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Spring Rate Thought/Opinion

jsparhwk

NAXJA Forum User
NAXJA Member
Location
Richmond, VA
So I’ve done some reading on spring rates and gathered this information….
sorry I should have been better about recording sources
but some of its from good ol NAXJA some from other forums…

So here are some of the options I’m looking at,
stock springs are 180lbs per inch (for comparison)
Iron Rock Offroad 3” 200lbs per inch
Rubicon Express 1300 (Cherokee) 3.5” 240lbs per inch
Rubicon Express 1341 (Grand Cherokee) 3.5” 150lbs per inch
Rustys 3” 150lbs per inch
Rustys 3” HD 180lbs per inch
BDS 3” 240lbs per inch

So what I’m asking is has anyone ran any of these and ended up swapping them months later due to ride quality/performance?

Before I looked up these numbers I was going to go Rubicon Express, but after seeing how high the spring rate is I’m rethinking...
 
I think you'll find anything less than about 200-220 too soft on a lifted rig. And that some of your numbers are wrong.

RE are actually pretty soft and rusty's are TOO soft, like a slinky. Performance XJ coils are in the 240-285 range.
 
I don't know how accurate the numbers are but my stock DD is very loose and anything that is close to that is going to be flopping around a lot. Stiffer is better off-road.

I ran the RE 3.5 for a long time and they were very firm. RE publishes the spring rates on their product pages so I believe their numbers. I could drive on the road without the swaybar and had no problem with excess body roll. Lots of control on the trail, not much flopping, some jarring stops but some of that was probably related to short arms at the time.

I am currently running the metalcloak 4.5 coils now for the extra relaxed length, to prevent them from unseating. MC doesn't publish their spring rate but I can tell they are closer to the RE than they are to stock. I can also drive on the road without a swaybar, and its a little looser but nowhere near stock looseness. Still pretty good control on the trail but a little more floppiness and less jarring.
 
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RE makes 2 3.5 INCH kits with different rate.springs. I have the softer of the 2 and the ride is very good for daily driving and a bit softer off road. I would recommend it for a DD.
 
What kind of ride height are you looking for?

Currie's CE9132F is 132/150 for a combined rate of 70, with 4" lift.
Currie's CE9132F1 is 132/150 for a combined rate of 70, with 3" lift.

I have not tested the F1, but I have run the F and it seems decent albiet very soft.
 
As to ride quality, I think stock XJ springs are too soft. My 2000 with RE 3.5" lift rides nicely on pavement and handles great off-road. I put together a Frankenstein lift for my 1998 with Rusty's 3" HD coils, a firm bastard leaf pack, and Bilstein 4600 shocks. It handles great on pavement, the ride quality is firmer than stock, but nothing objectionable

If you have lots of additional weight, skids/bumpers/roll bars/winch and other gear, you likely will want a higher spring rate.
 
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well I def don't want to spread bad info...
and in the interest of others who may read this I tracked down all my sources, however it appears RE's website is down atm.

IRO 3” 200lbs per inch -(verified)https://www.ironrockoffroad.com/product/xj-3-front-coil-springs.html
RE1300 (Cherokee) 3.5” 240lbs per inch https://www.naxja.org/forum/archive/index.php/t-1090144.html
RE 1341 (Grand Cherokee) 3.5” 150lbs per inch - ignore figure (can’t find supporting documentation)
Rustys 3” 150lbs per inch - https://comancheclub.com/topic/19121-are-rustys-coil-spring-any-good/
Rustys 3” HD 180lbs per inch (verified) - https://www.rustysoffroad.com/rusty-s-coils-xj-3-hd-front.html
BDS 3” 240lbs per inch - https://northeastoverland.forumotion.com/t285-spring-rates-for-jeep-guys
 
As far as what I was going for, I was going to do a 3” coil and ACOS coil spacers in the front for a total of 4.5” (to allow for ARB bumper and Winch weight adjustment)
Then in the back I was going to do a 3.5” full leaf pack with a 1” shackle.
Since shocks go hand in hand…I was going to do Bilstein 5150…but I found out they don’t make them anymore, so looking at the 5100

this will not be my Daily but I will be driving on roads/interstate to get to the trailhead, etc (avg 2hrs)
 
I ran the re 3.5” springs for about 5 years. My rig rode like a caddy on the road even with super stiff white rockets for shocks. I think the big difference for me was i had control arm relocation brackets. That made an enormous difference. The stiffer front springs make the leafs work more offroad. Transferring more motion to the rear. Much more balanced articulation in the rocks with stiffer front.
 
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