Did it handle / perform that much better in the terrain you typically wheel in when compared to your Currie short arm lift?
Long Arm Lifts vs. Short Arm Lifts
- Thread starter Stox5225
- Start date
Did it handle / perform that much better in the terrain you typically wheel in when compared to your Currie short arm lift?
Good timing. Or really really bad timing. I was at the point where I needed to move past the factory arms. Savvy was just about to release the mid arm kit and I was following along and learning and not listening to mrblaine. One of the things that Blaine was telling people was that the mid arm kit is intended only as an upgrade for a very well built 4" lift and 35s. And that if you don't know why you want it, you don't need it.
At the time, the introductory sale price was not much more than Savvy arms and a new rear track bar. I had a welder. And I had a DC rear drive shaft on the shelf. So I thought it would be a good idea to go for it. My Jeep had a 3" lift and 33s and was mostly stock.
The reality is that the mid arms started an avalanche of fast learning, mount moving and tummy tucking as I found myself building the Jeep around the control arms to make it work, instead of building the Jeep around my needs. Basically, I built the Jeep backwards without know what I was getting into.
How much better it was than my SA Currie suspension was apparent as soon as I got up into the hills and gullies up above Blaine's house which is adjacent to a lot of open uneven very hilly terrain. It was pretty dramatic even to a guy with an uncalibrated rear-end suspenso-meter as I have.
for me the shorter the arm/steeper the angle the more stress on the joints during heavy suspension travel. This is on larger lifts 4 or larger. Shorter lifts are not as prone to it because the angle is not as steep.
For me using same lift manufacturer same brand of shocks the long arm gave me a night and day better ride as oppose to the short arm even when I had a 4" lift. if I go fast thought RR crossings which here they are terrible I barely feel them as oppose to when I had a 4" short arm. Though I may be wrong but I feel when I rocked crawled it was easier for me to climb rocks etc.. with my current 6" long arms than 4" short arm I had before. Again same manufacturer and same Bilstein shocks same axles and same 35" tires.
For me using same lift manufacturer same brand of shocks the long arm gave me a night and day better ride as oppose to the short arm even when I had a 4" lift. if I go fast thought RR crossings which here they are terrible I barely feel them as oppose to when I had a 4" short arm. Though I may be wrong but I feel when I rocked crawled it was easier for me to climb rocks etc.. with my current 6" long arms than 4" short arm I had before. Again same manufacturer and same Bilstein shocks same axles and same 35" tires.
Wow, sounds like it's a nice upgrade!
The question is, what constitutes a "very well built 4" lift and 35s"? Those are Blaine's words, so maybe he knows better than we do, I'm just curious.
Basically a tummy tuck, relocated and outboarded shock mounts, correct bump stops and all the little details to make that all work well together.
The subtext is that if you are doing trails that don't require these things, then you don't need longer arms.
At a more practical level, the Savvy kit does not work with the factory skid plate. It does not work with the rear bump stops in the factory locations after the pinion had been raised for the lift and the tummy tuck. Tires smaller than 35s will drag the arms more than ought to be acceptable.
Most importantly, a spring lift below 4" doesn't need to have its instant center corrected. Read that sentence again.
Does everyone grasp the existence of the instant center?
There is another imaginary line called the antisquat line. This is a line that connects the rear tire patch and the height of the center of gravity above the center line of the front tire. I don't fully understand why this is. But we will accept that it exists, because engineers have found it.
The position of the instant center in relation to the antisquat line will have an effect on the on the behavior of the rear suspension while the wheels are spinning and applying traction to the ground.
If the instant center is located anywhere above this antisquat line, the control arms will push the rear axle into the ground. The further above the line, the harder the push. This is a resistance to squat or antisquat or positive antisquat.
If the instant center is located anywhere below this antisquat line, the control arms will pull the rear axle away from the ground, causing the vehicle to squat. The further below the line, the harder the pull. This is negative antisquat.
If the instant center is on the antisquat line, then the control arm's effect on the axle will be neutral. In the image above, this is called 100% antisquat.
Antisquat numbers above 100% are positive, numbers below 100% are negative. I don't know why this is.
This video covers too much ground and isn't as simple as I would prefer.
Pay close attention to 8:30, the red buggy followed by the green. This is what matters for us.
There is another imaginary line called the antisquat line. This is a line that connects the rear tire patch and the height of the center of gravity above the center line of the front tire. I don't fully understand why this is. But we will accept that it exists, because engineers have found it.
The position of the instant center in relation to the antisquat line will have an effect on the on the behavior of the rear suspension while the wheels are spinning and applying traction to the ground.
If the instant center is located anywhere above this antisquat line, the control arms will push the rear axle into the ground. The further above the line, the harder the push. This is a resistance to squat or antisquat or positive antisquat.
If the instant center is located anywhere below this antisquat line, the control arms will pull the rear axle away from the ground, causing the vehicle to squat. The further below the line, the harder the pull. This is negative antisquat.
If the instant center is on the antisquat line, then the control arm's effect on the axle will be neutral. In the image above, this is called 100% antisquat.
Antisquat numbers above 100% are positive, numbers below 100% are negative. I don't know why this is.
This video covers too much ground and isn't as simple as I would prefer.
Last edited:
This is confusing stuff. Read through and watch the videos a few times.
All that we need to understand is that an instant center and an antisquat line exist. And that the instant center's location above or below that antisquat line will have an effect on the rise and fall of the rear axle as you apply power to the wheels.
We are working our way to this...
All that we need to understand is that an instant center and an antisquat line exist. And that the instant center's location above or below that antisquat line will have an effect on the rise and fall of the rear axle as you apply power to the wheels.
We are working our way to this...
Last edited:
Sometimes I think what gets lost in the long arm short arm debate is the value of triangulation.
I think there will always be an argument between the two groups... Those that prefer the single hump camel versus the double humpers.....
But leaving the science and geometry aside , a lot of the handling of the vehicle is dependent upon the consistency and quality of the bushings and their relationship both to the arms and the chassis .... I'm of the opinion that you can get a great driving vehicle with most any system if you do it completely and do it correctly.
I think there will always be an argument between the two groups... Those that prefer the single hump camel versus the double humpers.....
But leaving the science and geometry aside , a lot of the handling of the vehicle is dependent upon the consistency and quality of the bushings and their relationship both to the arms and the chassis .... I'm of the opinion that you can get a great driving vehicle with most any system if you do it completely and do it correctly.
Triangulation vs a 4 link/track bar vs 3 link/track bar is a more of a discussion of inherent bind. All three can have great and awful geometry for exactly the same reasons.
I'm also working towards something. But it requires understanding some concepts of suspension geometry.
This is getting deep...I like it. I'm going to have to go get a copy of Race Car Vehicle Dynamics by Carroll Shelby, and review it again. I knew some of this stuff back in the day, but haven't dealt with it in 20 years.
I've always wondered what folks were talking about when they asked how much separation one got with the arm mounts, and am starting to understand a few things. Not enough separation and your instant center gets too high.
Yes. Quite a technical thread. More than just you need “a” arm for lifts over “b” height for “c” performance
There’s so much more to understand and within good reason for following a thread like this
Before reading through this I would assumed that Long arm kits require out boarded shocks and extended wheel base simply because the narrow footprint of a Jeep wouldn’t safely support anything about about 5”
There’s so much more to understand and within good reason for following a thread like this
Before reading through this I would assumed that Long arm kits require out boarded shocks and extended wheel base simply because the narrow footprint of a Jeep wouldn’t safely support anything about about 5”
I'm tracking so far, and learning a lot more than I had known before all of this... This may be the best thread of the year.
Correct me if I'm wrong, but if the control arms were extended more, it would reduce the antisquat significantly... all relative to the length of the control arms being installed. No?
Not quite. Remember the imaginary lines that define the instant center? Simply making the arms longer won't change anything. If the goal is to move the instant center to the other side of the antisquat line, what could we do?
Here is a typical bolt on long arm setup. This is the type where the arms attach to a center skid. Typically, the frame side of these arms connect at the same point. This is done for ease of installation. No welding required. The antisquat is still in the 170s. The arms are a lot longer, but the geometry wasn't fixed. And now there are arms in the way where there weren't any before!? What was accomplished?
Last edited:
I figured if the control arms were extended and new mounts were welded on the frame to support the longer control arms, that would bring that instant center line down, closer to the purple antisquat line. Or in my mind, it looks like if you extended the wheelbase enough, you'd eventually bring the instant center down further.
It seems to me that the further up you go with the lift, the more of an angle you have with the control arms. That instant center line is relative to the angle of the control arm angle (from the way I'm looking at those images at least), so this is where I'm getting my thought process from.