Hello everyone. I have just ordered the JKS Jspec 2" lift from Quadratec. I am going to install it next week and report back.
JKS JSPEC suspension kit
- Thread starter bobthetj03
- Start date
OP
Does anyone know the free length of the JSPEC 2" TJ coils? I have a OME lift right now and it rides great but the rear is a little lower than I'd like and they don't make a coil at 140 lbf/in with a longer free length for the rear. I saw on the JSPEC 2" lift product launch that they 2" springs have a rate of 150/220 lbf/in. The OME springs I am running are 140 lbf/in. My Jeep is light and the armor and bumpers I have are also light in comparison to many out there.
Thanks All.
Specs:
2004 Jeep TJ Rubicon
Savvy Front Bumper with Warn M8000 Winch & 100 ft Synthetic line
Savvy Aluminum Rockers with steel rock slider
Savvy Gas Tank Skid
Savvy Under Armor
Savvy Aluminum double adjustable control arms with JJ's (all 8)
1.25in BL w/ 1in MML
OME 2" Lift (2932 Front/ 2941Rear)
255/85r16 Cooper ST MAXX mounted to Stock Moab TJ Wheels
Pictures of the Heep attached.
Thanks All.
Specs:
2004 Jeep TJ Rubicon
Savvy Front Bumper with Warn M8000 Winch & 100 ft Synthetic line
Savvy Aluminum Rockers with steel rock slider
Savvy Gas Tank Skid
Savvy Under Armor
Savvy Aluminum double adjustable control arms with JJ's (all 8)
1.25in BL w/ 1in MML
OME 2" Lift (2932 Front/ 2941Rear)
255/85r16 Cooper ST MAXX mounted to Stock Moab TJ Wheels
Pictures of the Heep attached.
That spring rate you listed is for the front coil. The rear coil in the JSpec kit is 190/240. So its probably not the kit you are looking for. Deosn't OME make a small leveling spacer you could put in the rear? If you like your ride, I would recommend just putting in a poly spacer in the rear.
Thats a good looking TJ. How do you like the ST MAXX? When I went to my 255/85s the choice was ST Maxx or KM2. I went the KM2 route. But I like the slightly wider look of the ST Maxx better.
OP
Awesome shot at TOTW. I'd agree with Fargo, just add the OME 10mm spacer, or a 3/4" poly spacer if you want a little more rake. Don't fear the spacer.
Thanks, I did so many google searches and couldn't find any information on the springs or shock lengths. I finally just ended up emailed JKS and got a reply which matches what you said so I appreciate it. It's not normal having a company actually open about releasing their spring rates. I wish companies would just post the rates on their website haha.
I love the ST MAXX but I haven't had them on but for 5,000 mi. I had 33x10.5r15's KM2's on a previous Jeep and liked them when they were new but as they wore down they got louder and louder. I am currently tracking down a humming sound that is speed related but I think it's the front hub unit bearings going out as they are the original ones and have over 80k miles on them. If It's the tires then I'll be hugely disapointed cause the ST MAXX were supposed to be a "quieter" tire then the KM2/3. I wish more manufactures would make 255/85r16 tires. I prefer the look of "Pizza Cutters" even though these are not actually that but are more narrow than 285/75r16's. They also perform very good offroad.
The Issue is not so much just adding a spacer but maintaining the up travel in the rear. Adding a spacer does not solve my sole problem. The Jeep on a day to day drive had a Thule 2 bike rack on it but on occasion I have a 250lb dirt bike on a rack on the back. A spacer does not keep the spring from riding on the bump stop. Granted it's not every day that I transport the dirt bike but when I do it's for a couple hours to get to the trails. I was hoping to find a spring like the JKS dual rate that would allow the Jeep to ride well when not loaded but then when loaded it would support the extra weight.
From what I can see the JKS rear springs are going to be too stiff when the Jeep is not loaded so I agree that the JKS JSPEC springs are not going to work for me. Interesting that JKS advertises the springs to be designed for a light weight jeep yet their initial rate is quite higher than the stock jeep springs.
So break down for info to be in one place:
JSPEC 2" Front Coils: 150/220 lbf/in - 19 in
JSPEC 2" Rear Coils: 190/240 lbf/in - 14 in
OME Front 2931 ZJ I6 - 140 lbf/in - 20.08 in
OME Front 2932 - 140 lbf/in - 18.89 in
OME Front 2933 - 140 lbf/in - 19.48 in
OME Front 2934 ZJ V8 - 160 lbf/in - 20.08 in
OME Rear 2941 Hard Top - 140 lbf/in - 15.35 in
OME Rear 2942 100KGS - 160 lbf/in - 14.96 in
OME Rear 2949 LJ Hard Top - 216 lbf/in -14.57 in
OME Shock Lengths
Front: Extended - 22.4 in, Compressed - 13.2 in
Rear: Extended - 22.1, Compressed - 13.03 in
JKS 2" Shock lengths
Front: Extended - 22.9 in, Compressed - 13.9 in
Rear: Extended - 22.95 in, Compressed - 14.56 in
With that new info, the JKS might work for you. It could be a little stiff when empty, but shouldn't be bad. But it will carry the load much better when you are loaded down. Other companies make dual rate and progressive rate springs, but most of them are designed so the soft coils are in full coil bind at ride height. Which means the only purpose they serve is that they are a longer spring so the spring doesn't fall out at full extension. They provide nothing for helping to carry extra weight.
OP
I've been running the 933/942 OME's for some time now, first with OME's original Nitro shocks. Wore them out and got Rancho RS5000X shocks, which btw, ride very similar to the 1st gen OME's. I've considered the JSPEC springs, but am still undecided.
I agree that the rear's would work and would just ride stiff when unloaded. Considering my jeep is mostly unloaded with exception of a bike rack and 1 or 2 mountain bikes I keep it pretty empty. I removed the rear seat the day I bought it and haven't put it back in since.
I am looking at getting a set of air bag coil spring supports and have read good things about them. Also they are only $100 bucks so a lot less money than buying a set of JSPEC springs. Since I can run the bags at a low psi when unloaded and then just air them up enough to support the extra weight I think right now that's the route I am going to try first. I wish currie or savvy would make a progressive 2" spring but is what it is. I had Savvy's 3" springs on my 97 and it too was a light build and netted me about 3.5" since I didn't have enough armor or weight to get them to their proper sag point. That's the reason I went with OME 2" springs this time. Also I don't do a lot of rock crawling anymore and after wheeling my jeep in Colorado stock with a tummy tuck and highway tires I learned for the type of wheeling I do 2" on 33's is more than enough. I could go down to 265/75R16 and might on my next set of tires.
Appreciate the input and have enjoyed poking my head in and out of this forum from time to time. Cheers.
I really admire guys like you. You know your needs and you are just building for that. My Jeep usage is pretty much limited to a 1000 miles of highway out to Colorado for 2 weeks every couple years. And like you, I realized that I don't need a lot of lift and big tires to do the trails I do out there. But yet, I find that everytime I buy tires, I have to buy something the next size bigger. I'm now planning on moving up to a 34" tire for my next purchase. Not because I need them, but just because 34s would look so dang cool on my LJ.
I was going to mention the Savvy springs to you but it sounds like you are already familiar with them. I did think of a couple other options for you though.
Looking at a little spreadsheet I keep of spring info, I found that I called Synergy at one time and thier 2" springs are 130/150 for the front and 130/195 for the rear. This was too soft for my needs, but it might work well for you. Rock Krawler also has a dual (or was it triple) rate spring. All I got from them was it rides on 145 front and 180 in the rear. This might also be an option for you.
Ok, so I just Got my 2” JKS lift kit installed today. Coils, shocks, quick disconnects, extended brake line brackets, front and rear adjustable track bars( rear was not included in the kit) and rear bump stops. Also added a teraflex steering shock.
Only drove about 20 miles so far but the difference from my stock coils with the front bilstein shocks and rear pro comp shocks is huge. Waaayy smoother over bumps, yet firm. Responsive suspension that feels tight. No issues on the install. Came with all the hardware labeled and easy to follow up. I love the height with my 32’s. All parts are quality, beefy parts. Will report back after more testing but so far I am beyond excited. Night and day difference.
Only drove about 20 miles so far but the difference from my stock coils with the front bilstein shocks and rear pro comp shocks is huge. Waaayy smoother over bumps, yet firm. Responsive suspension that feels tight. No issues on the install. Came with all the hardware labeled and easy to follow up. I love the height with my 32’s. All parts are quality, beefy parts. Will report back after more testing but so far I am beyond excited. Night and day difference.
Thanks for the review and the pictures of the coils. It looks like there is still plenty of soft coil left before you get into the heavy rate. Can you measure your coil. How much lift did you get?
Hey Fargo,
Did not measure the lift yet but I will do it in the next couple of days. It definitely looks like more than 2” and that’s because of the flat fender flares too. I have some good bumps on my way home and did not feel any bottom ups. It feels smooth and tight compared to my stock coils and old shocks
Added lift will be interesting. Farmergreg said he got 5 3/4 inches from his 3 inch jspec springs (he was on stock springs with high miles).
Not what I said!
Gained 3 3/8" spring lift if I recall. From the 5 3/4" have to back out the BL and the tire size increase and the possible sag from the tired oem springs.
My mistake. In my best Roger Clemmons' voice, I "mis-remembered."
I was really looking forward to these photos, but without stock flares, they don't help in my case. The flat flares have so much more room it's hard to see what it would look like without those.
Thanks for posting, though.
Thanks for posting, though.