a true rear sway bar
Junior Member
Joined: Feb 2005
Posts: 5
From: Valley Springs CA
Ok. Lets look at what an anti-sway bar is supposed to do.
First and foremost reduce body sway.
Second, do so without negatively affecting suspension travel.
So how does it do both?
First it connects the left and right suspensions with a torsion bar. (For those of you who don’t know, a torsion bar is just a straightened out coil spring) When cornering, the side which is on the outside of the corner is compressed, which pushes up on the lever connected to the torsion bar. At the same time, the opposite side is extended, which pulls down on the opposite lever. Since one side is pushing and the other pulling, the bar is twisted. This effectively increases the spring rate when cornering. But if both sides are compressed (when hitting a dip in the road for example) the bar simply turns in it’s mounts (on a “proper” frame mounted anti-sway bar) so it has no effect on spring rate.
On our wonderful boxes, the rear axle is basically a very crude form of independent suspension. While the left and right sides are connected by the beam. The U-shape and engineered in flex it allows, basically acts as two independent suspension assemblies. Stiffening this engineered in flex has the same effect as a “proper” anti-sway bar. While it does not leverage against the chassis to do this, it still has the proper effect (increasing the left to right spring rate differential, without affecting the ride by artificially increasing the spring rate in normal non cornering situations). This reduces body sway but allows for full travel, thus doing what it is an anti-sway bar is “supposed” to do.
The only benefit a “true” or “proper” anti-sway bar will give you is adjustability. This would be nice in many situations, but can be achieved with currently available suspension parts.
Boxing the beam would have the same effect as the available “stiffening bars” but most likely would make it way too stiff.
Remember that the majority of street cars out there are already way too stiff. Very often stiff feels fast, but isn’t necessarily so. Sliding thru a corner makes you look like a hero (at least in your own mind), but hitting the apex perfectly without a squeal is almost always faster.
First and foremost reduce body sway.
Second, do so without negatively affecting suspension travel.
So how does it do both?
First it connects the left and right suspensions with a torsion bar. (For those of you who don’t know, a torsion bar is just a straightened out coil spring) When cornering, the side which is on the outside of the corner is compressed, which pushes up on the lever connected to the torsion bar. At the same time, the opposite side is extended, which pulls down on the opposite lever. Since one side is pushing and the other pulling, the bar is twisted. This effectively increases the spring rate when cornering. But if both sides are compressed (when hitting a dip in the road for example) the bar simply turns in it’s mounts (on a “proper” frame mounted anti-sway bar) so it has no effect on spring rate.
On our wonderful boxes, the rear axle is basically a very crude form of independent suspension. While the left and right sides are connected by the beam. The U-shape and engineered in flex it allows, basically acts as two independent suspension assemblies. Stiffening this engineered in flex has the same effect as a “proper” anti-sway bar. While it does not leverage against the chassis to do this, it still has the proper effect (increasing the left to right spring rate differential, without affecting the ride by artificially increasing the spring rate in normal non cornering situations). This reduces body sway but allows for full travel, thus doing what it is an anti-sway bar is “supposed” to do.
The only benefit a “true” or “proper” anti-sway bar will give you is adjustability. This would be nice in many situations, but can be achieved with currently available suspension parts.
Boxing the beam would have the same effect as the available “stiffening bars” but most likely would make it way too stiff.
Remember that the majority of street cars out there are already way too stiff. Very often stiff feels fast, but isn’t necessarily so. Sliding thru a corner makes you look like a hero (at least in your own mind), but hitting the apex perfectly without a squeal is almost always faster.
Senior Member
SL Member
Team ScioNRG
Joined: May 2004
Posts: 757
From: NJ
Originally Posted by hotbox05
Maybe the progress bar really is enough , well that and the trd echo piece.
I've looked at it...and its not impossible but its not going to be cheap.
maybe someone can talk to these guys for us. I'd do it...but only if their was a real list of buyers.
http://www.chassisengineering.com/rearsuspension.html
Senior Member
SL Member
Joined: Jan 2005
Posts: 2,030
From: Wheaton, IL
fjcracker, you are my hero!!
I was going to post, "if a *proper* sway were better, then
why didn't TRD make one for us?".
What, you think they don't know how? If it doesn't exist, then
I'm sure there is a reason for it being that way. I think
fjcracker nailed it.
I was going to post, "if a *proper* sway were better, then
why didn't TRD make one for us?".
What, you think they don't know how? If it doesn't exist, then
I'm sure there is a reason for it being that way. I think
fjcracker nailed it.
Senior Member
SL Member
Joined: Jan 2004
Posts: 645
From: San Ramon, CA
Originally Posted by fjcracker
Ok. Lets look at what an anti-sway bar is supposed to do.
First and foremost reduce body sway.
Second, do so without negatively affecting suspension travel.
So how does it do both?
First it connects the left and right suspensions with a torsion bar. (For those of you who don’t know, a torsion bar is just a straightened out coil spring) When cornering, the side which is on the outside of the corner is compressed, which pushes up on the lever connected to the torsion bar. At the same time, the opposite side is extended, which pulls down on the opposite lever. Since one side is pushing and the other pulling, the bar is twisted. This effectively increases the spring rate when cornering. But if both sides are compressed (when hitting a dip in the road for example) the bar simply turns in it’s mounts (on a “proper” frame mounted anti-sway bar) so it has no effect on spring rate.
On our wonderful boxes, the rear axle is basically a very crude form of independent suspension. While the left and right sides are connected by the beam. The U-shape and engineered in flex it allows, basically acts as two independent suspension assemblies. Stiffening this engineered in flex has the same effect as a “proper” anti-sway bar. While it does not leverage against the chassis to do this, it still has the proper effect (increasing the left to right spring rate differential, without affecting the ride by artificially increasing the spring rate in normal non cornering situations). This reduces body sway but allows for full travel, thus doing what it is an anti-sway bar is “supposed” to do.
The only benefit a “true” or “proper” anti-sway bar will give you is adjustability. This would be nice in many situations, but can be achieved with currently available suspension parts.
Boxing the beam would have the same effect as the available “stiffening bars” but most likely would make it way too stiff.
Remember that the majority of street cars out there are already way too stiff. Very often stiff feels fast, but isn’t necessarily so. Sliding thru a corner makes you look like a hero (at least in your own mind), but hitting the apex perfectly without a squeal is almost always faster.
First and foremost reduce body sway.
Second, do so without negatively affecting suspension travel.
So how does it do both?
First it connects the left and right suspensions with a torsion bar. (For those of you who don’t know, a torsion bar is just a straightened out coil spring) When cornering, the side which is on the outside of the corner is compressed, which pushes up on the lever connected to the torsion bar. At the same time, the opposite side is extended, which pulls down on the opposite lever. Since one side is pushing and the other pulling, the bar is twisted. This effectively increases the spring rate when cornering. But if both sides are compressed (when hitting a dip in the road for example) the bar simply turns in it’s mounts (on a “proper” frame mounted anti-sway bar) so it has no effect on spring rate.
On our wonderful boxes, the rear axle is basically a very crude form of independent suspension. While the left and right sides are connected by the beam. The U-shape and engineered in flex it allows, basically acts as two independent suspension assemblies. Stiffening this engineered in flex has the same effect as a “proper” anti-sway bar. While it does not leverage against the chassis to do this, it still has the proper effect (increasing the left to right spring rate differential, without affecting the ride by artificially increasing the spring rate in normal non cornering situations). This reduces body sway but allows for full travel, thus doing what it is an anti-sway bar is “supposed” to do.
The only benefit a “true” or “proper” anti-sway bar will give you is adjustability. This would be nice in many situations, but can be achieved with currently available suspension parts.
Boxing the beam would have the same effect as the available “stiffening bars” but most likely would make it way too stiff.
Remember that the majority of street cars out there are already way too stiff. Very often stiff feels fast, but isn’t necessarily so. Sliding thru a corner makes you look like a hero (at least in your own mind), but hitting the apex perfectly without a squeal is almost always faster.
Member
Joined: Dec 2004
Posts: 16
For the guys that wanted to play around with boxing in the rear beam... You don't need to do the whole thing and make it solid, that's not what I meant. 
... Just start with an 8" long piece in the center, and add width once per week until you find the setup you like. Or you can weld in tabs every couple inches instead... Any combination will work, until the desired effect is attained.
... Just start with an 8" long piece in the center, and add width once per week until you find the setup you like. Or you can weld in tabs every couple inches instead... Any combination will work, until the desired effect is attained.
Senior Member
SL Member
Joined: Jul 2004
Posts: 13,961
well i just got my Progress Technology Rear Anti-Roll Bar/beam stiffener and it took me 30 minutes to install it too, can't really feel any difference in handling yet and i loc-tite nuts and bolts just for added safety
but this is a good mod to do if your on a budget
but this is a good mod to do if your on a budget
Senior Member
SL Member
Joined: Dec 2003
Posts: 232
From: San Diego, CA
If you ever tried to corner hard with a stock XB, it is an plowing, understeering fool of a car. I think even worse with a front strut bar.
The substantial progressive rear sway bar reduces the roll, but more importantly reduces the understeer. Way more balanced (perhaps trickier at the limits). One of these days I'll have to test those limits. I need a good, empty parking lot.....
The substantial progressive rear sway bar reduces the roll, but more importantly reduces the understeer. Way more balanced (perhaps trickier at the limits). One of these days I'll have to test those limits. I need a good, empty parking lot.....
Senior Member
SL Member
Team N.V.S.
Joined: Sep 2004
Posts: 13,706
From: Sacramento, CA / Nor*Cal
Originally Posted by jomo
I need a good, empty parking lot.....
Thread Starter
Banned
SL Member
Team N.V.S.
Scinergy
Scion Evolution
Scinergy
Scion Evolution
Joined: Jul 2003
Posts: 4,770
From: 886motorwerx
Originally Posted by hornet_on_flower
well i just got my Progress Technology Rear Anti-Roll Bar/beam stiffener and it took me 30 minutes to install it too, can't really feel any difference in handling yet and i loc-tite nuts and bolts just for added safety
but this is a good mod to do if your on a budget
but this is a good mod to do if your on a budget
Senior Member
DeepSouth Scions
SL Member
Joined: Oct 2004
Posts: 463
From: New Orleans, LA
Originally Posted by Tamago
well, i ordered the TRD rear brace system.. gonna give it a try, and if i like, i'll be selling my Hotchkis rear "sway" bar.
