What Difference Does Free Length Make In Coil Springs?

[SSTJ]

Replaced my OEM rear springs with Moogs. OEMs were sagging about 1/2 inch after 25 years. However, OEMs are about 1" longer than Moogs when uninstalled (free length).

Does free length matter much once installed?

My first thought was that, in theory, less free length means that the spring could pop off the lower perch at full articulation. I noticed that unlike the front springs, the rear springs don't have a clip to hold the spring in place on the lower perch. I can cycle my suspension to find out of course.

 

[freedom_in_4low]

That's all it is...more free length to keep the spring seated when the shock is fully extended. if it produces the same ride height as the shorter spring, then it implies a softer rate but that doesn't really matter. You want a spring long enough to stay seated, short enough not to stack solid before full stuff, and the rate to produce your desired height within the boundaries of those lengths. It's really that simple.

 

[LONGJP2]

Longer free length should mean more pressure or traction to the ground at max droop.
Assuming you take advantage of the extra length.

 

[pagrey]

I can cycle my suspension to find out of course.

Were the springs loose when you jacked up the axle to put the lower shock bolts in? One of the great parts about actually taking the time to cycle your own suspension is you learn the basics of how it works so when you swap parts out you know what to look for. Focusing too much on theory tends to do this. You were right there with the springs and actually did the test to see if they would fall out, you have to as part of the installation, but since you've never cycled the suspension you had no idea what to look for.

 

[SSTJ]

Were the springs loose when you jacked up the axle to put the lower shock bolts in? One of the great parts about actually taking the time to cycle your own suspension is you learn the basics of how it works so when you swap parts out you know what to look for. Focusing too much on theory tends to do this. You were right there with the springs and actually did the test to see if they would fall out, you have to as part of the installation, but since you've never cycled the suspension you had no idea what to look for.

Touché.

And yep, I checked it on the first spring as I re-attached the shock. But when I do the second spring later this week, I'd like to flex it a bit further to be sure.

 

[JMT]

A longer spring will allow for a longer travel shock without unseating.