Leaf spring woes...

[WrenchMonkey]

Edit: Warning! Old post alert!
I'm just bringing this back up to explain why this didn't work...

Well, the XJ is officially on injured-reserve.

The rear leaves have been sagging for years. I've been running a set of HiJacker air shocks to get back about 2" of lost lift.

They actually worked really well: as the air moved from one shock to the other, they would actually make the rig flex more than it normally would. And I've been amazed at how well they've held up, 18 months and at least a dozen wheeling trips.

Til Saturday.

Now they just won't hold air. It's slow enough that I can't track down the leak, but they'll bleed off 80psi to nothing in a half hour.

Without em, my springs are almost completely flat, even a little S shaped. And losing those 2" is enough to wreck havoc on my driveshaft angles. That's how I blew a ujoint on the maiden voyage with the new engine.

Eventually, I'm gonna need leaf packs, obviously. In the meantime, though, there's something I've wondered about for years, and this is a golden opportunity to try it.

I'm gonna do blocks.

[WrenchMonkey]

Yeah, I know, blocks suck. The peril, as everyone knows, is axlewrap.

But I figure, if I make the block out of 2x2 or 2x3 box tube, I can make it as long as I want.
And if I make it, say, 24" long, it'll run out under the front spring hanger, like an old Lakewood traction bar.

Maybe put a rubber bumper on the top, and it should eliminate the axle wrap. At first glance, it looks like I'll lose that 2" of ground clearance, but if I taper the box tube, it really won't hang any lower than a properly arched spring would.

I may lose a little flex. Droop shouldn't be affected at all, but it could increase the compression spring rate. I could hit the bumpstops pretty easily before, so I don't think a little stiffer would be too bad.

[WrenchMonkey]

There's probably a dozen reasons nobody has done this, and a dozen more why it won't work like I want.

But I've really got nothing to lose. For one, I just can't drive the XJ like it is. With the angles that far off, the driveline vibes are just awful. I know I'll kill another ujoint before long. Two, I really don't have the cash for a decent pair of leaf packs right now. And with three different club meetings in the next seven days, "right now" is the timeframe I have to work with. Three, what's the worst that can happen? I could kill the leaves I've got, that are already way past retirement age anyway.

But most importantly, it's something I've always wondered about trying. This is as good an opportunity as I'm likely to see. I figure what the hell, worth a shot.

A WrenchMonkey's greatest joy is the flinging of poo, and his ultimate goal is simply to see what sticks!

Wish me luck!
Robert

(Ooo, look, post #666... That's some sorta sign...)

[flatlander757]

Or add two more leaves to your existing pack... I took an XJ main and second leaf and added them to my pack...

I cut the eyes off the mains and put the leaves in the pack and made some unique clamps to allow it to droop but control body roll.

Since I'm on 1 tons I captured 3 leaves with my clamp at the back... for you probably 2(the two mains) would be better for flex and just as strong.

By adding the two springs, it helped to gain a small amount of arch back, and it also adds some load carrying capacity. Depending on how you clamp them together, it will droop just as well as before or better or worse... whatever you want. I clamped the hell out of my leaves because I've got a locker and could care less if I lift a wheel... it's dead stable and feels great.

Here is the way I clamped the packs at the back:



I don't have an official "before" picture, but here is one where you can see how badly it was sagging a week or two before I fixed it:



This was where it sat AFTER adding the two extra leaves:




I was in the same boat as you(springs S shaped and sagging), and think this will work for quite a while.

All you really need are some 5/16 allen head bolts(and nuts) to replace your center pin, and some kind of clamps to replace the old ones. If you're careful, you could try reusing them, or you can go to a spring shop and get the hammer-on style clamps that I used. The "kit" for spring clamps that I got was from Autozone... you'll need either 2 kits(for the extra plates), or some 3/16" plate to make your own.... Basically I welded the lower plate to the U-bolt looking piece... then the other one gets sandwiched with nuts around the top leaf.



Here are the hammer-on style clamps I used... I put one each on the other side of the packs(my ghetto homemade clamp at the back, hammer on at the front).



Those are stupid cheap... should be no more than like $6 each.

Note, on my TJ the XJ leaves are swapped around backwards, so the long side is the front and the short side is the back when I refer to them up there.

[itbrokeagain]

As I recall you are at 5.5 inches in the rear? From the little bit of research I did on Naxja, an Xj Mj bastard pack will give you a healthy 5.5 inches. This along with my current 2 inch shackles and shackle relocation brackets are my ultimate goal.

[flatlander757]

Originally Posted by itbrokeagain

As I recall you are at 5.5 inches in the rear? From the little bit of research I did on Naxja, an Xj Mj bastard pack will give you a healthy 5.5 inches. This along with my current 2 inch shackles and shackle relocation brackets are my ultimate goal.

You know that I have these on a TJ right?

As far as stock TJ coils vs XJ springs... basically "stock" XJ springs will give you about 4" of lift over stock(axle vs frame heights).

I am about 5.5" over stock using basically stock but beefed up XJ springs.

[itbrokeagain]

Sorry for the confusion. That was my solution for Robert.

[WrenchMonkey]

Thanks guys...

I know lots of guys have built packs like that, and ended up very happy for very little money. But there are SO many variables (each leaf's length, arc, springrate, and age) that it always takes a lot of trial and error to dial in both the ride, and the ride height, you're after.

Frankly, I really want something quick and easy, and get it back on the road. The thing was in the garage all spring, and the next 30-60 days are the very best time of year to dd an open jeep. To say nothing of the three different club meeting I'm gonna try to make in the next six days!

Besides, I've always wanted to try the traction bar, just to see how/if it'll work.

Robert

[blazerbrad]

A guy in our club uses what sounds like the same idea on his 1-ton SOA YJ.



You can see how long the block/bar thingy is in the front, and it's the same length towards the rear. With being this long it has almost zero uptravel and the thing rides like a gut wagon (he has really stiff springs on the front also). I guess it accomplishes his goal of eliminating axle wrap as he was killing rear u-joints.

[jfiscus]

Chevy springs & 2nd XJ main springs will fix you right up.
The block idea doesn't sound like it'd be a nice ride at all & I'm usually open to ANY type of idea...

[WrenchMonkey]

Well, sure Brad, if you run a solid bar from springmount-to-springmount, I imagine it will limit uptravel, and ride like it's sitting, well, on a solid bar. (Pic didn't work for me, though.)

I do expect that running my bar on just the front half will still stiffen up the ride a bit, but my springs are so old and soft I don't think it'll be too bad.

Even if it is horrible, it'll still buy me enough time to sort out a more traditional replacement.

I got the bars made up at work tonight, and I hope to get em installed in the morning.

We'll see!

Robert

[WrenchMonkey]

Bars are in, test drive was good, taking it to work!

Wish me luck!

Robert

[humpy]

or go to greg hauck in fayettville and tell him you need an add a leaf kit for rear of a half ton chev truck..take out a similar length leaf from your pack and add the add a leaf and rock on...i used to run blocks when wheelin...seen a guy toss a complete rear axle housing and all out the back on the side of a hill...its not a fun trip out...dont run blocks..

[WrenchMonkey]

Originally Posted by humpy

seen a guy toss a complete rear axle housing and all out the back on the side of a hill...its not a fun trip out...dont run blocks..

Oh, I've heard plenty of horror stories about leaf blocks.

Do you know if this guy broke the spring, or just spit out the block?

I don't think either is as likely with my version, but we'll see...

Robert

[WrenchMonkey]

So here's what I came up with:


2x2 box, .250 wall, about 24" long. 30* cut at the leading edge, 45* at the other.

On the topside, there's 1/2" hole accept the springs' center pin, and a 1/4" hole at the front to mount the rubber snubber.


On the bottom, I drilled and tapped a 5/16" hole, and used a set screw to position the shim, like so:



Loosely assembled, pardon the BigRock mud:


In that pic you can kinda see how I redrilled the springplate to move the axle back about 1.5", here's a better one:


Anyway, with weight on it:


And clamped down:


I should have taken a nice nice finished profile pic, but I didn't.
I was running out of time to get to work, so I threw the wheels on and test drove it around the block.

[WrenchMonkey]

Drove it to work, and then the ORFW meeting last night, and it did great.
It obviously lifted me back up to a full 6" lift, which realigned the driveshaft angles, and smoothed out my vibes.

But I swear I can feel the antiwrap working, too. When I get on it, the ass end tries to rise a bit as it puts the power down.

The ride is a little firmer, but not at all harsh, or even stiff really. Just like it's better put together.

They do hang down just a little lower than I'd like. The angled nose should help,
but adding a small skid to the front would bridge the gap between the bar and the spring.

For a few hours work and a bunch of scrap material, I'm thrilled.

I still don't know if I'll keep it long term, but it'll certainly keep me out of the garage till I make up my mind about something better!

Robert

[gothodgie]

looks almost like some old school traction bars.... As long as they don't hang up on everything, i think it is a good fix.... just my .02


chris

[WrenchMonkey]

Originally Posted by gothodgie

looks almost like some old school traction bars...

Yep, that's exactly what there are: a homemade, offroad version of the old Lakewood traction bars:



That is, of course, why I just had to paint them yella!

Robert

[Coppertop]

Looks good Robert...I'm curious to see how they perform offroad.Yella traction bars bring back some great memories.I had a set on my 69 cougar.

Nick

[adamkn]

Hey Robert - good to meet you last weekend at Big Rock! So, what happened with your Jeep?

[WrenchMonkey]

UPDATE:

I just realized I never posted back to report how these worked offroad. Bluntly, they didn't. Not at all.

I had less traction and more wheelhop than I ever had before, to the point of destroying the old leaf packs. I sheared the centering pin, separated the leaves, and had to strap the axle in place to limp it out of the park.


Now I had suspected at the time that I might have issues:

Originally Posted by WrenchMonkey

There's probably a dozen reasons nobody has done this, and a dozen more why it won't work like I want...

...but I never understood exactly why it went so badly, especially when it seemed to work so great on the street. Til now.

I've been doing some suspension research lately, playing with ideas for the Willys I'm gonna build "one-day." And I now realize that what I built way back when was essentially a crude radius-arm. And I had given myself a clue to the impending doom when I wrote:

Originally Posted by WrenchMonkey

But I swear I can feel the antiwrap working, too. When I get on it, the ass end tries to rise a bit as it puts the power down.

That wasn't "antiwrap" I was feeling, that was antisquat. And crazy antisquat numbers are why nobody uses a radius arm rear suspension.

I had heard that term, antisquat, but I never understood it. Now I'm learning. Basically, the torque of the rear axle, that previously caused axlewrap, was now being delivered to the bottom of the jeep, actually lifting it slightly.

On pavement, this was okay. The bar pushed up on the body, the weight of the jeep pushed back down, the tires dug in, and off I went.

But offroad, the limited traction threw everything into chaos. Since the rear tires were now trying to actually lift the weight of the jeep as well as trying to move it forward, I was fighting against myself. I would have needed more traction to climb the same hill.

And when that traction wasn't there, really bad things happen. The tire slips, the torque is removed from the bar, and the lifting force vanishes. The body of the jeep drops back to and then below ride height, flattening and even inverting the leaf. All in a split-second of violence. (There's a name for this, too, that I'd heard but never really "got": Unloading.)

Immediately, the suspension bottoms out, the tires dig in, the traction returns, the axle rotates, the bar lifts the body, and the cycle repeats. And chit breaks. Bad.


None of this really matters now, I put a new set of leaves in it right after this failed experiment three years ago.

But for future reference, in case anybody else considers it, this is why my idea didn't (and won't) work...

So don't try this at home.

Robert