I got a little thinky...

[6spdYJ]

Well, I got looking at it today and re-convinced myself to go with the rear lowers. My reasoning is two-fold; the weight of the vehicle is supported by the springs and the arms just keep the axle located. By having the arms mount parallel to the centerline on the rear, I eliminate the brackets being in shear when forward resistance is met (shoving a tire against a rock). This will effectively push the axle tube into the brackets and the lower arm. The other advantage is by raising the axle mounting point while using the same frame mount I will get a flatter lower arm.

Thoughts or experiences?

[aw12345]

Sounds like the way to go to me

[6spdYJ]

Art, how wide is the opening on your upper mount for the front link? I'm also wondering about moving the upper mount on the axle back toward being more directly above the lower. I'll have to do some graph paper engineering to see if it would help.

[aw12345]

Art, how wide is the opening on your upper mount for the front link? I'm also wondering about moving the upper mount on the axle back toward being more directly above the lower. I'll have to do some graph paper engineering to see if it would help.

The opening on my upper mount is 2 and 3/4 inch so it fits the large Currie JJ. You got to figure out if you want to use a JJ, a heim or the stock oem bushing, that dictates that measurement

[6spdYJ]

Considering this, would there be any disadvantage to building the tabs 2 3/4" and putting a 1/8" spacer (like a high misalignment spacer) on either side to allow a bit more flex from the stock bushings? It would also allow me to put a large JJ in there in the future if I ever grow up.

[6spdYJ]

Well, I got the lower mounts built. They're 1/4" thick and gusseted. They're probably the strongest components that will ever go on the Jeep. As it turns out, there just ain't room enough to come straight off the back. I have to move them outboard a bit. Back to plan A. The angles and longer arms will allow for the offset. I'll just have to swing them lower than I originally wanted, but overall they'll still be higher than the stock pad, spring pack and u-bolt flip.

I'll have to figure out what I'm doing for the upper link before I build the actual mount. Since I have to swing the lowers under, it will allow me a lot more room to play with the height of the upper link end. The taller it is, the longer the lever is for the upper link to act on the housing. If I center my lowers, they come in at exactly 5 1/2" below the disco housing top surface where I'm putting the upper link bracket. Distance from the lower center to axle centerline would be 3 3/8". Axle centerline to the top of the disco housing is 2 5/8". To get the upper leverage 200% of the lower, I'll have to have the upper height at 4 1/8" above the top of the disco housing - making a total height above the tube on the passenger side 5 1/4".

The load on the upper is being spread across a flat surface roughly 4" square - with webbing reinforcements on two axis, not wrapped around a 2 1/2" tube, so I'm sure I'll have plenty of strength there.

Most of what I see suggests 70% of the lower to be the "right" length for the upper. This may be a dumb question, but would it be reasonable to look at using a JK front upper? Here's my reason for entertaining this thought... They can be re-drilled to get 77% length. They are made from tube and fully welded at the ends - not bent sheet. I can make the upper mount with a bushing much like the TJ/XJ and have the JK arm mount to that - with lots of room for deflection. I really don't question the eye end of it. They're the same as the lowers. I'm just not sure about the strength of the tube. I'll have to see if it's the same material as what the rear lowers are. Should I aim for having it stronger than the lowers or just plain strong?

Back to the above, with the upper leverage at 200%, would it seem reasonable to use one JK upper link, or build custom? Keep in mind, I'm looking at what's safe - and possible for a guy to accomplish with what's just laying around.

Art, when I finally come over for those spring mounts, I'll try to remember to bring these goodies for you to see them.

[6spdYJ]

Another option... Should I mount the upper link beside the frame rail, or directly under it? I have gobs of room to work with, so clearance isn't an issue. If I go under, it will be dirt-simple to double-shear and provide a touch more angularity against the panhard. But, will it interfere with movement? If I go to the inside, well, it goes to the inside. I can fit a 70% length upper either way. Thoughts?

[aw12345]

You want some separation between the lower and upper links so the lowers go under the frame and the upper on top

[6spdYJ]

I saw a Fabtech kit that had the upper (4 link) arm located under the frame rail about 3" above the lower mount. That's what got me to ask. It just seems to me that the closer to parallel from front to rear I can get the links, the more flex I can get before binding. I figure what I'll do is make a saddle bracket to go under the frame and have the upper link run to the inside. Using 1/4" and putting tubing inside to keep from squashing the frame will make it plenty strong. I drew it out on graph paper and found the more the frame end of the upper link points toward the frame mount of the lower link, the more it holds the pinion angle toward the T/C yoke. Of course this depends on the axle end height, but I pretty much have that figured out. I'll have to draw it full scale to get my exact measurements. Thanks for the input!

[aw12345]

Quite a few so called factory long arm kits have crappy geometry. Try to get a bit more separation than 3". actually on a YJ the front shaft has no CV joint so you want the same link length when viewed in straight lines square to the axle and equal separation on axle and frame side, that way you have no caster change and the driveshaft yokes will stay parallel when cycling the suspension. Or atleast something close to that, it isn't really all that hard to acomplish.

[6spdYJ]

I'm pretty much unlimited on the height of the upper mount both at the axle and frame. Being on the passenger side, I don't have to get around any exhaust or steering. So, are you saying to keep the upper link close to the same length as the lower? Most of what I've found suggests 70%. As far as height separation, I'm aiming at 7-8" at the axle. I just noticed on paper that the pinion pointed at the T/C more consistently throughout upper and lower travel when the upper link frame mount angled down toward the lower link.

[aw12345]

Here is the thing you do not have a cv driveshaft in the front so you want the yokes to stay parallel, which is better for keeping the caster angle constant also. 7" separation front and rear ought to work just fine.

[6spdYJ]

I drew it out with the upper 70% of the lower. With 7" and parallel it showed the pinion staying at a relatively similar angle (within 5 degrees)from 5" of up-travel and 5" of droop. After that, the up-travel started canting the pinion down pretty hard. Same for the droop - pinion down.
Just for curiosity, I did 8" at the axle and 6" at the frame. Up-travel canted the pinion downward after 2". Although it's more agressive of a response, it's still within 5 degrees. Plus, I'll only have about 4-5" before I hit the stop. The droop is what I find interesting. It started raising the pinion after 2" but kept the pinion pointed at the T/C through 12" of droop. If the pinion angle stays very similar in the first full 4" of travel (2"up-2"down) I'd estimate that to be safe for the u-joints on the street. But after that, I would think it's good to have the pinion aiming toward the T/C when you get more articulation.

Aside, I'm swapping out the 3.07's from my original housing to a set of 4.10's. They were both marked with a zero depth. The preload just seems too high. I didn't even get 100 lb-ft on it and it's over 30lb-in preload. Why would the preload change? Could it be the depth of the shoulder to seat the yoke?

[aw12345]

If it tightens up to quickly add a very thin shim behind the small pinion bearing, you got a Dana HP right that doesn't have a crush sleeve.

Something like 0.003" should reduce preload

[6spdYJ]

I learned something. If you're recieving heavy artillery fire, get under the D30 spring pads on a YJ. Divide and conquer was the only way they'd come off. I did a little bit of clearancing on the shock brackets, so I will be running the rear lowers straight off the back of the tube. The length of the axle brackets and the lower arms puts the center of the tube at 23" from the frame mount - just a hair longer than stock at full compression.

On to the upper link. Options, options... I'm considering using one of the front uppers. It's slightly shorter than the lowers but not by much. The ends use 1/2" hardware and the tube is 1"OD. Either that, or I can go with 1 1/4", .25" wall and rod ends with 9/16". I'm not into getting airtime with this, so I'm just questioning how far to go. I know, build it bigger and be sure. But, I wonder if one of the stock uppers would be up to the task.