Evening all

Can anyone verify the required torque for the rear hub nut on X300? I read somewhere its 300-320nm which is massive - even my largest torque wrench only goes to 200nm. Can get a Teng 350nm wrench for £110 but don't really want to spend that unless I am sure.

Also with that amount of torque is it okay to just tighten it with handbrake on in "P" on should it be torqued up on the ground with wheel on and centre cap removed from wheel.

Any "real world" advice appreciated.

 

Yes the factory spec is 304-336 Nm.




* Note: the reference above to the other procedures just contains a warning NOT to re-use the nut.


In the real world you will probably struggle to actually achieve that figure with a just torque wrench unless you're a very big guy or use a scaffolding tube over the wrench.

I obviously don't recommend it, but in the past I have just tightened these to the most I can achieve swinging on a 600mm breaker bar and not had any wheels fall off.

I also use a 3' crow bar wedged between wheel studs and garage floor (with plastic sleeve to protect threads) as a counter force when tightening.

 

Hi Brendan - my hub nut finally arrived!! Hallelujah!! I notice the nut itself is the same both sides but the coil inside is set back 1 or 2 threads one side and perhaps 3-4 the other. Do I go "coil side inwards" when installing it? Its a genuine Jag nut, was still in its bag.

 

Short answer is I don't know. Intuitively I would say same as you, coil side in.

Maybe the nut spec has changed but I don't remember it ever being unclear which way the nut should go on. There's no reference in the factory manual so it's probably not a critical thing if the nut is symetrical.

 

It shouldn't matter which way the nut is installed. That coil insert deforms under torque and is supposed to keep the nut from unwinding on its own. The reason the nuts are not to be reused is that the coil deformation prevents it from working properly if it is removed and reinstalled.

I find it easiest to achieve full torque with the wheel installed without its center cap, and the car on the ground with its full weight on the wheel.

I don't know if this is true in Spain, but in the U.S. some auto parts stores will rent out a torque wrench that can measure to 340 Nm / 250 ft. lbs.

Cheers,

Don