Sway Bars: Can they be to stiff?

[Bob the Noob]

Hi All,

So I'm likely going to be getting some BMR sway bars (front/rear) soon, but I've got a question: Can they be to stiff?

Naturally I think "more is better", but I've never upgraded parts like this so I'm not sure what setting to use. Are there downsides to putting them on the stiffest settings?

-Bob

[SRG963]

I've found having the front set to soft, and the rear set to medium or hard, is the perfect combo.

[Bob the Noob]

By "soft" you mean set to the first holes, and the rears set to the middle or last holes? Does the ride quality decrease as you go firmer on the sways?

[SRG963]

Yes, hole 1 is soft, 2 is med, 3 is hard.

Ride quality remains the same. The amount of understeer/oversteer is changed with different settings.

With my car, front set to hole 1 and rear set to hole 2, feels perfectly balanced.

If you want to kick the rear out a bit more, hole 3 on the rear bar will help.

http://i879.photobucket.com/albums/ab359/SRGSRG963/BMR_Sway_Bars.jpg

Front Sway Bar Settings
Hole 1 - 87% stiffer than OE bar
Hole 2 - 137% stiffer than OE bar

Rear Sway Bar Settings
Hole 1 - 91% stiffer than OE bar
Hole 2 - 164% stiffer than OE bar
Hole 3 - 286% stiffer than OE bar

[Bob the Noob]

Okay, I'll try those settings first when I get them.... Is that a sticker in the middle that comes with the Kit? I got one with my RotoFab intake but haven't put it on the car 'cause I'm goin' for a sleeper vs the "Hey look at my cool stickers!" style. :)

[greggy]

yes, sticker.

Me: Front soft, rear full stiff.

[SRG963]

Stickers add 5hp minimum, as any fart can owner lol

[Eidolon]

At my first HPDE, I ran the front full soft and the rear in hole 2. For my second track event, I ran the front full soft and the rear as tight as it would go, so...

Depends on what you're wanting. Front full soft, rear medium is a good combo for performance driving that is still safe. If you manage to get the car out of sorts, that combo will give you tons of margin while still pushing (understeering) at the limit. And understeer is MUCH easier to handle than oversteer, since understeer also kindly scrubs some speed for you by wearing the tires. (Understeer is a gradual thing, by the way, not a snap "Oh, crap, no traction!")

Setting the rear full hard will increase your limits overall and let you tackle a turn more quickly, but you'll have to be more careful on the throttle because the front-soft/rear-hard combo balances the car to the point where going into a corner wrong gives you understeer and coming out wrong can give you oversteer. It's great for track use.

If you don't often push your car to the limit, I'd go front soft, rear medium.

[Bob the Noob]

Awesome! I got final approval from my wife, and just put the order in for them. I should be able to pick them up this saturday when the Mid-length Kooks come in :thumbsup:

[Napalm]

Yes you can get your suspension too stiff. This applies to bushings as well as anything else. Including springs and struts.

For street use with street tires, I would probably never use hole # 2 on the front bar.

My recomendation: start with a hole 1 combo when you first install. Drive it, feel it, and see how you like it. Then move to hole 1 front, hole 2 rear. again drive and feel.

Then so you know how it acts, run hole 2 front, hole 1 rear. I don't recommend keeping it this way, but I do recommend trying it. as you progress through the settings, try full stiff. I suspect you won't like it.

So on and so forth. In the end I suspect you will end up with hole 1 front, and hole 2 rear as your street combo but its a matter of taste.

[BMR Sales]

There definitely comes a point were the suspension can be too stiff. Every person has a different feel and tolerance they are looking for so we generally tell people to play with the settings and go with the setting that feel and perform the best to them. Since the sway bars are easy to adjust take the time to play around with them and find the settings that are ideal for you.

[DZG8GT]

Well I have a problem that the rear slides out too easily. I have it on the middle in the rear but have adjustable rear links. Should I adjust them so the bar sits level when the car is on the ground? Just seems when I go around corners..if tires break loose I really fishtail. I know the stock tires suck but it gets scary sometimes. Any suggestions.

[Eidolon]

Well I have a problem that the rear slides out too easily. I have it on the middle in the rear but have adjustable rear links. Should I adjust them so the bar sits level when the car is on the ground? Just seems when I go around corners..if tires break loose I really fishtail. I know the stock tires suck but it gets scary sometimes. Any suggestions.
Adjusting the links won't help with fishtailing unless you've got the links pretty far off in terms of length, resulting in bar preload. My suggestion...

Adjust them to be the same length - and preferably stock length - if you can rather than eyeballing the bar. If you still have your stock links sitting around, remove one of your aftermarket links and loosely bolt the stock link back in on just that one side. Then adjust the aftermarket link on the opposite side so that there's no tension on the bar. Finally, remove the stock link that you subbed in and put your aftermarket link back in, then again adjust it so that there is no tension on the bar. Done!

If your rear bar is on the middle hole and you find you're sliding, you can bump the rear down a hole (further from the pivot) or else the front up a hole (closer to the pivot). If you're hitting the throttle mid-corner and the transmission is kicking down a gear, the sudden burst of torque is going to kick the tail out no matter what you do. So either switch it to manual to force it to hold a gear, or else avoid large changes in throttle input mid-corner.

[WhatNext]

Adjusting the links will have no noticeable effect. If you can set your front bar stiffer that will compensate for the rear and keep your car's tail from breaking loose so easily. If your front bar is already set to the stiffest setting then you should change the rear bar to soft.

[WhatNext]

If you still have your stock links sitting around, remove one of your aftermarket links and loosely bolt the stock link back in on just that one side. Then adjust the aftermarket link on the opposite side so that there's no tension on the bar. Finally, remove the stock link that you subbed in and put your aftermarket link back in, then again adjust it so that there is no tension on the bar. Done!
Can't you just dis-connect one side from the bar, adjust the still connected side to what ever position you want, then adjust the length on the dis-connected side so it lines up with the mounting hole in the bar and re-connect it?

[Eidolon]

Can't you just dis-connect one side from the bar, adjust the still connected side to what ever position you want, then adjust the length on the dis-connected side so it lines up with the mounting hole in the bar and re-connect it?
Yep. My suggestion was just for getting it to stock length. Length does matter, though more for suspension part longevity than for suspension tuning. If the links are too short, they can pull on the bar and cause wear on the links when the suspension unloads.

[oesman]

Essentially what everyone said is what you should consider. The ratio of stiffness between front and rear controls the under/over steer. As the stiffness of the rear bar approaches the stiffness of the front bar, the car will oversteer more. You can combat this by stiffening up the front bar, or by softening up the rear bar. If you leave the rear bar stock and stiffen the front bar, the more you stiffen the front bar the more the car will under steer. The balance you want is drivers preference for maximizing performance on the specific road conditions you will be experiencing.

The other benefit of controlling sway bars is that you can reduce body roll and change the handling characteristics of the car without changing the springs and shocks. This can help preserve ride quality and characteristics of your current springs. The stiffness of the sway bars should be considered if you already have or will be replacing the stock springs & shocks or when setting up your adjustable coil over kit.

As a general concept of stiffening the suspension as a whole, yes you can go too stiff. A car that is too stiff can be dangerous or actually slower around a track. A very stiff setup will impact ride quality. Assuming you do not care about ride quality, grip will grow as the car gets stiffer. You will also find that the 'sweet spot', controlled by velocity and throttle input, where the car is achieving maximum cornering speeds, but not yet sliding/drifting, becomes much smaller.

It takes a lot of skill to drive a car that is very stiff to it's potential, since it will be a lot less forgiving of mistakes. Because the "sweet spot" becomes small, its very easy to go into oversteer where you expected grip. This is how you see people wrecking exotic cars, with seemingly endless grip. Reality is the grip does eventually run out, especially if the road condition is unknown/unpredictable, and unlike a big soft boat which is easy to recover, you end up with a car that will spin or slide off the track.

[Eidolon]

You will also find that the 'sweet spot', controlled by velocity and throttle input, where the car is achieving maximum cornering speeds, but not yet sliding/drifting, becomes much smaller. It takes a lot of skill to drive a car that is very stiff to it's potential, since it will be a lot less forgiving of mistakes. Because the "sweet spot" becomes small, its very easy to go into oversteer where you expected grip.
Good post! This quote above is also why most passenger cars, including ours, are set up to understeer from the factory, so that going into a corner too hot and even giving it throttle in the corner causes the front to push, which scrubs speed at the cost of tire life rather than kicking the tail out, which is much harder to handle.

[WhatNext]

Length does matter, though more for suspension part longevity than for suspension tuning. If the links are too short, they can pull on the bar and cause wear on the links when the suspension unloads.

To your point about pulling on the bar, I was thinking about that too. I think its more important to have the links as vertical as possible as then the links act in tension and compression. The more off vertical they are, the more bending is put into those slender links (the result of pulling on the bar) which is not good. (yes I am an engineer)

[Eidolon]

To your point about pulling on the bar, I was thinking about that too. I think its more important to have the links as vertical as possible as then the links act in tension and compression. The more off vertical they are, the more bending is put into those slender links (the result of pulling on the bar) which is not good. (yes I am an engineer)
Sounds like you are. :) I'm an engineer, but of the computer/electrical sort. Not quiite the same thing.

But I agree. You can definitely have these links too short, but it's harder to have them too long. Length matters most at their stiffest setting, which is when they have to "reach" the farthest. At stock length, with the suspension fully unloaded (car is in the air), the angle between the bar and link is at zero degrees (which is, I'm guessing, what you mean by vertical). At rest under the car's own weight, that length brings them closer to 90 degrees.

[WhatNext]

It takes a lot of skill to drive a car that is very stiff to it's potential, since it will be a lot less forgiving of mistakes.

In the distant past, i had a car with an overly stiff rear bar (non-adjustable) and the tail would tend to come around. I wouldn't let my wife drive it because of that.

[oesman]

Good post! This quote above is also why most passenger cars, including ours, are set up to understeer from the factory, so that going into a corner too hot and even giving it throttle in the corner causes the front to push, which scrubs speed at the cost of tire life rather than kicking the tail out, which is much harder to handle.

Thanks! Yea people always seem to forget this. While the sweet spot moves up (to higher speeds) since you have more grip, it significantly shrinks. I had this grocery getter buick a while ago, just for when project cars were down, it was real fun to swing around since it was basically impossible to crash, it slid well before you'd get to a speed where you couldn't recover. Regular cars, performance cars and everything short of exotics are generally setup exactly like you said, for understeer.


In the distant past, i had a car with an overly stiff rear bar (non-adjustable) and the tail would tend to come around. I wouldn't let my wife drive it because of that.

Yea this is especially bad if the car is very stiff. If it's just kicking out but very soft (big sweet spot) recovering the oversteer isn't TOOOOOOO complicated, you just have to remember not to freak out and avoid the urge to rapidly pop off the gas (lift oversteer, result: over-compensation & terminal oversteer). If the car is very very stiff and kicks out the rear, good luck managing it without going into the bushes or spinning.

[WhatNext]

This might clarify: With the car sitting on its suspension, the sway bar link should as vertical a possible (up & down).

When the top of the link and bottom of the link are not vertically lined up, the lateral offset between the top and bottom results in a bending (moment) being applied to the link (when pushing/pulling on the sway bar). But as you point out, if you attach the link to the middle or farthest mounting hole on the sway bar, that just increases this offset in the link. Adjusting the length of the link can only compensate a limited amount for this configuration, so do the best you can to get the link vertical.

[Napalm]

Adjusting the links won't help with fishtailing unless you've got the links pretty far off in terms of length, resulting in bar preload. My suggestion...

Adjust them to be the same length - and preferably stock length - if you can rather than eyeballing the bar. If you still have your stock links sitting around, remove one of your aftermarket links and loosely bolt the stock link back in on just that one side. Then adjust the aftermarket link on the opposite side so that there's no tension on the bar. Finally, remove the stock link that you subbed in and put your aftermarket link back in, then again adjust it so that there is no tension on the bar. Done!

If your rear bar is on the middle hole and you find you're sliding, you can bump the rear down a hole (further from the pivot) or else the front up a hole (closer to the pivot). If you're hitting the throttle mid-corner and the transmission is kicking down a gear, the sudden burst of torque is going to kick the tail out no matter what you do. So either switch it to manual to force it to hold a gear, or else avoid large changes in throttle input mid-corner.

Indeed. aside from setting, if you already have a preloaded conditon in the bar. then you are running stiffer than you think. This would be the first thing I would look at.


To your point about pulling on the bar, I was thinking about that too. I think its more important to have the links as vertical as possible as then the links act in tension and compression. The more off vertical they are, the more bending is put into those slender links (the result of pulling on the bar) which is not good. (yes I am an engineer)

engineers untie

Personally don't think of it as vertical but more like perpendicular. there are some sway bars that are mounted at an angle anyway. Like the rear bar on the G8, its natural alignment is at a slight angle.

It is similar to a 4 bar linkage so don't worry about vertical as oppose to adding too much displacement. (I mean being vertical when you have the car on ramps or whatnot might not work either). The whole reason for adjustable links is to reduce preload on the bar. its a torsion spring. You can use the stock links but unless one of the holes in the bar is exactly where the stock bar was - then stock links could induce preload too or with the attachment geometry too far out of line could cause binding at the limits.

Infact based on previous experiance with other cars and sways I wouldn't use hole 1 (stiffest) on the g8 without having adjustable links. Not because of loads but because of geometry.

To the guy with oversteer issues. Try taking the rear and the front to the softest setting, and start from there. And like mentioned check the lengths of your aftermarket links.

[WhatNext]

Personally don't think of it as vertical but more like perpendicular. there are some sway bars that are mounted at an angle anyway. Like the rear bar on the G8, its natural alignment is at a slight angle.

I'm referring to the connector link not the sway bar. The wheel goes up and down (that's vertical). You want the connector link (rod) to be as vertical as possible to reduce the bending in the rod. Of course it won't be perfect and there might be other things in the way.

Also with the car level, there should be no preload on the sway bar. Its only when the car starts to roll and there is relative up/down displacement between the the left and right rear wheels that the sway bar gets loaded.

[Napalm]

if the endlinks are not equal length - then you will create sway bar pre-load. because the bar will have to flex to make the connections. This is made obvious when you try to get the endlinks connected.

[WhatNext]

Ah, the stack up of tolerances. But with adjustable links, you can dial that out (if you have them). It seems almost mandatory that adjustable links be used with after market adjustable rear sway bars because you will end up reaching for the other holes. Didn't realize some are using the factory links.

[Virus]

The Pedders bars allow for more balance between over/understeer. I have the BMR bars and with my particular setup I cannot set the front bar to full stiff because it has way too much understeer. Setting the front full soft and rear full hard provided me with the perfect balance of oversteer when combined with setting the front camber to -1.0 and rear camber to -.50.

[Napalm]

well that's another thing too. Other alignment changes affect over steer and underster drastically as well. for example - running significantly less Toe in (significant in this case means less than 1/4 of the stock value)

With suspension tuning as with most tuning. you need to concentrate on one major adjustment at a time. yes if you alter away from stock settings, you might need to re adjust your sway setup.

Likewise anyone with a BMR run full stiff on DOT R compound tires? I did it once on my GTO and will probably never do it again. Grips on the track like a MOFO, but it is SO different in feel.

[DZG8GT]

Thanks for all the info guys. I will inspect again and shoot for a level bar.I do still have the stock link and when I install, I tried to closely mimic the stock length. I may also drop to a lower hole on the rear. Sorry for late response as I was on vacation all last week with no puter.

[SpeedRacerX]

The Pedders bars allow for more balance between over/understeer. I have the BMR bars and with my particular setup I cannot set the front bar to full stiff because it has way too much understeer. Setting the front full soft and rear full hard provided me with the perfect balance of oversteer when combined with setting the front camber to -1.0 and rear camber to -.50.


well that's another thing too. Other alignment changes affect over steer and underster drastically as well. for example - running significantly less Toe in (significant in this case means less than 1/4 of the stock value)

With suspension tuning as with most tuning. you need to concentrate on one major adjustment at a time. yes if you alter away from stock settings, you might need to re adjust your sway setup.

Likewise anyone with a BMR run full stiff on DOT R compound tires? I did it once on my GTO and will probably never do it again. Grips on the track like a MOFO, but it is SO different in feel.

There's great info in here.

Do your opinions on sway settings change when a staggered setup is run? I would think so...

[Napalm]

I never got to a stagger setup on my own car.

But I put 2 hotchkis kits on other GTO's with larger rear tires. Honestly with the limits of grip and the limits of roll - we ended up with the same settings. med front, med strong rear. Hotchkis GTO bars had 4 settings in the rear. probably didn't need them all.

I could see where running a larger tire on the rear of a G8 might make you want to have a stronger front bar to balance out the grip of the rear. Maybe. Again it would be a case of try and see.

Side note: I have always advocated parking lot testing (some call it cutting donuts). Every time I get new tires, or I change up a part I would run fig 8's in an empty parking lot to find the chassis behavior at the limit. For me I think of it as a safety thing. When I got my G8 I did this as well and I must say this level of stability assistance is amazing and a bit disconcerting when you actually use it at the limit for the first time. again though my 0.03

[SpeedRacerX]

Oh I agree. I always try to test the limit in the safest setting I can so I know about where it is.

Quite frankly, with my son about to get his license in about 3 weeks, part of me believes these kids should learn what a slide, understeer, oversteer, losing the front tires, sliding in rain, locking up brakes or abs kicking in, etc feel like to help them understand what to do if a real world situation pops up.

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[Napalm]

Oh I agree. I always try to test the limit in the safest setting I can so I know about where it is.

Quite frankly, with my son about to get his license in about 3 weeks, part of me believes these kids should learn what a slide, understeer, oversteer, losing the front tires, sliding in rain, locking up brakes or abs kicking in, etc feel like to help them understand what to do if a real world situation pops up.

Sent from my SAMSUNG-SGH-I997 using Tapatalk

They would in Sweden and in Norway