Forums
New posts
Search forums
Image search
Shop
Amazon Store
T-Shirts
Stickers
Members
Current visitors
Supporting Member Upgrade
Sponsors
About
Log in
Register
Search
Search titles only
By:
Search titles only
By:
New posts
Search forums
Image search
Search
Search titles only
By:
Search titles only
By:
Menu
Install the app
Install
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Jeep Wrangler JK
JK General Discussion
I guess I've joined the JK owners club. Introducing my Anvil JK.
Reply to thread
Message
<blockquote data-quote="Fargo" data-source="post: 443452" data-attributes="member: 20727"><p>Not entirely true. Raising the track bar will also raise the roll center, (not to be confused with the center of gravity). Raising the roll center raises the point at which the body rotates around. Thus it has less body roll. Raising the trackbar will also bring the trackbar and drag link back into parallel planes so it will have less bumpster and handling quirks. On the other hand the 2.5" lift has less lift so these items are less affected. Its kind of a give and take. Thats why I go back and forth between 3.5 and 2.5 lifts.</p><p></p><p>From AEV: <a href="https://www.aev-conversions.com/12-things-know-lifted-suspension-engineering/" target="_blank">https://www.aev-conversions.com/12-things-know-lifted-suspension-engineering/</a></p><p></p><p>Roll-Center Geometry</p><p>Roll-center is the imaginary point around which the body leans in a turn and also around which it moves when the suspension flexes on a trail. There is one roll-center each for the<a href="https://www.aev-conversions.com/product/ram-hd-3%e2%80%b3-dualsport-suspension-rt-2019/" target="_blank"> front and rear suspensions</a>. The location of each roll-center for most solid-axle suspensions is defined by the geometry of the track-bars (aka panhard bars). On late-model solid-axle Jeeps, the front track-bar runs in front of the axle from the frame on the driver’s side to the axle on the passenger’s side. The rear bar is behind the axle and the attachments are reversed. The actual roll-center is found by drawing an imaginary vertical line down the middle of the vehicle and another straight line between the bolts at the ends of the track bar (ignore the bends in the bar). The intersection of these two lines is the roll-center.</p><p></p><p>Roll-center is important to suspension engineers because its correct placement relative to the center of gravity is central to managing both body lean and weight transfer in turns. The farther apart the roll-center from the center of gravity, the more lean you have and the more handling degrades. If the roll center location is not ideal for the vehicle, it forces the engineer to try to ‘correct’ the problem with spring and/or shock tuning – which always results in a loss of performance somewhere else. This is one of the critical geometry parameters that must be right before you tune, or lift, the vehicle. When properly located relative to the center of gravity the roll-centers (defined by track bar placement) will allow the engineer to further optimize overall suspension performance via springs and shocks, etc. – without the burden of having to attempt to compensate for poor geometry. If one looks at the track-arm locations on AEV JK suspension systems, one will see that both the front and rear track-arms have been significantly repositioned to place the roll-centers in the optimal locations for either 3.5 or 4.5-inch lift heights.</p><p></p><p>Steering Geometry</p><p>Since any street-legal vehicle must have a mechanical steering connection from driver to tires, this system is critically affected by any suspension height change. Most enthusiasts are by now aware that for solid axle vehicles, the track-bar and steering drag-link must be parallel to avoid ‘bump-steer,’ but that’s just the beginning of the considerations. Roll-steer is caused when the steering linkage doesn’t pass through the roll-center of the suspension geometry – meaning that every time the vehicle leans or articulates, there is a steering input that the driver didn’t intend. This happens because there is a small lateral shift of the axle relative to the pitman arm on the steering box. This shift effectively steers the vehicle without driver input. To visualize this, think of holding the steering wheel (and consequently all of the linkage) steady and moving the axle side-to-side. Since the steering didn’t move but the axle did, the steering knuckles must rotate to make up the difference – which creates unwanted steering. On twisty, bumpy roads, roll-steer, along with the larger problem of rear suspension roll-steer (see #2), can keep the driver very busy trying to maintain the intended direction. This is because the vehicle is always doing ‘extra’ things the driver didn’t intend. This quickly leads to driver fatigue and frustration with the behavior of the vehicle. To eliminate this in AEV’s JK suspension systems, AEV engineers developed the JK High-Steer Kit. This kit repositions both the track-arm and steering drag-link. The new positions flatten the operating angles and ensure that the drag-link passes through the roll-center of the suspension geometry. The overall result is reduced driver fatigue, improved safety and very precise steering response.</p></blockquote><p></p>
[QUOTE="Fargo, post: 443452, member: 20727"] Not entirely true. Raising the track bar will also raise the roll center, (not to be confused with the center of gravity). Raising the roll center raises the point at which the body rotates around. Thus it has less body roll. Raising the trackbar will also bring the trackbar and drag link back into parallel planes so it will have less bumpster and handling quirks. On the other hand the 2.5" lift has less lift so these items are less affected. Its kind of a give and take. Thats why I go back and forth between 3.5 and 2.5 lifts. From AEV: [URL]https://www.aev-conversions.com/12-things-know-lifted-suspension-engineering/[/URL] Roll-Center Geometry Roll-center is the imaginary point around which the body leans in a turn and also around which it moves when the suspension flexes on a trail. There is one roll-center each for the[URL='https://www.aev-conversions.com/product/ram-hd-3%e2%80%b3-dualsport-suspension-rt-2019/'] front and rear suspensions[/URL]. The location of each roll-center for most solid-axle suspensions is defined by the geometry of the track-bars (aka panhard bars). On late-model solid-axle Jeeps, the front track-bar runs in front of the axle from the frame on the driver’s side to the axle on the passenger’s side. The rear bar is behind the axle and the attachments are reversed. The actual roll-center is found by drawing an imaginary vertical line down the middle of the vehicle and another straight line between the bolts at the ends of the track bar (ignore the bends in the bar). The intersection of these two lines is the roll-center. Roll-center is important to suspension engineers because its correct placement relative to the center of gravity is central to managing both body lean and weight transfer in turns. The farther apart the roll-center from the center of gravity, the more lean you have and the more handling degrades. If the roll center location is not ideal for the vehicle, it forces the engineer to try to ‘correct’ the problem with spring and/or shock tuning – which always results in a loss of performance somewhere else. This is one of the critical geometry parameters that must be right before you tune, or lift, the vehicle. When properly located relative to the center of gravity the roll-centers (defined by track bar placement) will allow the engineer to further optimize overall suspension performance via springs and shocks, etc. – without the burden of having to attempt to compensate for poor geometry. If one looks at the track-arm locations on AEV JK suspension systems, one will see that both the front and rear track-arms have been significantly repositioned to place the roll-centers in the optimal locations for either 3.5 or 4.5-inch lift heights. Steering Geometry Since any street-legal vehicle must have a mechanical steering connection from driver to tires, this system is critically affected by any suspension height change. Most enthusiasts are by now aware that for solid axle vehicles, the track-bar and steering drag-link must be parallel to avoid ‘bump-steer,’ but that’s just the beginning of the considerations. Roll-steer is caused when the steering linkage doesn’t pass through the roll-center of the suspension geometry – meaning that every time the vehicle leans or articulates, there is a steering input that the driver didn’t intend. This happens because there is a small lateral shift of the axle relative to the pitman arm on the steering box. This shift effectively steers the vehicle without driver input. To visualize this, think of holding the steering wheel (and consequently all of the linkage) steady and moving the axle side-to-side. Since the steering didn’t move but the axle did, the steering knuckles must rotate to make up the difference – which creates unwanted steering. On twisty, bumpy roads, roll-steer, along with the larger problem of rear suspension roll-steer (see #2), can keep the driver very busy trying to maintain the intended direction. This is because the vehicle is always doing ‘extra’ things the driver didn’t intend. This quickly leads to driver fatigue and frustration with the behavior of the vehicle. To eliminate this in AEV’s JK suspension systems, AEV engineers developed the JK High-Steer Kit. This kit repositions both the track-arm and steering drag-link. The new positions flatten the operating angles and ensure that the drag-link passes through the roll-center of the suspension geometry. The overall result is reduced driver fatigue, improved safety and very precise steering response. [/QUOTE]
Verification
Post reply
Jeep Wrangler JK
JK General Discussion
I guess I've joined the JK owners club. Introducing my Anvil JK.
Top
Bottom