Talking about Springs....

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jondee86
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Talking about Springs....

Postby jondee86 » Sun Jul 13, 2014 7:57 pm

Here is one definition of a spring...
A spring is defined as an elastic body, whose function is to distort when
loaded and to recover its original shape when the load is removed.

I prefer to think of it as a device for storing energy. Those of us
who have opened an old wind-up clock to see how it works, and had
the spring unwind in our face, already know that. And if you tried to
take the spring off your front strut without using spring compressors,
you could be carrying the scars of learning :)

When talking about coil springs, the strength or stiffness of the spring
is rated in lbs/inch or kg/mm. This defines how much the load on the
spring has to increase to compress the spring by another inch or mm.
The conversion factor is 0.0179 which means that 250lbs/inch becomes
250*0.0179=4.475kg/mm or 6kg/mm becomes 6/0.0179=335lbs/inch.

The stiffness of a coil spring is determined by the thickness of the
wire, the diameter of the coil and the number of active coils. As the
formula Image for calculating spring stiffness is a bit tedious,
you could use the calculator provided by Wallace Racing

However, you do need to know this...
1. The fatter the wire, the stiffer the spring.
2. The more active coils you have, the softer the spring.
3. The bigger the diameter of the coils, the softer the spring.

Then you will understand how these different types of springs work...

Image

See Springs for my Ride for how this information can help you choose
the springs for your ride :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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burdickjp
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Re: Talking about Springs....

Postby burdickjp » Sun Jul 13, 2014 8:16 pm

No love for the correct SI unit of Newtons per Meter?
Pursuing the ideal

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jondee86
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Re: Talking about Springs....

Postby jondee86 » Sun Jul 13, 2014 11:53 pm

That makes 350lbs/inch into..... 61,294N/m. Somehow I don't think that
catches the public imagination in the same way as 6.23kg/mm ?

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

burdickjp
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Re: Talking about Springs....

Postby burdickjp » Mon Jul 14, 2014 4:38 am

You could also say 61.3 kN/m or 61.3 N/mm. It's all the same. The important thing is Newton is a unit of force, whereas kg is a unit of mass. When you start doing real math with it you need newtons.
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saiGone
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Re: Talking about Springs....

Postby saiGone » Mon Jul 14, 2014 10:51 am

Do you think it matters what direction dual rate springs go?
Club 4AG member since 05 (Formally SaigonsSon)

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jondee86
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Re: Talking about Springs....

Postby jondee86 » Mon Jul 14, 2014 3:02 pm

It is in the nature of coil springs that they do not lend themselves to having
both a high spring rate and a long unloaded length. They are either short
(fewer active coils) and stiff, or long (more active coils) and soft. Lowering
springs that are sold as "dual rate" are essentially short springs with an
integrated "keeper spring" on one end. The closely wound coils are fully
compressed (coil bound) once the spring is installed, and act as a spacer.
They only act as dual rate when the suspension is at full droop, and their
primary function is to keep the the spring captive.

Image

The spring itself does not care which way up it is installed, unless one end
is wound with a smaller diameter to suit the upper or lower spring perch.
When I had these on my car I put the closely wound part at the top where
it could not be seen :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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jondee86
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Re: Talking about Springs....

Postby jondee86 » Mon Jul 14, 2014 3:22 pm

burdickjp wrote:You could also say 61.3 kN/m or 61.3 N/mm. It's all the same. The important
thing is Newton is a unit of force, whereas kg is a unit of mass. When you
start doing real math with it you need newtons.

I have worked with Newtons, metres, kilograms, Nm and kgm for many years.
This country became fully metric a long time ago, but I am not familiar with
the degree of "metrification" in the US. Therefore when using metric dimensions
I use the ones that I guess the average punter will be more familiar with.

Different industry segments standardise on different measurements. For
example the garment industry works in cm, the building industry in metres,
and the engineering industry in mm. Pressure measurements get a bit more
confusing, as the Pascal, mPa, kPa, Bar are all used. But interestingly enough,
many people still inflate their tires to 30psi :)

Basically, there are some things that will take a generation or two for people
to change their thinking. Most people have no difficulty in visualising a 6 foot
tall man, but get stuck if you say he was 183cm tall.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

burdickjp
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Re: Talking about Springs....

Postby burdickjp » Mon Jul 14, 2014 5:19 pm

jondee86 wrote:I have worked with Newtons, metres, kilograms, Nm and kgm for many years.
This country became fully metric a long time ago, but I am not familiar with
the degree of "metrification" in the US. Therefore when using metric dimensions
I use the ones that I guess the average punter will be more familiar with.

Different industry segments standardise on different measurements. For
example the garment industry works in cm, the building industry in metres,
and the engineering industry in mm. Pressure measurements get a bit more
confusing, as the Pascal, mPa, kPa, Bar are all used. But interestingly enough,
many people still inflate their tires to 30psi :)

Basically, there are some things that will take a generation or two for people
to change their thinking. Most people have no difficulty in visualising a 6 foot
tall man, but get stuck if you say he was 183cm tall.

Cheers... jondee86


Absolutely true. I do all my engineering and machining in SI, for instance, which creates nearly unlimited frustration for machinists I have to work with, who were all trained on Bridgeports in inches. I still have trouble thinking in metric with wiring diameters, though. I can talk about wiring "gauges" all day long, but have to go to a conversion table to look at the comparative metric cross-sectional area.

I go out of my way to encourage metrification specifically because exposure is encouragement.
Pursuing the ideal

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oldeskewltoy
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Re: Talking about Springs....

Postby oldeskewltoy » Tue Jul 15, 2014 8:03 am

you guys.... worrying about minutia...... when the accepted conversion from one to the other is a very loose 55#/inch = 1kg/mm

Remember here... we are talking about a 30 year old Japanese economy car.... not an RB10
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

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