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Discussion Starter #3
my front springs are probably tired
 

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A lifts real value is 1.) how much it increases wheel travel 2.) how much larger wheel/tire it will accommodate 3.) how much it increases ride height

If you put a lift on just for looks, well I guess that is a good measurement.
 

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Discussion Starter #5
for this method of measurement does not affect the size of wheels
 

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I only ask this question about lifting because I have never done one, in my day it was lower/ chop/ channel. Is the sole purpose, other than ascetics, to allow you to put larger tires to raise the differentials higher for more ground clearance?
 

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I only ask this question about lifting because I have never done one, in my day it was lower/ chop/ channel. Is the sole purpose, other than ascetics, to allow you to put larger tires to raise the differentials higher for more ground clearance?
That is the basic idea.
 

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As stated earlier, it is also important to get a proper shock/spring setup for maximum wheel travel. With more wheel travel comes the ability for the wheels to travel up and over larger obstacles (uptravel). On top of that, in certain situations, the Jeep is at such an angle that one wheel will be off the ground due to odd inclines\rocks; greater travel allows that wheel to stay on the ground longer (downtravel). While yes, it is helpful to have larger tires for increased diff clearance/greater contact patch, travel is truly what helps when your doin' technical trails and not just haulin' a** though mud holes.
 

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OK for the original poster, I poo-poo-ed on his idea, but now realize he has a great idea. Regardless of how/why you're doing the lift, he has a good way to measure the result, so as to advice others on what to buy, that doesn't change with tire size and other variables. It is a smart way to do it.
my front springs are probably tired
Actually, good springs (and yes OEM is good springs) lasts for millions and millions of cycles, most cars in the junkyards still have perfectly good springs on them. If a spring is truly sagging, it was likely damaged by extending or compressing farther than its design. The old leaf springs in cars decades ago, it was easy to damage them, and yes, they often sagged. Modern cars with coil springs, it rarely happens.

What I suspect you're seeing, is worn out strut mounts. I just replaced my front shocks and strut mounts, with direct OEM replacement, no lift. My front ride height came up higher. I suspect it was the new strut mounts. The strut mount is a big rubber bushing between the top of the strut assembly and the body of the vehicle. I could be wrong, but looking at it, it does appear a softened and weakened strut mount might sag and lower your front ride height a bit.
I only ask this question about lifting because I have never done one, in my day it was lower/ chop/ channel. Is the sole purpose, other than ascetics, to allow you to put larger tires to raise the differentials higher for more ground clearance?
Ross did a good job describing it, what give you good off road ability:

1.) Wheel Travel, the ability of the suspension to let the wheel/tire travel up and down to go over obstacles.
2.) Wheel/Tire Size, wider and bigger diameter (i.e. taller) means a bigger contact patch to get traction. Another one people fail to realize, the bigger diameter (taller) the tire, the higher up the angled to front face of the tire is, giving you the ability to climb over taller obstacles.
  • With a 26" tall tire, if you come up to a 13" tall curb, the point of the tire that hits that curb is straight up and down, the tire just try to pushes the curb forward, which it can't, it doesn't roll over it, your stuck.
  • With a 31" tall tire, if you come up to a 13" tall curb, the point of the tire that hits that curb is angled, and the tire will roll over it.
3.) Ground Clearance, you can't go anywhere if the belly of the vehicle is hung up on a rock. Especially snow and mud, where the wheels will sink into the mud and snow, the belly comes to rest on the mud/snow, you're now floating in mud/snow and the tires have no pressure to get traction and the vehicle has a ton of drag with the belly scraping the mud/snow.

What does a lift do? It all depends on the suspension.
Even the cheapest worst lift kit, that just raises the vehicle with out changing anything else, will get you increased ride height, that might get you something.

A cheap kit that isn't a total farce, likely will allow you to fit taller wheel/tires underneath, that will get you something as well.

BUT, the difference between lift kits just for show and kits for better off road ability, are kits that increase your wheel travel, that will give all the advantages above, but the biggest capability multiplier is more wheel travel.

Unfortunately most of the kits out there don't increase wheel travel, especially for a Independent Suspension, which the Commander has a Independent Front Suspension. Live axles, because of how the suspension works on them, are pretty easy and cheap to increase wheel travel with a lift kit. Independent suspensions, NOT so easy, and often the only way to increase wheel travel is with a very expensive kit that replaces some, if NOT all, of the suspension pieces.

So, you can see why when the rumor went around that Fiat management of Chrysler, would be going with a front independent suspension for the next Jeep Wrangler, all the Jeepers were up in arms. They were convinced Fiat owned Chrysler was going to destroy the off road ability of the Jeep Wrangler.

Remember, if you just stick in a puck/block between the body and spring, sure the vehicle will be higher. You'll say, ahhh, my wheels can travel farther up when going over bumps. NOT so fast, that also means your wheels travel less going downward for when you travel over holes or one wheel goes up as the other goes down. Really all you've done is traded jounce for rebound, for the same amount of wheel travel. You really don't have much more off road ability.

Even worse, some pucks/blocks, since you re-use the same spring but since the wheel can travel farther up, will compress the spring even more, and the spring can bind and be damaged. The kit may come with a modified bump stop to prevent the damaged spring. But, with these kits, you traded jounce, for no rebound in return. You actually have less wheel travel than stock, you've decreased your off road ability, but the truck will look cool on the street all up and high like that.

Most cheap lift kits, for the independent suspension will trade jounce for rebound, so no increased suspension travel, but you get a little more ground clearance and can fit bigger wheel/tires for some improvement in off roading. The live axle though, most lift kits will increase wheel travel, so you can get even more out of a cheap lift kit. Remember, if the kit doesn't come with shocks, to get longer than OEM shocks. In the Commanders, and most vehicles, what limits the jounce of the live axle travel is the shock, so if its longer, the suspension can travel down farther. So you trade jounce for rebound, but increase jounce with a longer shock, you've got more suspension travel!
 

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OK for the original poster, I poo-poo-ed on his idea, but now realize he has a great idea. Regardless of how/why you're doing the lift, he has a good way to measure the result, so as to advice others on what to buy, that doesn't change with tire size and other variables. It is a smart way to do it.
I always ask for axle to fender measurements to accurately determine lift height.

I was under the impression that this was common knowledge here. Glad that this post was made.
 

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Yep, I got real long in my post, missed or lost a few things.

For the Commander, that has a Front Independent Suspension and a Rear Live Axle, longer shocks will get you more wheel travel in the rear only.

The Front Independent Suspension on the Commander, up and down extension is limited by control arms and suspension parts, the only way to get more up and down travel out that suspension is to redesign it, so you'd need to get a kit with new suspension pieces that does that. It only gets more complicated in that the universal/cv joints have critical angles as well, and if you exceed those angles (which greater travel downward or upward is likely to do) you will wear or break them. So increasing independent suspension travel might also include redesigning the driveshafts as well.

The rear live axle suspension control arms are much simpler and allow more downward motion than it comes with OEM. So designing a lift kit, or adding parts to a lift kit (like longer shocks) can be done much easier that will allow more upward travel and more downward travel. Keep in mind, just because you raise the ride height, does NOT necessarily mean you have increased the upward travel, you have to look at the design of the suspension and the lift kit and see exactly what is being changed.

If you lift the rear by 2", but add a new bump stop that stops the upward suspension travel 2" earlier, you've got a net 0 gain in upward suspension travel. The lower bump stop may be necessary to keep bigger tires from rubbing or springs from binding. If the lift kit doesn't add any downward travel to the suspension, you'll be subtracting 2" of downward travel by raising it that amount, thus you're overall suspension travel has been decreased. But, just installing shocks that are 2" longer will get you that 2" of extra downward travel.

Then there's driveshafts angles, the axle angles will change as it moves up and down, with universal joints, the end yokes of the driveshaft have to be in parallel planes, or the rotation will NOT be uniform. For the suspension bouncing up and down, those yoke ends going a few degrees off is acceptable, they are built to take it. BUT, they are also designed for the vast majority of the time, riding level, that they are at the exact proper angle. So raising the suspension on a live axle "may" put your yoke angles out, and that would have to be corrected with new control arms or adjustments. It also might NOT, if the suspension is good a 2" change in ride height might NOT change the angle at all.

Whew, see how complicated it gets?
 

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Also, see why big off-roaders prefer live axles to independent suspension? The true die-hard Jeepers are very miffed about Daimler taking every new Jeep and redesigns of existing Jeeps, except the Wrangler, and putting independent suspensions on them?

Front live axles do have their drawbacks, especially on paved roads, since the front suspension is more critical than rear, and both wheels are solidly connected to each other, anything that happens to one front wheels has a drastic effect on the opposite side wheel. You can get shimmy, they don't ride as smooth, its more likely to roll over, heck just hitting a curb at an angle where one wheel goes over the curb before the other at too high a speed will roll you over, while a front independent suspension would not.

And perhaps the biggest advantage to front independent suspension, since left/right wheels operate totally independent of each other; that suspension can be damaged, have worn out components, blown shocks, front brake problems and wheel balance problems, totally neglected by the owner or the owner totally blowing off necessary repairs that are obviously needed and continuing to drive it, and NOT get into effects that could be dangerous are at least alarm the driver.

A front live axle, you do the same neglect and continue to drive the vehicle, you can get into extreme shimmy, called Death Wobble.

In this world of class action lawsuits, and ignorant car owners, selling vehicles with front live axles is asking for a lawsuit, and Jeep went through a big "Death Wobble" lawsuit from class action lawyers arguing their idiot clients shouldn't have to maintain or repair their vehicles, Jeeps should be just like every economy car on the road, you owe them.
 

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Discussion Starter #17
Measure your lift, and upload photos.For comparison. Thx
 
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