Slightly off topic -

I just traded in a Sahara on an 09 Rubicon and they were the same height sitting side by side. There was a base X with steel wheels nearby and it looked noticably shorter. Now I wish I would have measured!

 

This thread should settle the spring issue:

https://www.jk-forum.com/forums/stock-jk-tech-12/lets-solve-stock-springs-question-85825/

Some of the X models have the exact same spring p/n as the Rubi. The only place clearance can come from is from tire size. Tire sizes available in 2008 (2007 and 2009 may be different) and the axle Ground Clearance relative to the Rubi:

Model: X
Tire Size: P225/75R16
Height in Inches: 29 5/16
Ground Clearance: -1 3/8

Model: X
Tire Size: P245/75R16
Height in Inches: 30 7/16
Ground Clearance: -13/16

Model: X
Tire Size: P255/75R17
Height in Inches: 32 1/16

Model: Rubicon
Tire Size: LT255/75R17
Height in Inches: 32 1/16

The bottom line is it is incorrect to state the Rubi has 1" clearance over the X. The springs vary between models and options with some of the same springs being used on both the X and the Rubi. The tires may make over an inch of axle clearance depending on which X model and options were selected, but does nothing for fender clearance.

 

See my post https://www.jk-forum.com/forums/showthread.php?t=85825
Lets solve the stock springs question

Heres the deal.

If you have a jeep with an F in the fourth place on your vin your GVW is 4000 to 5000 pounds.

If you have a jeep with a G in the fourth place on your vin your GVW is 5000 to 6000 pounds.

There are a lot of spring combinations out there from the factory.

If you have a G vehicle, going to any other stock spring set will not help and may move you backwards.

If you have an F vehicle going to G springs will allow you to increase your GVW without making the jeep sag.

If you go from an F 2 door to G Rubicon four door springs, especially if the four door had the towing option you will see an increase in stiffness and you may gain a bit until you load yours up.

I have a set of Rubicon G four door springs that I put side by side with my X 2 door F and they are an easy inch taller.

 

I can attest to that. I originally purchased a bone stock X model w/ 3.21 gears, no tow package, etc and swapped out for some JKU Rubi springs/shocks and gained about an inch in the rear and about an inch and a half up front.

This was also accompanied by an immediate improvement in handling and totally did away with a bottoming out problem in the rear end.

I have since added a 2" spacer lift and 275/85R16 ProComp Extreme AT's and it ROCKS!

 

May be true, but what we can't tell by the part numbers is what the spring rate is. If the taller spring is softer, that isn't necessarily going to translate into more lift when on the vehicle.

I'll I was trying to point out is there is no hard-and-fast "the Rubi is an inch higher than the X". Might be. Might even be more. Also, though, might not be. A "G" X with 255/75R17 tires will be +/- the loaded weight difference of a Rubi. In fact, but the time you factor in the Rock Rails, eDisco, and other weight adders, I would bet an unloaded X with an empty tank of gas would be considerably higher than a fully loaded Rubi with a full tank. OK. Unfair comparison. But you get the drift?

 

Exactly!! So far, I haven't been able to find spring rate info.

Although, it does look like Rubi's generally have the higher spring part numbers. Based on what I've seen so far, it wouldn't be worth a swap unless you're going to increase the spring part number by 2...ie., swapping a 14AB and 15AB set of springs for 16AB+ and 17AB+ springs.

I would assume the same for the rears.

 

The TJ springs on a Rubi and Non Rubi are the same. Just like the JK it depends on the spring rate. An unlimited X TJ with a hard top and 6 cyl would have a stiffer rate than a regular wheel base Rubicon with the soft top and if each set of those springs were put on the same TJ you MAY get a little more height from the X springs in that case. Also on the TJ there were some 4 cyl models too some I believe there were more spring rates available.

However on the TJ forums there are plenty of threads asking if the Rubicon springs will lift an x, and the answer is the same as here on the JK forum.

 

I have both a 2009 Rubicon Unlimited 4dr and a 2008 Unlimited X 4dr both have 32" tires and 17" rims. The tread on the Rubi is more aggressive. The X has the heavy duty suspension. The Rubi is 3/4" taller at mid door.

 

So take this all the way. What are the front and rear spring part numbers? Need both left and right front springs - they are different, off by one. What is the actual tire diameters? The 32 1/16 nominal for a 255/75R17 offers the manufacturer a bit variance. Are the tires inflated to the same pressures? Different manufacturer's tires will have a different contact patch even with the same pressure. Bigger contact patch will effectively lower the height of the axle. Especially true when comparing a LT tire (Rubi) with a P-Metric tire (X). The Rubi will be a Load Range C. The X will probably not have a load range listed. Either way it is impossible to compare a LT to a P-Metric load range. Did both have the same options? Can't because of the Rock Rails on the Rubi, for example. Did you add aftermarket accessories to either vehicle (such as rock rails to the X, winch, etc.)? Did both have the same load, such as the gas tanks being about the same on both, same number of tools, etc? 3/4" at both doors or just the drivers? Are both "G" in the 4th digit of VIN?

Still too many variables to be a conclusive statement!

BTW - I'm extremely jealous you have TWO Unlimiteds!!

 

I see your point. to clarify a little bit, i am just talking about tire clearance, not ground clearance. so if i decide to do a 2.5" coil lift, it would give me more like 3.5"s of lift if i have the shorter springs?
this doesnt call for any extra work though does it?