I haven't toyed around too much with suspension systems. I am considering upgrading and would like to know the pros and cons of a couple different types of 4" systems. Of course a long arm system would be ideal but very pricy. What are the real advantages of a lift kit that uses the existing upper and lower flex arms vs. a kit with replacement adjustable upper and lower? So far my understanding is that you will be able to fine tune the suspension with the adjustable ones. What the fine tuning is I'm not sure. Will the adjustable flex arms also help with on-road handling? I really don't want to sacrafice any handling on the road. This is also my daily driver. I am going to look for a kit with front and rear adjustable track bars and will be installing longer driveshafts when this all takes place. Will I have to replace both driveshafts or can I do one now and the other later? I was also wanting to keep my Budget Boost on for a little extra room. Hope I don't sound like I'm clueless. Just trying to learn .

The other thing me being in florida I don't know how much I will utilize the "true" potential of a long arm vs. adjustable upper and lower.

 

long arm kits are king when it comes to flex. but if ur not rock crawling, then a short arm or mid are kit should be fine. adjustable arms are what corrects your pinion angle to reduce binding. rockcrawler has a 3.5" kit that is upgradable to 4.5" (or is it 5.5"). my buddy has that kit on his 4dr rubicon. the arms are adj and very stout. what size tires you wanting to run? it's 35s then your fine with 3.5" or even 2.5"

again, excess lift is for flex. if ur not gonna be flexing (just mudding), you dont need a lot of lift.

 

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OK - I'll try to simplify this, but leave enough meat to chew on......


The way your suspension works is like this-

First - what's under there: (I'm skipping the obvious like brake lines, etc...)

1. You have two live axles, and each axle is positioned beneath the jeep in several ways, so as to allow it to move up and down/follow the terrain, yet not fall off, etc.

2. You have coil springs that hold the jeep's frame up from the axles....you have added a 2.5" BB, meaning, in addition to the coils springs, you added spacers that go between the coil and the frame, raising the frame another 2.5". (As in, taking out the stock coils, and adding 2" Lift coils, with the 2.5" BB, yields at least 4.5" of total suspension lift)

3. You have front and rear track bars...these run parallel to the axles, with one end attached to the end of an axle, the the other end attached to the opposite side of the frame.

4. You have a steering system that goes from the steering box, to the pitman arm, to a drag link, etc....when the pitman arm pulls or pushes the links, it steers the tires.

5. You have control arms, an upper and a lower, at each corner....they reach forward at the front to the axle from the frame, and rearward from the frame to the axle in back.

6. You have anti-sway bars, that run along the frame, and then have links that drop down to each side of the axle, front, and another set for the rear.

7. Drivetrain - you have a transfer case with one drive shaft going to the front axle (Diff), and one going back to the rear axle's diff.

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Second - What happens to these things, relative to what each type of lift part does for you:

1. When you EITHER install a lift, OR droop the tires (Same thing reallly), the axle gets further from the frame....

2. Everything attached to both the frame, and the axle, either gets longer or swings straighter with the motion (Like a shock or coil get longer, the arms swing, etc), or STOPS the motion (Like something that's too short, etc...)

3. Track bars do not get longer, but they swing...but, that means the AXLE attached has to swing too....so, the front axle swings towards the frame mount, and the rear axle swings towards ITS frame mount (They are mounted on opposite sides, so the rear swings to the passenger side, the front swings to the driver's side, etc.)

If you lift enough, that swing makes the axles too far over in the above directions...so, you'd make the track bars LONGER, to allow them to swing less and still reach the ground, etc.

4. For the same scenario....when you lift the frame from the axle, it pulls on the steering linkages....and the jeep tires are are turned by the lift....so, you loosen the clamps, and let some slack out, and re-tighten it, so that the steering is centered again....

.....and, depending upon the lift....for steering geometry...you want all of the steering linkages more or less level, or, if you hit a bump, the tire that hit the bump ends up steering the jeep, instead of the steering wheel (Bumpsteer)....so, making the pitman arm drop down longer, or the bracket for the steering linkage come up higher to meet it, etc....helps keep the various steering linkage rods more level.

5. Control Arms - Ever see a motorcycle with the front tire WAAAY out front of the bike, a "chopper"?

That's a lot of CASTER...and, for a guy cruising a long distance on a hog...its very stable and comfy.

Caster is related to how well the rig steers/drive down the road....the more caster, generally, the better for the ride, but, too much caster, and its harder to change direction quickly, etc.

An office chair has "caster wheels", but the opposite caster direction...if you ran an office chair really fast (Well, for an office chair....), the wheels would wobble like crazy....as on a chair, or grocery cart, etc...the wheels swing behind the pivot point when in motion....an unstable or less stable at speed caster setting, but easier at very slow speed (Slow for a jeep on a road, etc...)...so the office chair can change direction very easily, but, you'd hate to go 70 miles an hr to work on it.


Well - lets say you raise the frame, that's going to make the axle swing further under the jeep, as the axle(s) swing inwards on the control arms.

So, that means the control arms are pointed more downwards....and, therefore, considering htat they position the axle, that also means the axle is tilted forward, like the face of the diff is tilted down...and I've brought the axle inboard of the original pivot point....less caster.

So - just like a longer track bar....an adjustable control arm lets you un-tilt the diff and axle, and, allow it to reach the ground where it used to, instead of swung more under the jeep, etc.

Obviously...the longer the control arms, the further the axle can droop as well....and, of course, on stuffage, when the damn thing swings back UP at the wheel well, well, its going to come up forward of where it used to, etc.

6. Anti-Sway Bars.....their primary function is to brace the axle against the frame, so it can't let the axle move, which holds the jeep frame and axles parallel......to a degree.

It does let it move some...but, for a lift, or more droop, the links are too short, and they pull you to a stop on the way down. You can disco them....you can install longer links, or chuck them, etc.

Most people disco the front bars to offroad, and connect again for the street.

Alot of people who've checked it out, have merely thrown the rear bars into the trash, ebay, etc....others got longer links, and/or disco'd to offroad, etc.

The front links are 6" long....the rear links are 9" long....and they can be swapped....except that the 9" rear links push the front sway bar ends DOWN a lot more than the 6" ones (Well, 3" further down anyway...)...on a 2.5" BB, close enough for ride height...but, still stopping you from full droop offroad.

7. Drivetrain - OK - those shafts running from the t-case to the diffs....

If the frame is raised...the diffs are further away, and, the shafts have to point DOWN more to reach them. If the diffs were ALSO tilted back, etc, that increases the ANGLE that the shaft enters the diff...which, if too much of an angle, can vibrate, etc.

Extra joints to relieve the angles, and extra shaft lengths to reach the diffs, etc....can be needed when going too high.

The 4 dr shafts are longer to start with, and it takes more lift to make the angle too severe....so 2 dr people need to make drivetrain mods after about 3" of lift....4 dr people seem to be needing these mods closer to 4-6".

Depending on if you have an Auto or Manual tranny, etc....the shafts can hit skid plates and so for on the way down to the diffs as well, if the angles run them there, etc.

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So - that's all I have time for now...

Its basically covered why a longer control arm, and/or an adjustable control arm, or track bar, etc, might have a use, and for what.

Generally, for mud - you really want the tallest, fattest TIRES you can fit...because ONLY taller tires get your diffs up, and in mud, your diffs are like anchors....pushing axles and diffs through deep mud is an effort in futility.



I'd therefore concentrate on the footprints, get as much flotation and traction as you can....and go from there to maybe a snorkel......as, at least around here....where there's deep mud, there's water, and, sometimes, its hard to know the depth/avoid a drop off, etc.

A snorkel will help avoid hydrolocking the engine.......hydrolocking is very bad, you do NOT want to do it.



Another good thing to have when off roading in deep mud...a freind to pulll you out of trouble....and, one of you having a winch really helps.



Hope that helps a bit.

 

WOW. I'm glad you simplified it.

 

I apprecaite the walk through. I'm actually getting a very slight vibration from the Budget boost at highway speeds. It's hard to pinpoint what is causing it, tires etc. To me it feels like something with the driveshaft angles like was mentioned earlier. But i guess I would feel that at all speeds then and not just highway. Anyway thanks for the reply.