Is there any need for copper slip on the contact faces between hub, disc and wheel? I have always made sure the faces are clean and assembled dry ( the way I was taught years ago ) copper slip on wheel nut threads yes. I have never experienced any problem doing this.
I noticed in a tyre fitting place recently that the fitters were slapping copper slip on liberally with a paint brush So I get to wondering why? I asked one of the fitters and he didn’t seem to have a reason other than " the boss said so "
I have certainly used copper grease on the alloys wheel faces after having a job getting a couple off in the past. But you don’t need much and it isn’t strictly advisable, according to a motor industry engineer I have heard on the subject, especially if you use the car very aggressively.
The torque under acceleration or braking should be transmitted mainly by the friction between the faces, not by the wheel studs which are designed to provide the tensile force to pull the faces together. In fact, on my Outlander, the nuts have flat seats rather than taper seats and locate into a space around the stud, so the studs on that are clearly not designed to transmit the torque since the shear force can only be applied at the nut end of the stud.
It’s also strictly speaking inadvisable to grease the threads or tapers of wheel nuts/bolts/studs, as Ninja 59 has mentioned. Tightening torque is only a way of getting to the desired stud/bolt tension, and lubricating the threads or tapers means you end up with a higher tension than intended. The trouble is that you can sometimes get quite a lot of corrosion going on, so I tend to use a bit of oil on the first thread or two to clean them up if they are getting really stiff. WD40 wiped off is probably a reasonable compromise, it’s paraffin more or less and doesn’t really hang around much - the GT85 is probably too effective for this job!
Appreciate this might be slightly fussy, and many people have greased hub faces and oiled wheel studs without dying!
what John said above. I’m sure there was a thread on here a year or two ago and someone with motor engineering experience advised against it as you are indeed relying on the friction between the two surfaces, the wheel is not just there hanging off the bolts…
In the handbook for my car it states that the wheel studs should be dry, no lubricant, copper grease etc. I have greased wheelstuds for years so why the sudden change? perhaps something to do with the torque being greater if the studs are greased.
Facinating reading, from this I get that friction between the hub and wheel is desirable, so I shall continue to clean the surfaces and assemble dry, I am unlikely to suffer a corroded on wheel as for one reason or another the wheels are off quite frequently anyway.
I am going to clean the wheel nut and stud threads and torque up dry,
Well, you know what they say about rules - for the guidance of wise men, and the obedience of fools!
When I was messing about with cars 30+ years ago, the only thing anybody was likely to use a torque wrench for was cylinder head bolts, which have to be evenly tightened. I don’t remember anybody using one on wheel nuts, and it’s obviously something most people of a mechanical bent can do by feel. I have to say though, it was fairly common to find they were difficult to remove when fitted by a gorilla at the tyre bay!
At any rate, if you grease both the hub face and the wheel studs, the reduced friction coefficient will be compensated for by the extra stud tension, so long as they don’t actually yield;-)
Large nuts in structures, where bolt tension is critical, are sometimes tightened onto washers with ‘bumps’ on, rather than by a torque setting. The bumps deform in a predictable way as the nut is tightened, and the tension can be set accurately with a feeler gauge under the washer.
Well…I have had a stud shear once, but I suspected I had forgotten to tighten it. I have also known someone who had all 4 shear while hooning it round the lanes (although it probably started with one failing and the rest just followed). But how and why exactly they started weakening, who could say for sure?
It certainly makes engineering sense and I have never greased them myself. However I suspect that in reality, as long as the studs are properly tight, no amount of copper slip would break the friction between those plates. I’m comparing in my head a clutch plate (shiny smooth) being held firm against all of the engine’s torque…by a spring, then comparing that to two (relatively) rough metal surfaces bound by 4 very tight studs, and I just can’t imagine it slipping when subjected to half the torque.
I’d guess that over tightening is the most common cause of stud failure, or loose wheel nuts. I’ve had one shear while removing a nut (put on by the local tyre bay). It wasn’t hard to undo, it was obvious the stud had already yielded before I got there.
Intuitively, I agree with you that copper grease is very unlikely in practice to reduce friction at the hub face below what is needed, given the clamping force. I suppose the common sense conclusion is to use just enough of something to stop the surfaces bonding, rather than an excessive slathering. A small amount smeared on, then almost polished away with a rag, is what I do now and I never have to repeat it once done, and I don’t expect it to be a problem even if it isn’t strictly recommended.
Perhaps a bit of wax polish would do just as well, all it has to do is prevent the majority of the corrosion that occurs with bare metal surfaces.
I have some new wheels coming in a week or so, I’ll test the theory!
As above. I have seen (in my early years with the club) someone have to have their mk1 alloy cut apart to remove it from the hub and have struggled myself to remove alloys that have been fitted dry - not so much on the Mazda, but certainly on other marques.
I seem to remember a memo coming round the garage trade in about 2006 to 2007 time from V.A.G. saying that Volkswagen and Audi’s were to have copperslip on the hub face. This was because it was found in a lot of cases the wheels had bonded onto the hub due to the corrosion between the alloy wheel and steel hub (electrolysis).
I distincly remember laying under an Audi on a ramp, belting the wheel with a 38 pound dead-blow hammer for several minutes before it relinquished it’s grip with the hub. God help anyone at the side of the road with a puncture.
It’s worth saying you would only need copperslip on the hub with alloy wheels, steel wheels aren’t affected.
And I’m another who greases their wheel nuts. And also use a torque wrench (have 3 in the garage!!!).
Yep, exactly this happened to our 51 plate VW Passat. We’d had it new and it had 2 years dealer servicing when I came out the house to see a flat tyre. Tried to get the wheel off but no way and I didn’t want to pull the thing off the jack.
Phoned the dealer who said they sometimes stick and I was so annoyed by their nonchalent attitude I phoned VW customer services. They didn’t seem to understand the wheel wouldn’t come off and treated me like some sort of inadequate suggesting I should have their all inclusive breakdown cover. I said, what for a puncture on my own drive, and called the dealer again who then sent a fitter with a very big rubber mallet and hammered it off from the inside with much cursing. He said they often did it and the wheels weren’t scheduled to be removed at service, they just looked through them to the pads!
I then had them take the car in and do them all. Seems the VW may be particularly bad as it uses bolts for the wheels (rather than studs with nuts) and hence seems to have a deep spigot to give something to hang the wheel on whilst the bolts are fitted. So yes, a smear of copaslip on the spigot and the rest clean and dry.
Oh and yes on the dry studs/bolts thing. If they’re rusted and you feel you must put something on them just a smear of thin light oil (nothing with moly/teflon/copper etc) and most importantly nothing at all on the nut taper/seat where most of the friction/grip is. I once used coppaslip on an exhaust manifold nuts and the thing just wouldn’t stay done up even with spring washers. In the end I had to wash the studs and nuts clean again and it was fine.
So I get to wondering why? I asked one of the fitters and he didn’t seem to have a reason other than " the boss said so "
