Thread: B13 spring options. RM vs GC vs....

I'm very unhappy with the ride from my locally branded coilovers in my b13.

So much so that I'm tempted to go back to stock springs and KYB shocks. But off course it will look like a 4x4.

So, read a few threads and the concencus seems to be that most lowering springs are junk. With the possible exception of Road Magnets. My only concern is that they are a mere 1.3" drop, and will still look too high.

Aside from Ground Control, is there anything other springs I can consider? I'd like to retain the stock shocks if possible.

The reason they are only a bit over 1" drop is because you start to run out of suspension travel if you go much lower, which requires a heavier spring to reduce the travel, which requires a firmer valved damper to control the spring. Its a tough situation. Your only real way to go any lower with retained stroke is to go with shortened Koni inserts with the GC sleeves, and even then, you can still go too low and cause the same problems of insufficient stroke for the suspension to work.

What "few threads" have you read?

You're missing a few, that is a fact.


You do not have a basic understanding of your suspension travel and geometry.

Aesthetics over Performance?

You cannot lower your vehicle more than 1.5" with ANY spring, strut, or coilover system without ruining your suspension geometry. Unless you re-engineer other "hard parts" and mounting points of your suspension. In which case you would know enough about your suspension to not even have started this thread in the first place.


Not happening if you want a comfortable performance suspension. Unless you stick with your stock springs and the 4X4 look.


If you want to understand your suspension before you spend your money read this:

http://www.sr20-forum.com/suspension/1801-b13-b14-b15-suspension-information.html

Not quite sure how you missed that thread in your "reading."

If you want a comfortable performance street suspension, that would not feel the least bit out of place on a road-course or auto-cross, with direct replacement springs that will NOT beat you up, acquire (build or buy) a set of CSK's (struts) and pair them with Hyperco's.

http://www.sr20-forum.com/group-buys/47631-ny-hyperco-spring-group-buy.html

Buy the Hyperco's while you can. Which is right now.

If you want CSK-based coilovers so you can adjust your suspension, then see this thread and contact veilside180sx.

http://www.sr20-forum.com/suspension/46952-csk-builders.html

He can put you into a CSK/GC based set-up that will not beat you up, will be comfortable on the street, and fully track functional.

You sir, have a lot more reading and understanding to do.

You're welcome.

Haha. Ok guess I deserved that Shawn. Yes indeed the suspension threads on here are about a week end's worth of reading. Something I can't afford to do right now, but will be going through the threads bit by bit.

Quick question though. The CSK option looks like the best option to me, BUT, is it not possible to regain travel that you loose by lowering a car, by simply shortening an oem shock from the top? I.e. shortening and rethreading the top of the shaft. It's something that I've often wondered about.

shortening the shaft, you would end up blowing the struts quickly or worse, when the spring extended (for example, going through an intersection) and the damper "topped out" so to speak

Yes, you deserved that. Although I was trying not to be too impatient or terse.

The Suspension Thread (Sticky) prints out at 82-pages. I do not expect everyone, even myself, to know everything in there. However, when you "miss" one (1) of the only two (2) direct replacement springs that are Forum Exclusive Springs, I know you have not read enough.

Hyperco's are progressive-rate direct replacement springs that are in fact thee most comfortable direct replacement performance springs for your application (street/roadcourse).

Road Magnets are linear-rate direct replacement springs that will be more precise on a track, and less comfortable, but still tolerable on the street.

Both types of springs drop the car approximately 1-inch (+/- a quarter inch). Remember, you only have three (3) inches of stock travel. Which is why you cannot drop the car more than 1.5" no matter what you do, unless you start re-engineering the hard parts of the suspension. Like pick-up points and lower control arms, etc....etc.... If you knew enough to know how to do that, you and I would not be having this conversation.

I chose the Hyperco's for the comfort factor, giving up some absolute precision when on the track.

Those are your two (2) choices in Forum Exclusive direct replacement springs.

Either spring will work well with AGX's. However, either spring will work much better with CSK's and be more comfortable in a street application.

I'm on AGX/Hyperco right now, and having a set of CSK's built for me because I want more street comfort. I want to be able to drive comfortably to a track, drive around the track with an excellent performance suspension, and then drive my car home. Without getting beat to death on the way to or from the track.

You can also get to your goals with a GC/CSK suspension. Which is a custom built set of coilovers utilizing CSK's as the damper. veilside180sx can build them for you, at a very reasonable price considering the performance. And a GC/CSK suspension would be adjustable. You can fiddle with your ride height (within the parameters of your 3" of stock travel) for the track if you wish. You could also buy two (2) or more sets of springs and change out springs for the track.

Coilover springs and direct replacement springs are not the same thing. You can get coilover springs in both different lengths and rates all day long.

I do not care to "fiddle" with anything on my suspension. Hence, Hyperco/CSK for me. Bolt them on, adjust them properly, and I'm not going to touch my suspension again. Comfortable on the street, track-capable, and dead nuts simple.


I'm no suspension guru or expert, so I'm gonna go with Will's answer below.

Engineering something other than what is tried-and-true is not within my skillset or limited suspension knowledge. I know what I read, and I have read everything that the Suspension Gurus on our forum have ever typed. None of them have ever "shortened an oem shock (ahem...strut or damper) from the top" by "rethreading the top of the shaft."


I'll go with Will on that answer. Damn smart little engineering geek.

Thanks guys. Appreciate the input and patience. I'm on a set of local coilovers right now and not loving the ride. Spoke to a local suspension guru who also builds custom Koni suspensions for our (all) cars, and he also indicated that even with CSK, if the car is too low it will ride like crap. His company designed the coilovers I'm on now. They're pretty basic to be honest, but he says that adjusted to a reasonable height they will be just fine. I don't think I'm super low or anything, but I guess I can raise it up half an inch or so. May have to look at the condition of the actual dampners in case they got damaged over time riding too low - so lets see. I don't use the car daily, so I just need the suspension to be at least fairly tollerable (more for any passengers' sake than my own).

He also mentioned that most people forget that coilovers where originally designed MORE for the sake of being able to run thinner springs, in order to adjust camber more for the track, and that the ride height is almost secondary. But most people buy them for the height adjustment factor, and generally ride them too low.



Just getting back to my question about shortening OEM shafts, based on this illustration by benfenner, to me it seems that shortening the shaft will have the exact same end result as the shorter koni, mounted lower in the oem housing. If the shock was able to "
top out" then wouldn't it be the case with the koni as well?

Not at all. Shortening the shaft would reduce available suspension travel, not increase it. There would be less distance between the bump-stop and the top of the strut, not more. You would cause the shaft to ride higher than it was intended to inside the housing. We do not lower the insert in the housing to pull the shaft further out, but rather to maintain the same distance between strut and bump stop with a shorter spring. How would shortening the shaft increase the distance between the bump stop and strut?

Notice in Ben's diagram how the spring length stays the same while the distance between the top of the insert and the bump stop increases?

^^ That makes sense. Thanks for the explanation.

My reasoning was that shortening the shaft will not cause it to ride higher in the housing, since the car will be lowered by the same amount, bringing the shaft back to it's original position in the housing. So will that not maintain the original travel in the housing then?

I do however see what you're saying about reducing the travel between the bump stop and the top of the housing, and that the CSK conversion gives back the travel up and down.

But, let's say you're only lowering the car 1.5", and you remove about 1" from the bump stop (or 1.5" if possible), then aren't you keeping things in relative proportion to each other? I'm not sure how much travel there is between the tower and the bump stop, so not saying this will work, i'm just trying to reason it out.

You do not want to randomly cut up your bumpstops. They are what keep you from damaging your strut when you bottom out.

I cover the Koni bumpstops, and trimming them if necessary, in The Suspension Thread.

The Koni bumpstops (which is what you should be using if you read The Suspension Thread) are progressive rate bumpstops and effectively become part of the spring rate itself when you reach the end of your limited travel. They provide the last bit of cushion before you reach zero travel and a "BAM" that not only rattles your teeth, but can damage your strut.