63" chevy leafs on an XJ.

[blistovmhz]

In my quest for 6.5" (that's what she said!), I kept running into issues with leafs. Most 6.5" lift leafs just don't do anywhere near 6.5" and rely on shackles that are way to long for the leaf length, or super high arch leaf packs that run stiff as balls.
I had a set of RE 4.5" leafs that came with my current XJ, and after screwing around with 5 or 6 other packs, I gave up, installed a shackle relocation, long shackle, and an extra leaf to my RE pack.
That said, my XJ also gained a lot of weight over the past few years and while there may be good 6.5" leafs out there somewhere, there's NOTHING for an XJ with a 2200lbs ass (total weight is now 5150lbs). Plus, short leafs ride rough, and get rougher as the arch gets higher or the leafs get stiffer.

There were several reasons I wanted to do this swap.
1. Shackle relocation puts your springs at a bad angle (pointed UP forward), so on forward torque, you get wicked rear steer as the right wheel comes up and back, while the left wheel goes down and forward (and the opposite under negative torque). This is a moderate annoyance on the highway with the 4.0L, but it's frackin' terrifying with a 5.3L V8 when the hammer comes down.
2. Axle wrap and squat. My leafs were old and tired and even if they were new, each leaf is just too thin to deal with the v8 power. Took me about 4 minutes on my first test drive to blow up a pinion yoke when my pinion hit the chassis.
3. Longer leafs articulate nicer. Short leafs ride rough. Long leafs ride MUCH smoother.
4. Street handling. Again, short leafs, combined with moderately large lift and 35" shoes makes driving on the street ... less awesome than normal. Longer leafs should soften up the big hits, while the thicker individual leafs should provide better anti-sway.
5. Axle location and wheel base. With the high arch leafs and shackle box, the axle (at ride height) comes forward almost 2". I just barely clear the back of my sliders, and you can really feel that 2" during steep climbs. Given I've got 2200lbs on the ass end, moving the axle back 4-7 inches would be nice.


So, I finally gave in and threw in a set of 3.5" lift leafs for an old Chevy pickup. I used ProComp 13211 leafs for my project, as we have a set on my roomates K1500 (8-9" lift with the leafs, shackle flip, new shackle boxes, and 37's), and it flexes ridiculously well. So I did the math and the 13211's seemed about right with a 9" arch and 195lb/in rate (until the overload, which is around 450lb/in).

Unfortunately, my original math was assuming I was only around 4300lbs, and by the time I finally weighed my junk, I'd already designed the whole swap around the 13211's. Knowing that I was overweight, I figured worst case, I'd be just touching the overloads at loaded ride height, and I can always add a leaf and perhaps remove the overload.

That said, I started tearing out the old leafs and mounts last night. Just about finished the whole swap, but my u-bolts weren't long enough and I'd already put in 8 hours. Finished the rest this morning after picking up some 9" u-bolts.

The mounts are 6"x3"x0.25" plate, each with 5x 9/16 mount holes for adjustment. The front mounts are burned in to my frame stiffeners and sliders, and the rears are burned into the bumper. I may add more bracing to the rears. We'll see how she bends.

The result:

As my drive shaft is of finite length, I was limited on how far back I could mount everything. I did however, drill 6 holes for each mount and I'm currently using the second hole from the front, so I've got another 5" I can go back when the new drive shaft arrives (and I get un-lazy and cut out my wheel wells and probably relocate the fuel tank).

Front mounts start 5" forward of the stock mount hole.

My scary welding in the wind job:

Yes, they're welded on both sides. Calm down.
P.S. I really hate out of position, upside down welding in the wind.

Pinion angle ended up being perfect, but I had shims just in case.

Yes, I'm aware my splines are sticking out. Waiting on TomWoods. New shaft should be here Tuesday.


All in all, the swap went really well. I haven't wheeled it yet, but as my final math turned out to be bang on, and I'm riding on the overloads, I get the feeling she won't compress real good, but I'll have tonnes of down travel for now. I'm looking for another leaf to throw in the pack, but finding something with a 9" arch is ... fun.
Bonus, because I'm riding on the overload, the wrap has pretty much solved itself.


I took it for a quick test drive. Rides much smoother than any XJ over 2" I've ever been in. Ride height ended up being 6.3", so I have just enough left over to sneak that other leaf into the pack without going over 6.5". Double bonus, If I remove the overload, I can bring myself down to 4.5" (for when I do my low COG work sometimes probably this year). Street handling is much nicer. Corners like stock height with new leafs and rear sway bar. Bounced it around the yard a bit and it flexed better than I was expecting. I'll check tonight if I can bounce high enough to lose my DS, and if not, I'll take it out wheeling this weekend for some flex.

I can't ****ing believe I squish those leafs to the overloads, when the k1500 fully loaded with wood and garbage doesn't. Heavy ass jeep mang.

 

[cal]

yota guys often end up on the overloads too, with an empty yota pickup.

i believe it has something to do with shackle angle.

 

[blistovmhz]

Maybe on a yota? No idea. I do know that the math on mine puts me JUST touching the overloads.
Took it for a spin. As I've only got 1" spline engagement on my already worn driveshaft, it was a bit rough. Something in the suspension is slapping, but I think it's probably the leafs hitting the overloads on bumps. Sure does ride nicer down the highway though.
I'm a bit nervous that it'll ride like crap on the trail until I get rid of the overloads. Was going to tear the pack apart this afternoon and get it done right, but I lost fuel pressure on the way home and gotta address it first as my engines hitting 25% LTFT under minor load .
Guessing it's something simple like the hose from the pump to the plate on top of the tank.

 

[jbain08]

I'd be interested in how much axle wrap you experience.... I swapped my stock XJ leaf end for end to gain wheelbase and added an antiwrap bar. The antiwrap does it's job but since my truggy is so light in the rear it also limits all my flex.... I'd love to get rid of it

 

[blistovmhz]

I'd be interested in how much axle wrap you experience.... I swapped my stock XJ leaf end for end to gain wheelbase and added an antiwrap bar. The antiwrap does it's job but since my truggy is so light in the rear it also limits all my flex.... I'd love to get rid of it

I'll let ya know when I know. New driveshaft should be here by tuesday. Until then, I can't even really test anything as I've only got 3/4" spline engagement.

After going for another drive last night and thinking about the weight issue, I think I'm going to remove the overload and replace it with 2 XJ leafs (on each side). The overload rate is around 250lb/in, and at ride height, I'm JUST touching it. That makes my effective spring rate about 450lb/in on compression (from ride height) and only 195lb/in on droop. I'll have essentially no up travel.
May also just try cutting off the ends of the overload, but I suspect we'll need at least one more XJ leaf in there.

As for the physics of the wrap, I'm pretty confident this will solve most of it. This leaf pack in-particular, is all long leafs. The shortest leaf is about the length of a stock XJ main. Plus the individual leafs are about 150% the size of an XJ leaf. Overall, same pack thickness but all that antiwrap action is being dealt with with a much thicker main leaf. I guess I should just wait to test my theory

 

[blistovmhz]

It's working!

I remembered that because I haven't really chopped the rear wheel well, the Jeep LOOKS raked back when it's actually level (as measured from the axle up to the frame and ground to sliders). So I clued in and measured the ground to sliders, and lo and behold, the rear end was actually an inch too high. As the overloads are exactly an inch thick, and if I lift the Jeep by hand, I can get it off the overload with one hand, I figured I could just remove the overload and call it a day.
As I'm lazy, I wanted to do this with the leafs still on the Jeep so I did the following:
* Lift up axle, remove tire, block the axle at ride height.
* Lift the chassis from the bumper a few inches.
* Loosen the u-bolts a touch.
* Remove shock (annoying mounted on the u-bolt, and because they go through the floor, there's no room to maneuver with the shocks installed).
* Drop the axle till the u-bolts are holding the axle up a bit.
* Remove u-bolt nuts (with axle on stand) and remove u-bolts.
* Drop axle far enough to pull the centre pin (I spell centre the american way right?)
* Clamp the leafs together with a bench vice and ball-joint press and remove centre bolt.
* Tap the bolt with some more thread as we're losing an inch and stick it all back together (and chop off the extra inch of bolt from the top once the nut is back on.

From there, I stuck the wheel back on and checked out ride height. Unfortunately, I ****ed up due to paranoia. My driveway is horribly uneven, and last night when we were trying to shift the axle around under the leafs, the Jeep started falling over and we had to brace it. Still can't figure out why, given we were on 4 axle stands, but mysterious gravity seems to plague my driveway. So of course, today I was paranoid and had a 2x4 bracing the Jeep the whole time. When I was doing something or other, I set the 2x4 against the side of the Jeep and forgot about it. When I dropped the chassis to check ride height, the 2x4 jammed itself under the passenger door handle

Whoops.

Nothing the Jeep hammer can't fix.

So now at ride height on the passenger side (the side I've finished), I'm sitting dead on 27" from ground to slider, front and rear.

That said, it's nowhere near as stable as it was with the overload. With just my 170lbs, I can throw the rear passenger side all over, while I can barely budge the driver side. We'll have to just see how it handles. I get the feeling it'll articulate like a whore (the good kind), but not sure about highway stability. If it's scary, I may end up adding a Jeep leaf into the pack, but I'm really happy with the height and (theoretical) articulation right now.

 

[blistovmhz]

Other leaf took 20 minutes. Flexes much better. Lifting just one rear wheel, I can get to about 4" from stuff. Should be simple with the opposite front wheel lifting as well. Test drive soon!

 

[IH392]

If it's not stable, maybe you can put in a beefier swaybar.

 

[blistovmhz]

Been thinking about that. It's been not too bad (actually pretty good considering the lift), but just giving the ass end a shake in the driveway, it feels like it may be a bit on the soft side for street. Can't really test it properly until the driveshaft comes in on Tuesday.
....
Unless I get bored and just move the axle forward another inch until Tuesday, which I'll probably end up doing as I'd like to get out for some wheeling this weekend...

 

[Johnnie Walker]

What shock valving do you gave in the rear?

 

[blistovmhz]

I don't recall. Bilstein 5150's, 12".
Why do you ask?

 

[Johnnie Walker]

If you valve shocks stiffer, they help with sway and driveability to a point. THe best valving 5150's had was 255/70. Since you have a heavy heep, different shocks with higher valving would help.

 

[cal]

they will help to a point, but not massivly.

they won't help against the sway of chevy 63's. thats one of those things that comes with a cheap mod.

 

[blistovmhz]

Well got it out for a test yesterday. Articulation and ride is substantially better than anything I've experienced from a Jeep. It may be a little too light for my weight at this point, and I may have to add a leaf with very little arch to compensate. Driving the FSR to the trail with 12psi and sway bar disconnected was a bit terrifying for sure. I drive that road every week and usually have no problem drifting all the corners and doing donuts wherever I want. With the longer leafs, the ride was crazy smooth (better than the coil sprung front even), but TONNES of sway.
The first few minutes on the trail I felt like it was way too light, but as the drive progressed, I felt better about it. Within' an hour or so, I was climbing at 45 degrees out of tank traps that would've definitely flipped me over with the old springs.
No problem stuffing the rears at all anymore.

Still feel the sway is a bit much after a few hours of driving, but we did some rocks later in the day and I pulled off lines I've never previously been comfortable with, and most of them were surprisingly easy.
I think my side-hilling ability still sucks though. What can I do about that? It just wants to throw the top over end. Yea, get rid of some top end weight or add more un-sprung mass, but is there anything I should be looking at with regards to suspension first? Would adding another flat-ish leaf help or hinder with side-hilling?

 

[yossarian19]

Sway bar?

 

[blistovmhz]

Front sway bar solves it, but I'm of course not running it on the trail. I'm debating giving it another wheeling trip to decide if it's okay or not, or just add another leaf with very little arch just to soak up some of that sway without adding any up. My spring rate is a touch low anyway and I've got no problem stuffing the rears. I could probably add another XJ leaf and still have no issue.

 

[blistovmhz]

Well, not sure if you can tell from the picture, but I think I've already bent my lower leaf due to wrap.

Probably should've installed another leaf sooner.
On a positive note though, you'll notice my new TW xc/x splined driveshaft is installed. Its 36.5" at Center. I think its 8" spline, and its compressed to 35" with my leafs mounted as far forward as possible, so it should be just right when I drag the axle back another 3".

 

[blistovmhz]

Took a quick video trying to get an idea of what sorta axle wrap I'm dealing with.
P.S. Volume is insane.

https://goo.gl/photos/NxoHsHV8JyCiLR6w7

I'm not sure, but this to me doesn't look like a tonne of wrap. Looks like the rear end of the leafs are jacking up a bit while the fronts are staying pretty level/flat.
Thoughts/opinions?

I was going to try a few different things to deal with the wrap this week, but I took out my back on Monday somehow (it's a mystery) and have been laid out most of the week.
Stuff I was going to try:
1. Add an XJ main leaf (with ends cut off) on top of the main leaf.
2. Add an XM main leaf (ends cut off again) just below the main leaf.
3. Half leaf (forward) on top.
4. Stick the overloads back in and chop them down to about 8" on the front, and flush on the rear.

I really don't want to smash my shiny new DS, but I also don't want to mess too much with my spring rate nor go through all the un-necessary work.

 

[DeftwillP]

time for a traction bar

 

[jbain08]

I put an anti wrap bar on mine and hate it.... lost a ton of flex. That's why I'm following this thread. But on the plus side I have zero axle wrap.