Lotus Elan

New Center Lock Socket and Interesting Torque Question

PostPost by: jbeach » Sun Jan 18, 2015 7:53 pm

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:
2015-01-17 RDent Center Lock Nut Socket.jpg and

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:
2011-01-17 Socket Cheater Bar.jpg and

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
Last edited by jbeach on Wed Jan 21, 2015 12:14 am, edited 1 time in total.
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PostPost by: rgh0 » Sun Jan 18, 2015 10:23 pm

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
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PostPost by: john.p.clegg » Mon Jan 19, 2015 6:21 am

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

John :wink:
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PostPost by: ricarbo » Mon Jan 19, 2015 12:34 pm

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
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PostPost by: john.p.clegg » Mon Jan 19, 2015 4:53 pm

Take more water with it...

John :wink:
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PostPost by: Esprit2 » Mon Jan 19, 2015 6:16 pm

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
Last edited by Esprit2 on Mon Jan 19, 2015 10:34 pm, edited 2 times in total.
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PostPost by: elancoupe » Mon Jan 19, 2015 10:13 pm

Just remember that you will need a wrench that will torque in both directions.
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PostPost by: elansprint71 » Mon Jan 19, 2015 11:24 pm

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. :twisted:
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PostPost by: elansprint71 » Mon Jan 19, 2015 11:26 pm

ricarbo wrote: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. :twisted:
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PostPost by: elj221c » Mon Jan 19, 2015 11:28 pm

elansprint71 wrote: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. :twisted:


:lol: :lol: :lol:
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PostPost by: elansprint71 » Tue Jan 20, 2015 12:48 am

elj221c wrote:
elansprint71 wrote: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. :twisted:


:lol: :lol: :lol:


Don't even think of supporting me- you know this road leads to madness... :wink:
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PostPost by: jbeach » Wed Jan 21, 2015 12:27 am

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
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PostPost by: mac5777 » Mon Jan 26, 2015 6:21 am

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.
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PostPost by: pharriso » Mon Jan 26, 2015 6:26 pm

mac5777 wrote: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=
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PostPost by: jbeach » Mon Jan 26, 2015 8:17 pm

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
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