Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of January's Ride of the Month Challenge!
1 - 13 of 13 Posts

·
Registered
Joined
·
645 Posts
Discussion Starter · #1 ·
I'm currently running a Rock Crawler 2.5" "Flex" system with Bilstein 5100s. I replaced the front LCAs and track bar with Synergy and also run a Synergy flipped drag link, tie rod, and sector shaft brace.

Rear track bar and control arms are stock, but using the RK geometry bracket that came with the original kit.

I'm running Tom Woods shafts, so no issues with pinion angles.

The Jeep rides and handles great, but I'm running a heavy rear bumper/tire carrier and only getting <1" lift in the rear. I often tow a ~1,800 lb camp trailer (about 150 lbs tongue weight). With the trailer, the Jeep sits lower than stock height in the rear (and about 3" lift in the front).

I run a few hundred pounds of gear in the back of the jeep (rear seats removed, plywood deck, 12v fridge and storage).

I'm running 35" tires with 4.88 gears along with MCE flares, so no issues with fender contact at full stuff.

I'd like a suspension setup that will retain (or improve) the great ride I already have, but better support the weight of the gear in the back and the trailer, and reduce the trailer "squat".

I'm looking for ideas on which components (short of a wholesale system swap) to replace/upgrade.

I like what I read about the AEV 3.5" dual sport setup, (I think I've read that they make some heavier rear springs to go with the kit for Jeeps that tow?)

My gut tells me that a set of 4 matched springs along with a rear trackbar and geometry bracket (maybe rear LCAs?) would do the trick. Then the next question becomes "which ones"...

Thanks in advance for the ideas.

Brent Christensen
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #5 ·
Thanks guys. I ran Airlift bags on my Tundra with 3" lift for towing a boat and I was really happy with them, but I thought I'd heard that putting them on a jeep decreases flexibility off road?

I definitely like the fact that you can use the air springs only when you need them. But that being said, my current setup is too low even when I'm not towing... (Measuring against factory settings, I've determined that I have a 0.57" lift on the rear pax side and 0.96" lift on the drivers side (before setting the trailer). The front, in contrast is nearly 3" so the Jeep isn't really level, even without the trailer.

With respect to the front end setup, I had the track bar and tie rod/drag link installed by Synergy (Polyperformance) and at the time they told me I was "on the edge" of flipping the DL so they recommended flipping it. (they said if I had 2.5" or less they would not have flipped it, but since I was a touch over 3" they flipped it). They also installed the bump stops and I just measured them - they are 4"at the front. It sure looks like I don't have much room to flex downward! This is also part of the reason that leads me down the path of considering a different (3.5") lift, as I've never really been happy with the RK stuff that was on the Jeep when I bought it. (the only things left being the springs and the front sway bar links)

With regard to trailering, I've got that pretty well dialed. The trailer has brakes and the setup stops very well both on road and off (even with the stock calipers and rotors and OEM pads). I run 30-32 PSI regularly and increase that to 34 front/36 rear when towing. (but then air down both Jeep and trailer when off road). Its an incredibly capable combo
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #10 ·
I have a similar setup. 2016 JKU with 2.5 inch Rock Krawler lift with adj lower control arms on all four. I always thought it sat low in the back. I then got a 2000 lb camping trailer and it was close to the bump stops with about 180 lbs of tongue weight and gear in the back. I measured my actural lift empty and it was 3 inch in front and 1 3/8 in rear. This is after about 3 years of age. I though about air bags, but had issues off road on my prior XJ with them.

Decided to put 3 1/2 Rock Krawler springs in the back. I thought they would give me around 2 1/2 inch lift if they performed anthing like the original 2 1/2 inch springs. Of course they gave me a full 3 1/2 inches. So now the rear is 1/2 inch higher than the front plus the built in factory rake (which most lifts get rid of) of 1 inch, it looked like I was rolling down hill. I then went back and put 1/2 inch pucks in the front. Now I have 3 1/2 inch all the way around and it holds the tongue weight well. For some reason I think Rock Krawlers 2 1/2 inch rear springs have a lower spring rate.
Thanks. I’ve thought about just adding Teraflex spacers to the rear but I’ve never liked the way spacers “preload” the suspension.

I might consider that RK trick with 3.5” springs, but I honestly don’t think the RK stuff is well made. At least their finishes suck (rust and chip off very quickly).

I’m wondering if swapping out just the springs for a 3.5” AEV SC kit and then adding the AEV rear geometry bracket and track bar (and possibly Synergy LCAs) might be the way to go. I think the Bilsteins that RK spec’d with the 2.5” kit are the same as the ones they used to spec for the 3.5” kit…


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #13 ·
@sbsyncro I run spacers in every Jeep application I have. It's just like a motocross bike when adjust the rear spring to set ride height (droop). In the front of my LJ I have 1.5" spacers... It's not preload, it does not compress the spring further, it just raises the body. Measure the pinch seam to ground right behind the front tire and right in front of the back tire... Then add 1/4" and that's the spacer size to get you level. So if your rear is 3/4" less than the front at that pinch seam, you need 1" spacers in the rear. Easy, cheap and effective.
Thank you. I think I’ll just do that then. A set of Teraflex spacers. Probably 2” on the passenger side and 1.5” on the driver’s side, but I’ll measure. (I’m making that assumption since the rear is currently 0.5” and 1” whereas the front is at 3” from stock, so that should put the rear at 2.5” and even it out in both directions)

I ran spacers on my Gen2 Tundra for a while before swapping to Icon coil overs & control arms and I remember that the ride was HARSH with those spacers. Perhaps it’s a whole different game with IFS and strut/coil over suspensions…(?)


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #19 ·
Again, thank you all for the informative posts! Rob50lx you've got me drooling over the Synergy parts catalog again... A rear track bar and control arms are on my shopping list one of these days (once I finish a couple other things). rsmwrangler you got me motivated to get outside with a measuring tape and get a little dirty during my work day. Pressurized and GuzziMoto your knowledge continues to impress me every time I visit this site to research an issue and ask for help. The community would not be the same without you are resources. Thank you all!

For those curious, I'll post my numbers:

Based on information presented above (and other threads here on WF) I went ahead and measured everything again (rather than taking the word from a shop that worked on it a couple years ago). Here's what I'm showing:

FRONT

Automotive design Line Engineering Auto part Automotive exterior


Measurement "A"
DS shock measurement = 21.25 - 18.5 = 2.75" lift
PS shock measurement = 21.5 - 18.5 = 3.0" lift

Measurement "B"
DS spring perch measurement = 13.0 - 9.375 = 3.625" lift
PS spring perch measurement = 13.25 - 9.375 = 3.785" lift

Not sure why there is almost an inch of discrepancy between these two measurements... Perhaps its because I have a Rubicon?

REAR
DS bump stop cup to bump stop platform = 7.0 - 5.19 = 1.81" (versus non-Rubicon)
PS bump stop cup to bump stop platform = 6.785 - 5.19 = 1.60"

Interestingly, my pinch seams are the same front to back, so the Jeep is level. The driver's side is about 1/4" higher than the passenger side.

I have 2.5" of added bump stop in the rear (bolt on pad + puck)
There is 4" of bump stop added to the front (and only about 1" between the factory bump stop and the added pads).

I went ahead and ordered the airlift airbags - after measuring, I found that I needed 11" tall and 4" wide, so I went with kit # 60912. It was $102 shipped next day from Amazon. I figured that it is the most versatile (and easily reversible) solution. For those interested, the lookup table is here:

 

·
Registered
Joined
·
645 Posts
Discussion Starter · #22 ·
Looks to me that you mounted the airbags "upside down" from the instructions, from what I've heard this is the only way they will work correctly.
Air nipple up or air nipple down? Which way is the “only way they will work correctly”? (Per instructions or “upside down”?


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #25 · (Edited)
I'd think you'll want them nipple up cause then you can route the hoses through the openings at the top of the spring tower to avoid pinching them.
That is certainly the way I've done it with other vehicles in the past. Interestingly, I just found this video, where at about 3:35 he says "to be sure the nipple is going down" so he's installing them "upside down".. hmm


I'm hoping I can droop the suspension enough to squish them through the spring coils.. (and safely support the frame). This is where having a 5 ton floor jack becomes worth the weight and space...
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #28 ·
OK you guys. I just spent the last 45 minutes trying to stuff an airbag into my spring coil. There is NO way that thing is going inside that coil the way I'm doing it. I have lifted that side so that the tire is off the ground, but I have not disconnected the shock or the sway bar. Do I need to disconnect those to allow for additional droop? There is seriously only about 3/4" space between my coils when the rear wheel is fully drooped. No amount of four letter words seems to be helping. What am I doing wrong...?
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #31 · (Edited)
I just pulled the shock and the sway bar and it only gave me another 1/4" of clearance between coils. (I've just barely got the tire off the ground, but my 5T floor jack is maxed out). Now I have maybe 1-1/8" of space between the coils. My god what a giant pain in the a** compared to how "easy" I thought this would be. I still cannot see how this is physically possible without some kind of coil separator. I feel like I'm trying to do a heart transplant through someone's rib cage...

Maybe these Rock Crawler springs have a tighter wind to them? (another reason to dislike them). I can just get the end with the nipple between the coils but there is no way on earth the thicker bottom end will fit through. I've been swearing at this thing for a good 45 minutes now. I'm about ready to go back to the plan of putting in different springs or spacers - I think that would be easier to accomplish...
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #33 ·
Did you loosen the control arm bolts and trackbar bolts.
If the springs are multi-rate springs then the coils on one end are closer together than the coils on the other end.
Not sure why it is so important to fit the bags through the coils, for all the time it is taking you it would be faster to pull the springs and slide the bags in through the open end.
Sure, you could replace the springs if you want.
At this point I think I am going to just pull the effing springs and put the bags in from the tops. Every YT video and instruction on these shows people just slipping them through the coils with some effort but not like what I’m experiencing. Ugh. I’m at the point where my diff breather pulled free and my abs line needs to be disconnected so I might as well just pull the dang springs. I wrongly assumed this would be a lot easier than it is and foolishly thought I’d be done and enjoying a cold beer on a Friday afternoon by now. :)

Looks like I’m gonna just set it aside and deal with it tomorrow morning.

Honestly I’ve removed snapped off head bolts that were less frustrating than this! Lol


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
645 Posts
Discussion Starter · #36 ·
Yup that’s what I’m doing. Still required some muscle and soapy water to get those bags (deflated) down into the spring.





I’m gonna route the lines to behind the license plate and install the Schrader valve(s) in the license plate itself to make them easily accessible.

Now the question is whether to have them independent or tied together. Independent, I assume would allow once since to compress and send pressure to the other side when flexing but independent would allow me to correct my “JK Lean” by pumping up the passenger side a bit more. Hmm….
 
  • Like
Reactions: Rob50lx

·
Registered
Joined
·
645 Posts
Discussion Starter · #37 ·
For what its worth (and for others in the future reading this thread) I did not have to disconnect either the control arms or track bar. I also already had brake line extensions so didn't need to undo the mounts for the hard lines. I DID however need to disconnect the e-locker connection on the rear diff, the diff breather tube, and the ABS wires for both sides.
 
  • Like
Reactions: Pressurized

·
Registered
Joined
·
645 Posts
Discussion Starter · #39 · (Edited)
I just got back on after a while... Hate to see you struggled with them. But I have a set of RK springs here and you're right, the gaps are not as large as the Mopar's I have for sure. Would absolutely make it more difficult.

I have mine on a tee and the valve is in the pinch seam below the back of the fender. Out of sight for all that don't know it's there...

View attachment 4526478
Out of curiosity, are you running the spacers at the top? They seem like they will slide around, get pinched between the coils and cause problems…

I just put it all together and realized I forgot the dang tubing clamps on the nipples. Duh. Now apart it has to all come again!


Sent from my iPhone using Tapatalk
 
1 - 13 of 13 Posts
Top