How to make my rear flex more and my front less??(pics)

Hey guys, I'm having a problem that Farmermatt kinda put into words for me a while back. My front suspension seems to do all of the work on my Jeep, and my rear suspension determines what angle the Jeep sits at. What I'd like is for them to flex equally. My rear really doesn't flex much unless the front is already completely maxed out(regardless of whether I'm on a ramp or crossing a ditch,i.e. whether the weight is pushed onto the rear of the jeep or not). I was considering looking into the anti-rock, but I think that would just limit my front travel and not help my rear travel at all. BTW, here are my relevant specs....

Rusty's 4.5" coils
Rusty's 4.5" leafs
RE adj upper/lower CAs with JJs
1" pro-comp shackles
ARB front bumper
homemade HEAVY rear bumper

Any helpful tips would be great

Here are some comparison pics...



In those pics the front suspension is almost fully compressed on the passenger side, and the front isn't too far from fully drooped. However, the rear suspension is just beginning to do it's job. Thanks

Ary

P.S. I don't have front or rear swaybars hooked up(never had a rear swaybar to begin with)

Any brake lines/cable binding the rear, or it is usually your rear shocks. Did you change the mount on the rear axle?

oops, shoulda mentioned that I've got the RE stainless lines, so no bind there. Also the shocks are new Bilstein 5100s. However, I flexed it up without shocks, and the problem was still there.

I've been contemplating the rear shock mount shortening + shock hoop route just for clearance purposes anyway.

Ary

I can't see the pics, but on mine I have Rancho RS-9000's, and if I had the front and back on different settings, they one would flex and let the other determine the angle. I was able to adjust the control by setting them equal, but even if that didn't work for you, you could stiffen up your front more and soften up the rear so that the rear will be able to compress easier than the front or at least even it out.

Well just run some Bumpstops up front...as far as the rear? HMMMmmm I dunno...


That's the hard part.

Pics died for a second there for some reason, they should be working again. As for the shocks, mine aren't adjustable.

As far as stiffening my front and softening my rear, that's what I'm asking, how do I do that?? I don't really wanna swap springs again, but if that's the only way, I guess I could. I figured I already had the softest leafs on the market, being Rusty's and all.

i dont know if this is true but I heard that the stock shackles can sometimes bind on the frame in the back,,

Lately I've been hearing that Rusty's rear are stiffer and give a lot more height than advertised. Many have pulled out a leaf to soften it out, but then you may loose lift. How long have you had the springs? If not long put some weight in the back for awhile to break them in. My RE 1462 flexed ok when I first got them and now the flex really well and no sag.

steveVA said:

i dont know if this is true but I heard that the stock shackles can sometimes bind on the frame in the back,,

Click to expand...

Good Point!

Well, I've had them for about 4-6 months and they're well broken in. In fact, they're beginning to take on a "w" shape.

As for the shackles, I'm running a 1" pro-comp shackle and it sits just slightly angled back past vertical. Could that be my problem?? Thanks guys

Ary

P.S. With the springs and shackle I think I'm getting 5" of lift, but I don't have any real way to measure since I no longer have flares.

Measure from the top of the perch to the top of the bumpstop or frame. I feel that is a more accurate measurement anyway. The shackle should be fine then. Could you really try to flex it out again. I think your just not pushing it enough, maybe back into the curb or whatever you find to flex on.

Maybe i missed it in there somwhere. - DELETED - Hehe - i found what I missed - so I guess it isn't the rear sway bar

This has been a problem for every lifted XJ. If you want to see a really bad setup take a look at the pics of Rusty's longarm XJ. That thing has 99% of it's travel in the front suspension.

In stock form the XJ is actually quite balanced front to rear as far as the suspension flex is concerned. The problem arises when the truck is lifted. To lift the front all you need to do is make a coil longer... technically you don't even have to change the spring rate although most do as the stock rate is overly soft and increasing the spring rate allows the lift springs to have a shorter unsprung weight as well as handle heavier loads.

The rear leafs however gain their lift from extra arching and for some reason most aftermarket companies seem to retain the stock rear leaf length giving a less then ideal shackle angle for good "flex". Generally in my opinion the best setup is when the rear shackle is pointing rearward 25 to 30 degrees. Unfortunately this can't really be accomplished without modifying the frame mount of the shackle or getting slightly longer leafs. Going with a longer shackle will actually make the angle worse but it also increases the available travel of the leaf.

So, if you don't want to change your stock mount there is only a ocuple things to do...

Make sure you leafs are clean in between. Maybe add some teflon strips to aid in the "slipping" between leafs.

Be sure if there are retaining clips on your leafs that they aren't sandwiching the leafs together. i.e. they should retain them side to side but not hold them against eachother. If they are bend the retaining tabs up a bit or if there's a bolt like the RE springs remove the bolt so the springs can seperate.

Make sure you're running a shackle that is a little longer than stock to maximize the available travel. For a 4.5" lift a 2" longer (1" lift) shackle is plenty.

I also like to loosen off my shackle bolts when going wheeling to help them move easier. Just be sure to tighten them back up for road driving as you don't want one to work loose and fall out.

But in the end leafs have to be loved before they'll work for you. You need to get out and flex those suckers, work them in, load them up, read to them, kiss them goodnight, talk dirty to them.... whatever works. Only when they are ready will they start "loving" you back.

Here is an example...

RE 4.5" lift packs fairly new...
http://community.webshots.com/photo/64836838/64837742TkSWYR
Notice how hard and unloving they are... they didn't start working for me until I had a couple years to warm them up a bit.

The same springs two years and many wheeling trips later

http://community.webshots.com/photo/71396094/71396783VzIRiL
http://community.webshots.com/photo/71396094/71396792ZJiRWA
http://community.webshots.com/photo/71396094/71396797QdDhRy

Now they are showing me some love

I have to agree with Bender, the real leafs need to be broken-in to flex (lubed, loved, and let lose on a regular basis to love you back). This provides a softening (lowering) of the spring rate.

I have to add that the balance between front and rear spring rates has a significant impact to the combined flex.

Many XJ front lift coils add length for the lift height (or a spacer) and do not increase the spring rate. Combined with a rear leaf pack that must increase the spring rate to provide the lift height, the bias is to flex the front axle before gaining any flex at the rear axle.

Combine this with the difference in roll axis height (at the lifted front and rear axles) and you learn the front axle simply has more leverage to work the CG against a lighter spring configuration.

The popular ZJ-V8 lift springs do increase the spring rate, compensating some for the increased leverage provided by the lifted CG. This is why many owners feel an improvement in overall flex when they install the heaver springs (even if the lift height increase is not that dramatic).

A car control symptom that comes up at high speed in rough terrain is the rear axle bucking in a straght line. Run a series of whoops and find the rear tires avoid touching the ground (difficult to control and difficult to get the power to the ground). You can steer, but you cannot apply enough power to the ground achieve the speed needed to match the bounce with the terrain (find that rythym). This reflects too much rear spring rate, compared to the front spring rate.

Many tuners will dial the front shocks hard to add velocity dampening (thinking it provides an artifical spring rate change), although in my experience it just makes the front suspension stiff. The rear axle still bucks, but now the entire car is bucking (no rear traction, and now no front directional control). You can achieve some sense of rythym, but it's at a lower speed than what you could be doing. You also risk trouble if you find yourself sideways between whoops (the landing can trip the locked suspension, promoting a tank-slapper style rollover).

Fitting a softer rear spring (leaf pack) is not always easy (not if you want rear lift height). The compromise between rear lift and spring rate is one reason why typical competition off-road trucks have that tail dragger look (a leveling spring would unbalance the chassis at speed).

The other alternative is to fit a stiffer front spring, resulting in increased front ride height (again, agumenting that tail dragger look).

Many of the coilover tuners stack the primary and tender springs to locate the stiff spring rate transition at or slightly above the front static ride height (slightly into the extension travel range). This assures the working spring rate is stiff when the front end reacts to the terrain, even when the rear suspension is under throttle induced jacking. They tune the rear coilovers in a opposite fashion, with the stiff rate transition located deep into the compression travel range. This lets the rear end dance with minimal force on the springs (and little reaction force to buck wildly) when all the tractive force is jacking into the rear suspension links.

The short answer is to gain rear flex is get softer rear springs (love-um till they love back), or add stiffer front springs. As long as you still dust off the full travel of the front shock shaft wheeling, the front spring rate is not too stiff for the dynamic loads of your wheeling style (even if the stiffer rate limits the static ramp score).

XJ owners used to run away from stiff front coils, but now they welcome them. It's just part of the tuning evolution.

Just buy OME...........solved.
Ya might need some smaller tires.

I am running almost the same setup as you are, Rusty's 4.5, which netted me almost 6" front and rear (8 months on the XJ).

I had similar problems with yours, because our friend Rusty is making the springs too short for the application. When mine were first installed, they were standing with the shackle all the way forward touching the front of their mounts, which in turn caused the front bushing to give and the front of the springs to rub badly on the inside of the front mounts.

Rusty was ... generous enough to send me a set of .75" extended shackles and new bushings. Since the bloody springs were too stiff to start with, when I had them out to replace the shackles and bushings, I also removed the lower leaf. That gave me almost the same height as I had before (close to 6" front and rear) maybe I lost one centimeter at the rear, which made the truck more level (which I like). However, the leaf pack now seems to be getting a W shape. I am not sure how good is this, but given the quality of Rusty's things, I guess it cannot be good.

I assume I have to get some RE spring packs to solve the problem.

If you are willing to experiment a bit (I can't do that since I live in Athens Greece and shipping charges are too high), I would suggest you get some longer shackles at the rear and some spacers for your front. You will get some more flex (I think).

Rgds

wow, what a lot of great advise.

I had 2" shackles before and admitedly(sp?) the Jeep flexed more evenly/better, but it was much more unstable, and still wasn't nearly as flexy as the front. This is my second set of Rusty's springs, the first set I got from Emily(XJGrl) and they broke(bottom leaf broke in half) so Rusty warrantied them for me. Those flexed amazingly well, too well in fact(obviously 'cause they broke). They also had the W shape, so I'm thinking the W shape is a bad thing. A friend of mine suggested converting to a YJ shackle and getting some flatter leaves. The YJ shackle conversion involves capping off the stock shackle box and adding a piece with a bushing. Brent Orton did this and it seems to work well. I'm considering it, I just don't know if I wanna get into stuff that intricate and so structurally important. We'll see, keep the ideas coming.

Ary

Ary - Bender and Ed Stevens hit this right on.

I have the exact same problem only I am running the RE1462 leaf pack. At first it was incredibly stiff and hardly flexed. Now after a year and a half it has loosened up and flexes more but my problem is I am running the stock shackle. Part of my next major upgrade to the jeep involves lifting it another 1" or 1.5" and with an extended shackle in the rear it will improve the rear flex tremendously. On occasion I wheel with a guy in a lifted ZJ and the way he has balanced flex front to rear makes me sick! Of course thats because he has rear coils.

I know I'm echoing what the other guys have said, but the flex will improve as the leafs are softened up and then maybe you could also increase the length of the shackle.

I had the same problem with nation's leaf springs, I just had to let them break in (about a year), put some waight in the back and go flex them