JL vs JK - factory vs AEV suspension differences

I don't know the free lengths of JK and JL coils, but I do know that the JL has longer shock travel than the JK. This suggests that the JL springs might be longer (and maybe a softer rate) than the JK.

This gets into the messy debates about spring rates effecting ride quality. AEV mentions frequency tuned triple rate coils to go with their shocks.

While I think AEV has moments of interesting design and engineering, I tend to think they are also a luxury image brand with heavy marketing where some things should be looked at with critical suspicion. Basing their JL shock on the 5100 is a bit of a red flag and bolt on geometry corrections can only go so far.

I know what I like in the TJ world. I don't know what a JK equivalent looks like and know less for the JL. But I doubt AEV is it based on their description that also emphasises LCoG.
 
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@jjvw I too scratched my head when I read that bit about "frequency tuned" coils. Have no idea what that means. And why triple rate? A (crude, linear) approximation of progressive rate? So many questions.

The part about stiff springs and soft shocks and vice versa was interesting. One day perhaps I'll understand all this properly.
 
psrivats said:
@jjvw...

The part about stiff springs and soft shocks and vice versa was interesting. One day perhaps I'll understand all this properly.
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I haven't ridden in a JL yet and have had very little time in a JK. But since they are very different vehicles, I have a difficult time believing one can make meaningful comparisons like that between the two. Too many things are different.
 
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jjvw said:
While I think AEV has moments of interesting design and engineering, I tend to think they are also a luxury image brand with heavy marketing where some things should be looked at with critical suspicion.
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I could not put it any better myself. They are extremely good at marketing, my opinion on AEV has changed greatly since joining this forum and hearing from people who have actual experience with their products.
 
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A. Paul said:
I could not put it any better myself. They are extremely good at marketing, my opinion on AEV has changed greatly since joining this forum and hearing from people who have actual experience with their products.
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I agree with this as well.

I used to think AEV was top notch in terms of designing products that worked well, but I don't think that anymore. Nowadays I just look at AEV as being very, very good at marketing, and happening to have a cult following of people who will pay stupid amounts just for the name.

That's not to say they don't make anything nice. Their spare tire carrier for the JK is a very awesome design that works really, really well, and looks factory too.
 
Chris said:
I agree with this as well.

I used to think AEV was top notch in terms of designing products that worked well, but I don't think that anymore. Nowadays I just look at AEV as being very, very good at marketing, and happening to have a cult following of people who will pay stupid amounts just for the name.

That's not to say they don't make anything nice. Their spare tire carrier for the JK is a very awesome design that works really, really well, and looks factory too.
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How was the AEV jk 2.5” suspension you ran on your JK you had? Thought you loved it?
 
AEV is just like any other company, of course they have good marketing. The ones that didn't have good marketing have gone out of business. But the engineers and marketing team don't always speak the same language. I have no idea how a triple rate frequency tuned coil works or how one can tune a non-bypass shock to something that has three different spring rates. But other companies use the same technology and have their own buzz words. In the world of JL's the big players are Metalcloak, AEV, Teraflex, Evo, Rancho etc. I rarely see savvy even mentioned on the long list. Most of these companies offer bolt-on products with little to no fabrication or welding required.
 
psrivats said:
@jjvw I too scratched my head when I read that bit about "frequency tuned" coils. Have no idea what that means. ..
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As I recal, 'Frequency Tuned" was something that dates back to when Jim Frens designed the original Nth degree springs for the TJ/LJ. i don't remember the details, but it has to do with the frequency response between the front of the Jeep and the rear of the Jeep. The idea is to dial in the spring/shock combo between the front and the rear of the vehicle so when you hit a dip or big bump the front and the rear of the vehicle settle back into normal ride height at the same time. This takes into consideration the vehicles wheelbase as well as weight distribution. Some people might not notice the difference. Others, like me, will be driven nuts by a vehicle where the rear end doesn't settle in as quickly as the front or vise versa.

I have a good friend who used to have a JKUR with the AEV system and recently traded it in for a JLUR. I always thought that JK was the best handling Jeep I had ever driven or ridden in. Its an over used expression, but I really thought it was better than stock. My friend says he likes his JL better. He says the linear rate springs feel more, ahhh linear. He thought in some cornering situations the AEV springs felt too soft and it was noticeable when they hit the firmer rate. However, he never mentioned that issue until his AEV shocks had nearly 100,000 miles on them. So its not really fair to compare AEV shocks with 100,000 vs brand new JL setup.

Anyway, for me, I am a huge fan of AEV. If I ever get a JK I will put an AEV suspension under it. I don't even need to think about it. Nothing else comes close as far as I have experienced. (Which is admittedly limited.) However, the JLUR is a little diffent. Because it can run 35's on stock suspension, I'm not sure I would want a 2.5" lift. I would be very tempted to just throw on some 1" pucks to gain a little better breakover and call it good.

Now, the whole argument about a soft spring and stiff shock vs a stiff spring with soft shock is an interesting discussion to have. A soft spring with stiffer shock might give more options for tuning the ride via shock absorbers because the springs aren't the limiting factor for a soft ride. However, if your going to carry a load those soft springs will suck and you will be wishing you had a stiffer spring with a softer shock. Thats only the compression side of the equation. The rebound, which I think is arguably more important in how a vehicle feels will also be greatly affected by the spring/shock combo. I don't have the knowledge to really give an analysis of the differences, but I could sure speculate how they might behave. It would have been very interesting to listen to the Jeep engineers or even AEV engineers (who I believe consult with Jim Frens, a former Jeep engineer) weighing the pros and cons of these options.
 
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astjp2 said:
I have a set of jlur shocks in the garage, they were about an inch longer than the jkur shocks I put on the lj
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To bad you couldn't use the JL shocks. I understand they use some sort of adaptive valving. I forget how it works, but it sounded interesting.
 
It would require custom fabricated mounts, upper and lower, front and rear.
 
Fargo said:
As I recal, 'Frequency Tuned" was something that dates back to when Jim Frens designed the original Nth degree springs for the TJ/LJ. i don't remember the details, but it has to do with the frequency response between the front of the Jeep and the rear of the Jeep. The idea is to dial in the spring/shock combo between the front and the rear of the vehicle so when you hit a dip or big bump the front and the rear of the vehicle settle back into normal ride height at the same time. This takes into consideration the vehicles wheelbase as well as weight distribution. Some people might not notice the difference. Others, like me, will be driven nuts by a vehicle where the rear end doesn't settle in as quickly as the front or vise versa.
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After reading this, I started getting interested in suspension frequency. Every time I think I'm getting a grasp on how this stuff works, I find another layer I never considered. Even our "simple" 5 link solid axle systems are incredibly complex. If you are interested in this kinda stuff, google "ride frequency". I can say that when playing around with spring rates, I put a firm set of springs on the front and a soft set on the rear, and while certain bumps became softer and less jarring, the overall quality of my ride decreased in ways I'm still trying to understand.
 
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overit said:
aev is overrated slightly better then bds imo , you get what you pay for
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Depends on what you are looking for. If you want a hard core offroad rig, there are better options out there. But if you are looking into overlanding, you won't find anyone else who is specifically looking at the needs for overlanding. You won't find anyone else doing the research to improve the on-road handling charcteristics at the same time they improve the offroad capability. Things like the vehicles roll center, anti-dive during braking, as well as as the ability to carry more weight and/or varying weight loads while still maintaining a proper handling vehicle are only considered by AEV. There is no one else that I am aware of that considers the above mentioned design criteria when developing their suspension. These are the things that make the AEV suspension superior on-road while at the same time improving offroad capability.

I think the fact that Jeep adopted the AEV JK suspension design when they designed the new JL, speaks volumes about how good of a job AEV did with the JK suspension.

My only frustration with AEV is that they only support the current model vehicle. By the time I can afford a JK they will no longer be selling JK components.

FYI - My comments above are based on my experience with a friends AEV lifted JKUR and his new JLUR. I do not own any AEV products.
 
Back in the days when I was dodging dinosaurs to get to my Engineering Statics and Dynamics classes, I remember doing the spring damper problems. Maybe it was my Kinematics class, I can't remember. Complicated is somewhat of an understatement even given the fact I was only doing simplified dynamics problems.

Now they have computers to simulate motion and do all those hand calculations faster. They tore down the building I took classes in and built a new one because it was too old, so needless to say, it's been a while. I'd have look for an online dynamics simulator to play around with it.

It works sorta like this but both ends are free instead of one end being fixed. Two masses tied together with a spring and damper is more complicated.

http://techteach.no/simview/mass_spring_damper/index.php

And having varying spring constants based on length as well as varying damping really complicates everything and multiply by 4 times the complexity since you have 4 sort of tied together wheels that all are probably moving different directions at the same time.

What the driver feels for ride can easily be different then what the passenger feels, and ride may be affected by shifting center of gravity due to other seemingly minor modifications; like a front and rear bumper, winch, larger spare, etc. etc. etc.
 
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