So, let's talk about your nuts.
This post is about how to tighten wheel nuts on cars. The humble wheel nut (also called a ‘lug nut’) is more complext than you might think.
How hard can this nuts and bolts stuff - and in particular, tightening them up - really be? The answer is: ‘plenty’. And getting it wrong has consequences - bad ones. So here's how to tighten wheel nuts properly.
Tightening your wheel nuts incorrectly after replacing a wheel can warp the bake disc, leading to uneven wear and a condition known as DTV: ‘disc thickness variation’. This is where the clamping force on the disc is uneven, leading to uneven wear, and a brake pedal that pulsates annoyingly underfoot because the disc is warped – and this will happen every time you touch the brakes, not just when the ABS kicks in (the pedal is supposed to pulsate then, for a completely different reason). DTV isn't just annoying; it also wears your brakes out prematurely. Tightening your wheel nuts properly prevents this problem.
A few simple, logical wheel nut tightening steps will stop DTV in its tracks.
The basic recommendation with how to tighten wheel nuts is to get this right on all your wheels now, in the driveway at home. Apart from preventing DTV, you’ll also ensure that you can undo your wheel nuts at the roadside if you get a flat (because a lot of wheels are screwed down too tight by the pneumatic rattle gun at the tyre shop and are almost impossible to undo with the standard car’s toolkit). Tightening wheel nuts properly also optimises the clamping force of each wheel nut.
You will need: a jack, a wheel chock, a socket, socket extension and a long breaking bar for the socket (all preferably half-inch drive). You’ll also need a torque wrench, the car’s owner’s manual (or some other evidence of the correct torque specification for the nuts) and a small amount of grease.
Stability. Make sure the car isn't going to roll anywhere. Apply the handbrake and put the car in gear (or ‘P’). Chock the wheel diagonally opposite the one you’re going to work on. Here, we’re working on the right front, so we’ll chock the left rear. Use the breaking bar, extension and socket, loosen off the wheel nuts just enough to break their tension before you jack the wheel in the air. Its easier to do this on the ground than when the wheel is raised.
Apply the handbrake and put the car in gear (or 'P') so it doesn't roll anywhere
Chock the diagonally opposite wheel with a block of wood
Break the tension on the nuts before you jack the car. Less than a quarter-turn is all that's needed. It's much easier to apply leverage when the car's still on the groundNOTE: Choose a location away from traffic for this job. The ground underfoot should be hard, stable, flat and level. A concrete floor is ideal.
Removal. Jack the wheel in the air, and then remove the nuts completely. Gently lift the wheel off the studs – bear in mind that cars supported only by the jack are relatively unstable. Never work under a car supported only by the jack. If you intend to get under the car, or place any part of your body under the car, support the car on approved jack stand(s) first.
If you're not using the standard jack, lift somewhere that's structurally sound. Here, the trolley jack is lifting on the sub-frame mounting point, which holds the suspension and engine on the body
It's often easier to zip the nuts off using a socket extension like a screwdriver than it is to undo the nuts themselves, directly, by hand
Tyre-wheel assemblies can be heavy, so brace yourself with a straight back and bent knees to do the heavy lifting. Slide the wheel gently off the studs without unbalancing the car
Inspection. While you have the wheel off, check the brakes and other components for wear, damage and remaining service life. While the wheel is off, check the inner face of the rim for damage, as well as damage to the inner sidewall of the tyre. Check the tread face for uneven wear – wearing out in the centre means the pressure is too high, while wear on the shoulders (both shoulders) means the pressure’s too low. Excessive wear on one shoulder only means you probably need a wheel alignment.
Inspect the inside edge of the rim and the sidewall for damage while the wheel is off
You should also check the brakes and all the stuff you can't normally see clearly inside the wheel well for wear/damage
Check the tread face for uneven wear, while you have it out there in broad daylight - you might need to make pressure or wheel alignment adjustmentsSTEP 4
Cleaning. Clean the wheel mounting face near the base of the studs and the corresponding mounting face on the wheel – you want clean, flat, metal-to-metal contact to help prevent the disc from warping.
Make sure the mounting face on the wheel is clean...and make sure the corresponding mounting face on the disc is clean, too
Lubrication. Put a little grease – preferably molybdenum-disulphide grease – on each stud to prevent them seizing up under the effects of corrosion over the coming months. (No, it won’t pre-dispose the nuts to coming loose.)
Shortly after this page was posted Franco Petrella from Rosebery Smash Repairs sent a comment, which was bang on the money: "When you grease the studs you should also grease the nuts and the corresponding mating faces on the wheel," he says. "It's especially important if the wheels are alloy, as the nuts have a tendency to bind, which can result in a false positive reading (ie a loose wheel nut tricking the torque wrench into thinking the nut is tight enough)."
That's a great tip - I should have thought to include that. Mr Petrella is absolutely spot-on with that advice. So thanks very much for the positive input. Keep the feedback coming.
Grease the studs. It'll help prevent them from seizing and being impossible to undo at the roadsideA small amount of molybdenum disulphide grease is all that's required
Replacement. Replace the wheel on the studs. Often, it wants to swing away at the rear, which you can prevent with your boot (don’t stick your toes under the tyre, however, in case the jack slips).
It helps to rotate the wheel into the proper orientation to match the studs - before you lift
Engagement. Do the nuts up finger tight or slightly tighter with your socket set (gently).
Use the socket set like it's a screwdriver and do all the nuts up just finger tight
Torque specification. Read the owner’s manual and find the correct torque setting, which is often in the section on fitting the spare tyre. On this car – a Subaru Impreza WRX – the manufacturer’s specification is 58-72 lb-ft (also known as ‘ft-lb’, ‘foot-pounds’ or ‘pounds-feet’ – they are all the same thing).
Don't guess - use the torque setting specified by the manufacturer. DO NOT fall into the 'more is better' trap. It isn't - excessive torque can warp the discs and over-stress the studs
NOTE: Torque settings are specified for a reason – they’ve been shown after testing to provide adequate restraint without shearing off the stud, without subjecting the stud to excessive loads, without coming loose in service, and without warping the brake disc. Extra tension is not desirable, nor is it an improvement on the specified setting. ‘As tight as possible’ is a bad choice for any fastener for which a manufacturer specifies a torque setting.
Download table. If your torque wrench is calibrated in Newton-metres (Nm), which is the metric equivalent of ft-lb, download and print our conversion table here. It's a PDF, and you can use it to convert either Nm to lb-ft or vice-versa. (We did it that way so you could print it off and take it to the workshop ... where you might not normally have online access.) From the table you’ll see that 60ft-lb (near the bottom of the specified range) is the same as 81Nm, while 70ft-lb (near the top) is 95Nm – so, for convenience, I’m going to set the torque wrench to 90Nm.
You can download the PDF torque conversion table here.
Set torque wrench. Setting the torque wrench is easy. You just wind the black handle up, along the scale to the nearest graduation, which in this case is 84Nm. Each graduation on the vernier scale (on the black handle) is 1Nm, so I need to add another 6Nm by winding from the '0' on the vernier - at 86Nm on the main scale on the silver (stainless steel) body of the handle - to '6' on the vernier, because 84 + 6 = 90Nm. Simple. I could also have just left the wrench at 86Nm by leaving the zero on the vernier in place - because 86Nm is also within the specified torque range. (I always double-check the setting and also make doubly sure I am on the ‘Nm’ scale – because this Ampro torque wrench also has a ‘lb-ft’ scale on the other side - getting this wrong is a major problem.
90Nm equals 84Nm on the shiny barrel of the wrench plus 6Nm on the rotating black 'vernier' scale on the handle
Lock-off. Once you have the correct setting dialed in, tighten the lock screw at the base.
Locking the handle off stops it moving to a different setting as you do the job
NOTE: Torque wrenches tend to be more accurate when they're set to the middle of their range. This wrench goes from 28Nm to 210Nm - which is ideal for our wheel nuts, at about 90Nm. For more information on, and a review of, this Ampro torque wrench, click here [link coming soon].
If you need a decent, good value torque wrench for this job, send me an e-mail here.
Remove jack. Gently lower the jack and remove it, along with the diagonally opposite wheel chock.
You put the wheel back on the ground because it's much easier and safer to apply the final torque with gravity holding the wheel steady for you
Apply torque. Tension the wheel nuts – but do it in a very specific order. If you number them clockwise from the top ‘1-2-3-4-5’ sequentially as you look around the circle, tension them in the following order: ‘1-3-5-2-4’ (You are going from stud to stud in a star-shaped pattern, rather than around the circle). If your vehicle has six studs, do them in this order: ‘1-4-2-5-3-6’. And if it has just four studs: ‘1-3-2-4’. The correct tightening sequence minimizes the chance of warping the disc as tension is applied more evenly.
Start here with the torque wrench. A loud click with disengagement tells you when to stop turning. Apply pressure smoothly and, although the photo doesn't show it, support the head of the torque wrench with the other hand. See the video at the top of the page for the tensioning sequence and method in action.Torque this wheel nut secondTorque this wheel nut thirdTorque this wheel nut fourthTorque this wheel nut last. Then go over them all again, in order, to ensure you didn't forget one
NOTE: When using a torque wrench, apply the tension smoothly and slowly, and support the ‘head’ end with your other hand. Don’t use the torque wrench for jobs other than applying the final tension. A loud ‘click’ and a momentary disengagement of the load lets you know when you have arrived at the right load.
Double-check. Always go right around in the star-shaped pattern a second time. This confirms that you didn’t miss a nut the first time around, and that you got the torque right the first time. The wrench should click and disengage drive without the nut moving as a result this time around.
Repeat and finish. Do the other three wheels, and feel the car carefully the first time it’s back on the road. Stop and double check all work at the first sign of vibration or other malfunction.