JKS J spec or Rancho lift
03-19-2019, 09:10 AM
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JKS J spec or Rancho lift
Just looking for opinions from people who have run either or both lifts. I’m looking at doing the JKS 3.5 inch J Spec lift or the Rancho Crawler 4 inch lift. Both are right in my price range and with Racho’s rebate right now the 4 inch lift is looking good.
This is going on a 2007 JK 2 door with auto trans with D44 and 4:11 gears. I’m looking to run 35’s comfortably off road with no rubbing. I have ready you can do the same thing on a 2.5 inch lift but for the same money why not just go up the extra 1 to 1.5 inches.
This is going on a 2007 JK 2 door with auto trans with D44 and 4:11 gears. I’m looking to run 35’s comfortably off road with no rubbing. I have ready you can do the same thing on a 2.5 inch lift but for the same money why not just go up the extra 1 to 1.5 inches.
03-19-2019, 09:18 AM
#2
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So I'll start with the standard response you're likely to see.
1. Please be sure to read this thread as it'll be helpful - https://www.jk-forum.com/forums/modified-jk-tech-2/my-thoughts-lifts-288269/
2. The difference between a 2.5 inch lift and a 3.5-4 inch lift is quite a bit. (see thread above for reference). When you get past 3" of lift, more of the suspension and steering geometry is affected. This will require more than what either of those kits are going to address.
Lifts that are in the 3.5 and above range need to address the drag link and track bar being out of parallel. Also need to address the caster being too low now (either adjustable control arms or control arm drop brackets).
What, specifically, is your goal with you rig? Light trails? High speed driving off road? Rock crawling? Mudding? That should lead you to the tire size... the tire size should lead you to the lift size.
1. Please be sure to read this thread as it'll be helpful - https://www.jk-forum.com/forums/modified-jk-tech-2/my-thoughts-lifts-288269/
2. The difference between a 2.5 inch lift and a 3.5-4 inch lift is quite a bit. (see thread above for reference). When you get past 3" of lift, more of the suspension and steering geometry is affected. This will require more than what either of those kits are going to address.
Lifts that are in the 3.5 and above range need to address the drag link and track bar being out of parallel. Also need to address the caster being too low now (either adjustable control arms or control arm drop brackets).
What, specifically, is your goal with you rig? Light trails? High speed driving off road? Rock crawling? Mudding? That should lead you to the tire size... the tire size should lead you to the lift size.
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Rancho (03-19-2019)
03-19-2019, 09:49 AM
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So I'll start with the standard response you're likely to see.
1. Please be sure to read this thread as it'll be helpful - https://www.jk-forum.com/forums/modified-jk-tech-2/my-thoughts-lifts-288269/
2. The difference between a 2.5 inch lift and a 3.5-4 inch lift is quite a bit. (see thread above for reference). When you get past 3" of lift, more of the suspension and steering geometry is affected. This will require more than what either of those kits are going to address.
Lifts that are in the 3.5 and above range need to address the drag link and track bar being out of parallel. Also need to address the caster being too low now (either adjustable control arms or control arm drop brackets).
What, specifically, is your goal with you rig? Light trails? High speed driving off road? Rock crawling? Mudding? That should lead you to the tire size... the tire size should lead you to the lift size.
1. Please be sure to read this thread as it'll be helpful - https://www.jk-forum.com/forums/modified-jk-tech-2/my-thoughts-lifts-288269/
2. The difference between a 2.5 inch lift and a 3.5-4 inch lift is quite a bit. (see thread above for reference). When you get past 3" of lift, more of the suspension and steering geometry is affected. This will require more than what either of those kits are going to address.
Lifts that are in the 3.5 and above range need to address the drag link and track bar being out of parallel. Also need to address the caster being too low now (either adjustable control arms or control arm drop brackets).
What, specifically, is your goal with you rig? Light trails? High speed driving off road? Rock crawling? Mudding? That should lead you to the tire size... the tire size should lead you to the lift size.
I have owned a lot of Jeeps in my life (31 to be exact) ranging from an MB,CJ’s an LJ Rubicon, even an M715. This is my first JK and I’m kind of shocked that the JK needs so much more to lift it past 2.5 inches than a TJ/LJ. I’ve done a lot of reading and I’m willing run the lift and deal with the driveshaft issues later. The Rancho lift comes with adjustable arms and that was the main reason I wanted to run it, besides Racho’s reputation for quality products (they make great springs for a SOA lift on a CJ).
With the Rancho lift and a set of JKS sway bar discos what else would I need? I’d love to just do a 3.5 Rancho lift with the arms but they seem to only offer the 4 inch Crawler.
03-19-2019, 09:55 AM
#5
JK Jedi
03-19-2019, 09:58 AM
#6
So what some do (and I don't know the cost break down)
Is run our 3" SPORT, a front geo correction bracket and rear arms.
That would also be a nice setup
Rancho Control Arm Correction Brackets - RS6250B
RS66157B (rear upper)
RS66158B (rear lower)
And we still sale a TON of leaf packs too, usually RS440044
This is going to be my sons first Jeep so I would say light off-roading just teach him.
I have owned a lot of Jeeps in my life (31 to be exact) ranging from an MB,CJ’s an LJ Rubicon, even an M715. This is my first JK and I’m kind of shocked that the JK needs so much more to lift it past 2.5 inches than a TJ/LJ. I’ve done a lot of reading and I’m willing run the lift and deal with the driveshaft issues later. The Rancho lift comes with adjustable arms and that was the main reason I wanted to run it, besides Racho’s reputation for quality products (they make great springs for a SOA lift on a CJ).
With the Rancho lift and a set of JKS sway bar discos what else would I need? I’d love to just do a 3.5 Rancho lift with the arms but they seem to only offer the 4 inch Crawler.
Is run our 3" SPORT, a front geo correction bracket and rear arms.
That would also be a nice setup
Rancho Control Arm Correction Brackets - RS6250B
RS66157B (rear upper)
RS66158B (rear lower)
And we still sale a TON of leaf packs too, usually RS440044
This is going to be my sons first Jeep so I would say light off-roading just teach him.
I have owned a lot of Jeeps in my life (31 to be exact) ranging from an MB,CJ’s an LJ Rubicon, even an M715. This is my first JK and I’m kind of shocked that the JK needs so much more to lift it past 2.5 inches than a TJ/LJ. I’ve done a lot of reading and I’m willing run the lift and deal with the driveshaft issues later. The Rancho lift comes with adjustable arms and that was the main reason I wanted to run it, besides Racho’s reputation for quality products (they make great springs for a SOA lift on a CJ).
With the Rancho lift and a set of JKS sway bar discos what else would I need? I’d love to just do a 3.5 Rancho lift with the arms but they seem to only offer the 4 inch Crawler.
03-19-2019, 10:05 AM
#7
Super Moderator
Actually, my bad. The kit from Rancho that pulled up for me the first time didn't have the adjustable CAs. You'll still need to take a look at your steering geometry once the lift is actually on. Specifically, compare the drag link and the track bar. If these are not parallel, you'll end up with some flighty steering. Stay away from dropped pitman arms. You may need to consider a drag link flip.
The higher you go, the steeper your steering angles get. The steeper they get, the more susceptible you are to bump steer and the more shock is transmitted to your steering box. More bump force is sent down the length of the drag link and not lost thru rotation of the TRE. There are two ways to correct. A drop frame TB bracket and drop pitman arm is one way, but it lowers your roll center of the jeep, decreasing handling in corners. So it is advised against. Flipping the DL and raising the axle TB mount is the better method. It raises the roll center increasing handling. The key to either setup is the track bar and the draglink have to remain both parallel to each other, and in the same plane. You can not run a DL flip with drop frame TB mount, and you cannot run a drop pitman arm with raised axle TB mount. The ideal setup is both links perfectly parallel to the ground, raised, in the same plane. This is close to how it comes from the factory (slight angle) and to achieve this at higher lifts you may have to increase bump stops or notch frame.
The higher you go, the steeper your steering angles get. The steeper they get, the more susceptible you are to bump steer and the more shock is transmitted to your steering box. More bump force is sent down the length of the drag link and not lost thru rotation of the TRE. There are two ways to correct. A drop frame TB bracket and drop pitman arm is one way, but it lowers your roll center of the jeep, decreasing handling in corners. So it is advised against. Flipping the DL and raising the axle TB mount is the better method. It raises the roll center increasing handling. The key to either setup is the track bar and the draglink have to remain both parallel to each other, and in the same plane. You can not run a DL flip with drop frame TB mount, and you cannot run a drop pitman arm with raised axle TB mount. The ideal setup is both links perfectly parallel to the ground, raised, in the same plane. This is close to how it comes from the factory (slight angle) and to achieve this at higher lifts you may have to increase bump stops or notch frame.
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03-19-2019, 10:53 AM
#8
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Actually, my bad. The kit from Rancho that pulled up for me the first time didn't have the adjustable CAs. You'll still need to take a look at your steering geometry once the lift is actually on. Specifically, compare the drag link and the track bar. If these are not parallel, you'll end up with some flighty steering. Stay away from dropped pitman arms. You may need to consider a drag link flip.
The higher you go, the steeper your steering angles get. The steeper they get, the more susceptible you are to bump steer and the more shock is transmitted to your steering box. More bump force is sent down the length of the drag link and not lost thru rotation of the TRE. There are two ways to correct. A drop frame TB bracket and drop pitman arm is one way, but it lowers your roll center of the jeep, decreasing handling in corners. So it is advised against. Flipping the DL and raising the axle TB mount is the better method. It raises the roll center increasing handling. The key to either setup is the track bar and the draglink have to remain both parallel to each other, and in the same plane. You can not run a DL flip with drop frame TB mount, and you cannot run a drop pitman arm with raised axle TB mount. The ideal setup is both links perfectly parallel to the ground, raised, in the same plane. This is close to how it comes from the factory (slight angle) and to achieve this at higher lifts you may have to increase bump stops or notch frame.
The higher you go, the steeper your steering angles get. The steeper they get, the more susceptible you are to bump steer and the more shock is transmitted to your steering box. More bump force is sent down the length of the drag link and not lost thru rotation of the TRE. There are two ways to correct. A drop frame TB bracket and drop pitman arm is one way, but it lowers your roll center of the jeep, decreasing handling in corners. So it is advised against. Flipping the DL and raising the axle TB mount is the better method. It raises the roll center increasing handling. The key to either setup is the track bar and the draglink have to remain both parallel to each other, and in the same plane. You can not run a DL flip with drop frame TB mount, and you cannot run a drop pitman arm with raised axle TB mount. The ideal setup is both links perfectly parallel to the ground, raised, in the same plane. This is close to how it comes from the factory (slight angle) and to achieve this at higher lifts you may have to increase bump stops or notch frame.
So so could I get the Rancho 4 inch Crawler put it on and then add on as I go?
Is the bump steer any worse in a lifted JK vs a Lifted TJ?
03-19-2019, 10:53 AM
#9
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So what some do (and I don't know the cost break down)
Is run our 3" SPORT, a front geo correction bracket and rear arms.
That would also be a nice setup
Rancho Control Arm Correction Brackets - RS6250B
RS66157B (rear upper)
RS66158B (rear lower)
And we still sale a TON of leaf packs too, usually RS440044
Is run our 3" SPORT, a front geo correction bracket and rear arms.
That would also be a nice setup
Rancho Control Arm Correction Brackets - RS6250B
RS66157B (rear upper)
RS66158B (rear lower)
And we still sale a TON of leaf packs too, usually RS440044
03-19-2019, 11:32 AM
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Think about those two sentences. Lift 1 is out because it doesn't come with a component, but then you ask if you can add components to lift 2? You can add components to ANY lift. At ANY time.
This is my first JK and I’m kind of shocked that the JK needs so much more to lift it past 2.5 inches than a TJ/LJ.
At that point I’d just do the 2.5 inch lift
Last edited by nthinuf; 03-19-2019 at 11:36 AM.