it hard without damaging the extension etc before reaching for a proper 1/2" breaker bar
Penetrating/dismantling fluids often help but they usually work better when things are actually corroded. Personally i've never seen a wheel bolt that's corroded in... uncoated steel bolts are rare, wheel bolts are typically plated or zinc passivated and are disturbed too frequently for corrosion to get a proper hold unlike say a suspension or subframe bolt that may go 10+ years before being disturbed

People greasing wheel bolts or hub faces doesn't particularly bother me, the reasons often stated for or against doing so do a little as they often have little to no basis in fact. Personally i have never managed to break a wheel bolt (locking or otherwise) or struggled to undo one that i tightened dry. I have removed a few knackered locking bolts for neighbours/friends and of those where i managed to get the remains out in one piece it was usually clear that grossly over tightening was the culprit, not corrosion. Corrosion is always obvious, a bolt that's been tightened beyond yield sometimes more subtle. Especially when you have to clean off the remains of copper grease to see the necked and elongated threads
If you keep tyre monkeys away from greased wheel bolts then shouldn't be an issue. Especially if you're adjusting torque values to account for the lube

The debate about anti seize / copper grease on things like wheel bolts and spark plugs is probably never gonna go away... torque vs tension aside someone that understands corrosion and metallurgy may point out that copper and aluminium don't play happily together for example. The counter argument goes along the lines of i've never had a problem in X years of using copper grease. There's often also arguments about thermal and electrical conductivity when spark plugs are the topic too
Spark plug manufacturers started coating plug bodies to reduce galvanic corrosion and thread galling when aluminium heads became common. Some use nickel, NGK use zinc chromate and say the usual about overtightening with lubricants http://www.ngksparkplugs.com/pdf/dyk_5points.pdf and http://www.jagrepair.com/images/AutoRepairPhotos/NGK_TB-0630111antisieze.pdf in the second link they say when anti seize should be used, unfortunatly they don't spec a flavour but do show an example pic that definately ain't copper based

Search the internet for zinc anti seize spark plugs and you get a bunch of hits about aircraft sparkplugs & graphite based anti seize for plugs (Champion 2612 for example). Henkel (Loctite) point out that graphite based anti seize is excellent with regards to thermal and electrical conductivity and cite spark plugs as one of the common application examples. They also say that zinc based anti seize is ideal for soft metals like aluminium. Zinc is sacrifical to aluminium in salty water whereas aluminium is sacrifical to copper. Graphite is more noble than copper which is why some sources say it shouldn't be used with aluminium heads but then if water is getting into plug threads you have bigger problems to worry about...

In the real world overtightening as a result of lubing and blindly leaning on a torque wrench set to the factory dry figure is usually the only issue

That said the colour of cheap copper grease got mentioned in the thread i linked to... when it comes to copper based anti seize there's a LOT of differences, the MSDS for a bargin basement flavour might state something like 1 - 10% copper, same again for graphite while the MSDS for a premium brand like Rocol states 10 - 30% of each which makes all the difference years later when all of the oil is long gone (washed away/cooked out) leaving metal powder and some of the thickening agent. FWIW I stoped using copper grease on plug threads after removing a set of plugs from an engine that had likely had too much of a cheap/nasty copper grease applied. They needed carefully easing out all of the way with a ratchet as what was once (loosely speaking) probably copper grease had turned into a dry but sticky brown goop

 

[190]

Thanks for the tips hotrodder. I had thought about giving the bolts a sharp tap with a hammer so will do that. There is not a great deal of corrosion on the bolts I did mange to remove and replace except for the part of the threads not engaged in the hubs. I think it's just that the breakaway torque is at least double the 90ftlbs that these bolts are supposed to be tightened to. My plan is not to rush at this but wait until one of my sons is able to assist with perhaps one of us having a foot pressed firmly on the end of breaker bar to make sure the key remains engaged and the other applying the leverage. It may be a while before I get this done but I will feedback on the results.

The plugs on my old bike never stay in long enough to be problem and I always keep the threads clean enough that they will screw in by hand. I'm not even going to think about trying to remove the plugs in the car just yet. They are recently new so I guess they are good for a couple of years.

 

[AMGeed]

^ Using your son may be the best method. I had to get a new tyre put on my wifes A160 before we sold it recently. Got to the garage and the fitted called me over to show me the broken locking socket. Done by the fitter the last time a tyre was changed.

I had to got to the dealer and pay £32 for a new socket which the fitter couldn't guarantee would undo the locking bolt it was done up that tightly.
One guy on a long breaker bar and socket and another banging the socket as he slowly managed to release it. It was ridiculous the amount of torque put on that bolt. It did the job anyway so here's hoping that method will work for you.

 

[190]

Well sons have busy lives so I devised a safe means of breaking these security bolts loose single handed. The problem is how to ensure the security key remains fully engaged while at the same time applying the huge force needed to crack them loose.

What I did was to park the car close to my garage wall and use an old scissor jack between the wall and the end of the my socket T bar to force the key firmly and squarely into the wheel bolt. That left both hands free for me to lean on a 3 ft length of pipe slide over the T bar to apply what must have been in excess of 200 ftlbs. As you can imagine they let loose with a loud crack and once I'd moved them 1/4 of a turn I removed the jack and unscrewed them with the normal wheel wrench. They were still tight even then. I actually have one more bolt to do but I have no doubt it will succumb to this method. These bolts are originally plated but there was some surface rust on the two I did today so they went back in lightly lubricated and tightened with a torque wrench to 80 Ftlbs which is 20% below the normal full torque spec.

Reading the instruction leaflet that came with the locking bolts made me smile. It said "On no account must these bolts be tightened with an impact wrench" From now on every time this car goes near a garage I will be giving them very clear instructions not to over tighten the wheel bolts and I'll still check them afterwards.

 

[Hawkwind]

WooHoooooo!! :bannana:

Well done and very ingenious

 

[190]

Thanks,

When you are in a situation where you can see something is not going to work or is going to cause damage, the smart thing to do is stop and walk way until you can come back in a calm state of mind with a plan that is going to work.

 

[WG M-B]

Well done for cracking them loose.
It's ironic you mentioned garages.
We are so particular in our wheel tightening sequences!
The scenario you find yourself in arises at least a couple of times a month with us, and it totally messes up our schedule!

 

[190]

To be fair it wasn't a Mercedes garage or a specialist independent but it was one of the largest new and used car dealership chains in Europe that had Mot'd the car, fitted new tyres on the back and new pads on the front. So they must have had all the wheels off.

Your comments about being particular about wheel tightening sequences show that you care and whether amateur or professionals are doing a job, caring is always an essential ingredient.