Front/rear sway bar questions

Ralphatron

I was just about to post a new thread about this until that second to last sentence caught my eye...

I'm clearly a noob and wanted a very aggressive handling car so I threw a bunch of money at coilovers and both front AND back hotchkis sway bars for my 6 month old '20 sport . Now I wish I was kidding you when I say this, but I've already been through 3 separate coilover kits because I've been on a mission to find the right balance of street drivability and performance. First was the digressive series kit from BC, then the true rear BR series, and finally the divorced spring BR series.

Right now I have the divorced spring style kit, and BOTH hotchkis bars on my car. I'm about to give up and go back to just stock struts and lowering springs because the instability in the car when going over medium bumps is driving me insane, but I'm starting to truly suspect its the sway bars, or at least the rear sway bar (which I have the links going through the middle hole of the 3).

Aside from oversteer/understeer issues with a rear sway, I'm hoping someone can tell me that Im an idiot for not expecting this. I know the sways can act as additional spring stiffness when only one side hits an imperfection, but can it really make the car feel that much stiffer/unstable over bumps? I've got the dampers all set to the softest setting too, and default spring rates as well.

Sorry for the story book post, I'm just trying to figure this out.

Jhill

Really easy way to find out, disconnect one side of the bar and drive it. I’ve ran some stiff bars on another car and then moved to softer and could say the ride was better over uneven terrain but I don’t know if I’d go as far as saying unstable. Then again the hotchkis is a pretty massive bar. If spec on the net are correct I think the eibachs would be a interesting set to use since between the adjustment ranges it’s the only set I’ve seen that can go either way as a stiffer front bar vs rear (in ratio) or a stiffer rear vs front (in ratio). So theoretically they should have the widest range of tune ability.. I was pretty surprised to see the stillen even at the stiffest front setting only being marginally stiffer than the softest rear.

Brendan

There are a lot of variables there to consider. What are the spring rates you went with? What are the alignment settings? What is the ride height? How much down travel do you have? How are the dampers set up? Etc...

I ran into some really weird handling issues with my car when I went to higher rate springs. The car would dart around on bumps so badly that a passenger could feel it. My issue came down to not enough down travel meaning that one or more wheels was constantly struggling to make contact with the ground. What helped me was adding a set of helper springs to the car. This gave me way more down travel and made the car handle bumps a lot better.

I also don't run a rear bar because I found it much easier to get the power down without one. I just increased my spring rates to get the right balance or rotation for my needs.

Here is a link to my short write up from by build thread:
Rear helper springs

Spooler

Responded to your thread, I need to do this on my car.

Ralphatron

yeah, I think what I'm going to do first is move the end link to the outer hole (softest setting) on the rear sway. You're saying just unlink one side and basically leave the endlink hanging there to test this out? any potential issues I can run into while driving it this way for a bit?

Yeah, the adventure I've been on the past few months trying to get this right has taught me about all the factors that come into play with suspension.

the second coilover kit I put on had custom swift springs at 12k in the front and 7k in the rear (true rear, not divorced spring). This was BRUTAL to drive and I immediately threw on 10k/5k swifts and noticed a huge difference. But I assumed the custom valved dampers for the 12k/7k original springs on this kit were causing it to still be too stiff for daily street driving.

That's why I went with a completely new divorced spring kit, using default spring rates of 10k front and 8k rear. As I'm sure you know, the spring rate is basically double for divorced spring vs true rear coilover spring due to the wheel rate.

This was also noticeably better, but I'm still feeling what I think you described as "darting" (car slightly being thrown left or right I think?) when hitting bumps with one side of the car only.

The other thing too is that I have yet to get my alignment done, because I wanted to finalize my configuration before spending the 100 bucks and avoid having to do it again if I wanted to change something. I know this will affect handling, but I didn't think it would be enough to cause my issue, right?

As for ride height, I'm not slammed, and I'm not at stock height. I'd say right now I'm noticing this at maybe 1.5 inches lower than stock, so nothing extreme but was planning to fine tune the height adjustment to maybe a half inch lower than it is now, just waiting for springs to settle a bit first.

I'm not really sure what down travel is. I'm on the default dampers that come with the BR series coilovers from BC and I have them set to the softest of the 30 available settings.

I appreciate the responses, guys, thank you!

Rusty

You screwed up by not getting an alignment done. Everytime you change coilovers and springs. It changes your ride height.

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Ralphatron

lol, I said I haven't done the alignment yet since I'm trying to finalize my configuration and final ride height. I'm definitely planning to get it done as soon as I decide what I'm keeping on the car. Why would I get it aligned if I know I'm going to change the suspension configuration and then have to re-align it again at $100 bucks a pop.

geokots

Because not getting the alignment won't give you a true indication of the ride/fitment.

Rusty

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Rusty

Everytime you change spring rates. You have to get it align.

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wanker

How about purchasing a lifetime alignment deal? They are usually only a couple of hundred bucks.

Also that "darting" sensation you feel likely means that your car is "slammed." The springs are fully compressing.

I'd raise your ride height at least 1/2" and get an alignment.

Rusty

Everytime you change springs, the valving inside the coilover/shock should be change to match the new spring.

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Brendan

With springs that soft you should still have a lot of down travel. Without knowing anything else I would look at alignment.

And yes, by darting I mean rapid lateral movement independent of steering angle or input.