Progressive rate springs? Thread modified by OP please re-read

[petew]

Stock everything on the front end except the sway bar. Spring application is 1996 Chevy S10 P/U 2wd. Autozone part # FCS5662S current price on their website is $79.99 for a pair.
Car rides great with rpelacement gas shocks, no bottoming issues.

[lalessi1]

Pete, please post pictures and part #

Rich, all my contact with Eaton was by e-mail, fwd it to you last night.

I have no springs at all, car is sitting with 2x4 blocks in their place, I like the way it sits now with a slight rake and 3'' channel, would be ok with a slight hike upwards but definitely not 2.5 inches. The S10 springs might be just the trick even if I had to use a spacer.

Have to give the Ford engineers credit for figuring out all the different springs for 57 would love to see the formula they used and plugged into their slide rulers.

Thank you all again for contributing to this very worthwhile but confusing discussion.

Zap-

Zap, If you put a block in place of the springs that is roughly 9.60" long that will give you a "design ride height" assuming your bushings are good. You should adjust the length of the block to compensate for the fact it won't sit exactly where the spring sits, you want the spring seat surface to spring seat surface to be 9.60". You can play with the block after you "see"  design ride height you can then figure out what spring to use. Simply cut the block to a length that puts the height where you want it and this will give you a new "Height at Normal Load" compared to stock. Then by looking at free lengths and spring rates you can figure out what will give you the desired "Height at Normal Load". This seems complicated but it is really not especially if you have a car with no springs.

Another note, because of the control arm acting as a lever on the spring, a small difference in compressed length is magnified in ride height.

[Zapato]

I am going to assume that when ''height at normal load'' is achieved both a-arms are parallel to the ground. Or is that a wrong assumption ?

Zap-

[dgasman]

I will throw a fly in the ointment , on my 58 ranchero I have Eaton springs in the front with Granada brakes 1 1/2 drop and run a 215 70 15 tire in the front. The distance from the garage floor to top of wheel opening is 25 inches and from the floor to lower fender at rocker panel is 8 inches . I do have the original 352 in the ranchero and the springs have been in the ranchero for quite some time so that would account for some of my lower stance . The rear springs are also from eaton but I had eaton make them to sit 1 1/2 inches lower than stock.

[RICH MUISE]

Not really a fly in the ointment. I think it kinda confirms what I've been saying. Your tires are just slightly taller than mine, your spindle drop is an inch less (mine are 2 1/2), yet my rockers are at about 11". Yours would be at 7 if you had the 2 1/2 drop, so that's a 4 " difference one car to the next.
The differences have got to be in the drivetrains weights and distribution of the weight.
I know I'm making some assumptions here...like that we both have the same springs from Eaton, mine have not "settled in", etc.

[lalessi1]

I am going to assume that when ''height at normal load'' is achieved both a-arms are parallel to the ground. Or is that a wrong assumption ?

Zap-

That is a reasonable assumption, but it is an assumption. I would actually think that the a-arms would have a slight downward angle, (higher in the center). All cars have a factory "design ride height" so that specification is somewhere, that would be fun to know. The ride height, weight, and suspension dimensions determined that 9.60". All one needs to know that is missing for us is the actual weight on the wheels. If you know that you can take any spring and figure out the compressed length. In my case I am putting in an FE engine that is 100 lbs lighter than the stock one I removed. Most of that is on the front wheels.

Here is a picture of a lower control arm.... http://www.ebay.com/itm/ORIGINAL-OEM-1957-FORD-LOWER-CONTROL-ARM-RH-B7A-3078-A-SUSPENSION-/201409033899?hash=item2ee4e9f6ab&vxp=mtr

I am guestimating based on the sketch I posted that A/B ratio is 2.5, that is to say that the pivot to spring center is roughly 40 percent of the pivot to center of the tire distance.

100 lbs lighter total is 50 lbs per front wheel. That means that 50 x 2.5 = 150 lbs reduction of force on each spring.

Assuming I have a 400 lb/inch spring per the chart my spring will extend 150/400 = .375" Not much...but

This .375" spring extension will raise the car by roughly .375 x 2.5 = .9375"

My car height will go up almost an inch because I put aluminum heads, intake, and water pump on a cast iron engine!
This exercise is intended to demonstrate that a small change in weight can have a large change in ride height. That is why Ford had 8 different springs for our cars in 1957.

It is reasonable that Rich reduced the weight on each front wheel by 100 lbs or so. This would have raised the car almost 2".

[hiball3985]

Not really a fly in the ointment. I think it kinda confirms what I've been saying. Your tires are just slightly taller than mine, your spindle drop is an inch less (mine are 2 1/2), yet my rockers are at about 11". Yours would be at 7 if you had the 2 1/2 drop, so that's a 4 " difference one car to the next.
The differences have got to be in the drivetrains weights and distribution of the weight.
I know I'm making some assumptions here...like that we both have the same springs from Eaton, mine have not "settled in", etc.

Just looking at average engine weights since none are exact your 4.6 should be around 150 lbs lighter then a Y block. So climb in and sit on the engine while your wife holds a measuring tape at the front bumper  I'll bet the change isn't that much.

[lalessi1]

She would have to drive it to get it to settle!!!

[hiball3985]

She would have to drive it to get it to settle!!!

And with the advantage of the hood design he won't get bugs in his teeth 

[OUTLAW]

Zap, Y-blocks forever has a post in the tech section on the Aerostar springs. Just more info.......Rick 

[RICH MUISE]

Ya, but I'll bet they all have Y blocks, lol

[lalessi1]

Moog CC850 is a replacement for the Aerostar spring, Rockauto has them for $47.79 for a pair. This is a link to the specs for Moog springs....

http://www.moogproblemsolver.com/moog/wp-content/uploads/2012/08/MOOG_Coil_Springs_Spec.pdf

[lalessi1]

Here are  the Moog CC850/Aerostar spring specs

Moog Part #      CC850 
Inside Dia         4.07
Wire Dia           0.75
Spring Rate       605
Spring Load       1825
Installed Height  8.75
Free Height       11.65
End 1               SQ
End 2               TG

Comparing these springs to the 57 "Green" spring:

Spring Rate        400
Installed Height   9.60
Free Length       14.80

The design load required to compress the "Green" spring from 14.8 to 9.6 is

(14.8 - 9.6) x 400= 2080 lbs.

Applying this load to the "Aerostar" spring will compress it to

11.65 - 2080/605= 8.21"

This compared to the 9.60" is a change of installed spring height of 1.39"

This translates to a ride height drop of almost 3"

A couple of notes, the Aerostar spring is "stiffer" (it has a 50 percent higher spring rate) and it has a lower maximum load rating (1875 compared to 2075).

I will look to see what other Moog springs may be options

[57 imposter]

3  inches is a little scary on my car. I have to go back to step one and loosen everything up and make sure nothing got tightened too soon With the spindles that are in it and the 1/2 coil out, it should not be sitting where it is. I can't get close to it with any kind of greasy work while the painter is working on it so the check out will have to wait. We made a run yesterday from the Tri-cities down thru Tigard Oregon and got some front bumper brackets at Clayton Bauer's then down to Eugene to get a windshield from Bob's Classic auto glass then out to the coast. We will be in Seaside for the fall car show this weekend. hopefully the car will be about ready for paint by the time we get back..

[SkylinerRon]

Why not just call Eaton, tell them what you want and let them make you a pair.
They have been making them for decades.

Ron.