New Center Lock Socket and Interesting Torque Question

[jbeach]

Hello Lotus Community.

I'm posting this in "Tools" for lack of a better place, although the interesting question is engineering in nature.

First, the tool: I just purchased a wonderful socket from RD Enterprise to use on my center-lock wheel nuts:

The socket is a little pricey, but very well made and makes tightening and loosening my new Panasports a cinch without chipping their finish.

Now the question: I haven't invested in a torque wrench that goes up to the 180 ft./lbs. of torque required for the Elan center lock nuts. Right now I have what the colorful guys down at my local Ace Hardware tell me is a "cheater bar." Here it is:

So my engineer buddy tells me "you don't need no expensive torque wrench - all you need is to mark a few places on the cheater bar [which, as you can see, I have] and apply the correct amount of pressure."

He says I can impart 180 ft./lbs. of torque to my wheel nut by applying 180 lbs of pressure at exactly one foot back on the bar.

"Great," I say, "But I'm a lot less than 180 lbs."

So he says, "No problem, if you apply 90 lbs of pressure at 24 inches, you achieve the same result."

I say, "I'm not 90 lbs either. How in the world can I ensure I'm applying exactly 90 lbs.?"

He say, "Still no problem. How much do you weigh?"

I say, "about 135."

He smugly says, "So mark your bar at 18 inches (half way between 12" and 24") and you'll get 180 ft.lbs. of torque by applying your entire body weight of 135 lbs at the 18Inch mark - because 135lbs is exactly halfway between 180lbs and 90lbs. Problem solved, without having to buy another expensive torque wrench!"

Is my engineering friend correct? Is it really that simple?

Many thanks!

John

[rgh0]

Yes its really that simple.

Torque is the twisting effort and measured in ft lbs.

Multiply the load in pounds by the lever arm distance in feet or fractions of a foot and you get the ft lbs torque your applying.

i.e. 135 lbs applied at 1.5 feet = 202.5 ft lbs

Given your feet have a finite width it a little hard to be exactly precise where you stand on the bar but you can get it accurate enough.

cheers
Rohan

[john.p.clegg]

...and make sure the bar is horizontal when you take the final reading......that is if you are standing on the 18" mark.

John

[ricarbo]

If you attach a loop of rope/wire to the breaker bar, fixed at the right distance, you can put your size 12s in the loop and know all the effort is at the right point. But, how do you do it without falling over?
regards
Richard

[john.p.clegg]

Take more water with it...

John

[Esprit2]

The method is accurate as long as the target reading occurs:

1) while your weight is accurately applied at the measured position (how wide is your foot, and can you control your ankle to center the load on the mark?).

2) while the cheater bar is horizontal (it rotates with the nut, and is only accurate when horizontal... ie, gravity is perpendicular to the handle), and...

3) as long as your weight remains constant. For most people, that's a bit of a variable.

Okay, you've played with physics. Now go buy the torque wrench.

Regards,
Tim Engel

[elancoupe]

Just remember that you will need a wrench that will torque in both directions.

[elansprint71]

I trained as a Precision Tool-Maker... I just whack my three-eared knock-offs with a copper hammer until they feel tight.
With your girlie US hexagon nuts, I'd just invite a passing fat-bloke in from the street to swing on the end of your bar. That should just about sort it.

Heck dudes, these are Lotus cars... use common sense and then hit it again.

[elansprint71]

If you attach a loop of rope/wire to the breaker bar, fixed at the right distance, you can put your size 12s in the loop and know all the effort is at the right point. But, how do you do it without falling over?
regards
Richard

I like your attitude... boy.

[elj221c]

I just whack my three-eared knock-offs with a copper hammer until they feel tight.

Heck dudes, these are Lotus cars... use common sense and then hit it again.

[elansprint71]

I just whack my three-eared knock-offs with a copper hammer until they feel tight.

Heck dudes, these are Lotus cars... use common sense and then hit it again.

Don't even think of supporting me- you know this road leads to madness...

[jbeach]

Ha. An enlightening and entertaining discussion!

My engineer buddy is pleased you've confirmed his theory. He offered to make me a hard-rubber triangle about the size of my shoe to stand on - placing the point on the 18-inch mark. I told him I can get it close enough without risking the public embarrassment of falling off on the side of the road somewhere.

Tim, you are correct - I will, inevitably, bite the bullet and purchase a torque wrench that goes up to 200 ft/lbs, However, I'm not going to carry it around in my boot, so the cheater bar with the 18-inch mark truly does use a little physics to serve a practical purpose.

Thanks everyone!

Best,

John

[mac5777]

John, Lowe's had offered a quality 50 to 250 ft/lb, that is ratcheted, reversible with a case for under $60.00. And will torques in both directions -- MOST DON'T even if they say they are reversible. The Elan manuals states a torque setting of 200 to 220 ft/lbs for the ear-less type spinners. On my Elan's three eared spinners, I use 190 without any problems.
I do loosen them every 6 months or so and retighten.
Sarto

[pharriso]

John, Lowe's had offered a quality 50 to 250 ft/lb, that is ratcheted, reversible with a case for under $60.00. And will torques in both directions -- MOST DON'T even if they say they are reversible. The Elan manuals states a torque setting of 200 to 220 ft/lbs for the ear-less type spinners. On my Elan's three eared spinners, I use 190 without any problems.
I do loosen them every 6 months or so and retighten.
Sarto

Sarto, $80 now... still not bad! http://www.lowes.com/pd_337334-22328-85602_4294607657__?productId=3381202&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=

[jbeach]

Thanks Sarto and Phil,

I'm seeing $71.72 when I follow Phil's link. Looks like I'm headed to Lowes some afternoon this week!

Btw, I thought I remembered my workshop manual listing the center lock nuts at 180 lbs. I'll look again when I get home tonight to confirm. I hope it is 220, as the tighter I can safely torque them, the safer I'll feel on the highway!

Best,

John