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

[jjvw]

Isn't this always what we run into when working on our Jeeps? You try to address one issue and this leads to another so as you fix one thing you also have to address the other things that come up?
And yes the way you build a rig for one type of terrain is different for another. It's trying to make one that can work reasonably well in all types of terrain that is the hard part.

Another reason why this is so interesting. You know what mine is. You know where it's inspiration comes from. And you know that it is my daily driver that is subjected to quite a bit in addition to the trials of getting to the other side of the city.

 

[Blackjack]

I'm no expert in any way so I can't say I'm correct but I'd think geometry correction would offer better results than outboarding shocks. At least that is my understanding of how things work.
Isn't it the same thing as doing the Savvy mid arm while keeping the rear shocks in their stock location? Doing the outboard shocks make the kit better but it isn't a requirement.

What is the travel bias on these 12"?

Speaking for myself and not from what I've seen elsewhere, two of my three 12" outboards are on 4" short arms. 6-6.5" of up. We haven't seen ripped off CA mounts yet. All three of us report dramatic improvements in handling, both on and off road. Two of these tunes are from Paul.

It is two different paths to what you want the suspension to do and what you think the role shocks should play in that. Shock technology has allowed the shock to do more than just be a simple oscillation damper and we know that shock location also has a direct effect on its performance. We can all agree that TJ stock shock location leaves a lot to be desired and outboarding can address some of those issues.

The number of control arms and their angles control how torque is applied to the chassis. Dave chose to keep the four link and panhard which means the are more points constraining the axle to the frame compared to the triangulated four link that Blaine/Savvy chose to use. It also means their demands on the shocks is going to be different as well. Neither approach is wrong or right they are just different.

 

[Wildman]

Well said Blackjack and I concur with you. I don't think there is any WRONG way to build your Jeep. Be it a shortarm/midarm/longarm suspension. Each works for the person building their rig. Yes we know packaging a longarm suspension under a TJ can be difficult and doesn't work for some. But I'm not going to tell anyone not to if that is how they choose to build their rig. Same with other modifications. How I choose to build mine might not work for others. So be it.
If you ask for opinions or recommendations then you have to use that information and make your choices. Even if I disagreed with them I'm not going to fault you for wanting to choose a different route.

We all need to remember part of the fun of these rigs is figuring stuff out. How you go about that is your choice since it's your money paying for it.
I'm glad that there is more than one way to skin a cat.

 

[Brianj5600]

Geometry correction, in my version, raises the lower at the axle about 1 5/8", which is well below the axle tube center, and about 1" at the frame. The bolt center is 6.25" above the axle tube. The track bar is slightly higher and moved forward over an inch to fix clearance issues. I requires exactly 2" of bumpstop extension without a body lift.
The combination adds separation on both ends.

View attachment 177950

I measured mine and the axle UCA bolt is 6" above the axle. I guess I'm in the ballpark.

+

 

[Fargo]

ANY aftermarket spring that is 2.5" taller than stock, ABSOLUTELY REQUIRES a 2" bumpstop due to the compressed height at coil bind. 2" bumpstop extension is also required for any bolt on rear track bar relocation. ... the relocation bracket ...raises the roll center which is another thing that improves handling alone....My geometry correction brackets operate on a 2" bumpstop without a body lift. It's impossible to get more uptravel without modifying the frame to accommodate the coil bind point of the springs. 14" rear collapsed shock lengths require a 2" bumpstop in stock, unmodified mounts with stock length control arms.

View attachment 177497

A 2" lift spring requires 2" rear bumpstop extension due to the coil bind height which is 5.5", also the same as most springs upto 4". This means there is no loss of uptravel by adding geometry correction brackets such as jeepwest weld on brackets. They require a 2" bumpstop extension without a body lift material is 1/4" steel with integrated bracing. If they rip off its because you can't weld.

The normal 2.5" lift rear shock @14" collapsed length requires 2" extension in factory mounts. If you add a tummy tucker, rotate the pinion then put shock shifters in the mix, you can end up needing over 3" of bumpstop extension.
Goto a 3.5-4.5" lift, 15-15.75" the bumpstop grows to 3.75" or more, regardless of what comes in the kit, they do not match.

The addition of geometry correction takes away suspension binding in a 12 travel range using outboard shock towers set up on a 2" bumpstop extension and has virtually zero rear steer from a 4" or less lift height.

I'd sure love to use the Nth template or just have Dave set me up. Maybe one of these years I will just drive out to Oregon and let him at it. Until then, just a couple quick questions.

1) Is the red spring in the photo a rear coil compressed to 5 1/4"+/-?
2) I just received an email from JKS stating their 3" dual rate spring will compress solid in the rear at 4.5" and the front at 7.75". If that is accurate, it seems I should be able to get away with about 1 1/4" bumpstop in the rear. (using 5160s with compressed length of 13.42") Does that sound reasonable?
3) Would I be able to use your brackets with a 1" body lift on top of that?

I love the way you view suspension geometry. I wish I lived closer so that I could have you do some work for me. Thanks for the help.

 

[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.

Update on my original post over a year ago. While yes, the suspension characteristics improved, I felt there was still more on the table. Last winter I bit the bullet and did a complete suspension overhaul. Triangulated 4 link rear, and 3 link w/panhard in the front, and did a 2" front stretch while I was at it. Very simple mod if you're comfortable with a welder and a little fabrication. The project set me back ~$1700 gross, $700 net with the sale of my old Rokmen control arms and rear JKS track bar. It is now a totally different rig, and feel that for me and the driving / wheeling I do, the suspension re-design was the only way I was able to achieve the desired suspension feel. I'm happy.

 

[Wildman]

I'd sure love to use the Nth template or just have Dave set me up. Maybe one of these years I will just drive out to Oregon and let him at it. Until then, just a couple quick questions.

1) Is the red spring in the photo a rear coil compressed to 5 1/4"+/-?
2) I just received an email from JKS stating their 3" dual rate spring will compress solid in the rear at 4.5" and the front at 7.75". If that is accurate, it seems I should be able to get away with about 1 1/4" bumpstop in the rear. (using 5160s with compressed length of 13.42") Does that sound reasonable?
3) Would I be able to use your brackets with a 1" body lift on top of that?

I love the way you view suspension geometry. I wish I lived closer so that I could have you do some work for me. Thanks for the help.

You can borrow the template if you want but it will be a little while as someone else is getting it right now. But you would be next inline to use it.

 

[Fargo]

You can borrow the template if you want but it will be a little while as someone else is getting it right now. But you would be next inline to use it.

I'm not ready for it right now. But please keep track of it in this thread. I expect the day will come that I will like to borrow it.

 

[Brianj5600]

I used the traveling template to drill the pilot holes and sent it back to Wildman. It was a while later before I drilled the final holes. If you only move the LCA I don't think the upper will ever converge with the lower. I have no idea how the rear suspension will act with no defined instant center.

 

[Fargo]

... If you only move the LCA I don't think the upper will ever converge with the lower. I have no idea how the rear suspension will act with no defined instant center.

From David Kishpaugh previous post, I was under the impression the upper arms really need to be done with the lower. I have no idea what you are even talking about in regards to having a defined instant center. Although I can guess.

I am completely unqualified to be re-engineering my suspension geometry. That is why I don't need the template right now. I have too much to learn. At this point, I would rather drive out to OR and just have David take care of it for me. Although there is probably someone in the Black Hills or even in Minneapolis that might know about this stuff. So for right now, I'm just holding tight until I understand things better or I can find someone to do the work for me.

 

[Blackjack]

From David Kishpaugh previous post, I was under the impression the upper arms really need to be done with the lower. I have no idea what you are even talking about in regards to having a defined instant center. Although I can guess.

I am completely unqualified to be re-engineering my suspension geometry. That is why I don't need the template right now. I have too much to learn. At this point, I would rather drive out to OR and just have David take care of it for me. Although there is probably someone in the Black Hills or even in Minneapolis that might know about this stuff. So for right now, I'm just holding tight until I understand things better or I can find someone to do the work for me.

You can move the front of the lower arm by itself with no other changes but if you wish to do the axle side of the lower you must also relocate the upper arm mount on the axle.

 

[Fargo]

You can move the front of the lower arm by itself with no other changes but if you wish to do the axle side of the lower you must also relocate the upper arm mount on the axle.

Why is that? Aren't you still affecting the movement of the axle? It would seem to me that any change in the geometry could have profound effects on things. But I just don't know. That why I like bolt on stuff like the AEV geometry correction brackets for the JK. If they don't work you can ditch them and you haven't permenantly altered your Jeep.

 

[Wildman]

Why is that? Aren't you still affecting the movement of the axle? It would seem to me that any change in the geometry could have profound effects on things. But I just don't know. That why I like bolt on stuff like the AEV geometry correction brackets for the JK. If they don't work you can ditch them and you haven't permenantly altered your Jeep.

Not arguing this and yes bolt on is at times much easier than other options. But as was pointed out you are just drilling holes in the brackets at this point. You don't have to move anything yet. The one thing I can say is that you stand the chance of bending stuff more once you move the control arms in reference to your rear lowers. You can always move the arms back if you don't like the results.

I'm just glad I hadn't trimmed off the brackets.

 

[Fargo]

But as was pointed out you are just drilling holes in the brackets at this point. You don't have to move anything yet.

That is true. Thats why this is still tempting to me.

The one thing I can say is that you stand the chance of bending stuff more once you move the control arms in reference to your rear lowers.

Bending due to leverage on the bracket by lowering the bolt hole or is there something else you are referring to?

I'm just glad I hadn't trimmed off the brackets.

Did you revert back to stock? Or did I miss something?

 

[Brianj5600]

He now has Savvy mid arms that require the stock location of the stock LCA axle mount. I have seen some pretty beat up lower axle mounts. If I ever go that route I think I would replace the LCA mount with an thicker aftermarket one while I

 

[Fargo]

Ahh, I see. Savvy Mid Arm would be a nice way to go.

 

[jjvw]

He now has Savvy mid arms that require the stock location of the stock LCA axle mount. I have seen some pretty beat up lower axle mounts. If I ever go that route I think I would replace the LCA mount with an thicker aftermarket one while I

Weld some thick washers to either side of the stock mount.

 

[Wildman]

That is true. Thats why this is still tempting to me.

Yes you just have extra holes in your mounts which don't seem to affect their strength as far as I know

Bending due to leverage on the bracket by lowering the bolt hole or is there something else you are referring to?

I bent the lower parts of my axle control arm brackets because I had moved the control arms up after I redrilled them. I had planned on trimming the brackets off at some point but never did. Dragging them across rocks is what bent them.

Did you revert back to stock? Or did I miss something?

No I took the Nth Degree suspension off and am installing a Savvy mid arm kit now. So I am now using the stock locations again.

 

[Wildman]

He now has Savvy mid arms that require the stock location of the stock LCA axle mount. I have seen some pretty beat up lower axle mounts. If I ever go that route I think I would replace the LCA mount with an thicker aftermarket one while I

I have a aftermarket axle with thicker LCA mounts. I don't think I have any pictures of just how bent up they got but even with the thicker mounts they got pretty mangled.

 

[Blackjack]

Why is that? Aren't you still affecting the movement of the axle? It would seem to me that any change in the geometry could have profound effects on things. But I just don't know. That why I like bolt on stuff like the AEV geometry correction brackets for the JK. If they don't work you can ditch them and you haven't permenantly altered your Jeep.

Changing just the the front of the lower increases the separation of the upper and lower links at the frame. For the rear since you are raising the mounting point you have to also raise the upper arm mount so as to not decrease the link separation of the links on the axle. One of the things that the geometry correction does is to actually increase the link separation which helps with the loading of the upper links since we are moving the lower closer to the axle centerline.