Wheel nut torque

[rogerpalin]

I do not normally put any lubrication on wheel nuts, but following some corrosion issues recently I am thinking of putting some grease on. Obviously this will mean reducing the tightening torque, but I am unsure by how much, I guess perhaps 50%. Anybody got any information/ideas?

[J44EAG]

Roger,

Lubrication with grease or oil on wheel nut threads is a complete no no!

Just keep threads clear of corrosion with an occasional wire brush session.

Greasing of threads will lead to false torque wrench settings and the increased possibility of nuts working loose. The same goes for the use of grease with Nylock nuts where lubrication with nulify the effect of the locking powers of the nut.

Grease under the nut surface washer to alloy wheel will do no harm or light greasing on the wheel hub to prevent interfacial corrosion issues between the alloy wheel rim and the steel hub. But on threads, definately not!!

Mike

[johnburnsd]

What are the correct torque settings for Sepang 20 inch wheels on the XKR?

[J44EAG]

As I understand it, most modern Jaguar wheel nuts torque up at 115-135Nm.

Can someone please confirm?

Mike K

[Nik]

Sepangs (as all Jaguar BBS wheels) 65 - 75 ft/lbs ,

Hope this helps ,

Nik

[johnburnsd]

Thanks very much for the info.

All the best

[mike020150]

The subject of wheel loss from badly torqued wheel nuts is at its most graphic and dangerous in the world of commercial vehicles where much research into the problem has been completed. The current best practice advice (from the Institute of Road Transport Engineers) about replacing wheel nuts is to clean all threads and contact surfaces and to lubricate them with a light oil (WD40) before torqueing the nuts to the manufacturer's recommended figure. Although less important for cars that, typically, place less strain on studs and nuts, it should be noted best practice procedures for commercials include re-torqueing wheel nuts after a short time/distance. Mike.

[Montana5]

Yes indeed the world of HGV's wheels are an interesting and different ball game, as is the world of Caravan and Trailer Wheels and the study into why so many Near Side Wheels were detaching themselves from their axles.
For my sins, I did recently put the slightest touch of Lithium Grease on my wheel studs after cleaning them up, (sorry Mike) more because of the difficulty in undoing them and boy did they give off a noisy crack, also because of the stories about S Type studs coming adrift from the back, anyway will keep that for another post in the S Type board

[J44EAG]

Civil Aviation Authority best training advice and practice was that no lubricant should be applied to critically bolted or nutted units or structural components due to the lubricant reducing toque required to tighten a fastening.A lubricated stud would produce a much wider factorial torque spread than a similar item that had received no lubricant.

Lubrication having that effect on tightening torque also has the same effect on the amount of effort (ie force x distance) required to dis assemble nuts, bolts or studs. In other words, lubrication may lead to the loss of a component due to the fastening coming apart due in part to the well known effects of cyclic load reversal due to the effects of vibration.

I am tempted to write an article on the subject but fear that I might die of boredom in the process. Perhaps I might tempt the XK8 Forum Co-ordinator into penning such a document for the benefit of members here. I`m sure he would be keen to oblige! Such a nice chap.

I see from the above posting that Doug also has observations on stud lubrication.

Regret to say stud lubrication is not my practice. It goes against my CAA engineering training.

Let the debate begin.

Mike K

[mike020150]

I don't think it's part of our JEC remit to encourage members to nod off whilst reading the bulletin board so I won't rise to Mike K's bait and I ask you not to blame the messenger! However, if anyone is sufficiently interested, I'd encourage them to Google the IRTE investigations carried out over several years and to read the resultant recommendations. Essentially, manufacturers' wheel stud torque figures are there to ensure an adequate clamping load is produced between the wheel and hub which protects the studs from taking the dynamic loads generated on the road. If dirt, corrosion or thread friction prevents the generation of an adequate clamping load between the wheel and hub, studs will be overloaded, damaged and/or shear off. Hence, in the real world, a smidgeon of lubricant is the practical solution which has been adopted by the road transport industry and the relevant safety bodies. Unless you drive like Mike K (wheels off the ground for most of the time) the operating conditions for road vehicles and aircraft differ somewhat. Mike.