Lug nut socket and torque

[Slingshot]

I have a stock 93 and want to pull the wheels. Can I use any deep well socket or do I need a special socket setup for a torque wrench? What size socket fits the stock lug nuts? What torque?

[This message has been edited by Slingshot (edited 22 February 2002).]

 

[DanO]

regular 19mm socket will do. It's nice to have a 5" or so extension for the breaker bar/torque wrench so you don't scratch the wheels with the handle of the wrench.

Torque is 80lb ft. Tighten in star sequence, drive for a bit, let cool and re-torque.

DanO

 

[Slingshot]

Thanks a million Dan O !

 

[Russ]

Originally posted by DanO:
Torque is 80lb ft. Tighten in star sequence, drive for a bit, let cool and re-torque.

Does one torque/retorque with tires on or off the ground?

------------------
Russ
'91 black/black

 

[nsxtasy]

Always torque with tires on the ground.

 

[Russ]

Originally posted by nsxtasy:
Always torque with tires on the ground.

Thank you. My new 2001 Blades wheels are coming (hopefully) this week so this info will be put to good use very soon.



------------------
Russ
'91 black/black

 

[nsxtasy]

A few more comments and suggestions...

It's nice to have a 5" or so extension for the breaker bar/torque wrench so you don't scratch the wheels with the handle of the wrench.

I agree with this suggestion - but what would get scratched (at least, with MY torque wrench) is the paint along the edges of the fenders.

Torque is 80lb ft. Tighten in star sequence, drive for a bit, let cool and re-torque.

If you're not accustomed to changing wheels/tires:

1. Before jacking, loosen all the lug nuts slightly on the wheels you're about to remove.

2. Jack from the middle of the three jacking points (the three tabs that stick down on the side of the car, between the wheels). That way, you can jack up once and pull both wheels on that side.

3. Remove the lugs in a star pattern (as Dan indicated). Leave the bottom-most one for last, as it will keep the wheel from shifting until that lug.

4. Reverse the procedure when tightening. Make sure all the lugs are snug while the car is off the ground - so there's no play on the wheel if you try moving it - but don't fully torque them until the car is back on the ground.

5. Lower the car GENTLY back onto the ground.

Also, for steps 3 and 4, where you're removing/attaching the lug nuts while the car is up in the air - which involve a lot of turning without needing much force - you may find that it makes it easier/quicker if you have either a cordless drill with a socket attachment, or even a cordless screwdriver with a socket attachment.

[This message has been edited by nsxtasy (edited 24 February 2002).]

 

[Yellow Rose]

Q - Does one torque / retorque with tires on or off the ground?

A - Always torque with tires on the ground.

******************

It does not matter on or off the ground. All the wheel stud cares about is if its nut is torqued to the prescribed value. Doesn't matter how you get there.

In fact, it is better to torque the nuts with the wheels *off* of the ground, so as to ensure a more "centered" effect. Say, ever notice that all race cars torque with the wheels off of the ground? Not only in the hot pits but also back at the paddock.

The only reason us weekend mechanics may be inclined to torque on the ground is because we do don't have anyone handy to get in the car to press the brake pedal while we torque.

 

[Russ]

Originally posted by DanO:
It's nice to have a 5" or so extension for the breaker bar/torque wrench so you don't scratch the wheels with the handle of the wrench.

Any reason not to use an impact wrench to remove (not tighten) the lug nuts?

------------------
Russ
'91 black/black

 

[Andrie Hartanto]

Andy Vecsey is right. It is actually better to torque the wheels off the ground. This way there is no other force acting on it.

The manual recommends 80lb-ft. torque, but how tight is right?
During tightening, any threaded fasteners is subjected to 2 different stresses. First, the tension stress set up by actual stretching of the bolt as is tightened. This stress does not develop until the bearing face of the bolt/nut has contacted the work face. Second is the shear stress that is caused by friction between the male and female thread and between the undersurface of the bolt head and the work face.

The tension stress is what we are looking for. This stress will remain in the bolt after the the wrenches are removed, and as long as the total level of stress is within the elastic limits of the bolts. This stress will exert a strong clamping force on the assembly forever, assuming the assembly is rigid.

The shear stress is undesirable but unavoidable. It is undesirable because it is unpredictable. Fortunately this stress goes away almost as soon as we take the wrench off, well for most cases. The amount of friction involved, and therefore the torque required to produce a given amount of tension, varies with the cleanliness of the threads, the fit, the type, the plating, and the amount/type of lubricant used. This makes it difficult to determine the amount of torque required to produce a given amount of stress and resulting strain within the bolts.

This means that most fasteners are not tightened enough due to the friction variation between the female and male threads and bearing surface and work face.

Strange as it may seem, it is actually better to overtighten a bolt than to undertighten it.

The recommended tightening torque value of 12mm stud/bolt (which NSX uses) and grade 12.9 using engine oil lube is 79 lb-ft. That being said and because I don't use any lubrication, I like to use the value of 88 lb-ft.

The right way to tighten the nut is also by hand tight all of them, then use the wrench to tighten them slowly, in steps rather than just tightening them to its final torque all at once. By going a little at a time, we are giving the shear stress a chance to relax and we get more accurate reading.



[This message has been edited by Andrie Hartanto (edited 24 February 2002).]

 

[nsxtasy]

It does not matter on or off the ground. All the wheel stud cares about is if its nut is torqued to the prescribed value. Doesn't matter how you get there.

That's true - but it's damn difficult to properly torque a lug nut on a wheel that can rotate freely, and much easier to do so on one that is on the ground. Which, of course, is what you meant when you said

The only reason us weekend mechanics may be inclined to torque on the ground is because we do don't have anyone handy to get in the car to press the brake pedal while we torque.

 

[DanO]

Originally posted by nsxtasy:
That's true - but it's damn difficult to properly torque a lug nut on a wheel that can rotate freely

Agreed--not only is it difficult, but it can be hazardous (I lost a fingernail once by accidentally getting my finger wedged in between a wheel spoke and the caliper—Ouch!)

Fortunately it's not damn difficult to keep the wheels from rotating.

See www.danoland.com/nsxgarage/wheels/wheels.html for more wheel removal/install instructions

DanO

 

[Slingshot]

Wow, I almost didn't ask thinking I would be laughed at. Well, it definitely is more involved than adding windshield washer fluid

I picked up a torque wrench, 1/2" drive breaker bar, 1/2" drive 5 inch extension, and a 1/2" drive 19mm deep well socket, and am now armed with great tips and advice in doing a professional DIY job. Thanks again all for leading me through the proper procedures.