One missing wheel nut - MOT fail?

photome

MEM62 wrote: »

One missing wheel nut - MOT fail?

How many do you think should be missing before a fail? Two? Three?

The manufacturer of the car designed the wheel to be held on with the number of nuts that it came with from the factory - 4, 5, 6 whatever. It is not safe to have any less.

That was my thinking, I can’t think of any reason to keep driving a vheicle with a missing wheel nut

Jackmydad

Not having a dig at the OP, they obviously didn't know that it matters, but it does reinforce the fact that MOTs are a good thing.
(Whether I'll be saying that in a few days time is another matter, I've got mine coming up!)

System

[quote=[Deleted User];discussion/5973264]Is this now a fail?

On a similar subject, can you still have an MOT a month before and still use car even if it fails (unless its considered unroadworthy) or has that changed now?[/QUOTE]

It has ALWAYS been a fail. Get stopped at the roadside by the police and they'd throw the book at you. What makes you think that in any way, shape or form driving with missing wheel nuts is OK?

As for using a car if it has failed the MOT you can as long as it wasn't listed as dangerous however as your car doesn't meet the minimum legal standards for use on the roads you could leave yourself wide open to being charged/fined if stopped at a roadside check and the fault discovered.

System

[quote=[Deleted User];75544583]Not as easy as new nut btw. new wheel hub needed because the nut has snapped off inside.[/QUOTE]

Then that is even worse. That happens because the wheelnuts have been overtightened which means they all have and others are at risk of snapping too, especially now they have the additional load from the missing nut. It is possible to remove the stud left in the hub without needing to replace the wheel hub. All is needed is a drill to drill a hole in the snapped off stud and put in a stud extractor. This has a left handed tapered cutting thread so tightens as you turn it in the direction you'd normally turn the nut to remove it.

I wouldn't just replace one, I'd replace them all, every single one on the vehicle because as I said earlier it is due to overtightening so if one has been they most likely all have and some may be not far off failing themselves.

reddwarf2002

Tarambor wrote: »

Then that is even worse. That happens because the wheelnuts have been overtightened which means they all have and others are at risk of snapping too, especially now they have the additional load from the missing nut. It is possible to remove the stud left in the hub without needing to replace the wheel hub. All is needed is a drill to drill a hole in the snapped off stud and put in a stud extractor. This has a left handed tapered cutting thread so tightens as you turn it in the direction you'd normally turn the nut to remove it.

I wouldn't just replace one, I'd replace them all, every single one on the vehicle because as I said earlier it is due to overtightening so if one has been they most likely all have and some may be not far off failing themselves.

Had couple of tyres replaced last year and the rookie fitter that was there used an impact gun to (over) tighten it. Even then I had my doubts whether I would be able to undo it when needed but was too lazy to check.

Sure enough a few days ago I was jumping up and down on the spanner and it wouldn't budge.

Earlier today, went back to the garage and he couldn't undo it using the impact gun. He then brought out a huge breaker bar and even with that he was literally breaking his back, but finally managed to undo the wheels. Made a mental note to myself to never allow wheels to be tightened using impact gun.

OP, I would definitely try and get that bolt fixed as it weakens the wheel. Safety issue should come first.

Joe_Horner

Tarambor wrote: »

Then that is even worse. That happens because the wheelnuts have been overtightened which means they all have and others are at risk of snapping too

A sheared, as opposed to threaded, bolt is far more likely to result from under-tightening than over-tightening.

They're designed to work in tension, pulling the wheel against the hub, and it should be friction between the hub and the wheel which prevents relative movement. If the bolts are under tightened then that friction may not be enough and the bolts have to take the extra force as a shear load instead of tensile - which they're really not good at. It also tends to cause fretting corrosion and "necking" of the bolt where it passes through the wheel.

On the other hand, to over-tighten to breaking on a typical 12mm wheel bolt would need upwards of 100 lb-ft of torque, which is going some even for a tyre monkey with an air gun.

System

Joe_Horner wrote: »

On the other hand, to over-tighten to breaking on a typical 12mm wheel bolt would need upwards of 100 lb-ft of torque, which is going some even for a tyre monkey with an air gun.

Not really. The wheel nut torque on my cars is 82lb/ft and 85lb/ft respectively and its hardly struggling doing that with a torque wrench.

fred246

When I have tyres fitted I take my wheels off and take them to the fitters in another car. Stops them over tightening wheel nuts and prevents damage from incorrect jacking.

foxy-stoat

Just get it fixed before the mot - what car is it?

Jackmydad

Tarambor wrote: »

Not really. The wheel nut torque on my cars is 82lb/ft and 85lb/ft respectively and its hardly struggling doing that with a torque wrench.

Yes, but that's the correct torque. The breaking point is going to be a lot higher. Somewhere around what Joe says at a guess.