jdmspoonitr

iTrader: (1)

Well just doing some research. Reading some suspension setup articles on Longacre and a few other sites, but wondering people's experience here with a big rear sway bar and a stiffer rear spring setup.

From what I can gather/understand (not terribly much) a big rear bar and stiff rear springs are two solutions to the same problem. But should it be one or the other and not both? I know some of you guys have tried all of this and it's going to come down to personal preference, driving style, tire used, and track conditions.

But what are the actual pros and cons of a rear soft spring setup with a big rear bar (lets say 26mm solid) vs. a stiff rear spring and stock bar setup?

I understand that a stiff rear spring is going to be stiff 100% of the time and might make the car less comfortable to drive to and from the track. The stiff rear bar setup would only make itself apparent some of the time as it effectively increases spring rate as the chassis pitches.

What are people's experiences with a stiff rear bar and stiff rear spring setup? Any insights or videos to share?

I am going to be trying a Koni 8041 Race setup with 700#F/900#R setup and curious what if any benefits there will be to running a 26mm mugen bar with already stiff rear spring rates.

I am on 225 RS3's and plan on running them for the next few seasons and the track I run 90% of the time is quite smooth (Thill). So any help from the people that have tried all sorts of different setups, please chime in.


-Ken

Lo-Buck EF

Big bar is more progressive than the stiff spring.

TunerN00b

Fixed that for ya.

Swaybars come into play as the chassis rolls, not pitches. "Z bars" or a "3rd spring" are for pitch control without affecting roll.

jdmspoonitr

iTrader: (1)

Either way I am probably going to try the combos out myself, but am I going to have to be extra cautious with steering inputs with a stiff rear spring and big bar setup? Or is it more subtle as in I will be able to get the rear to hold a more aggressive slip angle even with wide tires?

RR98ITR

It is?

Scott, who is wondering if we're talking about a tapered wall bar...or maybe the links are progressively wound springs...Hmmmm, I can easily see the link in compression being progressive, but the side in tension...not so sure...ah, rising rate link geometry!...no, same problem I think maybe...

Scott, who...(never done it twice before)...just read in RCE that at least one of the NGTC teams is/are using progressive springs on the front...

FlewByU352

It's a touchy and totally track dependent subject. The ideal way to do it is the stiffest springs you can use to maintain traction. Then introduce sway bars to change bias and further increase traction.

TunerN00b

The further the arms twist from each other, the more bar twist for the same amount of endlink movement. Think "camber curve", and apply the same concept to the bar arms.

spAdam

iTrader: (1)

But the coil spring does the same thing... xx lbs of force compress the spring xx inches, xx pounds of force*zz inches of arm length on the bar twists the bar yy degrees.

It's all torsional stress to me, the sway bar is just an unwound coil spring. Granted this is all assuming linear geometries.

Using a setup like the ASR 32mm bar that uses a straight splined bar (a la Speedway Engineering and similar) and rigid moment arms, the only way I see the bar being progressive is if the arm starts out horizontal and moves through enough of an arc to effectively shorten said arm... and I don't think the motion ratio combined with the actual deflection of a rear stiff setup are going to allow enough change in that area to make a measurable difference.

And tapered bars? Now we're really complicating the equation, not to mention creating parts that are more expensive to manufacture. Tough sell on a crowd that's racing 15-20 year old $4000 cars...

Just my opinion, but I always love these discussions!

Derek128

I heard from a engineer sway bar is more effective(vs spring) in terms of controlling the balance of the car.

FlewByU352

Yes the swaybar controls bias or balance, but the spring rates should determine roll and traction.

Kozy.

So what are we asking here? If we say we have a fixed target LLTD, is it better to make this up with a more bar or more spring?

Some racers favour the 'softest spring that can handle the load transfer' approach as it provides the best mechanical grip. On that basis soft springs and big bars should work better for bumpy tracks, but then you have the issue of reduced independence over an axle which could cause a loss of traction itself...

What about your dampers? Always valved for your spring rates, but does anyone valve for the bars? A 24mm rear bar is equivalent to about 700lbs in spring rate during roll, if you've not accounted for it that is surely a considerable amount of underdamped energy being thrown from side to side which is going to affect tyre loads.

Do the springs not have any effect on bias? Are you saying that the bars have little effect on roll? Or that they should not? I fail to see how bars with upwards of 500lbs equivalent spring rate, as commonly used on the rear of Hondas, would not have any effect on roll.


He is correct, a small change to a bar is equivalent to a big change in spring rate. Going from a 24mm to a 26mm for instance, increases the ESR from 700lbs to 950lbs.

Changing the arm length by 1" either way on a 24mm bar might have a range of 520-970lbs ESR. Far more tuneable. Then you're back at your dampers. Can they keep up?

FlewByU352

If you look at a lot of professional road race cars they really don't use massive swaybars. I found it to be an eye opener like the majority of us are doing something wrong. This I believe is due to ride comfort bitchers. Springs that are too soft and bars that are too big is ever so common for those seeking performance but sacrificing real performance for comfort. It comes down to the choose one or the other and for the sake of this thread, I believe we are talking strictly performance.

That being said, springs should not be used for bias. That is what roll bars are for. Yes it can be done, but it is the wrong approach. Ideally you want to start with springs suitable for the track surface to maximize grip. Then you play with bars to change bias. Think grip is easier lost in a FF car with stiff rear springs. Even if they are the same front and rear, the weight distribution is usually a considerable amount less. This means the rear could hop over an imperfection and lose traction but the weight over the front would keep it planted. Again use springs to control grip.

Now where it can get really technical is introducing aerodynamics and utilizing splitters, spoilers, and diffusers. You have to compensate for the added force using spring rates. At slow speeds you might have terrible mechanical grip then. Suspension really is complicated and arguments can go on for days. I base my opinion off of the professional race teams I have talked to and checked out their cars. After a bit of thinking, I realized that they are doing it the correct way and most of us aren't due to budget.

Think of in budget terms, most OTS shocks can't handle the high spring rates. Revalving is costly and it is even more costly for a higher end shock that is originally built to handle true racing conditions. For that reason sway bars are cheap in comparison and I think often used to patch or mask a problem like needing higher spring rates.

Kozy.

Yes I have heard that small bar setup before in professional motorsport, but then I've also heard of soft spring big bar aero setups. More than one way to skin a cat and all that jazz.

The problem is simply saying professional teams do it is not particularly insightful. Can you elaborate which teams, cars, setups you are familiar with using this strategy? Are we still talking about production FWD cars turned into racers, or bespoke single seaters? What spring/bar split are they using compared to the average AXer in a 92-00 Civic that would be making up maybe 50% of it's rear roll resistance with the bar?

Derek128

Professional road race cars's suspension geometry is not the same as road car tho.

From using the factory mounting point with all custom length arms to complete custom suspension setup. (depends on rules & budget)

I'm not an engineer. But unless we know the wheel rate of those professional road race cars, I think we are comparing apple to water malon (orange is just not enough lol)

Black R

Ken,

Iirc, on Hondas we simply can't put enough spring under the car to make it handle well enough - so we use swaybars to aid.

I'd say start with your intended spring rates and then see how you like it.

Too loose in the rear? Add a softer rear bar.

jdmspoonitr

iTrader: (1)

Yah it's definitely something I will have to feel out myself. Plan is to put the Koni's on with the stock ITR bars and dial in some negative camber and see what it feels like.

This is the article I was reading: http://www.longacreracing.com/articles/art.asp?ARTID=30

But I have a feeling this didn't have FF honda's in mind LOL

daytonagp4

Now what about me......i have a 95 civic no swaybars at all and im trying to figure out what to do. I run a circle track only, it doesnt see the road. Ive been fighting a push all year and this is my next step. Springs are going to be eibach and koni yellows. Track is asphalt with about 13 degrees of banking. Ideas???

TunerN00b

Circle track cars get access to much different solutions than cars that have to turn both ways.

Increase outside rear spring rate
Toe both rear tires to the outside
Add a rear swaybar, use adjustable endlinks to preload it
etc...

miamirice

Agree with your last statement. This part:

"We can look at each corner of the car and think about new dynamics created by the soft set up as compared to traditional set ups. Each corner is affected differently and we can think about the new challenges and consider the adjustments required to make the big bar soft spring set up work best. All adjustments must work together. A complete package is the goal and you must tune the entire car to achieve improvements. A traditional set up that is completely dialed in would be much better than a big bar soft spring set up that did not address all of the variables."

I interpret as....if your really smart, have a ton of time, money and resources, you can make it work.

Black R

I always wanted to try mugen front and rear bars and the adjust springs accordingly...

Just sayin.

markertoo

Surely a sway bar is an easier tool to adjust or tune with?

I have always gone with big spring rates, and shocks to match, and THEN adjust for very minor stuff (balance, or extra roll control) with usually small-ish sway bars. Sway bars do too many bad things (especially at the front) for me to rely on them heavily.

My current setup:
99 Civic HB w/ITR swap
Tein RA and HA coilovers, with 10K F / 14K R springs.

I have some sway bars to go on (22mm F from an EX, and 13/19/23mm R), but I would like to see if I can find a smaller front bar before I put the EX bar on. I would like to figure out if the EG front bar will work, as I think it is the smallest one available.

Actually, I just did a search, and since it is a 21mm bar vs the 22mm EX bar, I won't bother to find an EG bar. I REALLY would like to find a smaller (15-19mm range) front bar, if I could. Does anyone think an EF bar will work?

Black R

If they're adjustable, yes.

Or you can simply unhook one end link to see the effects of no swaybar...

What I've resigned to doing on my autox car is to fight body roll with swaybars, and the "tail happiness" with springs.

I'm going back through and putting my shocks at the middle of their dampening range at this point also.

markertoo

Just about all sway bars are adjustable to some degree. Loosen the end link hardware, or put mushy bushings in all contact points.

IF you have the options in your class to do springs, shocks, bushings and sway bars, then I think you are going about it the wrong way. Springs will always make the car more responsive - sway bars tend to take longer to react. This is only my opinion, so ignore as needed.

The Koni Race shocks and high enough springs will likely be all that you need. Or, you could put a tiny 13mm bar on there, and take the end link off on high speed stuff, put it back on for autox. A complete rear sway bar change in the paddock surely wouldn't take more than 15 minutes - enough to do between runs.

Xian

Just IMO and all that but I think you're going about it backwards. The final setup for an autox car will be a little different than a track/club racer (due mainly to having to deal ith worse surface conditions/bumps and having to focus more on transitional handling).

Were it me, I'd:
#1- run the spring rate up to where you can pretty consistently stay of/out of the bumpstops or are using minimal bumpstop during typical cornering loads.
#2- Make sure to select a bumpstop rate/height that will support your final spring rate selection. i.e. a rate that will go progressively "up" from your final rate... if, at this point, you're running pretty high rates, you should be able to use relatively soft bumpstops since they'll be additive to your spring rate.
#3- Tune rear rotation with rear camber (keeping in mind that roll will cause the car to lose rear camber and that the car may tighten up as you increase spring rates/decrease body roll)
#4- Tune corner turn-in with the rear bar size.
#5- Tune transitional response with the front bar.

Of course you'll be playing with shock settings throughout this which will further muddy the waters of what does what...

Since you've got an EF (IIRC), I'd start with a small front bar (like the HF bar) and a largish rear bar... no sense trying to re-invent the wheel here, right?

On the big rear bar/stiff spring thing: the lower the spring rate, the more roll you get, and the more influence the bar will have to both the inside and outside wheels. Not good, IMO. Stiffer/higher rate springs allow you to better isolate control of total body roll better than trying to handle the bulk of it via just the bar.

My exception to the rule would be if you're constrained by rules... for instance, I've got the 26mm solid Mugen bar on my ITR with stock springs. Why? Because I want a stock class legal car and a big rear bar helps me tune rotation and put power down better coming out of turns.

Christian

r_wannabe

My race car setup is 32mm asr adjustable rear sway bar, 1200lb rear springs and some konis 2812. I love the setup, but it also depends on your driving style.