Trying to figure out rear springs on 97 TJ

[nuffsaid]

So as it goes when we buy a ride, it takes time to make it ours. I have had my TJ for almost 5 years now and it is getting closer to perfection. Two weeks ago I stumbled into a nice hardtop for 50.00 and made a friend too! Back to the subject at hand. My Jeep came with a Currie 4 inch lift and Currie Johnny Joints and Currie steering linkage. In the rear, the springs seemed short as they had about 2.5 inches of spacers on top of the coils to make the Jeep sit level. The rear Currie springs flexed well, but seemed to ride very stiff, even with the Rancho 9000 on the lightest setting, so I ordered some Skyjacker dual stage 4 inch lift rear springs hoping to get rid of the spacers. Didn't work! With the new 4 inch springs I had to add the spacers back to get the rear to sit level with the front. The first stage of the 4 inch Skyjacker springs are all touching, so there isn't a lot of spring for compression. They do flex great though. Two weeks ago I decided to try something new, so I ordered some Rubicon Express 5.5 inch lift rear springs for a TJ. They came in and I installed them without the spacers and the rear of the Jeep sits about 2 inches higher than it did with the 4 inch Skyjacker springs and 2.5 inch spacers? Due to my extremely short rear driveline I decided to remove the Rubicon Express Springs and send them back to Amazon, because something isn't right. Today I welded in some new upper spring buckets from Barnes 4wd to straighten the angles out a bit. I re-engineered their replacement spring bucket kit to include a billet steel extended bumpstop mount and I bent the brackets a little to get the buckets closer to parallel with the bottom buckets. I reinstalled my Skyjacker springs with the 2.5 inches of spacers and it sits level again.

I installed a pair of true trac diffs in my buddies 06 TJ yesterday and he also has a 4 inch lift (unknown brand) his jeep sits almost as high as mine with the exception that I have a one inch body lift. His rear springs have no spacers and look much better than mine. Anyone have a clue what could be up? I sent an email to Skyjacker to see if possibly my springs were miss marked and are only 2.5 inch lift.

 

[macleanflood]

How much does your Jeep weigh? How about the front axle vs rear? Same with your buddy?

My 97 weighs 4400 lbs without my hardtop. Currie 4" springs. Almost an exact 50/50 split between the axles. And she squats a little in the back when the top goes on for the winter.

-Mac

 

[nuffsaid]

My TJ is a little heavy, usually between 5200-5500. The rear is typically about 300 lbs heavier than the front. It has front and rear winches though, but the spring issue was there before I added any extra weight and doesn't change much even if the rear is totally empty. Right now, my spare tire is off because I have a rack mounted into the receiver hitch to haul my E pack wheel for elk hunting. I can't get the rear hatch open with the rack on. My Currie rear springs were pretty short unloaded. The Skyjackers are fairly long, but the coil diameter is about 1/16 inch smaller than the Curries or Rubicon Express springs.

 

[Rickyd]

It is my understanding that currie coils are on the longer,softer side compared to most. Try softer shocks like blackmax and less tire pressure?

 

[JMT]

My TJ is a little heavy, usually between 5200-5500. The rear is typically about 300 lbs heavier than the front. It has front and rear winches though, but the spring issue was there before I added any extra weight and doesn't change much even if the rear is totally empty. Right now, my spare tire is off because I have a rack mounted into the receiver hitch to haul my E pack wheel for elk hunting. I can't get the rear hatch open with the rack on. My Currie rear springs were pretty short unloaded. The Skyjackers are fairly long, but the coil diameter is about 1/16 inch smaller than the Curries or Rubicon Express springs.

That’s a lot of weight in the back. That’s your issue. Your springs aren’t long enough to give your heavy rig 4” lift.

 

[nuffsaid]

It is my understanding that currie coils are on the longer,softer side compared to most. Try softer shocks like blackmax and less tire pressure?

My currie kit is probably 20+ years old and the rear springs were short and stiff. They did flex well, but when I got the Jeep it already had the lift and the 2.5 inch spacers and it sat level.

 

[nuffsaid]

That’s a lot of weight in the back. That’s your issue. Your springs aren’t long enough to give your heavy rig 4” lift.

Winch weighs about 100 lbs, right now the spare tire and high lift jack are removed and it makes no difference in ride height. Bottom line is that something is off. When I put the Rubicon Express 5.5 inch springs in the rear of the Jeep jumped two inches with no spacers! Too tall for my short drive shafts even with high pinion diffs. I am maxxed out on extension on my upper control arms too. I thought about sleeving the tubing and adding 1.5 inches so I could rotate the pinion up more and move the axle back another 3/4 inch. I put it back the way it was because it works well, I was just hoping to lose the spring spacers.

 

[JMT]

Winch weighs about 100 lbs, right now the spare tire and high lift jack are removed and it makes no difference in ride height. Bottom line is that something is off. When I put the Rubicon Express 5.5 inch springs in the rear of the Jeep jumped two inches with no spacers! Too tall for my short drive shafts even with high pinion diffs. I am maxxed out on extension on my upper control arms too. I thought about sleeving the tubing and adding 1.5 inches so I could rotate the pinion up more and move the axle back another 3/4 inch. I put it back the way it was because it works well, I was just hoping to lose the spring spacers.

I know you want to get rid of the spring spacers, but technically there’s nothing wrong with them. 2” is excessive to me since they’re usually used to dial in a lift height.

If you know the sprung weight of each corner you can strategically buy a spring to give you the lift height you want.

 

[Rickyd]

My currie kit is probably 20+ years old and the rear springs were short and stiff. They did flex well, but when I got the Jeep it already had the lift and the 2.5 inch spacers and it sat level.

Currie has different springs for the lj. Maybe give them a call?

 

[nuffsaid]

While my Jeep seems a bit heavy, most of the added weight is unsprung weight from the Currie Axles. As far as sprung weight goes, my diesel engine weight is similar to the 4.0, a little extra weight with the klune vee doubler box and the atlas II transfer case probably weighs a bit more than a 231/241. I don't have a back seat installed and I usually carry about 150 lbs of tools parts etc in the rear of the Jeep plus 100 lbs for my rear winch. Right now I have deducted about 200 lbs for my rear tire carrier, spare 35 inch tire and high lift jack so that I can haul my pack wheel that weighs about 80 lbs total. Maybe Skyjacker will warranty their springs and replace them with 6 inch springs that would be perfect if they settle the same way the 4 inch springs settled. The problem I have with the spring spacers is compression travel, I have plenty of extension travel. I just can't believe how high my rear end sat with the Rubicon Express 5.5 springs.

 

[Rickyd]

You should be able to find spring rate and free length measurements for all these springs. From that you can make much better guesses on how different springs will react.

For instance,if the 4" skyjackers give X loaded height and have the same rate as their 6" version you can subtract the free height of the 4" version from the 6" and that will be the height increase.

Same with currie.they list all those specs.

Weigh the back end of your jeep and you can get close to knowing installed height with just some math

 

[nuffsaid]

I went to Curries website and looked at the specs for the new Rock Jock 4.5 lift rear springs. It shows a loaded height of 13.5 inches and a free length of about 18.5. I just loaded my Jeep onto my trailer for a elk hunting trip tomorrow and measured the rear springs. Top bucket to bottom bucket is 12" with a full tank of fuel and my pack wheel loaded into my rear hitch rack. The compressed 4 inch Skyjacker springs measure 9" , which leaves about 3" of spacers. I am currious what Skyjacker will have to say about this. On the Rock Jock website they state lift will vary depending on how much weight is in the vehicle. If my loaded springs were 13 inches they would be perfect! My original Currie lift springs were nowhere near 18 inches free and they were probably only 9 inches loaded. In contrast, the 5.5 lift Rubicon Express springs only settled about 3 inches with the same weight on them. The coil diameter was approximately 5/8 while the Skyjacker springs are only 9/16 and the original Curries were also 5/8.