paul jacobs Posted February 8, 2004 Share Posted February 8, 2004 I've been in the habit of putting a small bit of copperslip onto my wheel nuts when I've had the wheels off, I do this on all my cars so that I never have problems getting the nuts off again later. However, a friend, who is a professional mechanic said that this was not good practice as it could lead to the nuts loosening themselves over time and he was always taught to tighten them "dry". Has anyone any thoughts one way or the other on this subject? [i continue to put a small smear of Copperslip onto my nuts to give that smooth easy feel when getting them off ] Link to comment Share on other sites More sharing options...
Luke Beaumont Posted February 8, 2004 Share Posted February 8, 2004 I've always lubed the threads, and never had any nut loosening shenanigans. The advice not to lube the thread doesn't make any sense to me - it seems very iffy relying on the resistance of a dry thread to prevent loosening. I've also heard that one should leave the nut seat un-greased. This I do - I can't see the benefit of greasing that part of the nut/wheel interface, and IMO a dry seat would contribute more to 'locking' the nut than the thread. Link to comment Share on other sites More sharing options...
Chelspeed Posted February 8, 2004 Share Posted February 8, 2004 My road car (subaru) manual said don't lube the studs so I didn't. So far, in less than 2 years, I have had three nuts seized on the threads so badly I had to snap the studs to get them off. Needless to say they're now copperslipped. (Sods law said two of them were on the same wheel and next to each other - the tyre place wouldn't let me drive home and seemed amazed when I robbed one from the other side and drove home with 4 out of 5 on each front wheel, seemed obvious to me!) I think the reason for the instruction isn't to do with them locking themselves. It's to do with getting the right torque. If you torque a dry nut onto a dry stud to say 80 lbft it'll go on less far than if you torque it to 80 lbft with everything copperslipped. Whether this makes it more or less likely to come off by itself I couldn't say, guess it depends on whether the stud is expected to stretch a bit at this torque. Link to comment Share on other sites More sharing options...
Asklepios Posted February 9, 2004 Share Posted February 9, 2004 Chelspeed is correct .By oiling the threads they may be damaged as they are now effectively overtorqued. Stud faiure may result, but not by the stud body ,rather by the threads Nuts rusting on can be minimised I suggest by backed off /exercising them from time to time. Link to comment Share on other sites More sharing options...
Tony C Posted February 9, 2004 Share Posted February 9, 2004 There is a torque figure correction factor that can be used when lubricating the thread. Multiplying the DRY torque figure by 0.7 should do the trick. Detailed information in 7FAQ Good Engineering Practices/Torque Wrenches here BRG Summertime Brooklands SV 😬 It is only with the heart that one can see rightly; what is essential is invisible to the eye. (Antoine de Saint-Exupery) Link to comment Share on other sites More sharing options...
paul jacobs Posted February 9, 2004 Author Share Posted February 9, 2004 I wondered if it might be to do with the torque figure [about 45 lbs/ft for a Seven I believe?] but then why don't manufacturers give both dry and wet figures, to avoid the danger of seizure. Talking of which I've also had the wheel seize onto the hub face plate, so I tend to smear this area too. Link to comment Share on other sites More sharing options...
Rob Walker Posted February 9, 2004 Share Posted February 9, 2004 45 lbft for the live axle that has 3/8 unf studs the de dion should be 55lbft IIRC. I always coppa slip. Link to comment Share on other sites More sharing options...
Luke Beaumont Posted February 9, 2004 Share Posted February 9, 2004 The torque figure for wheel nuts is the tightest you can undo with the supplied spare wheel brace Link to comment Share on other sites More sharing options...
B11MOY Posted February 9, 2004 Share Posted February 9, 2004 Do not do it, if you do, one day your wheel will come off, if you have been greasing your nuts or threads and you have had no problems you have been very very lucky !! Billy Rudd Link to comment Share on other sites More sharing options...
Nifty Posted February 9, 2004 Share Posted February 9, 2004 Depends whether you jump on it or not I'm not clear on this point: Assuming a clean, well machined thread on the nut and stud then the distance down the stud that the nut travels before reaching a quoted torque is likely to be indistinquistable between greased and ungreased (in fact, in theory, may be microscopically less due to space taken up by the grease) and therefore stud stretch will be the same. Certainly the difference between the two is likely to be less than the accuracy of most torque wrenches. This torque figure is a function of the tension of the stretched stud. The use of the copperslip is to prevent corrosion between the surfaces requiring 55 lbft to put the nut on and 150 lbft to break the stud off! The only case I can see this being different is where the thread is imperfect and a torque greater than the quoted figure is required to break passed a "nuisance" part of the thread before the nut gets home. In this case using the copperslip may well facilitate this. This resistance (and thus torque requirement) would be a function of the friction of the thread and not the elongation/tension of the stud. *confused* Keep off the straight and narrow 😬 Link to comment Share on other sites More sharing options...
Nifty Posted February 9, 2004 Share Posted February 9, 2004 Sorry, just re-read that and noticed I haven't made myself at all clear. I'm arguing about the stud tension and a given torque causing stud to snap if copperslip used. I can clearly see that by lubricating the thread it will have less friction and therefore be more likely to work it's way back. (I don't copperslip my threads ) Keep off the straight and narrow 😬 Link to comment Share on other sites More sharing options...
CharlesElliott Posted February 9, 2004 Share Posted February 9, 2004 I have put Coppaslip on my wheel nuts, and have torqued them to 75Nm in line with the assembly guide. However, I do check them about every 20 miles (track) so am not too worried about working loose. They get removed a hell of a lot so ease of removal is more of an issue for me. Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
tomroche Posted February 9, 2004 Share Posted February 9, 2004 I always understood that a nut and bolt "worked" by the action of the threads stretching the bolt and thus locking the assembly. Accordingly, the only reduction in torque required will be to overcome the friction of "dry" threads (so 10% ought to be enough). I cant see a correctly tightened nut working loose...... but regular checks are always a good idea ! Tom Link to comment Share on other sites More sharing options...
mav Posted February 9, 2004 Share Posted February 9, 2004 I have coppasliped all my wheel nuts on all of my cars. I do however check them for tightness on a regular basis (usually weekly or there abouts) Link to comment Share on other sites More sharing options...
Chelspeed Posted February 10, 2004 Share Posted February 10, 2004 Billy Rudd - You seem to think we should all do the opposite of what we have all been doing. Do you have any reasoning behind your thoughts? You agree with my road cars manual and I agree they should know best but evidence posted here says the opposite. Do you have anything logical reasoning wise, engineering best practice or similar to back up your assertion that we have all been very lucky? Or is this just your view based on what the manuals say? Or are you jsut being mischevious and disagreeing out of principle. If so please note I'm not biting this time..... Link to comment Share on other sites More sharing options...
Bare Posted February 10, 2004 Share Posted February 10, 2004 Dunno about Copper Slip, but I've been oiling my wheelstuds eversince I've owned a car.. and the ONLY one that ever gave wheel nut loosening trouble was my Mini. But one would have to dimly aware indeed to 'not notice' as the resulting noise from even a half turn loose is enough to give one 'Religion'. Quite possibly this is inna 'instructions' for legal issues. Link to comment Share on other sites More sharing options...
New Barbie Posted February 10, 2004 Share Posted February 10, 2004 The wheels are always on and off my car so there is zero chance of them not being checked all the time. I used a small amount of coppsalip to prevent seizing of the threads and I'll continue to add a small amount and every so often. I don't see that this is bad practice and my wheels don't fall off 😬 shrewdcookie - my Caterham site - UPDATED ! Link to comment Share on other sites More sharing options...
Luke Beaumont Posted February 10, 2004 Share Posted February 10, 2004 Plus, even if they do loosen it's not like you'll be driving along oblivious and then, bam, all your nuts disappear and the wheel flies off. You get a mysterious clunking noise that sounds horribly like a bad CV joint first. I know - I drove my Sierra for about 5 miles like that wondering what it was and hoping I didn't need to spring for a new driveshaft. Got back home and found the nuts loose, it then dawned on me that I'd only finger tightened the nuts when I had the wheel off that morning. Link to comment Share on other sites More sharing options...
I reply to every thread Posted February 10, 2004 Share Posted February 10, 2004 Count - has your car been off it's trailer since the Brands Trackday? Link to comment Share on other sites More sharing options...
prs Posted February 10, 2004 Share Posted February 10, 2004 We've got 4 cars and I've always copperslipped the wheel nuts (in fact I copperease most nuts and bolts) been doing this for about 15yrs now and never had a nut seize but more importantly to this thread I've never experienced one come loose. I've always torqued to the manufacturers fiqures. Phil S7 SVN Link to comment Share on other sites More sharing options...
B11MOY Posted February 10, 2004 Share Posted February 10, 2004 Chelspeed I run quite a large fleet of vehicles and was just passing on information. A lot of the historic cases refer to boat trailers as people grease the threads because the rear wheels often go into sea water and because of this the wheels come off. Billy Rudd Link to comment Share on other sites More sharing options...
Super_Rich_Bernie Posted February 10, 2004 Share Posted February 10, 2004 Don't know if they still do it, but Alfa had back hand threads on the nearside wheel nuts, so if they were loose they would tighten rather than come off when driving. A good idea, but you do have to remember to tell tyre fitters so they don't shear the studs off trying to undo them. Spinners on knock off hubs are always like this. I have coppaslipped the bolts on my cars, but may only continue to do that on the Alfa. I also put coppaslip on the hub where it is contact with the wheel after having to turn out one cold night when my wife had a puncture and couldn't get the unbolted wheel off. Jonathan Link to comment Share on other sites More sharing options...
Asklepios Posted February 10, 2004 Share Posted February 10, 2004 Tony C seems to have answered my worry by supplying a correction factor for wet assembly. Thanks for that Tony. Only once had a nut back off on a wheel and probably had not nipped it up fully. It was in my "coppaslip days" ,but the problem was the closed wheelnut not betraying its un torqued state , as an open nut will (unless you are having a dreadful day ). Link to comment Share on other sites More sharing options...
PaulD Posted February 10, 2004 Share Posted February 10, 2004 The "troque book" should say whether the nuts are to be put on lubricated or not, you should do the same, unless you make allowances. The basic equation for defining preload in a bolt is P=T/KD where P is the preload, T is the torque, D is the bolt diameter and K is a "Nut factor" dependent on thread form, friction and other things. The important thing to note is that K can vary enormously; from about 0.12 for a well lubricated bolt, to about 0.2 for a dry bolt. The result is that if the torque was specified for a dry bolt, and you lubricate it, you are likely to overload the bolt. Conversely, if you are given the torque for a lubricated bolt and you fit it dry, the pre-load will be too low and the bolt will fail in fatigue! The moral is, do what it says in the book! Paul Edited by - PaulD on 10 Feb 2004 17:38:49 Link to comment Share on other sites More sharing options...
Tony C Posted February 10, 2004 Share Posted February 10, 2004 Looking at torque loading from a BASIC point of view, the object is to tighen the bolt so there's no relative movement between the various elements in the assembly and at the same time, neither tighten it too much so the bolt is overstressed in tension nor so loose that here is too much relative movement (Clankety, clunk). A screw thread is only a slope in the shape of a helix after all. A reasonable analogy to lubricating the thread or not is if you immagined a greased slope and a dry one. If you were trying to push a sliding mass up the slope (you're on a dry bit of course ) you could do it much more easily if you had the slope greased than dry. If you then immagine a wall at the top, it would be possible to apply more force to the mass against the wall if the slope was greasy rather than dry 😬 There being less resistance at the slope mass interface - blimey, that sounds good, can we make interface the word of the day? 😬 BRG Summertime Brooklands SV 😬 It is only with the heart that one can see rightly; what is essential is invisible to the eye. (Antoine de Saint-Exupery) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now