Author Topic: FYI - Lifting a Jeep  (Read 314 times)

87Warrior

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FYI - Lifting a Jeep
« on: June 21, 2011, 11:00:39 PM »
This thread is intended to be used as an introduction guide for anybody wanting to lift their Jeep and a discussion of 'lessons-learned' for those of us who have made foolish mistakes. This discussion will focus on the coil spring suspension found in the XJ, MJ, ZJ, WJ, TJ and JK (if we want to include the new minivan Jeep).

Terminology:

Articulation - How well each axle, or each wheel, will travel and "twist-up" when traversing an extremely off-camber obstacle. When off-roading, you want as much suspension articulation as possible to keep the tires on the ground and getting traction. (Superlift)

Bumpstop - Bumpstops limit the amount of up travel in your suspension. When we lift our trucks we can fit taller tires under it because the axle is further from the chassis. But what happens when the suspension is compressed and the axle pushed up as far as it could when stock with those tall tires? You eat fenders and often times damage the tire when it rubs seams along the wheel well. Front bump stops resemble hockey pucks (some actually use pucks) placed on the lower spring mount of the axle.

Control Arm - A combination of upper and lower suspension arms position and control axle movement on coil sprung Jeeps. The fixed-length OE suspension arms are bolted to the chassis and axle through rubber bushings to help reduce the transfer of noise into the vehicle. The rubber bushings also absorb torsional forces created by the suspension arms off-road. The adjustable design allows the user to control caster and pinion angle, as well as position the axle housing for proper tire clearance. Furthermore, each end of the control arm can rotate independently to accommodate extreme suspension travel off-road. (JKS Manufacturing) Aftermarket control arms with bushings that are less flexible (such as polyurethane bushings or arms with out a twisting capability) will over-stress the chassis and axle mounting brackets and should not be used. Many manufacturers provide these components with their suspension kits to save money.

Drag link - A piece of steering linkage that connects to a pitman arm on the upper end, and a tie rod or knuckle on the lower end. On lifted vehicles, sometimes an Original Equipment (OE) drag link is replaced by a "dropped" drag link to reduce link angle. (Superlift)

Pitman Arm -  The drag link is pushed or pulled by the pitman arm and in turn pulls or pushes the tie rod turning the tires of the vehicle. (Quadratec) A Jeep with a properly set up suspension system will utilize the OE Pitman arm. 

Shackle - The OE spring shackles should be replaced on Cherokee XJ models any time longer leaf springs are installed for the benefit of increased suspension travel. The OE shackle shape and size do not allow enough shackle "swing" to take advantage of the additional spring length. By inhibiting proper spring operation, ride quality and performance suffer and related suspension components wear prematurely. The proper shackle optimizes rear suspension travel by allowing full compression and extension of leaf springs and prevents binding and bushing fatigue commonly associated with OE and inferior shackle designs. (JKS Manufacturing)

Swaybar disconnects - The swaybar, more accurately referred to as the "anti-swaybar", helps stabilize the vehicle's body in relation to the suspension. It is attached to both chassis rails and connected to the axle housing using swaybar end links. The swaybar's spring steel construction allows it to function like a torsion bar, resisting vehicle body roll during cornering. On the road, the swaybar is critical to proper vehicle handling and control. Although virtually transparent to the driver, make no mistake about the importance of this device to vehicle safety. Jeep engineers carefully design swaybars to ensure the proper rate of resistance for each unique model. Off-road, however, the swaybar counteracts the suspension's ability to function independently of the chassis, thus preventing the tires from maintaining contact with uneven terrain. Unless equipped with a locking differential, engine power is transferred to the tires without traction and the vehicle is unable to continue forward progress. (JKS Manufacturing)

Trackbar - The trackbar controls lateral movement of the axle housing, and prevents undue stress on related components centering the swaybar for proper disconnect operation. It is attached to the chassis and axle on opposite sides of the vehicle with flexible mounting points (OE is rubber, aftermarket may be: rubber, heim joint, flex joint) to accommodate suspension travel. Unfortunately, the fixed length of the OE trackbar won't accommodate ride height adjustments. Changing the distance between mounting points forces the axle housing out of alignment with the rest of the vehicle. A trackbar properly aligns axle housing with the chassis, primarily for coil sprung Jeeps per our discussion. (JKS Manufacturing)

Parts Diagram:


(Introduction post to be continued...)


Onyx Dragon

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Re: FYI - Lifting a Jeep
« Reply #1 on: June 22, 2011, 12:37:28 AM »
Holy crap, that looks just like my XJ, JKS disconnects and all :lol:

87Warrior

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Re: FYI - Lifting a Jeep
« Reply #2 on: June 22, 2011, 09:40:24 PM »
Holy crap, that looks just like my XJ, JKS disconnects and all :lol:
JUST like it, eh? Your XJ must have the fancy body mount option  :lol:

Onyx Dragon

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Re: FYI - Lifting a Jeep
« Reply #3 on: June 22, 2011, 09:45:33 PM »
JUST like it, eh? Your XJ must have the fancy body mount option  :lol:

I meant the suspension and other stuff you circled..thus my comment about the JKS disconnects :P

Meatywand

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Re: FYI - Lifting a Jeep
« Reply #4 on: June 22, 2011, 10:04:08 PM »
Disregard Swaybar
Acquire Mad Flex
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Meatywand

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Re: FYI - Lifting a Jeep
« Reply #5 on: September 03, 2011, 07:53:56 PM »
Hey 87warrior, school me on Long Arms and 4 Links, I'm about to take the plunge in a couple months and buy the TnT Customs Long Arm kit with the belly up skid...what kind of shit am I about to step in?
Quote from:  Sergeant D
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I gazed through the open window upon a full moon.
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87Warrior

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Re: FYI - Lifting a Jeep
« Reply #6 on: September 04, 2011, 12:52:43 AM »
Meaty, my knowledge of long arms is a bit limited as I have never installed any. I have been researching them for several years. I will do my best at organizing my understanding of long arms later this weekend for you.

I really want to upgrade to long arms sing I have now busted bothe rear upper control arm brackets on the axle....

87Warrior

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Re: FYI - Lifting a Jeep
« Reply #7 on: September 05, 2011, 12:19:08 PM »
Meaty-

It looks like the TNT long arm systems utilize a 4-link rear end and a y-link front end. This is the most common type of long arm upgrade all of the major companies provide (Full Traction, Rough Country, Rock Krawler, etc). It is a proven set up and should work fine for you average weekend warrior wheeler.


The rear 4-link is a solid set up. Your new upper and lower control arms bolt along the same plane at the belly pan. Most suspension designers would agree this is the best way to go. The long arms are double triangulated therefore eliminating the need for the 5th link all Jeeps come with stock, the trackbar. The control arm triangulation keeps the rear axle centered. You will need to strip the rear axle of all brackets and weld on the new truss. Fewer parts in the suspension geometry mean it is less likely to bind up and have more room for movement. More FLEX MAN!!!!  This also means your current brake line, breather and drive shaft need to be double checked for compatibility with the addition movement introduced in the rear suspension set up.



The standard front Y-Link set up has been used for many years by manufactures making bolt on long arm kits. Rubicon express used Y-links front and rear for their long arms. The Y-link set up has 2 Long arms and 2 short arms. The long arms bolt to the belly pan connecting to the stock lower control arm brackets. Then the upper short arms bolt from the stock upper control arm to the lower arm. Thus, the Y name. Because this set up does not triangulate anything, you must use a trackbar retaining the 5 link setup. I know this type of long arm is debated by Jeepers across the world as to its functionality. On long steep climbs the Y-link set up is known to 'unload' allowing the front of the Jeep to come up.



You generally find Y-Links under the front end of long arm upgrade kits. This is because a 4-link just wont fit on a stock'ish' rig due to the motor. What you can use is a 3-link system. This type of long arm has two long lower arms and one long upper control arm. It does require the use of a trackbar to keep the axle centered. The 3-link kits are debated by Jeepers as well since there is only one arm connected to the top of the axle.

My plan is to buy the Clayton 4-link rear/3-link front long arm upgrade for my Jeep. Keep it at the same height but reduce the stresses caused by my short arm 5-link. The problem is, I would rather buy another MJ for the same amount of money I would spend on long arms..... :lol: