Lubricating hub faces before fitting wheels - I know many people do this and have done fault free for decades. It stops the wheel corroding to the hub and getting stuck on.
However the joint is designed, tested and validated to be dry (ie not lubricated) upon assembly. Lubricating this joint can reduce it’s load capacity down to as low as 33% of it’s design target. This validation is carried out using hundreds of cars, over millions of miles. More testing than any one person could ever do.
My professional opinion (after decades of engineering experience, an engineering degree and having spent two years responsible for validation testing for a major automotive OEM) is that it is directionally incorrect, that it eats in to the safety margin by an unknown amount.
As I say, I know many people do this and have done without reported failures for decades.
But I have a moral obligation to raise this as a safety concern after some posts on here. I have done so (this is something I have also done when watching other people fitting wheels - this is not just “internet posturing”). Feel free to ignore this post, or make your own considered judgement.
Do we perhaps need to make a distinction between lubricants and anti-sieze compounds?
In my experience a thin film of copper grease tends to lose most of its lubricant properties after a while, because it dries out and emulsifies to a certain degree. It does seem to retain its anti-sieze and thermal transfer properties though.
I can appreciate the point you are trying to make and certainly would not use a high-melting point lithium based grease (the type designed for lubricating wheel bearings) on hub faces.
After an admittedly brief search using Google, I could not find any other advice on the internet that warns against use of anti-sieze compounds on wheel hub faces (this does not prove conclusively that other experts do not share your view). I did find some articles advising against using anti-sieze compunds in torque-critical threaded fasteners, e.g. HGV wheel studs. This is in line with general advice not to lubricate threads where the torque setting is critical - many manufacturers specify that cylinder head bolts/studs should be torqued “dry”.
It does make me wonder though, if the prevention of slip is critical to prevent undesirable shearing forces acting on wheel studs/bolts then why do manufacturers not design some kind of device along the lines of a serrated shake-proof washer (knurling?) into the wheel-hub interface?
My point was that the testing work hasn’t been done, I can’t prove anything is unsafe, the only proof is that “clean and dry” passes the manufacturer’s durability and Pave testing. It might be that dripping in goose-fat the wheels will still be held on just fine, but until someone does a statistically significant series of tests we don’t know.
Because with a dry joint and correctly torqued bolts it is not needed. The same joint propertes are required for flywheels, and some of them (where they cannot fit the right number or size of bolts to ensure the right clamp load) use washers with artificial diamond faces to dig in to the hardened steel of the crank/flywheel. There are more packaging constraints on crank palms than on wheels.
With road wheels if you need a higher load capacity for your joint you just increase the number of bolts ( for example: 5-stud on the mk3, 6-stud on most off roaders, loads of studs on truck and coaches). Something light like an Citroen AX or Smart can get by on just three bolts. But no one tests any of these with various lubricants on them, so no one really knows (beyond a reduction based on friction numbers) how the joint is affected.
I must point out that this is a continuation from another post, that has been moved to here, concerning a chap that had problems with chrome dustcaps.
MUPPET
It sounds like you’re the only one going to loose sleep over this issue,if you are not keen,then don’t do it yourself ,problem solved,i have spoken to a number of mx/roadster Co’s today including some main dealers and independant mechanics(roadster robbie,give us your pennies worth) over this really deep and very sad issue you seem to want to create IMHO,now everyone i spoke to use’s copper grease as standard to stop fusing issues on the wheels,so i’m guessing around 98% use copper grease or similar,so if it means that much to your life, do the tests and give us the results,in the mean time if anyone reading this has reservations on using this method you can get an hub washer barrier thing(WHEEL MATE FROM MOSS £14 FOR A SET OF 4) that will do the same job without upsetting very deep members with some kind of safety issuses!!!WHY DON’T WE MAKE THIS INTO A POLL TO SEE WHO USE’S THIS REALLY BAD GREASE STUFF AS PROVENTATIVE MEDICINE!!!
REGARDS and will sleep soundly with copper grease on all my three car’s hubs doing an illegal eighty to ninety miles an hour down the motorway, feeling totally safe.Must go i can see a blue flashing lights behind me,oh no it’s the mobile hub inspectors!!!
I personally do not put grease of any type on the vertical face between the wheel hub and the brake disc or between the brake disc and wheel. I do however, when a wheel siezes to the hub due to alloy corrosion/oxidisation, clean the area up and smear anti-sieze grease to the circumfrance of the hub spigot.
I wonder how many daily driven cars are in use in the UK (not just '5s and Roadsters) where the engine, brakes and tyres are actually capable of generating a large enough torque reaction to shear the wheel studs/bolts?
It’s probably fair to say that the shearing forces on the wheel studs are at their greatest when launching from a standing start or when braking hard. Unless you have hot, sticky, slick tyres on a dry track the tyres will almost certainly break traction first.
Would the four relatively small bolts clamping the half shafts to the inner drive flanges on a 5/Roadster not shear before the wheel studs?
Wayne - thanks for your useful and contructive comments. I’m glad you respect my profession judgement enough to take the time to post.
Almost none. It’s shock loads from impact (pot holes, kerbs, etc) which cause the greatest loads to this joint. Hence the Pave durability testing (remember that Top Gear where just one length of Pave had bits falling off their old cars?)
I could be wrong, but I have a suspicion that some (?) of their car “tests” are less than scientific and are actually staged for entertainment/comedic value.
I had never thought of it in that way. Was always more worried about corrosion and issues getting them off after.
I always normally use a very small amount though, and normally after a while there is only a trace of it left, but it seems to stop it seizing too much. anti seize compound though not anything too slippy.
Totally the point,the only real problem i can see is that some numbty decides to but a 1/4 of a tin on each one resulting in anti seize greese all over the brake disc and pads resulting in nil stopping power,but i think this is or was called common sense,and if it was a major issue then there would be some serious warnings around to not use it on the backs of your wheels,as long as the wheel nuts are tightened up correctly and you do not but a bucket load of the stuff on i can not see a problem and never have,but the choice is down to the owner at the end of the day.
You will find that the paint would of stuck to rear of your wheels and will pull away from the disc hub when you remove it,i don’t think it would of fused,but i wonder if muppet will agree with this method,it may not have been tested!!!,is there a warning!!!
Thanks, again, for your respect for my professionalism.
I wouldn’t put a layer of paint in to the middle of a friction joint either, since you ask. No one knows how it affects the joint so I would err on the side of caution.
I may be over-cautious when it comes to safety, I’m humble enough to admit it. As a flaw it is relatively harmless.
It’s nothihg against you personally and what you know and what you do,it’s just about this issue that i don’t agree with thats all,and i’m sure you could blow my mind with what you know,i have never wanted to show you no disrespect,and if i’m wrong i will be the first person to hold my hands high,but i think we have just different views on the subject,thats it,and there is nothing wrong with being safe and its a good flaw to have and i would not but a layer of paint there either,but thats his choice,we can only recommend different options at the end of the day and offer advise and wisdom.
Just one more thing - somone in another thread recommended you for work, then someone else asked how to get in touch. I posted that you were on the forum and had contact details in your sig. I’ve just noticed you don’t, so either add a phone number to your sig or pop along to here:
Depends on the car, Mazda3 rears are really bad for it, RX-8 rears also. NA/NB wheels (genuine) don’t give much trouble. Discs commonly stick to the hubs but a light tap with a hammer normally frees them easily. Mazda6 fronts can be very tight though.
hi both, missunderstanding , i painted the hubbs to the very edges of hubb faces,leaving faces as is, thanks for in-put anyway… ill do a test at w/end…if any probs captain, what would you advise, club hammer or sledge hammer mate…
i painted the hubbs to the very edges of hubb faces,leaving faces as is, thanks for in-put anyway… ill do a test at w/end…if any probs captain, what would you advise, club hammer or sledge hammer mate…