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Long Arm Lifts vs. Short Arm Lifts

jjvw

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.... I think the reason the redrill did not catch on is that a lot of people thought you had to run the stinger and Jim did not push his standard short arm stuff as much as I think he could. I am sure I am one of the only people to be running what Jim called the Handling Improvement Kit.

If we assume the redrill works as promised, I can also see the very idea being confusing once the Nth short and long arm kits are compared side to side. The full short arm kit hangs down lower than a stock short arm, which is the opposite of the Nth long arm. The same (presumably smart) guy designed both systems. If we can understand the importance of mount locations and instant centers, then maybe we can start to understand why these two kits can look so different, yet are striving towards a similar goal.
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Mike_H

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There is no good way to answer that because they understand suspension and the value of good geometry. They dallied with a cut and weld kit for awhile and discontinued it due to bad installs.

Would that be the "J-Arm" lift they produced? I've always heard that was a great performing system. As I'm learning about control arms, it looks like a very interesting solution...
 
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mrblaine

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Would that be the "J-Arm" lift they produced? I've always heard that was a great performing system. As I'm learning about control arms, it looks like a very interesting solution...
Yes, it worked very well but methods and tech bypassed it due to it have no install flexibility for both its function and anything else you might want to do like outboard shocks. That was due to the J arm mounts on the axle being directly located where the lower end of the rear shocks mounted. In the front, the arms attached to the front side of the axle and messed with the trackbar location. There was also not a good option for the uppers and they set the rear shocks at a severe angle.

It worked and very well but there were far too many limitations with it.
 
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Blackjack

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If we assume the redrill works as promised, I can also see the very idea being confusing once the Nth short and long arm kits are compared side to side. The full short arm kit hangs down lower than a stock short arm, which is the opposite of the Nth long arm. The same (presumably smart) guy designed both systems. If we can understand the importance of mount locations and instant centers, then maybe we can start to understand why these two kits can look so different, yet are striving towards a similar goal.
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I think what Jim hurt himself the most was he dumped a lot of product to the market IMO in too short a time frame. I know a lot of people scoffed at those short arm mounts but a non bent arm long hung down lower at that point and had stuff to drag on further forward.

Then you add the torque arm in the mix as a lot of people did not understand what it tried to accomplish. Or that the long arm and the short arm had the same instant center and thus the same antisquat numbers. The control arms at that point are there to just locate the axle and their angle controlled just roll steer.

The kit I have is what I believe the majority of TJ owners need and would be very happy with. It lowered the instant center significantly without a bunch of major surgery. I will see if I can get my rig into a warm space and take some pictures.
 

Mike_H

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I think what Jim hurt himself the most was he dumped a lot of product to the market IMO in too short a time frame. I know a lot of people scoffed at those short arm mounts but a non bent arm long hung down lower at that point and had stuff to drag on further forward.

Then you add the torque arm in the mix as a lot of people did not understand what it tried to accomplish. Or that the long arm and the short arm had the same instant center and thus the same antisquat numbers. The control arms at that point are there to just locate the axle and their angle controlled just roll steer.

The kit I have is what I believe the majority of TJ owners need and would be very happy with. It lowered the instant center significantly without a bunch of major surgery. I will see if I can get my rig into a warm space and take some pictures.
I would for sure be interested in seeing it. I've got all kinds of ideas spinning around in my head...
 

Blackjack

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Had to come in and warm up. So a few specs for my ride.

98 SE Softtop with too much armor and carries too much stuff.

Front springs are Nth Degree 3in standard and rear are 3in heavy with the coil relocation kit for a unloaded lift height of 4in in the front and 4.5 in the rear. Skocks are old OME LTs with the rear on Nth shock shifters

Control arms are ones that I built originally with a combination of Clevites and RE cartridge joints. As they wear I have been replacing with Synergy Dual Durometer bushings.

The big thing is the upper control arm brackets. They raised the axle mount by either 2.5 or 3.5 inches. Along with redrilling the lower dramatically changed the instant center with little effort and works with just about any aftermarket arms. Simple and effective.
 
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Blackjack

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Since I had the wheels off and I happen to be using an early Rubicon Express long arm skid I took a couple pics to show where the arms would be at my ride height.
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Sent from my iPhone using Tapatalk
 
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AndyG

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It is regional until you try both side x side and it also depends on if you are right handed or left handed and you cut a lot of roofs and stairs. I've used worm drives from Skil, Bosch, Makita, and one more that I don't recall the brand of. I have a couple of sidewinders and I've used them from smallish to monster beam saws from Makita along with a few trailer mounted radial arm saws swinging 24" blades.

You get to use and try a bunch of different saws when you spend several years as the saw man building custom homes. I cut all the studs, fire blocks, vent blocks headers, king studs, trimmers, and beams for the homes we built.

After we finished the framing, we set up a mill in the garage and I ran the table saw for the cabinets we built. In and amongst that, I built the door jambs and prehung all the interior doors for the finish carpenters.

I currently own 2 sidewinders, 1 compound radial arm chop saw, 1 regular chop saw, 4 jigsaws, 4 worm-drives, and a couple more oddball saws.

If you told me I had to get rid of everything but 1 saw, I would keep the worm drive.
I know I'm waaay off topic....my Festool and Makita tracksaws are my favorite saws ...are they great saws ? Not in the sense of being rugged framing saws , but they bring a level if accuracy we have never had to the jobsite.
 
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Mike_H

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A Slight derail, but those pictures that @Blackjack posted really have me thinking...I've been playing with the 4-link calculator from Pirate, and came to the same conclusion last night...I have a body lift so I have the room to raise my upper link mounts. That would get the arms back to "normal" flat conditions... Its interesting. I will need to spend some time with a tape measure under the jeep and with my nose buried in a book to really learn what anti-squat and roll center means...or more importantly, what effect they have on the jeep.
 

jjvw

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A Slight derail, but those pictures that @Blackjack posted really have me thinking...I've been playing with the 4-link calculator from Pirate, and came to the same conclusion last night...I have a body lift so I have the room to raise my upper link mounts. That would get the arms back to "normal" flat conditions... Its interesting. I will need to spend some time with a tape measure under the jeep and with my nose buried in a book to really learn what anti-squat and roll center means...or more importantly, what effect they have on the jeep.

A comment about the Nth axle side mounting. Broadly speaking, when the lowers are raised, the leverage against the mounts is decreased. When the uppers are raised, the leverage against the mounts is increased and ought to be strengthened. It isn't uncommon to see these raised mounts bend if the bracing is insufficient. Raising the uppers eventually also reduces the up travel to where the mounts will eventually hit the floor of the tub.

This is one of the problems you'll see when guys try to add ground clearance by moving the lower axle mounts higher.
 

Mike_H

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A comment about the Nth axle side mounting. Broadly speaking, when the lowers are raised, the leverage against the mounts is decreased. When the uppers are raised, the leverage against the mounts is increased and ought to be strengthened. It isn't uncommon to see these raised mounts bend if the bracing is insufficient. Raising the uppers eventually also reduces the up travel to where the mounts will eventually hit the floor of the tub.

This is one of the problems you'll see when guys try to add ground clearance by moving the lower axle mounts higher.

Yes, lengthening the upper mount would increase the torque (or moment arm) trying to tear the mount off the axle. As it is though, with a track bar relocation bracket in there, I think you have quite a bit of room to raise that upper mount. I haven't crawled underneath to look at it, but from memory, that bracket is taller than the CA brackets.
 

mrblaine

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Yes, lengthening the upper mount would increase the torque (or moment arm) trying to tear the mount off the axle. As it is though, with a track bar relocation bracket in there, I think you have quite a bit of room to raise that upper mount. I haven't crawled underneath to look at it, but from memory, that bracket is taller than the CA brackets.
Before I knew better and was brute forcing design, I built a few rigs with the uppers at the frame fairly close together. Not the close that you see with a lot of kits but maybe 4" of vertical separation. I had a helper at the time who was as distracting as you can possibly imagine with the sheer stupidity and annoyance of his questions. He was one of those that will look at a pair of horses, one black and one white and ask you how you tell them apart.

I was up under the rig welding the upper mounts to the platform that was also a gusset for the crossmember that carried the lowers and I missed 1" of weld between the two tabs. The owner called me from the desert a few weeks after he picked up the rig with that mount ripped off the platform. Later, another one that I had built had a similar issue with a single mount on the front at the frame. I got plenty of weld on that one but the mount design was incorrect without enough vertical separation and it started cracking the material near the base.

I changed the design, learned some about vertical separation and the leverage involved and have not had a single issue since with the best part being that the suspensions have worked better and better.

Before you get too invested in the calculator, understand that it is only accurate for static applications. It is only as accurate as your input, or garbage in, garbage out. If you don't know where the COG is exactly, everything else is just an approximation.
 
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Mike_H

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Before I knew better and was brute forcing design, I built a few rigs with the uppers at the frame fairly close together. Not the close that you see with a lot of kits but maybe 4" of vertical separation. I had a helper at the time who was as distracting as you can possibly imagine with the sheer stupidity and annoyance of his questions. He was one of those that will look at a pair of horses, one black and one white and ask you how you tell them apart.

I was up under the rig welding the upper mounts to the platform that was also a gusset for the crossmember that carried the lowers and I missed 1" of weld between the two tabs. The owner called me from the desert a few weeks after he picked up the rig with that mount ripped off the platform. Later, another one that I had built had a similar issue with a single mount on the front at the frame. I got plenty of weld on that one but the mount design was incorrect without enough vertical separation and it started cracking the material near the base.

I changed the design, learned some about vertical separation and the leverage involved and have not had a single issue since with the best part being that the suspensions have worked better and better.

Before you get too invested in the calculator, understand that it is only accurate for static applications. It is only as accurate as your input, or garbage in, garbage out. If you don't know where the COG is exactly, everything else is just an approximation.
Yup. I'm well aware of the Garbage in / Garbage out theory. I guess I was more thinking of doing some comparative analysis with different mount locations, vs trying to work up a design in the calculator that will then carry over to my jeep 100%. Hell, for me, its probably more of a method to satisfy my curiosity than anything else. My normal wheeling trips don't have me trying to climb vertical rockfaces. I've never felt the rear axle try to crawl under my rig. I will say though, that I'm starting to understand your comment about the midarm suspension you designed for Savvy, and why you don't need it until you know you do.

However...I do plan on buying control arms that will allow me to add longer links in the future, if I'm so inclinded.
 
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mrblaine

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However...I do plan on buying control arms that will allow me to add longer links in the future, if I'm so inclinded.

It would be rare for that to work. We generally tell folks with the Currie Short Arm that do the mid arm to just take the set and sell them intact. The only joints that work are the lowers moved up to be the ends of the 3 uppers and then you are left with 1 lower and 4 uppers to do something with IF you are working with something like the Currie or Savvy arms.

If you move to a "3 link" front with a single upper, I recommend the larger body for more durability but with the smaller 1" shank. You don't need the bending resistance of the larger shank so the smaller one works fine.