Why do the shocks hang so low in the rear?
06-13-2008, 03:56 AM
#1
JK Enthusiast
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Why do the shocks hang so low in the rear?
Ive see rock krawler offers a relocation bracket that connects your rear shock to the top of the axle. Why isn't it like that from jeep? Is there a geometry issue with relocating the shock mount to the top of the axle?
06-13-2008, 05:58 AM
#2
JK Junkie
You just have to be careful about raising it too much and limiting your up-travel. I have about an inch before my shocks will bottom out and plan on raising mine. I would gain an inch of drop by doing that too. I will need brake lines before I do that though... If the stock Jeep had higher mounts, a shorter should would be necessary. That would limit travel.
06-15-2008, 04:43 AM
#5
I don't know why they are mounted so low. I would think that moving them closer to the outside would improve ride quality. I don't understand all the geometry of making an axle work for on and off road but I don't think it would take much to improve the clearance on the bottom of the rear axle. 
06-15-2008, 06:05 AM
#6
JK Jedi Master
The Jeep is a compromise of off and on road capability. We know it favors the off road end of the spectrum, but the engineers have to design for the road, too. I wouldn't say the end product of an engineer's design is always right, but I'll bet there isn't much they don't look at.
06-15-2008, 08:19 AM
#7
JK Jedi Master
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06-15-2008, 08:27 AM
#8
JK Super Freak
The shocks are part of the suspension geometry....and, as they damp up/down/twisting motion, and can limit droop, there are are compromises made to improve/compensate for various factors.
1. The Longer the total shock length, the more wheel travel is possible.
2. To get a longer shock length, you need the upper/lower shock mounts as far from each other as possible.
3. When under power, an axle will twist, and if it reaches its twist limiting factor, and loses traction, the tire will lose traction, and the axle will return to its un-twisted position (Axle hop).
4. The shocks are therefore placed (Typically) on opposite sides of the axle, so as to help FIGHT axle hop, and, if you ever used a lever arm to move something, or brace something...the longer the arm, the more force can be applied.
5. A lower shock mount on top of an axle has a very short lever arm to act upon axle twist...a lower axle mount below the axle has a longer lever arm to control the twist of the axle/damp rotational motion.
6. The use of a lower axle mount below the axle therefore allows a longer overall shock, and therefore more overall wheel travel, as well as providing additional leverage to damp rotational axle motion.
7. Of course, the compromise, is that the more the mount protrudes below the axle, the worse the ground clearance.
8. The point of diminishing return is typically the lower level of the diff itself...so, the lower limit of the lower shock mount typically gets a long enough lever arm, a long enough overall shock length, and the least overall reduction in TOTAL ground clearance, by putting it below the axle at roughly the elevation of the diff's bottom or so.
These are all of the reasons why almost every truck on the road has lower shock mounts that protrude down below the axle....and, are mounted so that one shock is in front of the axle, and one is behind the axle.
There ARE ways to compensate for the above factors...but, simply relocating the lower mount higher merely pre-compresses the shock....but, can allow the same length shock to provide more total droop...IF IT HAS ROOM TO FULLY ALLOW STUFFAGE AS WELL....otherwise, you have more total droop, but can't stuff the tires anymore, etc.
So, new shocks with more total travel, allowing full compression, AND more extension so as to make the relocation IMPROVE articulation, would be required to take advantage of the new location.
Ladder bars, or other links/braces/trusses that add axle wrap/hop resistance to the suspension, can compensate for the control of axle twist...but tend to sometimes bind/limit articulation if not engineered well enough.
As traction of a drooped axle is primarily related to cantilevered forces...inboard shock locations tend to improve downforce on drooped sides, and, tend to actually require LESS total shock length for the same wheel travel on opposite side stuff/droop situations....but, MORE overall shock length for all OTHER droop.
--------------
So - the lower shock mount location is not really a brain fart...like, "DOH.... JUST MAKE IT HIGHER!"......its more of a way to achieve several goals simultaneously....with the clearance being the sacrificial lamb.
Moving the mounts further inboard, and proportionally increasing the valving, proportionally to compensate for the loss in leverage such an angle imposes on damping control, etc....can accomplish many of these objectives for example, but typically require the diff to be modified to allow that kind of angled mount etc...($).
Hope that helps!
1. The Longer the total shock length, the more wheel travel is possible.
2. To get a longer shock length, you need the upper/lower shock mounts as far from each other as possible.
3. When under power, an axle will twist, and if it reaches its twist limiting factor, and loses traction, the tire will lose traction, and the axle will return to its un-twisted position (Axle hop).
4. The shocks are therefore placed (Typically) on opposite sides of the axle, so as to help FIGHT axle hop, and, if you ever used a lever arm to move something, or brace something...the longer the arm, the more force can be applied.
5. A lower shock mount on top of an axle has a very short lever arm to act upon axle twist...a lower axle mount below the axle has a longer lever arm to control the twist of the axle/damp rotational motion.
6. The use of a lower axle mount below the axle therefore allows a longer overall shock, and therefore more overall wheel travel, as well as providing additional leverage to damp rotational axle motion.
7. Of course, the compromise, is that the more the mount protrudes below the axle, the worse the ground clearance.
8. The point of diminishing return is typically the lower level of the diff itself...so, the lower limit of the lower shock mount typically gets a long enough lever arm, a long enough overall shock length, and the least overall reduction in TOTAL ground clearance, by putting it below the axle at roughly the elevation of the diff's bottom or so.
These are all of the reasons why almost every truck on the road has lower shock mounts that protrude down below the axle....and, are mounted so that one shock is in front of the axle, and one is behind the axle.
There ARE ways to compensate for the above factors...but, simply relocating the lower mount higher merely pre-compresses the shock....but, can allow the same length shock to provide more total droop...IF IT HAS ROOM TO FULLY ALLOW STUFFAGE AS WELL....otherwise, you have more total droop, but can't stuff the tires anymore, etc.
So, new shocks with more total travel, allowing full compression, AND more extension so as to make the relocation IMPROVE articulation, would be required to take advantage of the new location.
Ladder bars, or other links/braces/trusses that add axle wrap/hop resistance to the suspension, can compensate for the control of axle twist...but tend to sometimes bind/limit articulation if not engineered well enough.
As traction of a drooped axle is primarily related to cantilevered forces...inboard shock locations tend to improve downforce on drooped sides, and, tend to actually require LESS total shock length for the same wheel travel on opposite side stuff/droop situations....but, MORE overall shock length for all OTHER droop.
--------------
So - the lower shock mount location is not really a brain fart...like, "DOH.... JUST MAKE IT HIGHER!"......its more of a way to achieve several goals simultaneously....with the clearance being the sacrificial lamb.
Moving the mounts further inboard, and proportionally increasing the valving, proportionally to compensate for the loss in leverage such an angle imposes on damping control, etc....can accomplish many of these objectives for example, but typically require the diff to be modified to allow that kind of angled mount etc...($).
Hope that helps!
Last edited by TEEJ; 06-15-2008 at 08:33 AM.
06-15-2008, 12:38 PM
#10
JK Jedi Master
The shocks are part of the suspension geometry....and, as they damp up/down/twisting motion, and can limit droop, there are are compromises made to improve/compensate for various factors.
1. The Longer the total shock length, the more wheel travel is possible.
2. To get a longer shock length, you need the upper/lower shock mounts as far from each other as possible.
3. When under power, an axle will twist, and if it reaches its twist limiting factor, and loses traction, the tire will lose traction, and the axle will return to its un-twisted position (Axle hop).
4. The shocks are therefore placed (Typically) on opposite sides of the axle, so as to help FIGHT axle hop, and, if you ever used a lever arm to move something, or brace something...the longer the arm, the more force can be applied.
5. A lower shock mount on top of an axle has a very short lever arm to act upon axle twist...a lower axle mount below the axle has a longer lever arm to control the twist of the axle/damp rotational motion.
6. The use of a lower axle mount below the axle therefore allows a longer overall shock, and therefore more overall wheel travel, as well as providing additional leverage to damp rotational axle motion.
7. Of course, the compromise, is that the more the mount protrudes below the axle, the worse the ground clearance.
8. The point of diminishing return is typically the lower level of the diff itself...so, the lower limit of the lower shock mount typically gets a long enough lever arm, a long enough overall shock length, and the least overall reduction in TOTAL ground clearance, by putting it below the axle at roughly the elevation of the diff's bottom or so.
These are all of the reasons why almost every truck on the road has lower shock mounts that protrude down below the axle....and, are mounted so that one shock is in front of the axle, and one is behind the axle.
There ARE ways to compensate for the above factors...but, simply relocating the lower mount higher merely pre-compresses the shock....but, can allow the same length shock to provide more total droop...IF IT HAS ROOM TO FULLY ALLOW STUFFAGE AS WELL....otherwise, you have more total droop, but can't stuff the tires anymore, etc.
So, new shocks with more total travel, allowing full compression, AND more extension so as to make the relocation IMPROVE articulation, would be required to take advantage of the new location.
Ladder bars, or other links/braces/trusses that add axle wrap/hop resistance to the suspension, can compensate for the control of axle twist...but tend to sometimes bind/limit articulation if not engineered well enough.
As traction of a drooped axle is primarily related to cantilevered forces...inboard shock locations tend to improve downforce on drooped sides, and, tend to actually require LESS total shock length for the same wheel travel on opposite side stuff/droop situations....but, MORE overall shock length for all OTHER droop.
--------------
So - the lower shock mount location is not really a brain fart...like, "DOH.... JUST MAKE IT HIGHER!"......its more of a way to achieve several goals simultaneously....with the clearance being the sacrificial lamb.
Moving the mounts further inboard, and proportionally increasing the valving, proportionally to compensate for the loss in leverage such an angle imposes on damping control, etc....can accomplish many of these objectives for example, but typically require the diff to be modified to allow that kind of angled mount etc...($).
Hope that helps!
1. The Longer the total shock length, the more wheel travel is possible.
2. To get a longer shock length, you need the upper/lower shock mounts as far from each other as possible.
3. When under power, an axle will twist, and if it reaches its twist limiting factor, and loses traction, the tire will lose traction, and the axle will return to its un-twisted position (Axle hop).
4. The shocks are therefore placed (Typically) on opposite sides of the axle, so as to help FIGHT axle hop, and, if you ever used a lever arm to move something, or brace something...the longer the arm, the more force can be applied.
5. A lower shock mount on top of an axle has a very short lever arm to act upon axle twist...a lower axle mount below the axle has a longer lever arm to control the twist of the axle/damp rotational motion.
6. The use of a lower axle mount below the axle therefore allows a longer overall shock, and therefore more overall wheel travel, as well as providing additional leverage to damp rotational axle motion.
7. Of course, the compromise, is that the more the mount protrudes below the axle, the worse the ground clearance.
8. The point of diminishing return is typically the lower level of the diff itself...so, the lower limit of the lower shock mount typically gets a long enough lever arm, a long enough overall shock length, and the least overall reduction in TOTAL ground clearance, by putting it below the axle at roughly the elevation of the diff's bottom or so.
These are all of the reasons why almost every truck on the road has lower shock mounts that protrude down below the axle....and, are mounted so that one shock is in front of the axle, and one is behind the axle.
There ARE ways to compensate for the above factors...but, simply relocating the lower mount higher merely pre-compresses the shock....but, can allow the same length shock to provide more total droop...IF IT HAS ROOM TO FULLY ALLOW STUFFAGE AS WELL....otherwise, you have more total droop, but can't stuff the tires anymore, etc.
So, new shocks with more total travel, allowing full compression, AND more extension so as to make the relocation IMPROVE articulation, would be required to take advantage of the new location.
Ladder bars, or other links/braces/trusses that add axle wrap/hop resistance to the suspension, can compensate for the control of axle twist...but tend to sometimes bind/limit articulation if not engineered well enough.
As traction of a drooped axle is primarily related to cantilevered forces...inboard shock locations tend to improve downforce on drooped sides, and, tend to actually require LESS total shock length for the same wheel travel on opposite side stuff/droop situations....but, MORE overall shock length for all OTHER droop.
--------------
So - the lower shock mount location is not really a brain fart...like, "DOH.... JUST MAKE IT HIGHER!"......its more of a way to achieve several goals simultaneously....with the clearance being the sacrificial lamb.
Moving the mounts further inboard, and proportionally increasing the valving, proportionally to compensate for the loss in leverage such an angle imposes on damping control, etc....can accomplish many of these objectives for example, but typically require the diff to be modified to allow that kind of angled mount etc...($).
Hope that helps!
Ya, the above is what I meant when I wrote this:
Shock rate and travel were probably what they considered. It is close to the end of the axle to be ok MOST of the time.
The Jeep is a compromise of off and on road capability. We know it favors the off road end of the spectrum, but the engineers have to design for the road, too. I wouldn't say the end product of an engineer's design is always right, but I'll bet there isn't much they don't look at.
The Jeep is a compromise of off and on road capability. We know it favors the off road end of the spectrum, but the engineers have to design for the road, too. I wouldn't say the end product of an engineer's design is always right, but I'll bet there isn't much they don't look at.