Help Me Decide on Stiffer Suspension, Plz?

I love my Swift springs, but they're only 252 lbs/in (front and rear). The stiffer rear rate helps address understeering tendencies, in conjunction with my JBR RSB.

I have Koni Yellows in the front, and Bilstein B8s in the rear. My understanding is both sets of dampers can easily handle up to 400 lbs/in. So, which route should I go? My main goals are good DD comfort (which I understand will be compromised some), and also a similar articulation rate front and rear. For instance, if I go over a bump on the highway, my rear settles faster than the front because although it only carries 38% of the weight, it has the same spring rate as the front. Ideally, I'd want both the front and rear to settle at the same time for the car to feel more balanced. @phate, @Nliiitend1, and @ConeKiller, and @VTMongoose, does this mean that I should have the same 62/38 ratio in my spring rate to accomplish my goal? Any tips or things I'm overlooking? I've researched all of this, but it's a black art to me and since you guys are pros in this area, I has hoping for a little guidance. Here are the two options I'm considering (as opposed to buying $1,500-$2,500 coilovers):

1) Contact Swift to custom wind springs for me at spring rates I determine. Benefit: could be a little less cost. Also, Swift springs are absolutely top-notch in multiple regards. Sacrifice: I'll still have no ride-height adjustability, particularly for corner-weighting.
2) Contact Ground Control to get their adjustable spring/perch kit and specify my desired spring rates. I honestly believe Swift >>> Eibach, but Eibach is no slouch either. I'd hope I could get linear rate springs, but I'm not sure. This would run ~$450 and I'd retain the use of my Koni Yellows in the front and Bilstein B8s in the rear. Benefit: ride height adjustability (not a big deal - I like about 1" drop anyways), but most importantly, the ability to corner weight the car.

Any insight/experience from whomever would be greatly appreciated.

 

Not sure why, but that mention didn't go to my alerts.
maybe that's the case for @phate @Nliiitend1 @VTMongoose

IMO-
1) No one else is qualified to tell you about what will be comfortable for DD. You have your own tolerances and daily commute- no one else has the same. It's a try it and see affair.

2)GC kit (compatible with your yellows) is designed for 2.5" SAE springs, free length 6-8", of which eibach is a distributor. Swift makes 60mm coilover springs (link) which is a size commonly adapted to 2.5" seats (link).If you don't like the adapter, then you can choose other dampers that use 60mm springs off the shelf (H&R, BC, etc.) and combine them with whatever rate coilover spring you choose.

3)You might try going to 400&400 in/lb. springs next to increase the overall response of the car as a proven starting point, which is more heavily sprung than you're at right now. I'm not going down the rabbit hole of trying to estimate what would happen if you deviate from the recommended natural frequencies (i.e. disproportionately jack up spring rate on one axle). A heuristic I hear cited sometimes is a 10% higher rear natural frequency than the front for street cars- but take that with a heavy grain of salt.


http://www.optimumg.com/docs/Springs&Dampers_Tech_Tip_1.pdf
http://www.racingaspirations.com/apps/wheel-frequency-calculator

Fingers crossed that I confused @phate again.

 

I got your tag @ConeKiller but didn't get Redline's.

Honestly @Redline what I would do first before you make any solid plans is just read read read and learn more as much about suspension as you can. Your post indicates to me a lack of knowledge about some suspension basics (please don't take offense to this because 6 months ago @ConeKiller was typing long e-mails to me trying to explain this shit and probably banging his head against the wall while reading my idiotic responses).

Read @phate's by the numbers thread. Also go on "autocross to win" and read all that shit on there. You will really do yourself a solid by doing this, as the knowledge you acquire now will directly turn into better purchases (for your purposes) and a better performing suspension, and save you some trial and error. If I had to go back in time, I would probably have tweaked my spring rates a little bit, although I am pretty happy with how my car sits.

I will say that the dampers have far more of an influence on suspension comfort than the springs - common misconception I have experienced first hand with my car.

Personally I have not tried (and haven't had time) to address the understeer "issue" with my car yet. It still understeers just a tiny bit at the limit, but overall the balance on the car is profoundly improved with the new suspension to the point where I don't see the understeer as the limiting factor to my speed right now. It understeered like a WHORE on the stock suspension.

Concentrate on the following IMO:
1) What ride frequencies you want
2) What kind of dampers you want and how you want them to perform - may wish to have your koni yellows revalved or replaced with reds or other dampers
3) What kind of adjustability you want your suspension to have, ie, do you want to add camber plates/arms, and do you want to have adjustable damping or not.
4) How important NVH is to you - you may not want to add suspension components with spherical bearings, and you may not want to put dampers on your car that have a lot of compression damping. Ride in other cars to get a feel for things.

edit: Also, I forgot to mention, I would definitely go for the Ground Control kit. I have zero issues with it. It's a well put together kit that does exactly what I need it to do and their customer support has been second to none. You can get whatever spring lengths and rates you want. I would suggest getting 7" springs for Koni's in the front, likewise 7" springs in the rear unless you're planning on slamming the car.

 

I hear ya about DD comfort being highly subjective. I think I have a good tolerance for it overall, but I'm definitely not "hardcore." Honestly, maybe it's just that I got used to the Swifts, but they don't feel much stiffer than stock. And since they're 252 lbs/in, I was thinking the 350-400 range is what I need, and what would work well with my dampers.

My main concern is trying to get the correct spring rate ratio, front:rear, so that the car recovers from bumps/undulations/etc. in the front and rear at the same time. I realize dampers impact this too. From the admittedly little I know in this area, it seems like keeping the same ratio as our weight distribution (62/38) would help toward that end. But that doesn't factor in lots of the variables in the equations relative to suspension theory. I definitely need to read more. Having said that, having the same spring rate F/R with the Swifts in conjunction with a JBR 125 RSB on the middle setting has the car feeling great. Based on the little I know, and some things I saw @phate say, I'd think I'd want a frequency of ~2.0.
[doublepost=1467909884][/doublepost]

There's much more to learn, for sure. I'm a fast learner, but suspension equations have so many variables. It's hard to mentally grapple the overall picture as a neophyte.

Like I said above, I think 2.0 is a good frequency to shoot for. My main goals are: 1) 1-1.25" drop as a starting point, then corner weighing/adjusting the car with me inside. Would the 7" spring length you mentioned allow this? 2) As close to neutral handling as possible, with erring on the side of slight understeer (becuz DD) 3) selecting spring rates that will not be too harsh (so maybe 350-400) in a F:R proportion that facilitates the front and rear of the car settling from suspension articulation as close to simultaneous as possible.

That seems to me like it'd make a good performance/DD setup. But then again, I'm sure I'm overlooking many influential variables, so I'll definitely be reading more...

Thanks so much, guys, for the links and input! Do you guys know if any of our cool vendors (who do discounted sales) offer the GC kit? I know RPM does, but they're literally in the same city as me, so I have sales tax that essentially counters most of any discount. I suppose I may have to talk to GC directly.

 

I had the Ground Control kit before my V3's. I bought them in a group buy from the RPM store when they were first released. Donovan, the owner, put the kits together based on the driving style and conditions we specified in our orders. My initial order shipped with 525 in/lbs 6" linear springs in the front and 600 in/lbs 6" linear spring in the rear. Before I installed I ended up swapping the 600's for 400's and moving the 525's to the rear due a lot of people complaining about the harsh ride quality.

I really loved the way the GC's handled, it was definitely better and flatter than my V3's on smooth surfaces but whenever there was unevenness or bumps, the suspension would unsettle and bounce. It was also insanely jarring and uncomfortable when there were sudden drops or bumps in the road. I think a lot of this had to do with the OTS valving, you could really tell springs were way too much for the stock dampers to handle. The only way to make the suspension manageable was to turn the dampers to full soft which defeats the purpose of being adjustable in the first place. I think if you're going to run over a 400 in/lb spring on a Koni yellow you should revalve your dampers.

Additionally, the ground control kit came with some pretty short springs so the suspension travel was horrid. Anytime I would go diagonally into driveways or over uneven surfaces a wheel would come off the ground then would smack down once the surface was even again. That was pretty annoying on a DD. I think their 7 inch GC springs would be better for a daily.

Anyway, the GC kit only last a few months in my car before I spent the $2400 and bought some V3's. I absolutely love them, it's amazing how they can be so comfortable yet so firm and controlled at the same time.

 

Thanks for the reply, man. What I'm trying to wrap my head around is that all of these calculated spring rates that I'm seeing on threads are consistent with your initial setup of 400 front/525 rear. I crunched some numbers and came up with maybe running 410/470 for a frequency around the 1.8/2.0 range. Yet on KW v3s, we see them come with 400/290. This really confuses me. And people rave about how great they both handle, and how comfortable they are. They also say they're awesome on the track. This confuses me even more, LOL.

On the one hand, I'm being told my rears need to be stiffer than my fronts in pursuit of a certain frequency, even with a 62/38 weight bias. On the other hand, KW v3s and MS Coilovers (top-notch stuff) run 400/290. See why I'm confused?

 

Earlier today I read posts from you extolling the greatness of equal rates front and back. And you've said a million times hope wonderful and pleased you are with your suspension. That is all

 

'Tis true. I really do like my suspension. And I am very pleased and love how it handles. But I honestly would like it stiffer. I'm just leery of messing up a good thing in pursuit of something better. I do one day plan on retiring the Speed from DD, getting built, and tracking/auto-xing. I took the advice of all the peeps above and am suffering from information overload, LOL. I really am NOT an indecisive person, but I've just come to realize how much there is to it. This is why I'm now second guessing whether greater front, same rate front and rear, or greater rear, bearing in mind I have a JBR 125 RSB as part of the equation too.

Like I said above, the biggest thing that confuses me now is that if I use a similar approach to calculating what springs to use as @VTMongoose and @phate did, then that would have me with a good deal higher rear spring rate over front spring rate (like 410/470). Yet at the same time, two exceptional coilovers for our platform, the Mazdaspeed ones and KW v3s, use 400/290 F/R. Can you see how confusing this is? That's a HUGE difference in rear spring rate. The only thing I can think of to explain this discrepancy is that damping characteristics of the MSM ones and v3s address this and still make them awesome for both DD and tracking.

Any further insight would be greatly appreciated.

 

Regarding lowering these cars...first off, you're already sitting at a 1" drop with the swifts. My setup (which is dialed in at exactly the stock ride height) is very much centered around not using swift springs or most of the other OE replacement springs available for our cars, all of which lower the car. Even at the stock ride height (which is 1" lower than the mazda3 ride height), you will be smacking the bump stops on a near regular basis. The MS3 doesn't have a lot of compression travel to work with to begin with. My mentality is to let the suspension have some breathing room to actually work.

I don't know why the V3's use softer springs in the rear honestly. It's probably down to a tuning decision, and the fact that suspension doesn't always have to follow the rules you think it has to. I've never been in a car with those, so I don't know how they handle. I see the V3's as a ridiculous expense I could never realize the full benefits of. For what those cost, you could go crazy with modified, customized off the shelf components. I think conventional coilover conversions like the GC's and H&R's are perfectly suitable for most people.

Side note on the Eibach springs - download their catalog and make sure they have the rates you want. You can get them in 25 to 50 lb/in increments. When I went to the 6" springs from the 8" springs, I had to drop the fronts to 400 lb/in from 425 because 425 wasn't available in a 6" spring.

Side note on ride frequencies - I'm sitting at about 1.8 Hz. in the front and 2.1 Hz. in the rear. I would definitely not go any lower than this. Don't get me wrong, the car definitely feels at home on an autocross course, but higher ride frequencies would make the car feel a little sharper on quick transitions (without the need to valve the dampers with a ton of rebound).

 

I was thinking about going maybe 330/370 (so I guess 325/375 becuz 25-lb increments) so as not to overwhelm my Koni Yellows and Bilstein B8s. This would put the frequencies a little closer to the performance DD range instead of the dedicated auto-x range. Are you saying that's not a good idea? What do y'all think, @phate, @ConeKiller, and @Nliiitend1? Would this fare pretty well with 7" springs, running a ~1"-1.25" drop (before corner weighting) on OTS Koni Yellows and Bilstein B8s in your opinions?

 

You won't be able to drop it 1-1.25" with 7" springs. Go with 6" in that case.

 

Huh? I was told elsewhere 7" would be right for me. Maybe they didn't realize the full scope of my goals. Are you bearing in mind I'm on Koni Yellows in the front instead of Bilsteins, and Bilstein B8s in the rear?

Ideally, I'd have a height adjustability range that goes from stock level to -1.5" below stock level. I wanna start at ~1" lower than stock. The extra range is for corner weighting.

 

That was me. I was bearing in mind your Koni's and assuming you wanted stock ride height like me.

 

'Preciate it, man. This forum is awesome and so many helpful folks have weighed in that I sometimes forget who said what, LOL!

Anyways, I get your strategy of maximizing suspension travel for auto-x. I think 325/375 will be a good compromise for me, esp. for primarily DD'ing: a good deal stiffer but not so much so that it'll be really uncomfortable, it'll have the R frequency have a good ratio higher than the front for flatter handling, it's not so stiff that it'll overwhelm my stock dampers, etc. RPM's site was saying the kit will offer a 0"-1.5" drop rage, which sounds about perfect for me. And I can always get some nice, stiffer Swift replacement springs if I decide to ever retire it to track/auto-x duty.

I'm wondering if I'll go to the light setting on the JBR 125 RSB; it's middle now. We'll see. One of the benefits of having a robust rear bar is you can have softer springs yet still have a lot of rolling axis resistance in the corners.

 

So after reading through this entire thread http://www.mazdaspeedforums.org/for...port-coilovers-mazdaspeed-167667/index23.html , I'm thinking on going with ~375/425 F/R. My only concern is that OTS Bilstein B8s will work well with a 425 lbs/in spring rate, esp. since they're non-adjustable and I don't want to have to revalve them at this juncture. From what I can gather, OTS Koni Yellows should easily be able to handle 375 lbs/in. I have an email out to Edge to see what they think about the B8's ability to handle this spring rate. If necessary, I'll contact Bilstein directly.

Since I want the ability to adjust from stock height down to -1.5", it looks like 6" springs are the correct option. But in that thread I linked above, I saw more than one post about springs becoming unseated/popping out, and that really makes me pucker. If it's just a function of install fail, then I'm okay. I'll be going to a racing suspension shop that has a top-notch local reputation anyways. But if it is a design liability, it leaves me concerned. Perhaps not going to far beyond 1" drop will help. Or maybe I could just order 4 of these to take up any slack at full extension http://www.ground-control-store.com/products/description.php/II=493/CA=213 . But 4 of them is ~$200. That's a very significant add-on price and basically really negatively impacts the price advantage of going the GC route.

 

Soooooo, $130/each to revalve a Bilstein B8 + shipping and incidental costs if parts are broken/need replaced. New rear Koni Yellows are $135 each and known to be able to handle my suggested spring rates (375/425)... may go with Konis.

 

The ground controls should come with a spring cup. I had wheels off the ground all the time and my spring never became unseated. The only time they would unseat was when both wheels were off the ground.

 

Think going up to 6.5" springs would solve the problem? I should still be able to have up to a 1.1" drop, which will help have wiggle room for corner weighting.

 

They don't make 6.5" springs.

How do you know the Koni's have more rebound than the Bils...did you obtain shock dynos or damping specs from both companies?

 

I haven't seen hard data. But I did talk to shock engineers at Bilstein and they said I'd definitely need re-valving. Regarding the Konis, I initially was going by the fact that GC/RPM is offering the Konis on spring rates up to 700 and saying that they're appropriate for the application. I've since been in contact with GC and they indeed assured me OTS Koni Yellows are up to the task for 375/425.

Also, I read that whole MSF thread and did research on lots of testimonials of people who are using the actual kit and it appears that comfort goes out the window when you're getting in the 600-700 range, leading me to believe that though they may "work," they won't work well without re-valving, not really being up to the task of controlling that much spring rate.

It is for this reason that I think using 375/425 would be alright, being even lower than the lowest range GC/RPM normally offers. I've heard many times on our forums that Koni Yellows should be able to easily handle ~400 range. Worst-case scenario, I could always re-valve either the Konis or the Bilsteins to be appropriate. My inclination is to try OTS Koni Yellows first since all of my research points to them being up to the task. Nevertheless, I may put out a call to Koni too, just to see what they say, just like I did with Bilstein.

So on your 7" springs, your range of adjustability is +1" to -0.6", right? I don't think I'd ever get airborne driving and thus have both rear wheels of the ground causing a spring to unseat, but sometimes when working on the car the rear is jacked up. I really don't want to have to deal with the headache of unseating springs. Helper springs are an option, but would easily add ~$150-$200 with the necessary perches, etc.
[doublepost=1468529272][/doublepost]From Ground Control:
"The OTS Konis will handle up to 600lb/in direct spring rates. The baseline settings on the Konis would be 1 full turn off of full firm on the front struts and 1 1/4 turn off full firm in the rear. [These settings are in light of me telling them I'd be running 375/425] The rear rates are different force loading on the rear shocks, since they are divorced from the shocks."