At a given lift height, lets say 4 inches, a short arm suspension can only travel so far before the suspension mechanically binds. At that same given height in a long arm the suspension can travel further before mechanically binding. So while the limiting factor of up travel is the bumpstops and typically the limiting factor in down travel is the shocks, the potential does exist for greater overall suspension travel in a long arm. Its a mathmatical fact. Now whether or not most people make practical use of that extra travel is another issue.

 

At that point where it would "travel farther" the axles wouldn't be going up and down they would start to arc towards the center of the vehicle.... If u drop anything from a fixed point (like the control arm to the frame) it will rotate around under itself to be completely vertical which a vehicles axles can't do.... I understand where ur coming from.... I argued my head off on wayalife forum cuz I thought my old long arm gave me more flex.... Look.... It looks like I do don't it?

This was my 2010 JKU Sahara with 4" Rancho long arm suspension



This is my 2010 JKU Rubicon with 4" Skyjacker lift (factory control arms for now)


It didn't dawn on me till after arguing with Eddie aka wayalife (Moby's owner) about this that I DID in fact have LONGER and adjustable shocks on the Sahara that I do on my current Rubi..... And of course he was right.....

 

The OP asked about a 2.5" lifted Jeep.

It could be theoretically true, but it doesn't work this way in a Jeep suspension – unless you redesign and build it from scratch.

The upwards movement is limited by a bump stop, regardless of the arm length.
The downwards movement is limited by the length of the coil when uncompressed – again, regardless of the arm length.

The coil binds both forward~backwards, AND sideways, anyway.

It would be a very bad idea to let a shock limit the movement.
The shock should have more travel than the coil.

With too much travel, the coil will bend too much, both forward-backwards and sideways. (And there's the steering too...)

BTW, the OP has disappeared...

 

I noticed that too! Lol think he got more than he bargained for with that question!

 

Yes...
I also hope that it's not because he's from Oman, and someone from Israel replied him...

 

Hmmmm I'm on the app so I didn't even notice till u said that, then I went to the browser and can see locations.... I hope that's not why.... We're all jeepers here, no race, religion, government, color, sex, or anything else matters here.... We're all equal!

Big ol Jeep wave to the WORLD!

 

Okay so under those set of "facts" for lack of a better term, what is the point of a long arm suspension? If it doesn't increase usable suspension travel and it doesn't increase ride comfort, then why do almost all suspension companies make long arm kits? BTW i'm not being arguementative i'm just trying to wrap my head around this concept of yours. I have researched in depth and talked to a few different people in the industry and your view point seems to be almost entirely opposite of what they say. If i'm wrong then i'm wrong and i'm fine with that. Just trying to wrap my head around this.

 

AMEN !

That's one of the nicest things about this forum. Another is the good will and mutual help.

 

To correct the geometry of the axles.... The higher we go we change small angles and the long arms correct that so that it sits like it did when it was stock but now ur higher obviously......That's all it does.... That's why I decided NOT to upgrade my rubi to that... I'm installing skyjacker adjustable short arms, cause by doing this it gives us just enough adjustment to correct the geometry but the long arm can dial the suspension in a lil more precise.

 

You'll hear a lot of things, including myth or misconceptions.

Yes, people install long arms on 4" lifted Jeeps. Why? They think it helps, and IMHO they're wrong.
Some people even tend to believe in the mod they did so much, that they would actually feel an improvement which isn't there.

For "high end" lift, say 8" or 10" for instance, the geometry of short arms wouldn't work right, and long arm are needed.
4" lift is just not enough for long arms to make a true Difference.