Swaybars Upgrade Vs Stock Vs None

[XT6Wagon]

SO I finished putting the 10K rear springs on the GPMoto coilovers today. Rides virtualy the same as the 6K rear springs, but I can't test the handling quite yet because of......

 

A upgraded rear swaybar tore one of the swaybar mounts clean off.

 

So while the upgraded bars without stiffer rear mounts seemed to do nothign at all for the car, I am currently wondering if the correct solution to getting these cars to handlie great isn't to actualy toss the stock bars in the trash and run w/o any swaybars at all. I'm thinking that this will reduce some of the ride penalty from running stiff springs, and actualy provide more grip since it seems like the coilovers can keep the suspension in the correct operating range on thier own.

 

Just like to see others thoughts on this topic.

[mwiener2]

um, no. You kinda need a swaybar

[RobY]

SO I finished putting the 10K rear springs on the GPMoto coilovers today. Rides virtualy the same as the 6K rear springs, but I can't test the handling quite yet because of......

 

A upgraded rear swaybar tore one of the swaybar mounts clean off.

 

So while the upgraded bars without stiffer rear mounts seemed to do nothign at all for the car, I am currently wondering if the correct solution to getting these cars to handlie great isn't to actualy toss the stock bars in the trash and run w/o any swaybars at all. I'm thinking that this will reduce some of the ride penalty from running stiff springs, and actualy provide more grip since it seems like the coilovers can keep the suspension in the correct operating range on thier own.

 

Just like to see others thoughts on this topic.

 

 

 

Pictarz Plz?

[Xantium]

Without sway bars, the outside tire in a corner will be doing almost ALL the work, you need a sway to push the other wheel down.... when the wheel on the right is compressed, it compresses and other wheel and decompresses itself a bit... do you understand how sway bars work?

[XT6Wagon]

Um, swaybars ADD load to the outside tire... And yes I've got a BS in ME so I know about these sorts of things.

 

 

Basicly what happens is the body rolls compressing the outside suspension. This also extends the inside suspension. When that happens the swaybar comes into play. It pushes down on the outside suspension, UP on the outside swaybar mount Down on the inside swaybar mount, and Up on the inside suspension. This reduces the load on the inside tire and adds load to the outside tire.

 

I only wish there was some magic way to keep from transfering wieght to the outside, but there isn't really one.

[Xenonk]

add, "negative add", however you see fit, basically, a sway bar is there to tie the two ends of the axle together so that the suspension actually loses corner suspension independency.

 

(I firmly agree that it ADDs load to the outside tire since the whole car wants to tip over and thus making the inside tire lift.. if you all know how go-karts dont have suspension, so just think of it as if your Legacy had a 500mm solid "sway" bar welded from hub to hub, the car will tip if you have enough tire grip and will lift the inside tires off the ground).

 

The easiest way to prevent weight transfer is weight resistance, so stiffer springs will do the job.

 

Btw, rally cars doing full gravel or snow dont even bother with sways. The shocks are the key to their set up since they run really tall and softer springs. But you gotta keep the independcy at each corner for maximum grip.

 

I forgot to add this note: A sway bar without any good mounting points to act as "tie downs" doesnt do much for the car, hence the feeling that you are getting of, well, not really feeling any. The more points you add to the car for the sway bar mount, the more roll resistance that you will get. It's like welding a solid bar across the two hubs along the chassis of the car (aka "infinite-mounted sway bar"). The bar needs some kind of fulcrum/medium to make the transitition from negative downforce to positive down force.

 

 

 

Keefe

[Borti]

add, "negative add", however you see fit, basically, a sway bar is there to tie the two ends of the axle together so that the suspension actually loses corner suspension independency.

 

(I firmly agree that it ADDs load to the outside tire since the whole car wants to tip over and thus making the inside tire lift.. if you all know how go-karts dont have suspension, so just think of it as if your Legacy had a 500mm solid "sway" bar welded from hub to hub, the car will tip if you have enough tire grip and will lift the inside tires off the ground).

 

The easiest way to prevent weight transfer is weight resistance, so stiffer springs will do the job.

 

Btw, rally cars doing full gravel or snow dont even bother with sways. The shocks are the key to their set up since they run really tall and softer springs. But you gotta keep the independcy at each corner for maximum grip.

 

I forgot to add this note: A sway bar without any good mounting points to act as "tie downs" doesnt do much for the car, hence the feeling that you are getting of, well, not really feeling any. The more points you add to the car for the sway bar mount, the more roll resistance that you will get. It's like welding a solid bar across the two hubs along the chassis of the car (aka "infinite-mounted sway bar"). The bar needs some kind of fulcrum/medium to make the transitition from negative downforce to positive down force.

 

 

 

Keefe

 

Solid post, especially the part about the struts on rally cars. My friend used to work for an automotive firm in California and his boss used to always say, "The key to a well-balanced/ well performing suspension is a good strut." Apparently he has loads of engineering experience as well, so its not total bs, if you think it is at all.

[sgt]

Sway bars basically make up for a lower spring rate.

Typically the proper spring rate is way too stiff for daily street use, so to maintain the ride

quality, a larger sway bar is used to help out the softer springs.

[rallispec]

umm.. what sway bar were you using that ripped the mounting brackets off?!

 

 

are the USDM mounts the same as the JDM mounts? I assumed they were, in which case you should have problem up to a 20mm bar.

[XT6Wagon]

Here is a picture of the lovely damage.http://www.ej255.net/swaybar.jpg

 

As you can see it tore right across the top of the upper welded on nut. looks like the single stiffening fold was good enough to force it to break off a good bit lower than the unstiffened side.

 

The bar was a prototype GPMoto bar, but since it follows normal swaybar routing, and is of normal size... I am 100% sure that its not the cause. But frankly looking at the space avalible, stock routing may not be the proper answer anyway. And certainly running the stock mounts is far far from the correct answer. Having looked at the construction of the stock mounts I bet one could "upgrade" even thier stock swaybar with a stiffer mount.

[ADirtyLegacy]

oi vey!

 

a set of stiff springs, a set of Penskes...who needs a sway bar?!?!?

 

Kenda

[rallispec]

wow.

 

It's amazing that nobody else has had this problem (that i'm aware of) -- with the number of people with stiffer sway bars.

 

 

 

still - considering that the JDM legacy comes stock with the stiffer sway bar - i would imagine that the stock moutns would be up to the task.

[XT6Wagon]

Likely much of it is that I've likely put more hard miles on a twisty road than most people... and much of my commute has elevation change coupled with the corners, and more than a few hard bumps. Basicly the commute is a twisty back road w/o anything to spoil the fun other than say a Jetta. Well I guess the guys with 80's toyota pickups + scratchbuilt POS trailers are almost as slow.

 

So its like breaking a paper clip by bending it constantly, I was just flexing the mount back and forth till it got brittle and broke.

 

Also while I don't expect a JDM swaybar to break the stock mounts, I would expect a "stiffer" bar to result from stiffening the mounts since it would stop extra motion that would rob the bar of some of its effectiveness.

[XT6Wagon]

Ok, I've pulled both front and rear swaybar off. So far the early impressions are that the 9/10K spring combo is plush. Its amazing how much the swaybars chew up ride quality. Haven't got a chance to test it on the concrete interstates that are the usualy bane of coilovers, but from the broken pavement, railroad tracks, and other evils of the industrial area I work it, it seems like it will be decent.

 

That said the roll stiffness so far seems a bit soft for my tastes. Haven't caned the car on a twisty road or roadcourse yet so the jury is still way out on this.

 

Then you get to one of the real issues of these setups. The stiffer the spring the less droop travel you will have with a linear rate spring. The 10Ks cause the car to sit nearly a inch up from the 6K springs. With the 12K or 13K springs that my gut tells me will be correct to run w/o swaybars for the feel I want, I worry that there will be little extention travel left. Tender springs could solve this but..... I'm not convinced they are approprate as commonly used.