Front/rear sway bar questions

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.

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

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

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

Ralphatron

lol I'm fully aware of why an alignment is needed and what it can do to the car when it's not aligned. Not just by being told or reading it, I've actually experienced it many times back in the day on my older cars.

Right now I'm specifically talking about the way the car handles over imperfect roads. The car actually feels great going straight on smooth roads, and even on smooth turns. but I'm specifically talking about hitting bumps on one side of the car only. If you guys are convinced it's my alignment causing what I'm feeling and can prove it to me somehow I'd be happy to send you an amazon gift card lol.

Rusty

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

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

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.

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

Jhill

He got a complete new kit BC BR 10/8 so that’s not the issue anymore. With his BC BR his ride height isn’t done by preload so that eliminates the slammed no travel issue. Definitely need to get your alignment checked because if your front toe is set - then it will absolutely be twitchy and darty (that’s why it’s done on auto cross cars). As for the bars I’m going off memory here and again totally different car with different suspension design so not even close to apples to apples but I do remember when I had the stiffer front bar before the softer one I put on later trying to eliminate under steer but I also found I had less kickback in the steering wheel on uneven rougher roads. Not sure if that’s what your feeling but ruling out the sway bars is easy enough by just disconnecting it. I guess I’d also pay attention to if it’s darting directly after the front wheel hits which would lead me to think your describing what I felt vs directly after the rear hits like it’s causing the car to step out.

It does seem more and more people are running no rear bar which is something I wanted to try at a safer track like button willow and learn to throttle steer better but then 2020 became a **** show so never got any track time in.

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.