Conversion formula for Nm springs to lbs-in.?

[hotshu]

What's the formula to convert 140Nm springs to lbs/in.?

[e30sd]

1 nm = 8.850 inch/lbs, so it would be 1239 lbs/in


p.s. i'm not a math major

[Hellabad]

I forget how I came up with this, but its right.
so, 798 pounds per inch

[B.Watts]

I've found multiple websites in the past that listed the conversion number as what e30 posted, so Jay's number confuses me. Jay, any help would be appreciated.

[hotshu]

I solved my puzzle, darn metrics & I'm in Canada too.

Seems H&R springs uses N/mm & others (Eibach?) uses N/meter. Sorta like Lb/in vs. Lb/ft.

1 N/mm = 5.7 lbs/in.

1 N/m = 8.8 lbs/in.

Ahh, so simple.

[B.Watts]

That makes more sense. So, the BMW Motorsport Eibach's we used at one point were correctly converted using the 8.850 number.

[Def]

I solved my puzzle, darn metrics & I'm in Canada too.

Seems H&R springs uses N/mm & others (Eibach?) uses N/meter. Sorta like Lb/in vs. Lb/ft.

1 N/mm = 5.7 lbs/in.

1 N/m = 8.8 lbs/in.

Ahh, so simple.

That can't be right since a meter is 1000 mm.


1 N = 0.2248 lb

1 m = 39.27 in

1 N/m = 0.2248/39.27 lb/in

1 N/m = .005724 lb/in (springrate)


1 N/mm = 5.724 lb/in (springrate)


1 N-m(torque) = 8.85 lb-in (torque)


Holy crap I need to stop trying to jump back and forth from an ECE lab report to this... I'm getting sloppy!

[techno550]

That can't be right since a meter is 1000 mm.


1 N = 0.2248 lb

1 m = 39.27 in

1 N-m = 0.2248*39.27 lb-in

1 N-m = 8.85 lb-in


1 N-mm = 8850 lb-in

hrm. some math (with conversion factors courtesy of onlineconversion.com :) )

1 lb = 0.4535924 kg

0.4535924 x 9.80665 m/s/s = 4.44822190946 N

lb/inch => 4.44822190946 / 25.4 => N/mm = 0.17512684682913385826771653543307

so N/MM devided by 0.175 = lb/in I think

I'm starting to hate simple math. Especially when I feel compelled to not chop off extraneous digits. :(

Edit:
the recip of .175 looks a helluva lot closer to our 5.714 number. (5.710146777071083501681323513583 being the number...)

[shopkins]

Google calculator is the only way to go with this!

Google Calc (http://www.google.com/search?hl=en&lr=&rls=GGLD%2CGGLD%3A2004-10%2CGGLD%3Aen&q=10+Newton+meters+%3D+%3F+Pound+inch)

[B.Watts]

Good point...I didn't really think through it...can anyone explain the 5.7 number that Jay lists?

[hotshu]

I'm no mathematician but see what H&R says the conversions are at their website http://www.hrsprings.com/site/index.html

BTW I didn't know H&R springs manufacturing plant was in Bellingham, WA.
Just over an hours drive from me.

[Hellabad]

The unit is Newtons PER meter, a measurement of force per distance, not Newton meters which is a measurement of force.
So 1 Newton-meter is 8.8 (pounds of force) per inch.

And 1 Newton per meter is 5.7 pounds per inch

Using my rusty skills I can't remember how to get the force out of the Newton, which as I remember is a unit of force not weight. And the pound is a unit of weight. There is a trick, I just can't remember it.

AND TYPING IT INTO GOOGLE IS CHEATING

Stay tuned, this is buggin the crap out me now....I hope I don't have to use long division.

[techno550]

Using my rusty skills I can't remember how to get the force out of the Newton, which as I remember is a unit of force not weight. And the pound is a unit of weight. There is a trick, I just can't remember it.


F = M * A
so if you have a F, and want to get the M term by itself, devide by A. ( in this case A = G :stickoutt )

[Def]

hrm. some math (with conversion factors courtesy of onlineconversion.com :) )

1 lb = 0.4535924 kg

0.4535924 x 9.80665 m/s/s = 4.44822190946 N

lb/inch => 4.44822190946 / 25.4 => N/mm = 0.17512684682913385826771653543307

so N/MM devided by 0.175 = lb/in I think

I'm starting to hate simple math. Especially when I feel compelled to not chop off extraneous digits. :(

Edit:
the recip of .175 looks a helluva lot closer to our 5.714 number. (5.710146777071083501681323513583 being the number...)

You must have made an arithmetic mistake. I used onlineconversion.com to see how many lbs 1 N equals. Then got how many inches go into a meter. Divide and you have 8.85 lb/in = 1 N/m


Sorry for the dash (-) I used earlier - I meant to put a slash (/). Just habit from looking at torque specs in metric.

[techno550]

You must have made an arithmetic mistake. I used onlineconversion.com to see how many lbs 1 N equals. Then got how many inches go into a meter. Divide and you have 8.85 lb/in = 1 N/m


Sorry for the dash (-) I used earlier - I meant to put a slash (/). Just habit from looking at torque specs in metric.

yeah, there's something not right about it. I dunno if maybe the math is for kgvs N or some such.

The problem is its too damn simple of a problem. Throwing us all off. Perhaps its Kg/cm to lb/in instead of N/cm -> lb/in.

Both the 8 number and the 5.7 number look familiar. :(

[Def]

Also, N/mm has to be higher than N/m when converting to lb/in for both. Same force, but N/mm is over a one thousand times smaller distance. So when converting to some equivalent force in lbs over the same distance(inch), the N/mm conversion should be much higher.

If you had something like N/km then the value would be extremely low in lb/in.

[Def]

yeah, there's something not right about it. I dunno if maybe the math is for kgvs N or some such.

The problem is its too damn simple of a problem. Throwing us all off. Perhaps its Kg/cm to lb/in instead of N/cm -> lb/in.

Both the 8 number and the 5.7 number look familiar. :(

I couldn't find anything wrong in your math, so I went back, and saw that I'm using the wrong operator even after changing the unit labels in my original post.

The confusion is coming from people trying to equate a torque force to a force/distance springrate. I've got the correct conversions in my first post now...


Now to finish this stupid report on induction motors. I now know why I blew this class(Mechatronics) off until my last semester.

[techno550]

I couldn't find anything wrong in your math, so I went back, and saw that I'm using the wrong operator even after changing the unit labels in my original post.

The confusion is coming from people trying to equate a torque force to a force/distance springrate. I've got the correct conversions in my first post now...


Now to finish this stupid report on induction motors. I now know why I blew this class(Mechatronics) off until my last semester.

Ah, good. I knew that other number looked familiar. So with the spring rate, 5.7 it is? Glad I'm not completely gone/nuts yet. :)

I think the problem is that someone just asked to convert units. Now if they had instead asked for the natural frequency of the spring... ;)

[Balthazarr]

You could look at the scales on a torque wrench handle if you have Nm and in-lbs on it.

You have to be careful about confusing mass with weight.
Not to sound pedantic, but
someone said the Nm is a force...it's not; it is torque which is easily confused as work or energy if you break it down to its contituent units.
1 Newton=1 Kg-m/ sec/sec => ma or mg as was stated for this situation.
Just that for torque there is an angle of application (actually sin) bc it is a x-product of force and lever arm.

[Reach]

I'm bringing this thread back to life, in hopes it may help someone else as it did me.

I've got to order some custom springs for my AST shocks, and I really had no idea how to do the calculation to figure N/mm which I am unfamiliar with into lbs/in which I am more familiar with.

If you google this topic, this thread is the very first result and the only one that is helpful at all. :)

With the help of a little math and google, I figured out that the 5.71 number is correct to multiply against a N/mm figure to get the more familiar lbs/in figure.

This website (http://www.huskyclub.com/springs.htm) even has a handy table that will help you eyeball convert lower spring rates. Enjoy!