Catchall Thread for Spring Specs

[chadjans]

I figured since alot of people seem to be going to coilovers and need to estimate weights of their rigs, it would make since to have a catchall thread for spring specs.

I called Rubicon Express this morning and asked for a spring rate spec for the springs I am using in the front of my rig, so I will start:

Rubicon Express
Part Number: RE1345
Spring Rate: 185 pounds
Free Length: Unknown
Disposition: Approximately 4 years old, and currently mounted in the front of my ZJ.

Pro Comp
Part Number: Unknown (Front 3 Inch Lift Spring for their ZJ 3 Inch Kit)
Spring Rate: 225 pounds
Free Length: 17 3/4" (Used)
Disposition: Used spring, being used in the rear of my ZJ.

Clayton Off Road Manufacturing
Part Number: Unknown (7" Long Arm Rear ZJ??? Spring)
Spring Rate: 220 Pounds
Free Length: Unknown
Disposition: Unkown




And my friends at Blue Coil have some good notes on spring rates: (http://www.pagedezigner.com/bluecoil/2009/rate.htm)

"Some thoughts on coil spring.... There has been a theory that spring rates change (pounds per inch of compression). A spring rate is derived from two things. First, the size of the material used, and second, the total number of inches of material used. If none of these things change, your spring rate will remain the same.


Think of a coil spring as a big "slinky" toy. The greater number of coils used, the slinkier it becomes. The same goes for removing coils, the less slinkily it is. The same principal applies to coil springs used in suspension systems.

Since you cannot physically add more coils to a spring, the rate will not get weaker. In effect, the only way to change the rate would be to cut coils or collapse the coils (by heating them) and making them touch each other. These things happening would increase the rate, as you are removing the amount of material in the spring, then comes into play stress of a spring. Our springs are designed to take the stress of racing. Having the right size and amount of material for the application insures it.

A coil spring may take a "set" or loose free length, shortly after installation. Usually this is caused by a poor design or over stressing the spring (using it in the wrong application will over stress a spring). When a spring takes a "set" the rate of the coil has not changed, only the amount of load it will handle does. For example, if you have a 10" free length spring, at 100 pounds per inch rate, it will handle 500 pounds of load. If you reduce the same spring's length by one inch of free length, it will only handle 400 pounds of load before it reaches coil bind (the point at which the coils touch each other)."

So does anyone have any known spring specs they wish to share?

Chad

[ATL ZJ]

The longer a coil spring is, the larger the wire diameter needs to be to maintain the same given rate. That means that longer springs weigh more per inch than shorter springs of the same spring rate. It's also why spring rate increases when you cut a coil spring down.

Spring weight differences become particularly noticeable when dealing with tall lower springs, such as those commonly used on 14" and 16" FOA shocks due to their short dual rate slider design. Although the additional weight may be minimal, it's an interesting realization especially as we are all trying to find ways to shave weight off our rigs.

[chadjans]

I posted the quote from Blue Coil because many try to explain spring sag as a loss of rate.

[downtowncb]

The rear spring rate from Clayton's 7" long arm lift is 220 lbs/in.

[ATL ZJ]

I posted the quote from Blue Coil because many try to explain spring sag as a loss of rate.

what I posted was completely independent of your post.

But since you bring it up, how can sag/set not be a loss of rate? Rate is how much weight a spring will support when it compresses one inch. If taking a set means it will compress more under less weight, how can the rate not decrease?

[faststang1]

Hey chajan,
BDS 6.5 ZJ springs are 240lbs/in front springs
Skyjacker XJ 6.5 are 220lbs/in front springs
just thought I throw them out cause everybody seems to be looking for stiff springs.

[xJoshx]

TeraFlex spring rates by chance?

[SirFuego]

I found out my rear 4.5" RE coils are 18.1" unloaded with a rate of 190 lbs/in.

From this thread:
http://www.mallcrawlin.com/forum/showthread.php?t=9562