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My thoughts on lifts

Old 10-15-2013, 10:02 AM
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Default My thoughts on lifts

My thoughts on JK lifts,



You see it posted almost everyday “new jeep owner, what lift?” and we go thru the motions of what are you going to do with it and what tire size. You also get endless posts of “I am running ***** lift and it is better then stock” along with a poser shot. I still to this day do not understand how someone can see the suspension on a rig from 25 feet away in a photo. Those two important questions to consider when doing a lift, tire size and what you plan to do with it are the keys to setting up your suspension. I am keeping these thoughts mainly on the bolt on kits for the JK.

Most of the op’s have the misconception that somehow a bolt on lift will give them more articulation or “flex” and that a lift will make the Jeep more capable off road. Most will not and some will even make them less capable in some areas when compared to the factory suspension. Reduced wheel base, coil unloading, and low roll center are just some of the things that can happen with an incomplete bolt on kit that will be detrimental to off road performance. Play around with a 4 link calculator if you want to see how much your lift is messing with the actual geometry of your Jeep. The higher you go the worse it gets too.

While a 4” lift will increase the amount of up travel you have if you don’t run a longer shock you will loose 4” of down travel for a net increase in flex of zero. Add a 2” bump stop to the above example and you just lost 2” of flex vs the factory suspension set up. I think most people have this misconception of increased flex due to the fact they usually add larger tires when they lift and that is where they are seeing the improvement off road.

Many manufactures will use names with the word flex in them to describe their arms, lift kits, or joints. These are just marketing terms and do not flex any more then another bolt on kit from other manufacturers. The “upgradeable lift” is another myth made up from the marketing team. Any lift out there is upgradeable, there is nothing special about one that advertises it as one. The term "mid arm" is also a term that is made up by a marketing team, in reality it is the same basic length as the factory arm. They use this term in comparison to the tj control arms that were really short.

I believe that a lift is needed to gain clearance for increased tire size. It can also be used to gain some belly clearance for break over angle (mainly on the 4 door) and for better approach and declination angles, although I would argue that tires should be used for these issues instead of just lifting. The bigger your tires the more total ground clearance you will have as well as improving your break over, approach, and declination angles. I understand that other factors will come into play with large tires, mainly gears, wheel bs, and fuel economy.

If you were to compare two Jeeps, one set up with a 4" short arm kit on 33" tires and one with a 2" lift and 37" tires with trimmed fenders the one on 37's, if properly geared, would run circles around the higher lifted Jeep. It would climb better, clear bigger rocks, be more stable in off camber situations, and would handle better on road due to the lower center of gravity. Both Jeeps would be the same height overall.

For me the thoughts on lifts would be to start with trimmed or flat fenders for 33’s add a 2” lift for 35’s a 3” lift for 37’s 4” for 40’s
Expect some trimming of pinch seams as your tires get larger in size.

Wheel bs should be included in the discussion as well to maintain full steering. Wheel back spacing for the previous lift recommendations on factory width axles.

Net max back spacing:
5.5” for a 33x12.5
4.5” for 35x12.5
3.5” for 37x12.5
1.75” for a 40x13.5



The Parts:

Coils:

Coils are what gives your Jeep it’s ride height, in its most simple form a lift is just longer coils or a spacer placed on top of the coils. The benefit of a longer coil vs a spacer lift is that it will have a bit more travel built into it so you can droop a bit more and run a longer travel shock. A dual rate coil is made with a light coil rate section that will compress at ride height and allow for an even longer throw at full extension allowing for the potential of increased articulation. A coil that minimizes lift and maximizes unloaded length will give you the most benefit for increasing flex and off road performance.
One drawback from a coil that is really long is unloading that occurs on a steep climb or decline when the coils push the jeep away from the axles and give you the possibility of flopping onto the roof. Limit straps and suck down winches can help with that problem. ORI struts have a built in feature that eliminate this problem as well.

Shocks:

Shocks control the compression and rebound of the coils, quality of the ride, and the upper and lower limit to a suspension. To increase articulation, total travel is what you are looking for. Typically for 33”-35” tires you will be looking at a 10” travel shock. With 37”-40” a 12” travel shock will do. These are for bolt on kits, if you want to get adventurous and are willing to cut and weld 14”-16” are doable with considerable effort.

When running a longer travel shock you will have to take into account the rotation of the axle when one wheel is drooped and one is stuffed. The stuffed wheel will travel farther into the wheel well and you will experience more axle shift where a driveshaft may make contact with the fuel tank or oil pan.

http://www.jkfreaks.com/forums/showt...uide-to-shocks

Bump Stops:

Bump stops are there to keep your tires and other suspension components from rubbing on fenders and the frame. They are also used to keep shocks from totally compressing which can potentially damage them. When adding larger tires or doing a drag link flip you will need to add bump stops to keep things from rubbing. You can also trim fenders or notch the frame to gain extra up travel. Remember when adding bump stops you are limiting your up travel and are reducing your flex. Trimming fenders or running flat fenders is a good way to increase flex if tire rubbing the fenders is your limiting factor vs running longer bump stops.

Limit Straps:

Limit straps limit your down travel and can reduce your flex. However If set up properly the limit strap will prevent your shocks from totally extending, potentially damaging them, and can actually allow you to increase flex by overcoming the limitations of other components such as the drive shafts. By placing a limit strap at the differential you can limit the angle of the u joints or keep a driveshaft from making contact with the exhaust cross pipe while still allowing more droop at the wheels so the axle can rotate over obstacles. I have not seen a single lift that offers limiting straps, though they should be in every kit over 3” at least at the front driveshaft.

Sway bars and links:

While most of you disconnect your sway bars when off roading, (I don’t run them at all but my set up is far from a bolt on) should you run off road with them connected you run the risk of flipping your sway bar forward if your sway bar links are too short. This will lock up your steering and will likely bend stuff. They should be sized so they are +- 5 degrees from level. I would error at the +5 if it were me as I have flipped mine a couple of times when I over extended the front end.

Disconnecting the links will give you more potential travel in your suspension but will also make it less stable in off camber situations. After market sway bars like the TeraFlex duel rate or the Currie anti-rock will give you extra stability while having a softer twist rate for articulation.

Track Bars:

Track bars keep your axles centered on the Jeep. As you articulate your suspension the axle will shift from side to side. When you droop the front the axle moves to the driver side. The opposite happens on the rear. As you lift the track bar becomes more angled and due to that angle will shift more then a stock or level track bar. The track bar also determines your roll center. This is a line drawn thru the center of the front and rear track bars to determine how the vehicle will roll on its suspension from side to side. Think of a top heavy feeling from a low roll center. Raising the rear axle side track bar bracket will increase the roll center and make the Jeep feel more stable during off camber situations and on road cornering. The front track bar needs to stay parallel to the drag link for proper steering geometry and only should be raised when in combination of a drag link flip (done typically at 3.5”+ of lift). Many bolt on lift companies will give you an adjustable front track bar to re-center your axle and a raised rear axle side bracket that raises the track bar mount by the same amount as the lift which will center the axle with the factory track bar. Some of the manufacturers that make lower end kits will address the track bar issue by including a frame side lowering bracket as well as a drop pitman arm. While this will correct the steering geometry, it will lower the roll center of the Jeep making it less stable in cornering on road and more tippy in off camber situations. The drop pitman arm will also increase the stress load on the steering box and can lead to bent sector shafts as well as leaking seals on the steering box.


Adjustable Control arms:

Adjustable control arms allow you to re-center your axles in your wheel wells, regaining the loss of wheel base due to lifting and will allow you to adjust your caster and rear pinion angles. A full set of 8 arms are needed to move an axle vs using a pair to pivot it on the opposite control arm mounts. Some after market arms will have bends in them to provide for extra clearance mainly the front lowers for oversized tires. Most after market arms will have a fixed joint at one end and an adjustable end joint on the other. some will use a double adjuster on one end so you can adjust them while they are connected. This type is very handy to have on the upper arms to adjust for caster and pinion angles. If you are on a budget and will be buying arms a pair at a time I would do front lowers first followed by rear uppers then rear lowers and front uppers. Some manufactures of lower priced lifts will include cam bolts to adjust caster, while they will do the job on limited lifts they are prone to slipping and twisting when used hard on an off road vehicle. I would avoid the use of cam bolts. Some manufacturers will use a control arm drop bracket to correct the caster and to retain the overall factory suspension geometry. They do have the drawback of hanging down below the frame and cause a loss of ground clearance. For a Jeep that is on road most of its life and only sees mild trails the control arm drop brackets offer a good alternative to adjustable control arms.

Fixed Length Control Arms:

These are offered on some lower priced kits to keep the cost down while correcting suspension geometry (mainly caster) for the amount of lift in the kit. They typically use the same low priced clevite joint that the factory arms use.

Rod End Joints:

End joints are used to help comfort the ride from vibration and give it some flex in the connection point to allow for articulation. The more the misalignment built in the joint the more flex you can do without putting stress on the control arm mounts. Will some joints allow for more articulation then others? The answer is yes in theory but when installed on the JK factory brackets all aftermarket joints will perform about the same due to other constraints on the JK that limit articulation. This is one of the areas of a lift kit that can really bump up the cost. If a lift manufacture used 16 Johnny joints vs the factory style clevit joint the cost difference would be in the $500 range. A double adjuster on a control arm will increase the costs roughly $35 per arm. An overview of some different joints can be found here.
http://www.jkfreaks.com/forums/showt...son-and-review

Steering:

Steering linkages is another discussion for another day but will play a part in lifts 2.5” and taller.

Just for disclosure, I have never actually purchased a "lift kit" although I have installed them on others rigs.

These are just my thoughts on lifts after years of messing around with TJ’s and JK’s other people may have different thoughts and experiences and feel free to jump in the discussion. I would prefer the discussion to concentrate on bolt on kits for the JK and not suspension theory of rock bouncers and koth rigs.


Please do not PM me and ask what lift you should buy. I do not give recommendations on brands.
Most individual kits will have their own strengths and weaknesses. I have not found a perfect lift kit as each person may have a different need out of a suspension.
Some kits are set up for expedition type running and some are built to be more hard core rock crawling and of course budget comes in to play.

Last edited by TheDirtman; 01-24-2015 at 05:01 PM.
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Old 10-15-2013, 10:40 AM
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This needs to be a stickie. it is awesome.

So in your opinion for a non extreme ie black diamond type trails is say running a 2" spacer lift with 33-34" tires safe and sufficient?

Last edited by jadmt; 10-15-2013 at 10:42 AM.
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Old 10-15-2013, 10:42 AM
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Thanks for the great information for a newbie. Lots of questions I have had answered in this writing!
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Old 10-15-2013, 10:54 AM
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But what about the difference between long arm and short arm flex! Just kidding. Really good stuff there
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Old 10-15-2013, 11:06 AM
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Thanks for posting this
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Old 10-15-2013, 11:24 AM
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Excellent!
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Old 10-15-2013, 11:27 AM
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Originally Posted by jadmt View Post
This needs to be a stickie. it is awesome.

So in your opinion for a non extreme ie black diamond type trails is say running a 2" spacer lift with 33-34" tires safe and sufficient?
Yes that should be fine.

I find it comical that people think they need to build their jeep to the hilt when they only run off road 3-4 times a year or wheel dirt trails and fire roads. A stock jeep will handle those trails just fine with the exception of a JKU on steep camelbacks.

Tires are going to gain you the most in the off road capabilities, followed by gears, and lockers. Lifts imo are just adjustments so that you can properly run bigger tires.
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Old 10-15-2013, 11:38 AM
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Great info. ... even though next time I get on the forum I'm sure there will be another "what lift?" Thread started.
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Old 10-15-2013, 11:45 AM
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Well done
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Old 10-15-2013, 11:57 AM
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Dirtman, thanks for the write up. This is great info. Anyone new to jeep mods should read this before they start throwing mods on.

Thanks again for the great info.
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