Springs front end 2 high

Re: Springs front end 2 high

Reply #30 – September 08, 2005, 02:05:34 PM

there shouldnt be any problem cutting 1-1 1/2 coils off a spring unless its a progressive rate spring correct? I took 3/4 of a coil of my t-birds front so it would sit level with the rear (which was desiogned to sit lower

) and didnt notice any difference in handling or ride and I plan on doing the same on my Zephyr

Re: Springs front end 2 high

Reply #31 – September 08, 2005, 03:35:21 PM

Quote from: tbirdboy88

My question is, can springs that are the same length and thickness compress at different rates??? Is it possible for someone at the factory to put the wrong pressure spring in the box that looks the same as another????

If the two springs are made out of the same material, no.

Spring rate is determined by the following formula:

Rate (N/mm) = G d4/ ( 8 N D3)

G = Modulus Of Rigidity (N/mm2)
d = dia of wire.(mm)
D = Mean dia of spring (mm)
N = Number of Active Coils

So, theoretically, a spring with the same diameter, coil thickness, and number of coils will have the same spring rate.

Quote from: tbirdscott

there shouldnt be any problem cutting 1-1 1/2 coils off a spring unless its a progressive rate spring correct?

Cutting coils will increase the spring rate regardless of whether it is a progressive or constant rate spring. You can get a good idea of the increase by using the above formula.

Re: Springs front end 2 high

Reply #32 – September 10, 2005, 08:46:38 PM

Yup,
Same thing happened to us. Except I bought the springs. The Bird has the same higher front end appearance. ....a year later, it still looks the same. This explains why I couldn't compress one spring enough to install it--and so had to haul the car to a shop to have the job done(?) One benefit, the wind dam doesn't bottom on those concrete bumper stops seen on the ground--anymore.

Re: Springs front end 2 high

Reply #33 – September 10, 2005, 09:10:44 PM

Quote

If the two springs are made out of the same material, no.

Yes, two springs made from the same material and the same thinckness can have different rates to them. It all depends on how the spring is tempered from the factory.

Re: Springs front end 2 high

Reply #34 – September 10, 2005, 11:21:33 PM

Quote from: slamedcat

Yes, two springs made from the same material and the same thinckness can have different rates to them. It all depends on how the spring is tempered from the factory.

No. Modulus of Rigidity (Shear Modulus) is a material property. It cannot be changed by quenching/tempering a material.

AISI 4130 Steel, normalized at 870°C (1600°F), air cooled, 13 mm (0.5 in.) round

AISI 4130 Steel, water quenched 855°C (1570°F), 480°C (900°F) temper, 13 mm (0.5 in.) round

AISI 8620 Steel, cooled in carburizing box, reheated and quenched, 13 mm (0.5 in.) round

AISI 8620 Steel, annealed 13 mm (0.5 in.) round

If you follow the links, you'll find the Shear Modulus is 80 GPa for all 4 samples, regardless of the heat treatment given to the material.

Re: Springs front end 2 high

Reply #35 – September 10, 2005, 11:33:59 PM

temper can change it drastically...............like morons that torch them hot so they sag,,,,,,,as a resuolt of the spring losing its temper.

You can't just wind a coil of steel and call it good and through it in there.

And if I am thinking right you can't change a material just by heating it. It still has the same molecular structure even after heating.

Re: Springs front end 2 high

Reply #36 – September 11, 2005, 12:46:51 AM

No, as I said before, tempering a spring doesn't change its shear modulus. It is constant (in the elastic region). If you have any information that shows otherwise, I'd like to see it.

Take two pieces of mild steel, heat one up to 1000 degrees, and then drop it in cold water. Leave the other one alone.

Even after piece #1 is quench/tempered, they both have the same shear/Young's modulus. If you apply a force to both pieces, they will both deflect at the same rate.

Heating springs with a torch can "ruin their temper", but it won't change the shear modulus.

Re: Springs front end 2 high

Reply #37 – September 11, 2005, 11:52:22 AM

Quote from: JeremyB

If you have any information that shows otherwise, I'd like to see it.

I could get you the Caterpiller standard for you but I would run the risk of loosing my job over it.

The other thing is I could pull any spring drawing for Cats Data Base and they have all kinds of specs on heat treating and tempering.

Re: Springs front end 2 high

Reply #38 – September 11, 2005, 12:32:00 PM

heating up a spring also changes it at the moleculor level. I have seen plenty or springs that are diffrent after heat treating. It will harden and compress it. It changes the type of meterial that it is made of.

Re: Springs front end 2 high

Reply #39 – September 11, 2005, 12:42:16 PM

Not the type the grade of the material.

Re: Springs front end 2 high

Reply #40 – September 11, 2005, 03:00:23 PM

Quote from: slamedcat

I could get you the Caterpiller standard for you but I would run the risk of loosing my job over it.

The other thing is I could pull any spring drawing for Cats Data Base and they have all kinds of specs on heat treating and tempering.

You heat treat a spring to increase yield strength and fatigue limits, not to increase/decrease the spring rate. Heat treating a spring doesn't change the spring rate.

Once again, if you have any information to prove otherwise, show it.

Re: Springs front end 2 high

Reply #41 – September 13, 2005, 08:07:57 AM

Look up heat treatment of springs in machinery's handbook.

Quote

No. Modulus of Rigidity (Shear Modulus) is a material property. It cannot be changed by quenching/tempering a material

This is true for a torsion spring which is what some chrysler use but we have compresion springs. Which it states in there to keep its elasticity need to be baked.

So he couold have one that did not get baked hot enought or maybe long enough. Or the other one sat in there too long and turned hard.

Re: Springs front end 2 high

Reply #42 – September 13, 2005, 09:57:08 PM

Quote from: slamedcat

Look up heat treatment of springs in machinery's handbook.

Ok.

Quote

This is true for a torsion spring which is what some chrysler use but we have compresion springs.

No. The shear modulus doesn't change after heat treatment for any spring. Nowhere does it say so in the Machinery's Handbook (or anywhere else for that matter).

Quote

Which it states in there to keep its elasticity need to be baked.

On page 349 of the Machinery's Handbook (27th Edition) it states:

General Heat Treat Information for Springs. - The following is general information on the heat treatment of springs, and is applicable to pre-tempered or hard-drawn spring materials only.
Compression springs are baked after coiling (before setting) to relieve residual stresses and thus permit larger deflections before taking a permanent set.
...
Outside diameters shrink when springs of music wire, pretempered MB, and other carbon or alloy steels are baked. Baking also slightly increases the free length of these changes produce a little stronger load and increase the rate.

I will concede that heat treatment can change the spring dimensions, which will change the spring rate minimally. It is nothing you'd notice in your car though (unless you loaded the spring while heating it). But, back to your original assertion...

Quote

Yes, two springs made from the same material and the same thinckness can have different rates to them. It all depends on how the spring is tempered from the factory.

Not so for compression springs, or even torsion bar springs. You can apply a preload (initial tension) to extension springs, but this doesn't actually change the spring rate.

Re: Springs front end 2 high

Reply #43 – September 14, 2005, 07:14:06 AM

Quote from: Jeremy

Compression springs are baked after coiling (before setting) to relieve residual stresses and thus permit larger deflections before taking a permanent set.

Ok I guess I and everyother Caterpiller engineer are wrong when we put the heat treat and all the other specs on the drawing for Cat.

And it says right there that it permits larger deflection. Doesn't that mean it brings the spring rate up?

Re: Springs front end 2 high

Reply #44 – September 14, 2005, 09:17:59 AM

Quote from: slamedcat

Ok I guess I and everyother Caterpiller engineer are wrong when we put the heat treat and all the other specs on the drawing for Cat.

And it says right there that it permits larger deflection. Doesn't that mean it brings the spring rate up?

No, it means the spring can deflect further before setting, sagging, or otherwise succumbing to plastic deformation. The spring rate can change a bit, due to dimensional changes during heat treat, but that is something that has to be dealt with and designed for...not the primary purpose of heat treat.

I worked in the quench/temper section of a pipe mill, and we had heat treatment information on file for all of the different sizes/alloys. It is needed to ensure you make a quality product.