Edit: Look at my post on the bottom

I need some advise on where to do for the rear suspension of my flat fender. First off here is some info that you should know:

using stock 5 leaf wrangler leaves all around
SOA
front shackle reversal
full width axles outboarded of frame
rear 14 bolt ff axle with discs (alot of weight)
38" tsl-sx's
extending rear suspension mounts to 4-5" back from stock.
1"-2" lift shackles (not sure which)
will see very little street use
trails it will see: Choke cherry canyon, NM -Las Cruses, NM -Blanca, CO -AZ trails around PHX -Eventually the hammers and rubicon.

right now here is where I am at: http://members.home.net/brian4x4/homemade_stuff/weldingfronthangers1.jpg i have the front springs already on, time for the rear

Now before I started this project I had thought about doing this for the rear suspension:
http://members.home.net/42gpw/img11.gif
it is kind of like a 3/4 elliptical but it uses a solid bar and is pinned so it wont be used on the street or for minor trails. Here is a sketch i made to show it better:
http://members.home.net/brian4x4/homemade_stuff/pinned.JPG
Does this seem like a useful design, pros vs cons? Would it need a limiting strap? Driveline issues? I have not been able to contact this owner to ask him questions (a tan Flatfender jeep from AZ)

Also I thought about doing a traditional 3/4 elliptical with a cut off main leaf but Im not sure about it right now since I like to be able to control it by a pin such as above.

Finally, should I just use the wrangler springs and do nothing fancy?

I dont want to do 1/4 elliptical right now.

The reason I ask is because last night I was surfing around some buildups of flattys and saw one interesting point of view: Keep it simple to make fabrication and trail repairs easy (http://azrocks.alloffroad.com/photo4.html) -BTW that is a real nice rig This got me questioning what I wanted to do with the rear suspension.

Thanks for any help.

the one issue that I have seen with using solid links vs. buggy leafs is that the solid links don't pull back to the frame. Buggy's pull back kinda like a return to center effect. This, IMO, is better because your suspension is "in Control" more than the solid design which will droop uncontrollably if given the chance..does this make sense?...I'm tired & I'm going to bed....:rasta:

Another issue is twist when flexed. A buggy leaf can twist alot more than a solid link can. More twist = more flex.

you could use buggy springs with a pin.not sure if it is really needed though.

Originally posted by Tim Palen
Another issue is twist when flexed. A buggy leaf can twist alot more than a solid link can. More twist = more flex.

I have thought about the twisting motion and I know there will be alot of stress on it. The bar would be using a bushing but still will not have much twist.

Scout dude, yes that does make sense.

Any more thoughts specifically on just using the leaves and nothing else?

top

I like the keep it simple idea. The Wrangler springs SOA, with a heavy 14-bolt will have quite a bit of flex even without a buggy or drop link.

Originally posted by Ben W
I like the keep it simple idea. The Wrangler springs SOA, with a heavy 14-bolt will have quite a bit of flex even without a buggy or drop link.

this is what I am leaning more towards doing right now. How much flex (inches?) do you think it would have with the wrangler spring SOA and heavy 14b? Thanks again.

a buddy of mine has a 14bolt with wrangler leaves sprung over in the rear. with full width, and this (heavy axle,soft spring)combo, you will have lots of flex, and i would skip the buggy leaf. they do work, but i like conventionally located leafs better, as in less to go wrong. with this set up you HAVE to have a good traction bar or you'll S the springs every outing....later-brad

Thanks BRBx4, thats what I wanted to know. I think i will just mount the leaves conventionally which means less fab work for me. I figured I will have to use a traction bar anyway, i will get to that later.

Any more opinions? Thanks.

Man. from someone who went from unretaind coil spring to retained, this one is seriously scary.

In a leaf spring setup your leaf sping is all that gives your axle a font to back relationship. removing the rear attachment all together is asking your rear axle to wrap on climbs.

i would rather see revolver shackles which are limiting to some extent. I think this is extremely unsafe offroad. Thats my opinion

I've seen several buggy springs break and also wrapping up into pretzels when someone was trying to back out of a hole with the rear tires wegded into a rock. I think you'd be better of going regular spoa but then again I always go crazy and complicated 3 link 4 link blah blah blah wish I could keep it simple

I'm probably going to get flamed big for this, but I think all this articulation stuff is 99% trouble with lockers in both diffs. As long as rubber and not metal is on the ground, if you have lockers then 100% of the torque is going to the rubber. All the $$$ and energy and time spent on articulation, is, IMHO, a waste. Which is why I have lockers in all my rigs, which are all just solid axle leaf sprung rigs. Maybe articulation gets you a FEW percent more traction; but honestly, with a degree in physics, I don't see how assuming the diffs have lockers and assuming the tires have good traction on the corners of the tread. Which is where all the big lugs are on all our tires.
Personally, my main suspension concerns are: carrying the load, decent ride, safely getting to the trail, and not flipping over on the trail. Period. Long live lockers!
Charlie

IMO, flex and articulation are not about traction (if you have lockers/spools), but rather about stability and control. Not that a tire and axle using it's weight to drag down a buggy spring is helping that much but, if there is weight remaining on the tire, then radical violent shifts in orientation are at least partially controlled by shocks and springs. The shock thing helps even if there is *no* weight on the tire before the shift. With a stiff suspension, you can easily surprised by the speed that a vehicle can shift, dropping a tire until it hits rather than soaking it up in a shock. Perhaps even causing a role where a more flexy, properly designed suspension would have shifted with more control.

OK, good point, but for instance last summer I saw a FJ40 with custom 5 link suspension and 40" tires roll over sideways due to weight transfer with soft coil springs where my M37 just cruised thru with 37s and stock (+ 1 leaf) leaf springs. Both had double lockers. Extreme axle articulation also means potentially extreme body roll, unless MORE suspension pieces are added, like a torsion bar between axle housings (which I've never heard of!!).
It just seems like a hell of a lot of trading off for not that much benefit. Someone should do a test. Like a ramp test not when a wheel leaves the ground but when a vehicle stops moving. No rollovers allowed.
Charlie

Yes, overly flexy suspensions that allow a great deal of body roll can be bad. You can also wind up dropping a tire into a hole and breaking things.

It's all about balance and proper design. I have no burning desire to build a ramp queen that ramps 1000+ on a 30 degree ramp, but, I also don't want to lift tires pulling up on a curb. If you keep the springs relatively out-board on the axles, and don't let them just flop free like some of the setups I've seen on ramp queens (which can lead to rapid unloading and rolling), plus keep the shocks as far out as possible (and not angled in to the point where they don't control body role) then the flex shouldn't hurt unless it does let the tire drop into a hole. These are the things that are on my mind as I start the suspension work on my project...

OK, I just sold my Flat fender and I gotta say those that are bagging on Articluation NEVER had it. I started off iwht a standard SOA with a stock wheelbase. One thing I learned FAST was to lengthen the wheelbase quite a bit when you are going big. I was full width with a 44 front and a 60 rear, and 87" wide, long and tall. My advice is to stretch the thing to at least 100". I cut the back of the frame off and went all tubes and built my own 1/4 elliptic. I have to say this was the best mod i have ever done to it. I mean with all the work you are puttin into it, I would recomment the 1/4 elip as the ony way to go. You are building your truck almost exactly like I built mine. I was SOA front on a custom set of Wrangler springs, the rear was a 1/4 ellip. I had a 60 frnt and rear, Full width, Some 38's,... you know the drill. I recommend extending the drivelines more than anything else.

Dimitri

Thanks for all your replies. I have decided to just go with the basic SOA.

Dimitri, thanks for your opinions, I think your flatty is sweet and eventually i want mine to be like it but I dont want to go 1/4 elliptic right now. I am stretching the wheelbase by at least 6 inches. I hope to have about 90" when I am done but I mocked it up today and it only came out to be around 86" :(

I will have a locker in the back (detroit) and i do think it will have enough flex for now.