JKU Suspension dilemma

wandererr

Adventurer
I started asking questions in the Ursa Minor thread but figured I shouldn't hijack it too much, plus the topic is broader then UrsaMinor.

So here's the starting point: 2012 JKU Sport. Originally had the 17 and 58 springs. I just verified that I have the 19 and 60 springs (I upgraded throughout the years, though I thought that I had recon springs). Front also has the stock isolator and a .75" daystar spacer, rear has just the .75" daystar spacer. This theoretically should give me over 1" of lift over stock though the formulas (the front shock length measurement and the rear frame to axle show barely 1"). So it's possible that the extra weight that I have (I always carry tools in the back and some gear) have me sitting lower then expected.

I have the Ursa Minor top on order which will add 150lbs. I also tow a trailer from time to time (about 100-125lbs tongue weight) and have two extra passengers in the rear at the same time. I don't want to go taller, and understand that the trailer and passengers will always introduce some sag.

Some folks have recommended the OME springs, but the ones that would make sense and are designed for heavy load (300lbs) net about 2.25" of lift. So I'm looking at the Terraflex coils. Their 2.5" coils have 170lbs spring rate and are linear. So my logic is as follows:

The 2.5" Terraflex coils from what I read as posted by folks add over 2.5" of lift. I figure with the DV8 rear bumper I will have about 2.5". When I add the UrsaMinor top, that will drop the rear by maybe about .75" down to 1.75". The passengers and tongue weight might drop me by another 1" to 1.25".

So the daily will be UrsaMinor top with no passengers which means probably about 1.75" of lift - if more, I can always carry a sack of potatoes or two ;)

Linear coils will give me same spring rate as it compresses under weight.

Am I on the right track or did I lose my marbles? :)

Also open to other suggestions (btw, I am considering using airbags when towing, but that would still work with this plan as well).
 

kootenay

Intergalacticsuperintendent
I use airbags and love them. When towing it really helps prevent buck and dive on rough roads or frost heaves. You might find adding a set to the springs you have now is the solution, you can tailor the height (squat) and stiffness with air pressure. So when you are lighter just run less air.

If you want new springs I have heard really good things about the rockcralwer triple rate coil springs, many friends have switched to them an are very happy. I am personally running the Rancho 2" sport lift springs on my rubicon, so more like 1" lift? When I replace the springs, I will be looking at the rockcrawlers.
 

that_dude

Member
I guess I’m kind of confused...in your third paragraph you say you don’t want to go taller, but your question is about the Jeep not being tall enough?
 

wandererr

Adventurer
I use airbags and love them. When towing it really helps prevent buck and dive on rough roads or frost heaves. You might find adding a set to the springs you have now is the solution, you can tailor the height (squat) and stiffness with air pressure. So when you are lighter just run less air.

If you want new springs I have heard really good things about the rockcralwer triple rate coil springs, many friends have switched to them an are very happy. I am personally running the Rancho 2" sport lift springs on my rubicon, so more like 1" lift? When I replace the springs, I will be looking at the rockcrawlers.
I called RockKrawler and when I explained my dilemma they said that the way they designed their coils they wont work as well for me and I'd best be suited with linear coils.
I guess I’m kind of confused...in your third paragraph you say you don’t want to go taller, but your question is about the Jeep not being tall enough?
I want to stick with about 1-1.5" and when I add the extra weight I'd go lower then I am.
 
The 300lbs weight with 2.25" and harsh ride reported with no load.

If it was a 300lbs load spring with 1.5" lift I'd be all over it.

I've read similar complaints with the TeraFlex springs you are considering...just sayin'. You've done a good job of considering all weights and uses. I think that if you set it up for the 80 to 90% use level and do the air bags for the other 10% you'll have the "best" of both...any linear rate spring that is capable of handling the fully loaded weight is going to be stiff/harsh when you are under weight. I am kind of in the same boat in my decision making (albeit with different build/use) and am making the same kind of evaluations of my choices or at least I'm attempting to. I am finding that it is a bit paralyzing. I'm going to have to make a plan and go with it sooner or later! I'm going to do the best I can for the 80/90% use and then see if/what needs adjustment, or just accept it!
 

wandererr

Adventurer
So I got my hands on the Terraflex Outback 2.5" (for 4door) coils. They are just a hair over 2" taller uncompressed. They also have 2 more coils and are 2mm thicker on the coils. Wonder what will happen when I put them in...... I already have 2 5gallon water canisters and one 4 gallon fuel canister ready to be put in and counter the weight..... curious.... very curious ;)
 

wandererr

Adventurer
ok, so I swapped in the 2.5" outback coils..... whoever put the specs on the coils is off their rocker! On a stock JKU with a hardtop and some tools in the back (and I have quite a few of those) I net nearly 4" over stock suspension... WTF??????? When I added 22 gallons of water (183 lbs) I dropped about a .75 inch. When I hooked up my trailer (I had nothing in the back so it was front heavy at 200lbs tongue weight) I dropped additional 1" which still netted me over 2" over stock suspension.....

I'll be calling Terraflex tomorrow and having a serious chat with them about that. I would have been happy at most at 3" over stock to start with.
 

billiebob

Well-known member
I am considering using airbags
Just Do It

Full adjustability for a hundred bucks.
You dont even need a compressor, A bicycle pump will air you up in a minute.
I recommend 1 fill, not 2, let the bags equalize as you articulate.

"WTF???????"

yep, TeraFlex is a marketing company, not an engineering firm.
What they do, they do well, they make money for shareholders.
I'll never buy from them and I've owned Jeeps for 50 years.

I guarantee they recommend you buy something else.
 
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wandererr

Adventurer
Just Do It

Full adjustability for a hundred bucks.
You dont even need a compressor, A bicycle pump will air you up in a minute.
I recommend 1 fill, not 2, let the bags equalize as you articulate.

"WTF???????"

yep, TeraFlex is a marketing company, not an engineering firm.
What they do, they do well, they make money for shareholders.
I'll never buy from them and I've owned Jeeps for 50 years.

I guarantee they recommend you buy something else.
I spoke with them and they were surprised I netted as much and indicated that while springs will settle some, they won't settle that much and yes - if I'm not happy I should return them.... god bless amazon for free return shipping. I have 1.5" TF ones coming in that I'm hoping will fit the bill. I pressed again about the differences and turns out the 1.5" ones have spring rate of 180. So going back to my original calculations and thinking, if they net me a hair over what they advertise (probably not as much as the outback ones as they're lighter duty) this might be the ticket. Should they compress more under load, I can always stick the spacer I have to compensate. In general I need to get more lift then I have now and deal with the weight of Ursa Minor top when it comes in....... cue the tune titled "March of the gladiators" as I run around looking for an empty chair ;) (wonder how many will get the joke :D )

Air bags for the win!
When fully loaded I run them at 23psi.
When running around topless, 5psi

Ride quality remains constant regardless of load/towing.

I also added Rancho adjustable shocks for the win win.
Which airbags did you get? How did they mount? Air through the top?
 
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