If you have linear-spring coilovers that have separate adjustments for damping, spring pre-load, and ride height, what do you use the spring pre-load adjustment for?

The damping adjustment makes sense, and the height adjustment is obviously useful for adjusting ride height and corner-balancing the car, but I don't quite understand the point of pre-load adjustment with linear springs. Since they're linear, pre-loading them shouldn't change the spring rate (much), and you don't need to pre-load them to adjust ride height, since there's already a separate adjustment for ride height.

I *know* I'm missing something, but it seems like pre-loading a linear spring wouldn't do anything but reduce your suspension travel.

 

Yes, and No. (you knew that was comming... ) spring pre-load controls the amount of suspension "sag" and this has the effect of increasing or decreasing suspesion travel.

Let's assume a two way adustable coilover, independent height and spring pre-load.
At static ride height, as you pre-load a spring, you're also increasing ride height up until the point where the damper shaft is fully extended (assuming there is sufficient spring pre-load to do so). Assuming you had equal bump/rebound damping, now you're increasing bump damping but reducing rebound. Any more pre-load from that point on, will stiffen the suspension since you are now compressing the spring. The pre-load can be used to increase or decrease stiffness given certain parameters. Keep in mind that if you have to pre-load the spring significantly to maintain good damper travel, that might be an indication that you need a stiffer spring.

Now to the Mini, say you want the slammed look but are concerned about loosing damper travel. You can use the pre-load to fine tune the damper for optimum bump/rebound damping and then adjust ride height via the independent height adjustment to achieve the slammed look.

This is something you cannot do with a one way adjustable coilover, ie. non independent ride height/pre-load adjustments.

 

Thanks a lot - that makes sense. So, with coilovers that have separate height and pre-load adjustments, you use the pre-load to adjust the position of the shaft relative to the body when the car is at rest?

I can see how that would allow you to vary the amount of compression travel and the amount of rebound travel, while allowing you to adjust the ride height independently afterward.

So, on coilovers without a separate height adjustment, lowering the car by adjusting the pre-load reduces the amount of compression travel available, since the shaft will be further inside the shock body while the car is at rest, right?

I'm sure this will be clearer for me once I have the coilovers in-hand. I'm pulling the trigger on a set of JIC / CROSS two-way coilovers this week, and I'm trying to get smart on them before I talk to my alignment shop.

 

Yes, exactly.
In my situation as an example. I also own an cabrio (cb/b/b) and was very concerned about loosing damper travel since the cabrio weighs more than the regular MCS. I had experience more "sag" with the H-sport spring I was runnning and didn't like how low it actually dropped the car. Due to the additional weight of the car, I also lost damper travel withe the H-sport.
I wanted a way to control "sag", thus controlling damper travel, at a reasonable price. And at the same time, allow for independent lowering. This came in the way of Megan Coilover and after much testing and changing springs a couple of time I'm very happy with the ride.

"Keep in mind that if you have to pre-load the spring significantly to maintain good damper travel, that might be an indication that you need a stiffer spring." This is very important and make sure you check it once you mount your CROSS...

Do share pics of the install once you get them. And give us a good write up on your impression on ride characteristics (I'm specially interested since you own a cabrio). Thanks