How to get more flex out of my Xj

[notamechanic]

Hey everyone, just installed rubicon expresses long arm upgrade and it flexes more, but not quite what I was expecting. Not saying it’s the kit. Likely other limiting factors in my suspension.

Current set up is zones 4.5 coils, re long arms, bilstein 5100(BIL24-185943) fronts, bilstien 5100 rear, re3.5 leafs, 1.5” boomerang shackles, extended brake cables etc.

Any setup advice for gaining some more flex? I’m thinking 5.5 coils and some shackle relocators, but thought I’d ask before I start spending.

Don’t have many photos of the short arm flex or measurements. I think the gam was just a few inches.



short arms

Long arms

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[SlowXj]

Front-- You're probably restricted by shocks and or steering up front. It's my understanding heim steering usually adds more misalignment for droop. You may need to modify lower shock mount points (lower them) to fit a shock with more travel.

Rear -- longer shackle length and proper angle along with inboarding the upper mounts on the shocks can allow a longer shock be installed for more travel. Or the pricy coil conversion.

Don't get to hung up on travel.... There's a point of diminishing return... Then you get into the discussion with unseating coils causing instability and not enough pressure for traction etc etc....

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[bajabronco]

In the front I have found that if you remove your shocks and test, the steering as well as your track bar can bind, limiting travel. A knuckle over conversion as well as a good flex joint, double sheer track bar setup will help. In the rear you are right to look at a shackle relocation bracket. If your existing setup has a close to 90 degree shackle angle, then the rear droop is limited to just the flex of the leafs. If you have a longer shackle and decrease the shackle angle, it will allow for more travel - the actual movement of the shackle as well as the leaf. One thing to take into consideration when it comes to travel, is having balanced and usable travel is more important than overall travel. I actually limit the amount of travel I have in the front of my rig, and use a currie anti-rock swaybar on the softest setting in the front. It allows me to have much more balanced travel between my front and rear, more off-camber stability, without sacrificing usable travel. Tons of flex is nice for a RTI ramp, but not always the best when wheeling.

 

[RCP Phx]

Post a pic of your shackle angles, also do you have extended bumps in the rear?

 

[Evan03]

I'd raise steering and raise track bar to mach.

Lifting will only reduce usable travel because steering and track will be at greater angles. You want them as flat as possible at ride height.

From your photos I'm thinking you have plenty of flex anyways and could put money into lockers if you havent all ready. No reason in have a flex rig that only drives two tires.
I also dont see a winch maybe put some money in front frame stiffners winch bumper and winch.

 

[notamechanic]

more info on the setup.

running cavfabs high clearance 1 ton heim steering setup. tie rod under the knuckle. Definitely can see steering binidng, will check next time I'm at the shop.

RE double shear track bar. 1 inch home brew rear bump stop extension I made out of aluminum stock.

I didn't realize there is a limit to how much flex is safely used. I will need to do some more research on that. Any references would be greatly appreciated.

I will post a pic of my shackle angles tonight. I know they can be better but want to see what you guys think.

If it look good nuff I might just leave it be.


I have a winch and rear locker. Too scared to run a locker in the dana 30 with 35s. Front stiffeners are in the garage, need to find time for them.

 

[SlowXj]

Not to derail the thread but isn't a locked Dana 30 on 35s kinda common?

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[notamechanic]

Well would be derailed in a good way. I always hear about a locked/geared dana 30 breaking axle shafts. I couldn't afford a fancy selectable so it would be a lockrite for me if I were to do it.

 

[SlowXj]

I'm on 31s with a lunchbox, so apple to oranges, but I like it. COMPLETELY invisible in 2wd...

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[notamechanic]

I'd feel completely confident on 31's. I have 4.88s and 35s. I really want to run one up there, but might stress me out on the trail. Saving up for some jkur dana 44s.

 

[SlowXj]

I love the idea of the jk 44 swaps... I found a set for 2200 last year but ended up doing the 8.8 Dana 30 with factory 4.10s way cheaper...
As a side note with the radius arm front your running you may wanna brace your passenger side upper axle bracket. I've seen a few of those rip off due to the binding.

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[denverd1]

had my 30's locked on 33's for several years. and I'm not very nice to it....

OP you need to undo shocks and flex it to see what binds. running 4 links up front? pretty common to run 3 (remove passenger upper, IIRC) fas long as your joints can handle it. should let it drop out a bit more

 

[Rockwood]

Front-- You're probably restricted by shocks and or steering up front. It's my understanding heim steering usually adds more misalignment for droop. You may need to modify lower shock mount points (lower them) to fit a shock with more travel.

Rear -- longer shackle length and proper angle along with inboarding the upper mounts on the shocks can allow a longer shock be installed for more travel. Or the pricy coil conversion.

Don't get to hung up on travel.... There's a point of diminishing return... Then you get into the discussion with unseating coils causing instability and not enough pressure for traction etc etc....

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Or since most of us bump-stop to clear 35s, RAISING the lower shock mount to actually use all of the shock's travel. How much to raise the mount can be determined by adding a zip-tie to the shaft and seeing how much of it remains after FULLY flexing it out (bounce on it if you can to compress the stops more). Leave half an inch to be sure.

In the front I have found that if you remove your shocks and test, the steering as well as your track bar can bind, limiting travel. A knuckle over conversion as well as a good flex joint, double sheer track bar setup will help. In the rear you are right to look at a shackle relocation bracket. If your existing setup has a close to 90 degree shackle angle, then the rear droop is limited to just the flex of the leafs. If you have a longer shackle and decrease the shackle angle, it will allow for more travel - the actual movement of the shackle as well as the leaf. One thing to take into consideration when it comes to travel, is having balanced and usable travel is more important than overall travel. I actually limit the amount of travel I have in the front of my rig, and use a currie anti-rock swaybar on the softest setting in the front. It allows me to have much more balanced travel between my front and rear, more off-camber stability, without sacrificing usable travel. Tons of flex is nice for a RTI ramp, but not always the best when wheeling.

Yep. Even with a short arm setup, one of the biggest problems I have isn't that I'm lifting a wheel, but that the front and rear take an obstacle very differently since the 4 link flexes so much better. My rear windows bare the scars of this from brushing against rocks (they're surprisingly flexible... )

 

[gearwhine]

I used to have RE 4.5" leaf springs with RE 4.5" ZJ coils. I had the same issue that the front would go full flex before the rear really started....springs rates were just too different.

I ended up taking the shortest leaf out (and maybe the 2nd as well...it's been well over ten years since I did this), and added the 2nd longest leaf from my stock upcountry leaves just below the main leaf. It generally kept the same height, but gave a lower spring rate. I really liked that set-up and evened out flex between front and rear. I would recommend experimenting with something similar.