I only have the 3" Springs, but I love them. They were a huge improvement over the 2" BDS I had before using the same shocks. Whether that is the dual rate spring or the extra inch of travel can be debated, but I give credit to both. Very nice springs. I don't know anything about the rest of the system. The JKS/Fox shocks would be fun to try but I love my 5160s.
JKS JSPEC suspension kit
- Thread starter bobthetj03
- Start date
OP
I have the JSPEC shocks on my TJ. I have OME springs and 1" spacers to net 3" of lift. I choose the 2" lift shock for the front and the 3" lift shock for the rear based on my bump stop extension limitations. This gives me a fairly close 50/50 travel bias. I tried the shocks out of curiosity mostly, and the price was reasonable at $47 a shock. My previous shocks were Rancho RS5000X shocks for a 2.5" lift, (RS55239/RS55241). The RS55241 rear shocks gave me a terrible down travel, and I couldn't use the available up travel. Not thinking it thru, I could have just used bar pin eliminators for the rear upper shock mount, which would have given me more down. With that said, I tried the JKS shocks anyway.
Comparing them to the Ranchos, the JKS shocks are firmer, with small events being much more noticeable. Higher speed cornering is better than the Ranchos, with less sway. Off roadiing, the ride is harsher, even with tire pressures lowered to 15 psi.
My take away? If you like a firmer ride the JKS shocks would fit the bill. Maybe in conjunction with the JKS springs, results may vary. Maybe the lower rate of the dual rate spring compensates for the firmer initial valving of the JSPEC shocks?
I'll be putting the Rancho shocks back on and using BPE's for the rears.
Comparing them to the Ranchos, the JKS shocks are firmer, with small events being much more noticeable. Higher speed cornering is better than the Ranchos, with less sway. Off roadiing, the ride is harsher, even with tire pressures lowered to 15 psi.
My take away? If you like a firmer ride the JKS shocks would fit the bill. Maybe in conjunction with the JKS springs, results may vary. Maybe the lower rate of the dual rate spring compensates for the firmer initial valving of the JSPEC shocks?
I'll be putting the Rancho shocks back on and using BPE's for the rears.
I just bought the JKS 3" springs for my LJ and I now have a shock dilemma. I have a set of Bilstein 5100 for a lifted TJ but they are 0-2" of lift and I have access to a set of Fox shocks for a lifted TJ but they are 3-4.5" front and I believe the rears Fox says 4"-6" of lift. Can I even use either of these for an LJ with 3" JKS springs?
That depends on your bump stop length. Which will mostly be determined by tire size.
Assuming you installed the lift to fit larger tires (33?). You probably have a couple inches of bumpstop added. With that assumption. You could run the 0-2" Bilsteins, but you will have limited down travel because your shocks are too short. If you run the Fox, you will almost certainly need at least 4" of bumpstop to prevent the shocks from over compressing and destroying themselves. So with all else being equal, installing 4" of bumpstop on a 3" lift you will loose 1" (or more) of up travel. So you would constantly be hitting your bump stops.
My guess is that the Bilstiens will be too short and the Fox are going to be too long for your needs. You are most likely going to need a shock for a 2-3 lift. I am currently running the Bilstein 24-185264 and 24-185257. If I remember correctly I have approximatly 2 3/8" bumpstops and my wheels have 4.5" backspacing with 285/75R16 tires.
You need to get your bump stops setup first to make sure you have enough bumpstop to prevent your tires from rubbing when fully flexed. Then measure the compressed length of the shock that is needed when fully compressed (Best done before coils are installed). There are lots of other threads in the forum detailing how to check for rubbing and how to measure for shocks. After you have you measurements you can find the shock that works best for you.
After all is said and done, do you think the 2” JKS net a true 2 inches? Same with the 3”? I am trying to decide between the two for my stock LJ softop. I would prefer to be over 2” but 3” max.
i can say that the 2" springs seem to net you minimum of 2"-i am closer to 3" but suspect my springs had gone a little soft. dont forget you can go two and do a small spring spacer or body lift if you need to tweak the ride or wheel clearance. adding pics i have with measurements
Last edited:
Depends on the weight, some are pigs and some are light, spring height will vary.
Well depending on bumpers, skid plates, how much shit is inside it, tool box, etc. it’s not like my scales are there to weigh it.
Sorry its been awhile since I did the install and I can't find my notes. But I think I was pretty dead on with 3" of lift in the rear. But I have a hard top. Up front I have a winch and a 3/8" spacer to bring me back to 3". Its always a bit of a guess to figure out how much lift you will get. With a LJ with a softtop I would think the 2" coil would give you a solid 2". But I wouldn't expect much more. The 3" would also give a good 3" and possibly a little more. Its been my experience that 2" coils often under lift where 3" coils often provide additional lift. So you need to decide on which end you are more comfortable to error on. Would you rather get 2" of lift and need to install some 1" spacers or would you rather get 3" of lift and deal with a little extra height? Because you have an LJ, your driveshaft angle should still be OK even at 3" of lift.
What size tire do you want to run? Will you be running a body lift? Tire size is really a determining factor. You will need a certain amount of bumpstop to prevent your tires from getting over stuffed in the fender. It may be beneficial to determine your tire size (as well as shock length) and determine how much bumpstop you will need. Then you can adjust your spring height accordingly. You don't want to loose any up travel from stock. When I had my 2" coils I didn't have much uptravel and it caused a lot of headaches. For my use I found up travel was more important than droop. But both are needed.
Thanks. Helpful. I won’t be crawling. She is a beach Jeep and I am on 31s, likely going to 32x11s. It’s just looks, but I did think about 33x10s, even though I only have 3.73s. No plans for new bumpers or racks etc. Also wondering if I go with the 3in, will I need to do control arms in the near term. Would like too be able to put that off until a later upgrade.
When it comes to driveshafts, the LJ is a more forgiving than the TJ. I think you would be OK with the 3" lift, but its in a gray area that could go either way. Especially if you got 3 1/2+. I have adjustable arms and I believe I eventually adjusted my rear lower arms a little bit to tip the front of the pinion back down a little to keep the input shaft horizontal with the output shaft of the transmission. (This is the opposite of what you would do if you purchase a double cardon drive shaft.) I think I also adjusted the front a little bit to gain back a little bit of the camber I lost due to the lift. I think you could get away with stock control arms for a while, but you might get vibes at highway speeds.
One nice thing about a 3" spring is that it opens up more shock options. Typically with a 3" lift you will run a taller bumpstop so you can get a shock that is a little longer fully compressed. The issue I had with my 2" coils is that there are very few shocks that fit a 2" lift properly. The best options I found were the Bilstien 5100 for a 0-1" lift or the OME 2" lift shocks. Even the JKS shocks provided in the 2" kit are too long for the kit. The shocks will bottom out before you hit your bump stops. So you end up sacrificing up travel as well as destrying your shocks because they are bottoming out.
The disadvantage of a 3" lift is it can lead to needing driveshafts, and control arms. The control arms are also at a steeper angle which can have some negative effects on handling. Both the 2" and 3" should use a raised track bar bracket in the rear. A 2" lift can get away with the factory track bar up front. In fact even my 3" lift is using a OEM replacment tracbar.
In short, the 2" will maintain a little better geometry if you don't need the height. But it will restrict you a bit on shocks and tire options. But if you like OME shocks, I think they are a great option for a 2" lift. I've never run 32x11.5 so I'm not sure what height you will need or what offset wheel you will use. But either way a 3" will give more clearance and more options, but a 2" maintains slightly better geometry. I prefer the 3" lift and recommend a 3" unless you are certain you won't need to flex much and you will never run bigger than the 32". For a 33" tire, a 3" lift along with a body lift works best.
Another option, that is seldom considered is to get 17" wheels and run the 255/75R17 that the JK Rubicons used. This is a true 32x10 tire. It would actually be 1/2 taller than a 32x10.5x15 and only about a 1/2" shorter than a 33x12.5x15. But because its a narrower tire, you could likely run it on a 2" lift with little or no rubbing. The issue with this tire is that there are no hub centric 17" wheels that fit on a TJ. So you either need to run hub centric spacers with a factory JK takeoff wheel or get rims that are not hub centric. Its a much debated topic if hub centric is needed or not, as well as if spacers are safe or not.
I just did this using that holiday discount. Very happy with the 2” spring ride quality. It is a 1/8” thicker so there is a little more firmness but for me it actually makes the Jeep more stable on the road. A couple weeks in to this my slight drive line vibe has disappeared as things settled in.
I took the plunge. After long anticipating an OME lift, I pivoted to the JSPEC 2in kit. I think it is a nice combination of parts and the 20% off sealed the deal. I will likely replace the factory isolators, or I might add a new to the old to grab an extra half inch. I see readily available front isolators from MOOG, but the LJ seems to have a thinner and wider isolator on top of the rear springs. Doesn’t look like you could use the front style.
Don't confuse the isolator with a spring spacer. The 1/2 spacers are much firmer material and you will likely get noticeable NVH if you remove the factory isolator. The spacers are intended to work with the isolators.
Since your running the soft top, I'd be surprised if you need an additinal spacer in the rear. It seems more likely you might need the OME 10mm spacer up front to bring the front level to the rear.
Keep us informed on how the 2" JKS coils work out for you.
Since your running the soft top, I'd be surprised if you need an additinal spacer in the rear. It seems more likely you might need the OME 10mm spacer up front to bring the front level to the rear.
Keep us informed on how the 2" JKS coils work out for you.
Not likely. Mine currently has aluminum spacers without rubber on all four corners. And I have gone back and forth between rubber and aluminum multiple times with no perceivable difference in NVH between them.