Retorquing wheels

[canoetrpr]

It is very possible that my lack of mechanical knowledge is hiding an obvious answer here.

I've been thinking about adding a torque wrench to my arsenal to retorque wheels and such. Most of the torque wrenches I've seen are reasonably long - for the necessary leverage I imagine.

However, when I took a look at the rear wheels on my Kubota L3400 today, I realised that the tire is about a foot wide which means the spot where the bolts hook onto the wheel is about a foot in. I'd imagine I couldn't get a wrench longer than about a foot into there to tighten the bolt.

Am I missing something obvious here? or should I just be looking for a short torque wrench (under a foot) and expect that I will be able to tighten to the required torque without the leverage a great big wrench would give me.?

 

[deerhunterf350]

Thats what Socket extensions are for, however whenever using extensions on a Torque wrench , you "loose" some torque in the Extension. The Longer the extension the more torque lost. I don' know what the % of loss is, maybe someone else can chime in .

Dan

 

[RoyJackson]

I've always added a few ft-lbs (or whatever value I'm using) if using an extention longer then 3". Ballpark it about 5% of the value.
Although I've looked, I've never found a specific formula for this.

Just remember the torque is to provide a specific tension on mating fasteners. That means tight enough, yet not too tight.

 

[crbr]

I've always added a few ft-lbs (or whatever value I'm using) if using an extention longer then 3". Ballpark it about 5% of the value.
Although I've looked, I've never found a specific formula for this.

Just remember the torque is to provide a specific tension on mating fasteners. That means tight enough, yet not too tight.

We encounter this upon torquing anchor bolts on pipe supports (within the nuclear powered electric generating plants) with a specified amount of torque. There is a specific formula that is used. I'll look in a procedure on Monday if I don't forget.

As for RoyJ's explanation on torque and tensioning onto the mating surface, that is a true statement indeed. On very large bolts (over 2" in diameter) used for replacing the reactor's vessel head, torque goes by the way-side. We actually elongated the bolts (tighten) with a hydraulic system and measure the elongation in 1/1000ths. Interesting that RoyJ would mention this.


RoyJackson never ceases to amaze me....

 

[pat32rf]

My dad, who used to teach auto mechanics taught me that when a torque value is given it should be specified weither it is a dry torque or wet( lubricated with grease, oil etc). You must then start with a loose nut(on a stud) or bolt and tighten it to that torque value. Unless it is one of a series of clamping nuts or bolts such as wheel nuts or head bolts, in which case you tighten them in increments in a certain specified order.
To sum it up, unless you are just checking wheel nuts that were torqued previously you must first loosen all the nuts so they are below the specified torque value then retighten them. This all applies more to fancy rims on high speed road vehicles than 15mph tractors...

 

[cp1969]

I guess I'm missing something. Where does the torque disappear in an extension?

I can see it if you're using an impact, in fact they make things called 'torque sticks' to limit the amount of torque an impact can deliver to a fastener. But that results because the impact is of shorter duration than the extension can respond to.

But tightening with a torque wrench is essentially a static operation. If I hold 100 ft-lb on my end, why isn't 100 ft-lb coming out the other end? The extension twists, but it's acting like a spring.

 

[crbr]

I guess I'm missing something. Where does the torque disappear in an extension?

I can see it if you're using an impact, in fact they make things called 'torque sticks' to limit the amount of torque an impact can deliver to a fastener. But that results because the impact is of shorter duration than the extension can respond to.

But tightening with a torque wrench is essentially a static operation. If I hold 100 ft-lb on my end, why isn't 100 ft-lb coming out the other end? The extension twists, but it's acting like a spring.

A straight extension is a moment about the same axis. Where I got side-tracked in collective thinking was just what you pointed out. We have a formula for using a crow's foot and various extensions at an angle other than 90 degrees to the axis.

 

[hitekcountry]

I guess I'm missing something. Where does the torque disappear in an extension?

I can see it if you're using an impact, in fact they make things called 'torque sticks' to limit the amount of torque an impact can deliver to a fastener. But that results because the impact is of shorter duration than the extension can respond to.

But tightening with a torque wrench is essentially a static operation. If I hold 100 ft-lb on my end, why isn't 100 ft-lb coming out the other end? The extension twists, but it's acting like a spring.

Sure looks that way to me also.

Imagine you have one of those hanging scales that are in the vegetable section at the store. And lets say you took the basket off and placed a spring between the scale and the basket. Set the scale at 0 then add onions until the scale reads 10 pounds. Now do you have a true 10 pounds (I think so) or do you add onions until you get to 10.5?

 

[john_bud]

I just torque them to the spec. Extension or no.

Also, on retorqueing wheel nuts, I just slap on the wrench and have at it.

If you buy a torque wrench a clicker is easier to use than a pointer. Especially when in tight areas or with high torques. Holding 150# with one hand behind a wheel in an awkward position and craning you neck to see a pointer is just plain silly.

Remember too, that a torque wrench is one of the most important tools in the chest. You can snafu a good repair faster than a rat jumping on a cheeto with a junk TW. Buy quality otherwise you may as well just tighten until it feels right. Or like my high school buddy Mike, he tightened until the studs broke then backed off a 1/4 turn.

 

[RoyJackson]

My dad, who used to teach auto mechanics taught me that when a torque value is given it should be specified whether it is a dry torque or wet( lubricated with grease, oil etc). You must then start with a loose nut(on a stud) or bolt and tighten it to that torque value. Unless it is one of a series of clamping nuts or bolts such as wheel nuts or head bolts, in which case you tighten them in increments in a certain specified order.
To sum it up, unless you are just checking wheel nuts that were torqued previously you must first loosen all the nuts so they are below the specified torque value then re tighten them. This all applies more to fancy rims on high speed road vehicles than 15 MPH tractors...

It's called progressive torquing. I've used it in almost every application in which more then one fastener is used to hold components together such as an engine head (to the block), split wheel assemblies (aerospace) and automotive wheels (especially aluminum wheels) to the hub or axle.
The intent is to ensure an even setting of the components.


As far as cp1969's question "Where does the torque disappear in an extension?", the extension itself will twist (due to the fasteners' resistance to movement and the force applied by the wrench) and absorb a small percentage of the torquing force. The force is converted into heat.
How applicable is this in torquing a tractor tire? Not very, in my opinion, although it is in high stress components. For tractor wheel torque, I apply a modicum of Yankee common sense.

Crbr, thanks for the compliment. By profession, I'm a Quality Engineer and have worked aerospace, among other industries. Even an old dog like me picks up some information along the way...

Here's another tip: Never let anyone airgun your wheels on your car or truck. Odds are, they'll over torque and you'll have a heck on a time breaking them loose at 2:00 AM when you're trying to change a flat tire. Airgunning a cast aluminum wheel (to completion) can also result in cracking the wheel.