rear suspension travel.

O

outlander

NAXJA Forum User
Location
Columbus,Ohio
Got bored yesterday so I had my buddy fire up the john deer and use the bucket to flex the jeep(sorry no pics).I feel confident that I have the front bumpstopped properly but the rear has me wondering.
My question:Is it generally accepted that the rear leaves should never flex so much that they become inverted?Doesn't this lead to premature spring failure?
I want my rear suspension to flex to the point that the leaves are flat....and not inverted,correct?
Right now I have a RE6200 lift with full spring packs.
 
yes. yes. yes.
 
uhh.....most of us bend ours to negative arch regularly. If you have a nearly flat spring at ride height it has to bend to negative arch to get much up travel. It won't hurt a thing. Spring wrap, shaping the spring into an S, will kill a spring. Negative arch is just making the spring work.
 
Thanks for the replies.
The springs that I have now at static ride height have a fair amount of positive arch(5.5" RE 6200).Right now I think my rear shocks are too long and limiting up travel because my 34" tires aren't even close to stuffing into the wheel wells when flexed out(bump stops are 8" away from touching the axle tube).The leaf was just shy of being flattened out and still had just a little positive arch to them.

So the goal is to have the tire fully stuffed into the wheel well but not rubbing no matter if the spring is flexed into a negative arch???
I've had this lift on for awhile now and have finally got around to "tuning" it properly....

Don't know where I heard pushing leaves into a negative arch was a no no.......
 
IMHO If it's an arched spring making it go backwards is bad. A flat spring you are not left with any options in that department.
 
outlander said:
Thanks for the replies.
The springs that I have now at static ride height have a fair amount of positive arch(5.5" RE 6200).Right now I think my rear shocks are too long and limiting up travel because my 34" tires aren't even close to stuffing into the wheel wells when flexed out(bump stops are 8" away from touching the axle tube).The leaf was just shy of being flattened out and still had just a little positive arch to them.

So the goal is to have the tire fully stuffed into the wheel well but not rubbing no matter if the spring is flexed into a negative arch???
I've had this lift on for awhile now and have finally got around to "tuning" it properly....

Don't know where I heard pushing leaves into a negative arch was a no no.......
Click to expand...

I don't know where you hear it either. Just do it and don't worry about it, if you can get the sping to flex that much you won't hurt it.
 
It's been a long accepted truism that you don't want your leaf packs put into negative arch, I've heard that as long as I've been wheeling (going on 15 years) I've always set up my bump stops so my leaf packs don't go into negative arch. If you've never had an issue with sagging leaves, that's cool. Between preserving the amount of lift and limited room in the wheelwell, I can't imagine the rear leaves in my XJ in negative arch. The tire would be inside the cargo area. :D
 
I think this is largely related to the type of setup that is being run. If for instance a leaf spring with a relatively arched profile is installed with the OE shackle, e.g. a RE 3.5 the chances of flexing it until it inverts are slim. It will get close to being level and stop there. In such an instance not installing any additional bumpstops won't harm the springs as they won't invert because of space limitations. If however you're running relatively flat springs like OME springs and you've installed a budget lift kit with a longer shackle, the amount in inverted flex you get from the springs are quite substantial and will damage them. I've run this last setup and as can be seen in the pics below, the rear did flex quite nicely, but after a while it started sagging as the bottom most leaf of the packs actually bent away from the rest from being inverted too much.

To fix this I've had the leafs reset to its original profile, installed a short support spring below it and also bumpstopped it properly. The spring now flexes to just slightly past the level part and so far, so good.

IMG_4739.jpg


IMG_4738.jpg
 
fubar XJ said:
It's been a long accepted truism that you don't want your leaf packs put into negative arch, I've heard that as long as I've been wheeling (going on 15 years).
Click to expand...


Interesting. I've been wheeling at least that long and have never heard that. I'm not much for well accepted truisms..........like you can't run an auto locker in the front without hubs, a rig turns better with a locker in the rear and open in the front, more flex is always better, etc. etc.

Really, it doesn't matter. Yes, I've seen a short bottom leaf on a low quality leaf pack bend slightly backwards, but not on a good quality leaf, and not on the stock leaves, and if that low quality short bottom leaf bent it wasn't doing anything anyway. Have you ever seen the front leaves on an F250 or F350? They're negative arch from the factory. If you stand next to an obstacle on a trail with a bunch of leaf spring rigs going by, watch and see how many of them will flex to negative arch. It's all about quality steel, how much arch you start with, and how much travel you need or can use. Move that spring as much as you can move it and don't worry about it. If you have a spring with a lot of arch, and are concerned about it lasting a very long time, and have enough travel without it going to negative arch, that's fine. You probably couldn't get it to go negative anyway. Like I said, my leaves go to negative arch regularly, I count on it.
 
My springs negatively arch also.

I think the reason people think it's the negative arch that wears springs out is because most times a spring that is soft enough to arch that much also isn't near stiff enough to resist axle wrap which is way more to blame for wearing out springs.
 
I need to re-flex and figure out exactly why my rear tire isn't stuffing.Either the shocks are limiting articulation or the shackle is bottoming out......whatever the problem is the leaf still has a positive arch which means I still have rear articulation to be had.
 
Shackle is a problem for most suspensions, you have two options get boomerangs, or relocate the shackle brackets.
 
Goatman said:
Interesting. I've been wheeling at least that long and have never heard that. I'm not much for well accepted truisms..........like you can't run an auto locker in the front without hubs, a rig turns better with a locker in the rear and open in the front, more flex is always better, etc. etc.

Really, it doesn't matter. Yes, I've seen a short bottom leaf on a low quality leaf pack bend slightly backwards, but not on a good quality leaf, and not on the stock leaves, and if that low quality short bottom leaf bent it wasn't doing anything anyway. Have you ever seen the front leaves on an F250 or F350? They're negative arch from the factory. If you stand next to an obstacle on a trail with a bunch of leaf spring rigs going by, watch and see how many of them will flex to negative arch. It's all about quality steel, how much arch you start with, and how much travel you need or can use. Move that spring as much as you can move it and don't worry about it. If you have a spring with a lot of arch, and are concerned about it lasting a very long time, and have enough travel without it going to negative arch, that's fine. You probably couldn't get it to go negative anyway. Like I said, my leaves go to negative arch regularly, I count on it.
Click to expand...

I hear you, and understand what you're saying. Hell, I have one of said Ford trucks with the negative arch front leaf packs. I also agree that axlewrap is more prevalent in flat/negative rear leafs, due to their softness compared to a highly arched pack. I purposely bump-stopped mine low to avoid too much flattening, both for retaining the pack's shape and firmness and to keep from shredding tires against my bumper cap and wheelwell in the rear. Like I said, if it works well for you, that's great. Do you also run a anti-wrap bar in the rear? I absolutely had to in my mildly arched CJ rear leafs, otherwise I would have been tossing driveshafts and snapping yokes. I don't have an axlewrap issue in the XJ, and I think being set-up for more droop than stuff helps with that, keeping the springs in at least some arch throughout their travel.
 
Negative arch, Positive arch. Which is good, which is bad??

Take a look at an entirely stock XJ rear axle and bump stop. I have had my rear axle hit the bump stop many times. That only happens if the leaves are negative arched. Is it good for the leaves? Is it bad for the leaves? :dunno: My XJ hit the OEM bump stop many times running bumpy roads with plenty of weight in the back and wearing the stock 225X75X15 tires.
 
Goatman said:
Yes, I've seen a short bottom leaf on a low quality leaf pack bend slightly backwards, but not on a good quality leaf, and not on the stock leaves, and if that low quality short bottom leaf bent it wasn't doing anything anyway.
Click to expand...

I'm running OME034RA leafs - wouldn't really consider them low quality. I must admit however, and it only struck me now, at the time I was also using a 20mm block - that would have definately helped in bending the bottom leafs.
 
I had a similar question recently and after closer inspection, i found that my rear shackles were hitting the bolts holding my stock bumper on which in turn, was preventing my shackle from rotating backwards.

I spoke to the engineers at RE and they told me that they had seen this before and to hacksaw off the end of the bolt.

They also recommended I loosen and re-tighten the front and rear leaf bolts with the vehicle on the ground in case the leafs had seized in the shackles..

Something to check...
 
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