NEWB: how to adjust coil over suspension?

I was in on the k-sport group buy. I just finally got them installed. Since I am mostly inept and lacking tools for automotive stuff I had Smart Service in Shoreline, WA do the install. A nice group of guys to deal with.

I picked up my car after they closed so I didn't have time to grill them with my newb questions.

The did tell me how to adjust the stiffness, insert the long hex driver down the center of the unit and turn. Ok.

Other than that I am totally clueless.

I googled for a faq or how-to guide for adjusting these things and came up empty.

what do you need to know?

The shop probably told you how to adjust the dampening and that's it. If you dont have the tools at home such as a jack and jackstands, I wouldnt bother adjusting anything really.

Your K-sports should come with instructions, but then again, I dont know that for sure.

It's mainly curiosity. They came with a swell little brochure in Japanese. Not much use to me. There is some info on k-sports web site.

I'm just kinda surprised that there isn't some big faq on this stuff.

Ok, I can adjust the dampening. I think I know what that does but before I even try to play with it I'd like to read up and get informed.

There are three threaded rings on the unit.

Two I think are used to set the spring perch and pre-load spring tension. They are at the top of the threaded barrel up against the bottom of the springs. K-Sport suggests the default for these should be hand-tightened. Why? What does making them tighter get you? Once set the two rings are locked together using the provided wrenches.

At the bottom of the threaded barrel is the third ring which I think is to adjust ride height. The k-sport site says once the height is set to lock it down, using either allen wrenches or locking perches. There isn't a locking right and I don't see any place to apply an allen wrench, but I've not look that hard.

I don't have the K-sports, but you've got the idea. The top perch and locking ring are for adjusting the pre-load. You should generally set this perch snug against the spring, but no more. The preload is used to adjust the strut rebound/compression ratio and adding preload will cause an increase in perceptible spring rate. I say perceptible, because the rate doesn't actually change, but the springs will feel like they have a higher rate.

The bottom locking ring locks the lower body in place. Loosen the ring and rotate the entire strut body to raise/lower the car.

The dampening is probably 2-way like most brands, so adjust the dampening will change the rebound and compression rates of the struts.

A) I'm just kinda surprised that there isn't some big faq on this stuff.

 

B) There are three threaded rings on the unit.

 

C) Two I think are used to set the spring perch and pre-load spring tension. They are at the top of the threaded barrel up against the bottom of the springs. What does making them tighter get you?

 

D) At the bottom of the threaded barrel is the third ring which I think is to adjust ride height. The k-sport site says once the height is set to lock it down, using either allen wrenches or locking perches. There isn't a locking right and I don't see any place to apply an allen wrench, but I've not look that hard.

A) There's already a lot of explanations from other sites.. If I did post more on this stuff as a FAQ, the shops/vendors won't be able to make money off of you for doing corner balancing, ride height adjustments, and spring preload calculations

B) Yes, you are correct, the 3 "rings" are set up for the 2-way adjustment of spring preload and height adjustment, which one is the spring perch and the two other are locking spindles.

C) The one that the spring sits on is the spring perch, it also works as your spring preload setup. The higher it goes up to compress the spring, the more spring preload you have. It's to prevent "sag" when the car is loaded (statically) with weight. Different heights combined with your spring rate determines how much preload you dialed in. The stiffer the spring, the less you need to compress the spring for preload. Progressive springs are harder to compensate for that off the top of your head because of the variable spring rates that they have (usually they dont need preloading since it's, well, progressive, the most they need are helper springs to keep the spring in contact with the spring perch evenly). The bottom of the two spindles is the "locking" nut. To lock them, use spanner wrenches to push them together (spring perch spins down as the bottom locking nut spins up, so they push against each other to lock). I usually use the spanner wrenches to keep them tight, I do not use any hand tightening.

D) The bottom locking nut pushes against the hub flange assembly to keep the ride height set. Again, you use a spanner wrench to tighten the locking nut down and against the hub flange assembly. If the locking nut doesnt use an allen wrench (such as the Ground Control hose-clamp type of a locking nut), then you use a spanner wrench to tighten it down.

I don't have the K-sports, but you've got the idea. The top perch and locking ring are for adjusting the pre-load. You should generally set this perch snug against the spring, but no more. The preload is used to adjust the strut rebound/compression ratio and adding preload will cause an increase in perceptible spring rate. I say perceptible, because the rate doesn't actually change, but the springs will feel like they have a higher rate.

The preloading of the spring is to also prevent sag. I dialed in with more preload in the front than rear. Basically my car is already fighting against "roll and dipping" even before it turns. And yes, you can adjust for more preload, just not less.. you dont want the spring to be out of contact when the shock is at full length (such as getting airborn) and causing the spring to get improper alignment as the shock gets compressed (hence helper springs were invented with coilovers for some models, so you dont have to deal with zeroing in the coilovers for preload).

The springs dont act if they have a higher rate, they are just being compressed prior to the actual engagement of the shock. This is one way to have one bouncy car if your preload is set too high... think of it as the car is getting ready for a jump or push against the turn before it even reaches to that stage of the turn or bump.

Installed ISC N1 coilovers. After a trial and error process, I have now backed off of the preload on the front struts and have damping set halfway between hard and soft.

I worked on the rear set today and backed off the preload as much as possible and raised the shock to compensate. Before this change, there was a ton of preload and 3/4 damping in the hard direction. The car road pretty decent with a significant amount of crash and harshness over bumpy road sections.

After this, I decided to back off the preload and the damping to alleviate the crashing and harshness and the car now has a VERY pronounced bouncing effect.

I thought for sure that reducing the preload would increase the ride comfort but did not anticipate such a severe amount of bouncing. I plan on adding back half of the preload to eliminate this bouncing but I was hoping to find some information on what to do with the coilovers when specific observations are made on the behavior of the car.

Anyone know where I can find such specific information?