Nth Degree Rear Lower Control Arm (LCA) Geometry Correction Template

[Wildman]

My jeeps PO installed the stinger to the rear differential and it seems to work well.
However I will read the instructions and see if I need to double check the install.
Thanks for the post Wildman !

The stinger for the stock axles seems to be better than what I have. I'm not saying it doesn't work but I have had a popping noise in my rear suspension ever since I installed it. The first time it made this pop I pulled over to make sure I hadn't broken anything. And then I've had issues with the rear of my TJ hopping when trying to climb steep hills. It can get a little hairy sometimes when it will hop and my front slides to the side. The trails it does this on are not trails you want this to happen. I'm taking the longarm kit off my TJ this summer and installing a different suspension.

 

[Brianj5600]

That is a concern for sure. I am not sure if there will be a problem with shocks in stock location as they will be the up travel limiter. I doubt I'll outboard my shocks with short arms. If I do outboard I will probably use longer arms and triangulate the uppers ditching the track bar. Putting the uppers in the middle of the axle will allow up travel since the arms won't move as much vertically when articulating.

 

[jjvw]

That is a concern for sure. I am not sure if there will be a problem with shocks in stock location as they will be the up travel limiter. I doubt I'll outboard my shocks with short arms. If I do outboard I will probably use longer arms and triangulate the uppers ditching the track bar. Putting the uppers in the middle of the axle will allow up travel since the arms won't move as much vertically when articulating.

When the lowers get shifted, the uppers need to be shifted similarly. That is how the AS will be lowered and the IC located. Basically, this template will not work as intended without the other half of the kit.

Raising the axle side uppers will add stress to those mounts by increasing the leverage from the axle tube. There comes a point where the mounts need reenforcement.

The height of the upper axle side mounts creates the same limit to up regardless of where they are located. Remember the bump stops are out on the ends of the axle and the control arm mounts will always be inboard of the bump stops.

An outboard with better shocks will have a far greater overall improvement than messing with the arms. While the arm length will play a role in the positioning of the shock mounts and effect the amount of required bump stop extension, this should be treated as a separate project with a different set of goals.

 

[Mike_H]

That would great if you could post up those instructions.

Looks like @Brianj5600 beat me to it. I don't have anything different than he does.

 

[Wildman]

When the lowers get shifted, the uppers need to be shifted similarly. That is how the AS will be lowered and the IC located. Basically, this template will not work as intended without the other half of the kit.

Raising the axle side uppers will add stress to those mounts by increasing the leverage from the axle tube. There comes a point where the mounts need reenforcement.

The height of the upper axle side mounts creates the same limit to up regardless of where they are located. Remember the bump stops are out on the ends of the axle and the control arm mounts will always be inboard of the bump stops.

An outboard with better shocks will have a far greater overall improvement than messing with the arms. While the arm length will play a role in the positioning of the shock mounts and effect the amount of required bump stop extension, this should be treated as a separate project with a different set of goals.

All this is great information and I'm glad this thread is taking off. It looks like we're getting close to getting the information. Brain provided the instructions that talk about installing the extension brackets. It also talks about which bump stops are to be used.

Everyone needs to be sure of what they are doing before drilling their lowers. I glad I can provide one part of this but please know what this is going to affect if you choose to follow these instructions.

 

[Brianj5600]

@jjvw, my concern is the height of the UCAM will cause the UCAM to hit the tub before the stock mounted shocks bottom out. As far as the UCAM mounted on the pumpkin vs the axle tube, they both will contact the tub simultaneously only if both ends of the axle move the same amount in the upward direction. I only see that happening in whoops or jumping your Jeep. If only one side is lifted the UCAM on the tube will hit first.

The LCA is lowered at the frame mount and raised in the axle mount, leaving the LCA slightly downhill from frame to axle. Raising the axle UCAM 4" should put the axle UCAM slightly higher than the frame side.

I bought the below mounts because I did not want to rely on the stock mounts with extensions welded on. I was planning on cutting off the stock mounts and relocating them back to vertical anyway when I go dual cardon.

https://www.rustysoffroad.com/build...ys-control-arms-tj-rear-axle-upper-mount.html

I will be mating the above to these. The bottom hole will be the stock location and the top hole will around 7.5" from tube to center of the hole.

https://www.barnes4wd.com/Flat-Bottom-Link-Mount-Bracket-Pair_p_164.html

I am going to cut the stock shock brackets off and replace them with these.

https://www.rustysoffroad.com/rusty-s-straight-shock-mount-with-squared-end.html

And the track bar.

https://www.barnes4wd.com/Offset-Axle-Panhard-Bracket-14_p_71.html

 

[Mike_H]

I found the elusive right rear control arm extension instructions...

 

[jjvw]

@jjvw, my concern is the height of the UCAM will cause the UCAM to hit the tub before the stock mounted shocks bottom out. As far as the UCAM mounted on the pumpkin vs the axle tube, they both will contact the tub simultaneously only if both ends of the axle move the same amount in the upward direction. I only see that happening in whoops or jumping your Jeep. If only one side is lifted the UCAM on the tube will hit first.
....

Cycle the axle and see what happens. Does yours have a body lift? I think you'll be hard pressed to create the problem you are describing unless your upper mounts are going to be absurdly tall. While I don't jump my Jeep very often, I do use most of it's 7" of up often enough just driving around town.

 

[Wildman]

@jjvw, my concern is the height of the UCAM will cause the UCAM to hit the tub before the stock mounted shocks bottom out. As far as the UCAM mounted on the pumpkin vs the axle tube, they both will contact the tub simultaneously only if both ends of the axle move the same amount in the upward direction. I only see that happening in whoops or jumping your Jeep. If only one side is lifted the UCAM on the tube will hit first.

The LCA is lowered at the frame mount and raised in the axle mount, leaving the LCA slightly downhill from frame to axle. Raising the axle UCAM 4" should put the axle UCAM slightly higher than the frame side.

I bought the below mounts because I did not want to rely on the stock mounts with extensions welded on. I was planning on cutting off the stock mounts and relocating them back to vertical anyway when I go dual cardon.

https://www.rustysoffroad.com/build...ys-control-arms-tj-rear-axle-upper-mount.html

I will be mating the above to these. The bottom hole will be the stock location and the top hole will around 7.5" from tube to center of the hole.

https://www.barnes4wd.com/Flat-Bottom-Link-Mount-Bracket-Pair_p_164.html

I am going to cut the stock shock brackets off and replace them with these.

https://www.rustysoffroad.com/rusty-s-straight-shock-mount-with-squared-end.html

And the track bar.

https://www.barnes4wd.com/Offset-Axle-Panhard-Bracket-14_p_71.html

I'm not an expert but you don't want your rear shocks to bottom out. This is part of the reason you use a bumpstop. It keeps the shock from being what bottoms out and keeps your tires out of your body. I may not be explaining this properly but I hope you understand what I am trying to say.

I found the elusive right rear control arm extension instructions...

Awesome Mike thank you very much.

 

[Brianj5600]

I found the elusive right rear control arm extension instructions...

Nice! The upper bracket looks like the additional holes are not in line with the original hole. I wonder if that is to keep from increasing the length of the UCA when raising the pinion?

Cycle the axle and see what happens. Does yours have a body lift? I think you'll be hard pressed to create the problem you are describing unless your upper mounts are going to be absurdly tall. While I don't jump my Jeep very often, I do use most of it's 7" of up often enough just driving around town.

I don't currently have a body lift. My springs are a bit on the stiff side. I'll never see as much rear travel on the road. I'm going to see how they do when I'm loaded for camping. I have 7/11 to 8/11 off work and heading west with my son.

 

[Brianj5600]

I'm not an expert but you don't want your rear shocks to bottom out. This is part of the reason you use a bumpstop. It keeps the shock from being what bottoms out and keeps your tires out of your body. I may not be explaining this properly but I hope you understand what I am trying to say.

I have bump stops that keep the shocks safe. To get more uptravel I would have to make room for the tire and ditch the stock shock mounting. It's on the list.

 

[Wildman]

Brain, Good luck with trying to raise the UCAM. Please keep us posted on how this all goes. It has been a long time since my TJ had rear UCAM's. Now that I have another stock TJ in my house I can look at these things again, when my daugher isn't driving it. So if you guys report that it was worth the time to redrill the LCAM and raise the UCAM I will have to think about doing it to her TJ.

I'm curious how much room there is for up travel before the mounts hit?

 

[TJustin]

I recently got back from Moab using new new holes from the jig that @Wildman lent me. Because of my swapped-in 8.8, I only re-drilled the frame side LCA holes. I believe it to be beneficial to redrill the axle side as well if you can swing it. The geometry change did not eliminate my antisquat completely, but feel that it moved the needle in the right direction. I still get some hopping, but not as much as I used to, and the hopping action is more subdued. My next step will likely be repositioning the LCA mounts on the axle to further decrease the hopping motion. Overall, I feel that the suspension is in more of a neutral state compared to before. Install was straightforward using the included instructions. The process of re-drilling took roughly 2 hrs. I did have it on jackstands and did one side at a time.

The jig is headed to another member next, but recommend taking the time to do a cheap suspension mod for those of us on SA lifts.

 

[Brianj5600]

I think raising the uppers on the axle will be where you get the most benefit. Moving the UCA mount on the axle up 3.5" will reduce AS drastically.

 

[Wildman]

I recently got back from Moab using new new holes from the jig that @Wildman lent me. Because of my swapped-in 8.8, I only re-drilled the frame side LCA holes. I believe it to be beneficial to redrill the axle side as well if you can swing it. The geometry change did not eliminate my antisquat completely, but feel that it moved the needle in the right direction. I still get some hopping, but not as much as I used to, and the hopping action is more subdued. My next step will likely be repositioning the LCA mounts on the axle to further decrease the hopping motion. Overall, I feel that the suspension is in more of a neutral state compared to before. Install was straightforward using the included instructions. The process of re-drilling took roughly 2 hrs. I did have it on jackstands and did one side at a time.

The jig is headed to another member next, but recommend taking the time to do a cheap suspension mod for those of us on SA lifts.

Thanks for reporting your findings and experiance with the template.

 

[Brianj5600]

I passed the point of no return. I am going to relocate the stock upper and lower spring plates to line up correctly. I don't if I will be able to relocate the axle LCA because of the large joints on my control arms. I will be drilling the frame LCA mounts.

Bare rear axle tube

Upper control arm mount. A cut down thick stock type mount with adjustable piece to weld on. The bottom hole is a little higher than stock. The top hole is 7" above the tube.

Track bar mount adjustable too.

 

[TJustin]

I passed the point of no return. I am going to relocate the stock upper and lower spring plates to line up correctly. I don't if I will be able to relocate the axle LCA because of the large joints on my control arms. I will be drilling the frame LCA mounts.

Bare rear axle tube

View attachment 103193

Upper control arm mount. A cut down thick stock type mount with adjustable piece to weld on. The bottom hole is a little higher than stock. The top hole is 7" above the tube.

View attachment 103194

Track bar mount adjustable too.

View attachment 103195

How did the install go? What are your thoughts on the mods?

 

[Brianj5600]

I think raising the uppers on the axle will be where you get the most benefit. Moving the UCA mount on the axle up 3.5" will reduce AS drastically.

I was very wrong on this statement. After playing a little with the Triaged calculator, I found that the lower has more effect on AS and the upper sets IC length/height. With stock LCA mounts the AS line and the LCA projected line are close to parallel. Changing the upper mounts has little effect on AS.

I recently got back from Moab using new new holes from the jig that @Wildman lent me. Because of my swapped-in 8.8, I only re-drilled the frame side LCA holes. I believe it to be beneficial to redrill the axle side as well if you can swing it. The geometry change did not eliminate my antisquat completely, but feel that it moved the needle in the right direction. I still get some hopping, but not as much as I used to, and the hopping action is more subdued. My next step will likely be repositioning the LCA mounts on the axle to further decrease the hopping motion. Overall, I feel that the suspension is in more of a neutral state compared to before. Install was straightforward using the included instructions. The process of re-drilling took roughly 2 hrs. I did have it on jackstands and did one side at a time.

The jig is headed to another member next, but recommend taking the time to do a cheap suspension mod for those of us on SA lifts.

Did you move your axle mount?

How did the install go? What are your thoughts on the mods?

I will be moving the frame side LCA tomorrow and testing 12/31 or 1/1. I really want to move the axle mount too, but my control arm bushings are large and I'm not sure there is room. I will try measure for sure on fitment.

Here are some pics of the mounts installed. Passenger

Drivers side

Trackbar clearance to tank

Drivers UCA and trackbar mount

 

[Brianj5600]

I lowered the frame LCA mounts and it definitely reduced AS. Before the change the whole Jeep would raise up when quickly accelerating from a stop. It actually seems to squat or at least the rear is neutral now when accelerating. I am going to get a quick nap and hit the trails. I think the chance of wheel hop will be reduced and help keep some weight on the front tires when climbing.

I want to move the axle LCA mount up, but my joints are too big.

 

[TJustin]

Did you move your axle mount?

No, I did not. Since writing my post above, I had been him-hawing back and forth. I ended up pulling the trigger and selling all my control arms and rear track bar to forum members. I'm now mid-process of building an entirely new suspension. It will be triangulated rear 4 link, and 3 link w/ panhard bar in the front.

Beyond that, I haven't decided on specifics. It is not an off-the-shelf kit.

How's that for a long response to a simple question? haha

Side note- How did the modifications work out for you?