Technical Locking wheel nuts

[WitleyPanda]

Another complicating factor is the difference between steel and alloy wheels.

Steel wheels by design have an element of 'spring' in them; the centre of the wheel essentially acts like a large disc spring washer. This provides some of the clamping force that's holding the wheel in place, and makes unwanted loosening less likely.

Alloys have essentially no give in the wheel itself; the entirety of the clamping force is provided by the elastic deformation of the threads. This is one reason why recommended torque figures for alloys are often higher than those for steels.

The difference is very noticeable when fitting a wheel; with steels, you'll get a further half turn, or maybe more, after the initial resistance is felt. With alloys, practically none.

There's a huge margin of safety with steels; less so for alloys.


You could start with a lookup table showing the proof load for the size and material specification of lubricated bolts.

Having been the designer of steel wheel, from morris minor to Hilux, can clarify that the central ring being a spring is not a design feature, however the seat crowns are but would be very high effect spring rate. If you have wheel where the back is not flat or has significant distortion/convex form, reject has could be a sign of poor manufacturing processes.

 

[Pugglt Auld Jock]

The Scala comes with a steel spare and one of the first things I did was to try it on using the normal bolts. It fitted just fine, obviously designed to go with the bolts.

Daughter in law's Mazda had no spare though so we bought a space saver kit from a supplier in the midlands and I immediately tried it with the alloy bolts just to be sure - it was fine.

I'm not quite so keen on the Mazda's spacesaver though, it's considerably smaller than the alloys. The Skoda has a 195 space saver, compared to the 205 on the alloys. It's a different aspect ratio though so has same rolling diameter - which pleases me as it means it could be run on the front in an emergency without stressing the diff spider gears too much. Keeping my eye out for a used alloy of the same design as those on the car - yes it fits the boot space, I checked.

Reference the above comments. One thing I really like about the Scala spare is that it's a normal 196/65R15 H tyre with normal tread depth. I'm pretty sure it's the fitment, complete with steel wheel, which comes on the most basic model - which is not actually available in the UK. I like that it's a "normal" tyre though because it's got plenty of tread so could be driven on for quite a long way. Interestingly, or maybe not? My car has 4 Goodyears - 205/55R16 H on the alloys but the spare is a Continental. Of course, being a different size, it's subject to the 50mph/80kph speed restriction but I bet it'll feel much more secure than the rubber band in Becky's boot - or the one in the Mazda, which I think, if I remember, are around 125 or 135 section width.

 

[WitleyPanda]

Result of unlimited violence!
Finally removed
So tried ground down cold chisels to split the sleeve/ring : result bent cold chisels, no significant effect on sleeve.
Tried to weld ring to bolt head, see photo. Then hammered on a normal 7/8” 12 point/ bi-hex socket. ( not enough room in alloy to fit a IRWIN style left hand twist job. ) Sheared splines from socket. At this point was tempted to use a rota roach and saw hole in wheel, however more tea. More welding. Hammered ( sledge hammer ) on another socket 22mm this time. More welding, with some brazing as a by product of melting the tip shield. Welds sheared but socket still firmly on ring.
Out with slide hammer on end of mole grips to try to remove socket. More dark thoughts about bimetallic saw or rotabroach. Eventually slide hammer and a different mole grip combo removes sleeve. This now created enough radial clearance for a standard wheel nut left hand twist job off socket. Add 4 ft breaker bar and gently applying torque, finally removed.
There is a locking wire ring on the locking bolts than locates into the sleeve to retain it so only other technique may have been to rotabroach off the sleeve?
16 new wheel bolts arrived, will use smear of copper grease on thread and aluminium grease on back of alloy. Will use torque wrench but at moderate setting when I do the calculation.

 

[Pugglt Auld Jock]

Result of unlimited violence!
Finally removed
So tried ground down cold chisels to split the sleeve/ring : result bent cold chisels, no significant effect on sleeve.
Tried to weld ring to bolt head, see photo. Then hammered on a normal 7/8” 12 point/ bi-hex socket. ( not enough room in alloy to fit a IRWIN style left hand twist job. Sheared splines from socket. At this point was tempted to use a rota roach and saw hole in wheel, however more tea. More welding. Hammered ( sledge hammer ) on another socket 22mm this time. More welding, with some brazing as a by product of melting the tip shield. Welds sheared but socket still firmly on ring.
Out with slide hammer on end of mole grips to try to remove socket. More dark thoughts about bimetallic saw or rotabroach. Eventually slide hammer and a different mole grip combo removes sleeve. This now created enough radial clearance for a standard wheel nut left hand twist job off socket. Add 4 ft breaker bar and gently applying torque, finally removed.
There is a locking wire ring on the locking bolts than locates into the sleeve to retain it so only other technique may have been to rotabroach off the sleeve?
16 new wheel bolts arrived, will use smear of copper grease on thread and aluminium grease on back of alloy. Will use torque wrench but at moderate setting when I do the calculation.

Phew, what a phaff! But so satisfying when you succeed - well done that man.