Effect of sway bars after suspension lowering
 

What is the effect if you have stiffer springs (lowering), and stiffer shocks, but you kept the stock sway bar?

In particular, what does it mean when one enters corners at speeds? perhaps encounter some bumps and cracks on the road surface.

I just made this upgrade.

Big difference, all the energy that went into rolling the car, before it turned, is now going directly into turning it. Also, the new bars, with grease, seem to have provided a lot more fluid (no sticktion) motion. Definitely make the upgrade.

Thanks 04green for the feedback. I'm looking for more of an explanation of whats going on and all that. I know sways affect body roll, and they work together with the shocks and springs to reduce roll. But there must be disadvantages associated with having really stiff roll bars too.

So I am wondering now that springs/shocks already stiffen the ride, if I leave stock roll bars and not upgrade it, what advantages and disadvantages if I do that?

The main issue with roll bars is they connect wheels on opposite sides (duh) which means as you go up with bar size/thickness, you have a less-independent suspension. A bump on the right causes the left wheel to react as well. There's no one best solution, only compromises leaning one way or another.

Springs are not going to affect the sway bar directly. Springs are up and down, sway bar is side to side....

so what can stiffer sway bars do for a car that's lowered with springs and stiffer shocks? What advantage/disadvantages and under what driving conditions, track/street.

It's all related one way or another. Approximately: stiffer springs --> softer bars for a similar perceived reduction in body roll. Lowering by very much is generally a bad idea in any case, assuming one wants handling and not ricer bling points.

A stiffer sway bar will make a car handle better...Simple as that.

Can you go in more detail? That's a very generic statement. If stiffer sway bars make the car handle better, then at what point does it become too stiff that handling is no good? You see what I mean by when I say generic statement? Cause we all know that being infinitely stiffer is essentially having no suspension mechanism then that isn't going to work very well.

I'm looking for some detailed answers here, with respect to street driving and track driving.

There are many threads about suspension geometry and how roll stiffness is effected and etc etc...I'm not going into detail.

Buy a Progressive Tech sway, or the Hotchkis sway and you will notice a huge difference over stock. As far as how to make your car faster...Do some testing with different setups...

your daily driving will become a little more rough, but your track days will thank you...

It's not a generic statement, it's a general statement. What you want is an easy, simple answer (spoon-fed). Get and study a couple of good books on suspension engineering/tuning. Read some portion of the several hundred posts on the subject in the forum. If you're paying attention, you'll discover the only simple answer is "It depends ....".

The generic statement is: Search!

To the preceeding poster: If stiffer is always better, then why have any suspension at all? (Hint: what does 'handling' mean when the tires aren't in contact with the ground?)

HiFlite999,

I wrote specifically that I am looking for some detail answers here, so I'm definitely not here for "an easy, simple answer (spoon-fed). You have misunderstood me.

I am here looking for answers to questions, and you are here to flame me and educate me on how to learn. If you don't know the answers or you don't want to tell me the answers, you don't have to respond to this thread at all. On top of that, I know after this response, this is going to turn into another flame-war response thread going back and forth about opinions, so beyond this reply, I'm just going to ignore what you say because it's not helpful.

You have yourself a good day.

http://auto.howstuffworks.com/question432.htm

http://grassrootsmotorsports.com/articles/lean-less/

In a nutshell...

Springs, effect how hard it is to move a corner of the car up and down.

Shocks effect transitions, stiffer shocks, less rapid transitions, front to back, side to side, one wheel up or down.

Sways do that for roll. Think of them as special heavier springs that only work for roll (side to side) and not front to back. It all gets to how completely you load a wheel when you are turn. I did not notice any rougher rider when I upgraded mine. I did notice immediately that the turn-in was more precise. I expect, based on limited testing, I have a LOT more stability at the track. If you add adjustable sways, you get options for adjusting over and under steer over an above tire pressure. That is a plus. For more than that, get a copy of the Going Faster book. There is a great section on sways, problem is you have to read the rest of the book to understand. I also think I got a benefit in reduced stick-tion.

I replaced my shocks because they were worn out, I did springs because I had the shocks out. I have a feeling that, dollar for dollar, the sways are a better upgrade than shocks and springs, but that is just a feeling. I made my changes to a suspension with 80,000 miles on it...

Did any of this help? It is not an easy question. There are several religious camps out there. I think that means there are several valid ideas...

Good luck.

Thanks, these last two replies are very helpful.

I think you mean a stiffer shock setting. Assuming you are asking the "what if" question because your contemplating this buying decision, here is what I think you're going to experience. There is some missing information here but I think you'll understand where I'm headed.

Assuming you have increased your cars grip potential with either stickier or larger contact surface tire, you will find that using the existing stock bar but increasing to a firmer spring (and you offered lowered as well) you'll find a nice performance improvement. About the worse thing that could happen is that you have a really sticky tire (like an R compound) and let's also pretend you know how to drive it well, you'll probably get a ton of body roll AND you may run out of suspension travel/find interference. This depends again on how low the springs are, how much grip and how well you can tap into the tires potential grip.

The shocks won't really influence things as most people might think IMHO. Largely because about 99% of the people out there do not know how to operate them correctly.

Here is a great way to think about sway bars or anti-roll bars. As a general rule, racing in the rain or in poor grip conditions in an RX-8 (and most any other rear wheel drive car), you want a slllloooow transition from side to side. I like to share with people this: think about walking on ice or walking on a slippery surface. This is done will sllllow steps and placing your foot gently onto the slippery surface. This is the same for rain. Smaller (or no) roll bars will require a car to roll more (%) and take longer to do this (like the step you take on the ice). This slowly plants the left side of the car when making a turn to the right. BIG, HEAVY swaybars will more instantly transition weight to the outside tire. On a rain, wet or slippery surface this will have the car instantly load the outside when the wheel is turned. This would feel like instant turn-in.

The hot ticket is to run as less spring, shock and bar that you can and still make the car work. The opposite of this is to overburden the tire and to more easily upset the car as it navigates bumps, turns, curbs, etc.

Hope that helps.

Eric is a smart fella.

I'm going for bling factor mostly, but I will be adjusting my ride height and Agency Power sway bar for track use.
I wonder why when I went back to stock suspension for the winter it felt like the rear of the car was all over the place, on the snow/ice/cold roads of course (I don't have DSC). Someone suggested that I take the rear sway right off, so I did, and my car handles very good now?
When I put my coilovers back on I will put my stock rear sway bar back on.
The aftermarket front sway bar seemed to tighten up my turning.
Sorry I can't help with anymore technical answers.

I've a couple thoughts for you...

..with stiffer springs, you'll have less roll, and esp if you lower some, you'll have even less roll still...as you're COG if lower.

..with less roll for the same lateral force, the up/down deflection of your swaybar will also be less, and so a stock bar will have even less effect than when using stock springs.

..although less sway bar effect may be satisfactory as you aren't rolling as much with stiffer springs anyway, a stiffer bar will help regain the amount of effect the swaybar makes, just doing it with less defection. The goal of 'going faster' means the best balance between spring siffness, shocks resistance, and bar stiffness is one of those things that W.E. warriors and racers alike ponder and work at perfecting through theory first, and trial and error afterwards.

The difficulties in doing that process mean it's hard to tell when you get it right exactly... but you generally know when you get better...track times ... that is :yesnod:

That rear sway bar thing you experienced? ---- read my post again and it will make sense. By removing your rear bar you are now "stepping slowly" on to the ice with your rear outside tire and this does not all of a sudden throw a ton of weight on this outside rear tire when you turn the car. This makes the car less likely to have an "instant weight burden" which generally leads to a spin or some undesirable consequence.

With our race cars when we KNOW it's going to rain for an event or a race, we will reduce both our front and rear spring rates by about 100 to 150 lbs (depending on what tire we were running). We also disconnect both the front and rear bars. We also stand the tire up (run less negative camber) because the car has poor traction and the car doesn't "roll" much so therefore you can run less camber and get a better contact patch.

IF I were to drive our race car in the snow here in Indiana I would do what I suggest above: Take the bars off, run a low spring rate, run very little camber and run a good snow tire. This would allow the car to be nice and lazy (like when you need to walk on ice and not brake your azzz).

Have you ever seen a corvette or a mustang in the snow? All over the place? Firm bars and springs contribute to their more instantaneous wheel spin when cornering.

Great post. I especially like that you are running data acq----the unfair advantage

Thanks Eric, I totally get it now.
Seems like I have done the right thing.
I disconnected the sway, put the soft stock springs in and got an alignment when I put the winters on. (now I know why the mechanic told me he "squared out" my tires for the winter).

btw, It really made a difference and I drive like a pro in the snow.

yes, I met Eric a few times at Mosport for his races. Thanks Eric, that does make sense.

I currently have the Bilstein B8 shocks on Eibach prokit springs. I am contemplating a stiffer roll-bar, and hence why this thread exists. I'm trying to find out what advantages/disadvantages I would have if I do get some upgraded roll bars.

In relation to what you said, before when I had my stock suspension setup, in the winter on snow, it is easier to control, perhaps this is what you are talking about regarding slow transitions.

Then, I upgraded the springs ONLY, and noticed the car became twitchier at the limits and sometimes occasional crashing at high speeds over bumps; this is quite possibly the mismatch of spring rates with stock shocks.

Then, I added the Bilstein B8 shocks and everything dialed in nicely and the bumps are all absorbed much better with no more crashing. On a "test" corner, I was also able to gain an extra 10km/h without understeering.

However, I feel there is still more room for improvement, and why I turn to sway bars now. I can't modify suspension mount points but I don't think a 1" drop will warrant such a huge difference for a modest daily driven car. The biggest problem I have now is that the rear seems really soft.

At the exit of the turn whenever I want to full throttle out of the corner, the rear end slips out into an oversteer situation, it seems to lack grip. Can you give me some of your racing advice and comment on why that is occuring and whether sway bars will help?

^^^ I have noticed the rear end thing a little as well... I think my Tein S.Techs are starting to SAG as I have noticed my car sits lower than usual with friends and without friends in the car. I need to probably buy some new springs here soon but Id like to know the answer to this question as well...

Footman, what are your alignment settings? Most people find that they need a bit more negative camber in the front than the rear, at least on typical street setups. Toe-out on the rear can also cause corner-exit oversteer, as can cornerweighting issues, although those conditions are not as likely as simply needing a bit more negative rear camber in the rear.

I haven't done alignment since it was lowered so I don't know. There is visible negative camber in the front, and only ever so slightly in the rear. That would be another question which I will look around first as I'm going to be doing an alignment in spring, will research and find out what camber/toe I would need.

In that case, I wouldn't look so quick to sway bars to fix the problem. In fact, adding sways without first having the car aligned could just mask another problem problem.

While having more front negative camber is a good thing, it's also possible to have too big a split - which is to say, if you have, say, -2 in the front and -0.5 in the rear that could also cause corner exit oversteer. And I'd also say your toe is in question too. Again, even a little toe-out in the rear can cause power-induced oversteer.

Did you relax the suspension bushings (commonly called "pre-load" around here but I think that's a poor description) after you installed the springs?

Don't get me wrong, you may still like the car better with stiffer sways. But get the car aligned first, before you start diagnosing handling problems. Trust me on this.

BTW, I think it's great that you are asking questions. It's the only way to learn.

Let's pretend you do have an oversteer problem. The more correct way to address this is to understand what could be happening on a GLOBAL context

For example:

-Does the car Oversteer (OS) in both right and left hand turns?
-Does it OS in slow, med or fast turns?
-Is there any reason to beleive the tires are better (or worse) on the rear of the car? How about the front?
-Is it possible that this is an overinflated rear tire pressure issue? Why? What are the actual off track pressures of all four tires?
-Could the alignment settings be the issue? Why or why not? What do the tire temperatures say?
-Is something broke or improperly installed on the car?
-And the tough one----is it driver induced (which is often the case when describing car handling characteristics).

Assuming you've been done this road, chances are you'll want to soften up the rear of the car. The goal is to ADD GRIP to the REAR of the car. Because the car has poor traction (oversteering) we want to add more grip to reduce this undesired effect.

One way we can do this is to soften up the rear. This can be done in a few different ways. You can/could: Lower the rear ride height to lower the rear roll center (one of THE primary benefits of an adjustable height coilover system is ride height adustment and this is an easy trick to cure oversteer). Keep in mind that lowering or raising rear ride height will effect your static camber. Raise the car and you'll add positive. Lower the car and you'll receive more negative. Toe is favorable as lowering the car brings more toe in and raising gets you toe out. So, with coilovers you could lower the rear a big (assuming it's not slammed already---which i do not recommend).

Another way is to reduce the size of the rear bar, make the rear bar softer or remove the rear bar all together. Again, this has the effect of walking gingerly on the ice for the REAR of the car.

Depending on rear tire pressures you may be able to lower then and find more grip. You could also run a larger rear tire. Or even a more grippier rear tire in the rear only.

You could also decrease your rear spring rates which also slows down the rate of loading and unloading of the rear tires (think of dad's cadillac and how it rolls over big time).

I'm giving you several ideas because often a car driven to the track has few choices to fix suspension ailments. At each track we go to we are always tweaking something--- .2 more of less camber, a small change to the front bar and always, always, always record tire data. You HAVE to get good tire data or your barking up the wrong tree.

YOU COULD ALSO ADDRESS THE FRONT OF THE CAR TO REDUCE OVERSTEER

Because we have too little grip in the back of your car it is natural that we would have more in the front. Well let's steal some of that front grip. Where will it go? To the rear!

By taking away front grip (adding more understeer to the front) this will earn us more grip in the rear. Sometimes you only need a little. It is possible that your new suspension go-faster goodies had your car ending up with TOO MUCH front grip. Let's reposition some of this to the rear so the car handles better and we can drive her faster. You could do this by adding more bar to the front (makes the car understeer = less grip up front = more rear grip). You could do this by increasing front spring rate. You could overinflate your tires a bit. You could raise the front of the car which has an impact of the geometry and will reduce your OS a bit (think about a car that is waaaaay too lowered in front----can you see how the rear end would want to swing around or pivot around the front a lot?)

So there are lots of options. What is the best method to pursue? The one that is the most factual. The most scientific. The one that removes the "seat of the pants" feel to determine the problem in your equation. What are these options? Measuring tools.

-Tire pressure gauge
-Tire pyrometer
-Camber and toe gauge
-Ride height measurement device

Also, a good naked eye and a buddy with an open mind.

Here is what I would do if I were at a track and someone came up to me and asked for my help.

First off, I would ask them WHY they think they have this problem (see above questions). Then I'd ask to look at their tire data (and if they didn't have it I'd tell them to go obtain it). Then I'd ask them about their car and it's mods and when the last time it was aligned. I'd walk around the car and eyeball the camber and toe (which you get really good at after a few years). If it wasn't any of the items immediately above with tire temps, pressures, improperly maintained car or misalignment then I'd address the front or the rear of the car (see above).

MOST OF THE TIME a DIY suspension person boogers up their handling. When you add to this that they have often become better drivers (which is why they modified their car in the first place) they are exposing flaws in their cars that were already there but they had not driven fast enough to expose. The faster you drive the more you expose a cars flaws. This is normal. MOST novice drivers just keep driving these slightly flawed cars. SOME drivers mod their car, get undesireable results and blame the mods WHEN IT'S ACTUALLY THEM that is causing the problem. This is very, very, very typical in understeering feedback---it is often more a driver issue than the car. The idea behind adjustable suspension is exactly that---to adjust it. I would suggest to people to do the gross things first: springs and bars. THIS IS ASSUMING YOUR TIRE DATA IS TELLING YOU THAT YOU'RE GETTING SOLID CONTACT. Solid contact is defined by pulling into the pits BEFORE your cool down lap (and do it quickly and assertively) and taking temps and pressures (or your best friend does this for you). You then return to the track, go drive the crap out of the car and pull in again BEFORE the cool down lap and take data again. Data, data, data. If you are getting a 15F spread from inside to out on your tires you are in a good place with your camber settings. If your temps are higher in the center of the tire then you have an overinflated tire. Too hot on the outside? Then you need more camber. Assuming the tires are looking like a 15F spread (+/-5F) you then work on your ADJUSTABLE suspension: Bars and springs. Shocks are for fine tuning in my book and people who have 82 way adustable shocks have more problems than those that don't. Shocks require someone who drives very, very well to make them perform correctly. Springs and bars are easier to adust.

Having problems figuring out if the car is oversteering or understeering? Look closely at the pressure and temperature growth of the tires. If the rears are on average 30 degrees F higher, your car is sliding around in the azzzz (OS). The inverse is true if your fronts are both higher temps and greater pressure growth than the rears.

So.......if I were you I'd try something. Bars are super easy to change at the track so I'd get adjustable front and rear bars. Which means I would purchase swaybars that have a fair amount of adjustment. I'd also start taking tire data religously. Some people feel goofy because they may be the only one capturing this data but that is how your car has the ability to go fast---data collection.

Did that make sense?

Yeah, it was preloaded, I have been driving around for almost 8 months now unaligned. Well actually the timeline goes like this...

1) Eibach springs installed
2) Alignment done immediately
3) A year later, Bilstein B8's installed
4) 8 months later, I am here with this thread.

When the B8's were first installed, they actually dropped the car a little bit more. Most people say shocks won't lower the car, but in this case the B8 did (shortened shock, like Koni Yellows).

I will do the alignment in spring first and then see how the car handles, a lot of stuff is going to happen simultaneously in spring..

As right now my observations are based on my winter setup, which is 18 x 7.5 +42 on 225/45/18 Wintersport M3's

In spring:
A) Mount and install new 18 x 9 +36, 245/40 new rubber
B) Alignment
C) Transmission/diff flush

Maybe a lot of the car handling will change drastically. The more I think about it, the oversteering problem is becoming worse and worse could be because of my tires are getting old/worn. Both my summer/winter sets are getting old. At the same time, I'm getting more and more aggressive and discovering the car's limits.
If this is daily driver, with occasional track, do you recommend I just go with the manufacturer alignment settings?

Eric, that is really sound advice. I think I will start doing that from now on at trackdays. CASC-ON is quite organized for events. It's timed, I like it.

I would definitely add more camber to the car. Tire data will tell you this big time.

Side note: We align our race cars BEFORE we leave the shop, AS SOON AS we arrive at the track, AT the track, check the scales and then AT the track again and then when we return to the shop. THINGS MOVE. For bumpy tracks things move more. Does your home track have huge curbs? Things move.

I'm a big fan of adding camber to a stock car.

As always, great detail & advice from Eric.

I agree, if you enjoy pusing the car in turns, you will benefit from more negative camber than stock. It is hard for most of us to take temps and tweak, since alignments are expensive if you have to pay for them, but they are important. I'd say something like -1.5/-1.0 (F/R) or -2.0/-1.5 is a pretty good starting point for most street drivers, but there are always variables. I run -2.5/-2.0 for autocross, but it's hard on the inside corners of my street tires, especially if I put on lots of freeway miles.

As for tires, yes, tires have a huge impact on how the car handles. Don't judge the setup based on winter tires or worn summer tires. I once wore a set of Toyo T1-S tires down to the wear bars on a 100 hp Miata, and man could that thing oversteer on corner exit! It was fun, but slow, and as soon as I put fresh tires on the problem went away.

So yes, get your good tires on and get it aligned. Find a shop with a 30 day policy and maybe they will tweak it for you for free if you don't like your initial choice. But, as Eric says, your driving habits are a big part of it too.

As suggested, dial in some negative camber. I would start with the same setting as whatever they are able to get on the front (will be -1.5 or so) then tweak from there. This is what one of those 3 or 5 year alignments are great for. I would not play with toe on a DD. Tires are too expensive. There are several discussions on this froum, I think one is in the tire section. One school says that for a road course, have 0.5 degrees more negative camber on the rear than the front. I am going to shoot for that for an event in a few weeks.

Then get a set of adjustable sways (with grease fittings). Start softest, and then you can use the sway bar adjustments to tune over or under steer (stiffen the end that is NOT sliding, front for oversteer, back for understeer). Alignments are hard to mess with, and mucking with tire pressure off of what gives the best contact patch s hard on the tires. I got the progress ones from BHR and drilled and tapped for grease fittings. There are ones out there that come with them for about $100 more.

Good luck. Gotta Run.

Mike

Great advice guys. 1up!
Since I put my coilovers on last summer I have been getting schooled.
It is so beneficial to know all this stuff if you love your car.