Hi everyone,

Just yesterday I noticed the rear is looking a little low. Not by much, but just enough for me to notice. Maybe the rear coils have settled more than the front HD coils, or maybe it's the Expedition One bumper I added a few months ago... So I've been wondering about swapping the coils. What do you think would be a good match for the front FT 3" HD coils on a 4-door? Maybe the Rubicon Express 3.5" or Clayton 3.5"? Or should I go with 4" coils instead?

js.

 

Yeah. I have a sagging butt too. But back to your topic.

The hardest part about buying coils is finding out the spring rate. Jeep has over 20 different spring rates for the JK, depending on model. Some lift manufactures (like Superlift) have different spring rates for their 4" rears depending on if it's for a 2 door or 4 door.

Putting in a softer 4" might sag more than a firmer 3.5". A progressive-wound coil will certainly settle more, but probably would be harder to bottom out.

I'd love to see a coil-to-coil comparison of spring rates but haven't seen any so far. Most manufactures don't publish that info, but some do. For now I guess you need to rely on opinion. Unfortunately I don't have enough information on a variety of springs to offer much help.

Good luck!

 

Here's a picture. Like I said, it's a slight sag, but with some off-road gear and/or camping gear and/or trailer, it's a lot more apparent. The Jeep is empty in this picture. I've installed (manually inflatable) air bags in the coils for when the Jeep is loaded, but I think some stiffer and/or longer coils (maybe 0.5-1") would be nice...



js.

 

not sure if you've considered this, but you could get a 1/2" or 1" spacer for the rear springs.

 

Can you wheel with the airbags or do you have them deflated ?

But as for ride if you like those springs some TF 1 inch spacers would do the trick but a few bucks more you can get the FT 4 inch coils and would eventually settle at 3.5 all depends on you maybe some new purch that are centered I forget who makes them might just do the trick and put them on when you do your welds in the rear

 

You have to keep at least 5 psi in them. I usually run them around 15-20 psi when loaded with off-road gear.

I sent FT an e-mail to ask for a part number. Thanks.

I have them, but didn't get a chance to install them yet. There's some 'tweeking' that has to be done in order to fit them around my rear trackbar brace (welded to axle). They should fit ok though. Do you think I'll gain some height after re-aligning the rear coils? Hm. I'll have to measure before and after. :-)

I've read good things about RE and AEV coils too. Hard to tell which ones will give me that 1/2-1" I need...

Thanks,
js.

 

Well depending how much of a bow you have the coil is constantly flexingmore on that side taking more weight with them seated correctly the weight should be 50/50 just give back that 1/2 inch you want but what do I know I'm just a puck stacker lol

Waiting for my ship to come in and going 3.5 or 4 inch with all the goodies then I'll stop and start beefing up the drive train

 

At this point I have replaced all four of my sagging Full Traction coils with Old Man Emu coils -- just use their regular OME JK part numbers for the kit they advertise as 2.5". These springs will actually give you closer to 3.5" of lift initially and then they'll settle to right around 3", and tend to stay there.

For some reason, some people on the board will tell you never to run the X-HD rear springs because they're too stiff, but this is not the case, even when not fully loaded. I've seen your build on other forums (very nice by the way), and I can pretty much guarantee you'll be fine with the X HD's.

I was running OME X-Heavy Duty rears with my Full Traction fronts for a while with no problem, but eventually got tired of the sagging front, so I put some OME HD's on the front as well.

Incidentally, I also found a set of those Air Lift airbags at a junkyard under a Ford Aerostar (of all things) and they turned out to be the right size. Between them and the OME HD springs, I can load the crap out of my rig and it handles great, even over the rougher stuff:

 

I had the same issue with my RE 3.5 lift. After I installed my rockhard rear bumper/carrier system my rear was sagging. I called RE and they recommended either going to their next tallest spring or putting in a spacer. I installed the 4.5' springs in the rear only and now it sits much better.