JeepFreak21 said:
Some of the questions I have are:
-With a heim at the axle end of the wishbone, can/do the threads on the heim provide the vertical movement or does it need an uber complicated bearing like Beezil made?
-Which way should the heim/bushing be mounted?
-Would a RE SuperFlex Joint (or the like) work at the axle end of the wishbone?
-What's the ideal length for the links?
-Would it be possible to mount the wishbone (upper link(s)) to the lower links or would that be defeating the whole purpose?
I went through something similar Freak, I didn't like my 3link + TB and it was basically undriveable at freeway speeds due to DW. If I tweaked the caster/toe & rotated the tires just right it was ok, but I wanted the suspension to be right. I spent a week or so on POR reading & reading until I understood all of the geometry that I THOUGHT I had a grip on, I was wrong in a few ways.
With the unibody & lots of lift you've got problems getting the link angle within an acceptable range. I had to lower my LCAs 2.5" below the frame rail to get my AD (anti dive) axis back & below my CG, this is important if you want the front braking/accelleration lift to be correct, like anything there are compromises.
The other factor about my suspension that I didn't like was body roll, with the TB you have 2 roll axises, one at the frame mount & one at the axle mount. This makes your rig roll harder to one side than the other & just generally sucks on coilovers & 12" lift. With the new wishbone mounted 7" above the axletube I have raised my roll axis to a point where it's just below my CG, body roll is much much improved and it's now balanced side to side.
Link separation is something you need to consider. If you're running larger tires you'll want more link separation to give the links the leverage they need to withstand hi-torque situations, this was another factor in dropping my LCAs below the frame & raising the center link mount. I have about 8.5" of link separation at the axle and 6.5" of link separation at the frame, I'm running 38.5s.
My links are 26.5" long (ctr - ctr), no magic number really. I moved the front axle forward about 1", which didn't change any clearances really because I also flattened my link angles and increased the arm length which keeps the axle from moving very far forward during articulation. Even with the wheelbase stretched this amount, my tires dont get any closer to the front bumper than they did before.
I kept the LCAs I was using previously & just tapped one end for a 4" long 1" dia bolt. I welded the JJs I cut off onto the end of the bolt to stretch the arm length & make it adjustable. (Similar ends to the Currie pre-fab ends)
I butchered the UCA I was using before & used one of it's JJs for my wishbone center link. The JJ has 23deg of movement and is plenty for dropping the axle to the limits of the 14" coilovers. I do have a center limit strap that I'll be mounting soon that will keep the axle from dropping anymore than 3" below ride height (at the center anyway). I used a center mounted JJ because I wanted to keep my wishbone simple & tight to the oilpan. I didn't want to move my axle forward a great deal or mount the wishbone ahead of the axle because this would affect arm length & geometry and my LCAs were already built. I currently have less than 2deg of caster change throughout the range of travel, this is good because I wanted to drive it on the freeway occassionallly.
One thing to consider when debating full hydro is the strain you remove from the upper wishbone. My cylinder is mounted directly to the axle so when I turn there is virtually no stress on the UCA at all, it's all pushed through the T/R into the axle. All the wishbone has to do is keep the body over the axle, that's it, no steering stress anymore. This is a big plus with big rubber. Just sucks that I had already welded in an ORGS SBS2 into my framerails......oh well, made a nice steering valve mount!
Sorry for the long reply but I thought you might want to hear my decisions & why. I'd use the joints you already have, Richard Burrow (FullSizeXJ) is runnnig a rear triangulated 3 link with a SuperFlex joint & he gets full travel out of his 16" SAWs, that's how I knew my 14s wouldn't be a big deal.
Here's pics of my 3link front completed:
http://www.ofoto.com/I.jsp?c=7ha7rx...n&x=0&y=-y9utwh
Here's the build pics of the 3link:
http://www.ofoto.com/I.jsp?c=7ha7rxr.8zze49dz&x=0&y=iejoin
Hope that helps, I'm very happy with my setup, it works great, flexes good & is driveable again. I just drove 200 miles to JV & back for my wedding and aside from the tire wobble from the 38.5" x 14.5" TSL SXs & beadlocks, all was well. No more DW.
-jb