Stainless steel wheel nuts
Discussion
RobXjcoupe said:
Course thread on wheel nuts is unusual
I've also read somewhere on PH that Aston doesn't use a stock Ford/Jaguar/Volvo/JLR nut but that the Aston nuts have a unique taper/cone. I'm not sure whether this is true but I'd want to be sure before I bought alternatives, especially as the tightening torque specified is pretty high.PLEASE take extreme caution if changing the material for stud bolts. The tensile strength changes for yield and UTS vary significantly with material sand within material groups - Not all stainless is the same, not all Titanium is the same. Even selecting a "better" material with a higher tensile strenght can be bad news as the properties of the thread joint are influenced by the material being threaded into and the material of the clamping face / chamfer. Unless you have done the stress analysis, don't risk it.
It’s very easy to measure and determine the thread size and pitch. Even to measure the taper angle isn’t difficult. Material choice is relevant usually for the weight on the wheel, but even that is technically not true as it’s the centre bore of the wheel that locates on the axle that is holding the weight. The nuts/studs should just be clamping the wheel to the hub. So while stainless is inferior to stress and yield to all but the lowest grades of high tensile steel, you can use stainless for simple clamping purposes, for wheel nuts a4 grade I think is more than up to the job especially if m14x2. If you are still not convinced, a set of plastic covers will rid you of rusty looking parts 
If you race your car stick to the original material. If you just potter around with an occasional blip on the motorway at legal speeds everything will be ok provided you check and service regularly as all car drivers do.
If you race your car stick to the original material. If you just potter around with an occasional blip on the motorway at legal speeds everything will be ok provided you check and service regularly as all car drivers do.
Starfighter said:
I am struggling as to where to start with this post and the mechanical engineering and material science problems it contains.
Sometimes it’s easy to over complicate things. I appreciate the science involved in specific material grades and machining attributes especially if a heat treatment is involved but we are not dealing with rod bolts or crankshafts or even suspension pivots. 
Quite. We are dealing with a bolt designed to give a specific clamping force controlled by applying a given torque. Change the material and the same torque will apply a different clamping force due to the elasticity of the material.
The yield point and UTS of stainless steels are significantly lower than the alloy steel typically used for stud bolts. It would be very easy for the bolt to start yielding and lead to a fracture even at the relatively low torque levels used on wheel nuts. This is why torque and angle are monitored on many assembly lines.
See the spacers thread for what busted stud bolts look like.
The yield point and UTS of stainless steels are significantly lower than the alloy steel typically used for stud bolts. It would be very easy for the bolt to start yielding and lead to a fracture even at the relatively low torque levels used on wheel nuts. This is why torque and angle are monitored on many assembly lines.
See the spacers thread for what busted stud bolts look like.
Starfighter said:
Quite. We are dealing with a bolt designed to give a specific clamping force controlled by applying a given torque. Change the material and the same torque will apply a different clamping force due to the elasticity of the material.
The yield point and UTS of stainless steels are significantly lower than the alloy steel typically used for stud bolts. It would be very easy for the bolt to start yielding and lead to a fracture even at the relatively low torque levels used on wheel nuts. This is why torque and angle are monitored on many assembly lines.
See the spacers thread for what busted stud bolts look like.
I know what sheared metal looks like lol I’ve repaired many a broken machine shaft over the years. I’ve even flattened a m20 high tensile bolt in a power press by mistake. Was quite impressive tbh.The yield point and UTS of stainless steels are significantly lower than the alloy steel typically used for stud bolts. It would be very easy for the bolt to start yielding and lead to a fracture even at the relatively low torque levels used on wheel nuts. This is why torque and angle are monitored on many assembly lines.
See the spacers thread for what busted stud bolts look like.
The thing with wheel studs, they are generally fitted into a cast iron hub. So that in effect is the weak point. As cars are getting heavier 5 bolts are used to hold each wheel on. Just helps spread the load on the cast iron hubs.
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