AEV suspension discussion thread

[UglyViking]

After many conversations in numerous other threads I figured this topic was worthy of it's own thread.

[ Request ] I know that topics of one persons favorite or most hated brand can often become heated, and furthermore people will believe that because Company A does X well they must also do Y well, or because Company B only does X they must do it better than Company A, so on. Note that everyone will have different needs, different views on what "best" is, different finances, etc. it will be impossible for any single company to do everything that fits your needs or wants. Don't get trapped in a defensive argument based off nothing more than personal preference. Finally, let's do our best to at least make an attempt to describe why something is better or worse than something else.

Initial comment
Ok, so to kick us off. I've had numerous discussions on the topic of AEVs suspension in this forum and others. To speak frankly, I think that the primary thing that AEV does well with their suspensions is to maintain factory geometry as much as possible. I also think they cut no corners in their attempt to create what they feel is the best suspension option for their defined use case. I also absolutely love their OEM+ look. Their stamped steel bumper, their snorkel, their flares, their wheels all absolute hits in my eyes.

The thing I find odd with how AEV designed their Ram HD suspension is by doing a spacer lift. If you look at AEVs history of suspension designs, it's all coils as part of their suspension replacements. They have softer and stiffer coils depending on the needs of the end user, but coils are included in every kit from the JK, JL and Gladiator kits. However, they have completely ignored coils with their Ram HD kit. It took me a long time to realize but it wasn't until I listened to this podcast that @ramblinChet shared, then went back and looked at their suspension kits that I realized why they went the route they did, and I now believe it was 100% an OEM and payload decision.

AEV works very closely with FCA and GM, which I think has a pretty big part to play in why they are utilizing the factory springs (purely for payload and legal reasons). Furthermore, if you compare the Jeep suspension systems you can see they skew towards users who want to overload their vehicles. I think that reason is the primary reason that AEV went the direction they did, and it boils to legal and OEM.

Now, compare AEVs setup with something like a Carli or Thuren suspension setup. Both companies make suspension systems primarily for users who's trucks are empty, and who want to bomb it down open stretches in the desert or rock crawl MOAB. I would find it surprising if anyone wants to argue that the AEV suspension setup is a "better" system for anyone but getting a few inches of lift while maintaining factory payload numbers. If you are looking for increased travel, or a softer ride then the AEV setup is not for you.

So, without making any comparisons between the AEV suspension setup and those from Carli or Thuren I'm going to instead ask why all the additional work involved with the AEV suspension? What makes their system better than a simple spacer lift? I get all the changes they make to get the factory geometry back into line, but is that even necessary for the amount of lift they are trying to achieve? Furthermore, why even lift for the prospector truck? If the goal is to simply clear 37s, you can do that with the correct offset wheel and some very minor trimming. I'd argue that the truck would perform better by simply switching wheels and tires rather than adding the AEV suspension if your plan is to keep 37s.

I at least understand the argument for the prospector XL, in order to clear fenders and all that they raise and move forward the axle. Ok, sure makes sense. Is it necessary? I mean they are the OEM+ brand, so "yes" is probably the answer, but I still don't understand why they wouldn't simply change out coils, certainly they would have been able to get ones rated for the max payload and gone from there? It would have been a far simpler system to install that's for sure. Perhaps they got too carried away with the "this is what the Icelanders do" and just copied the design without exploring alternative options?

In the end, having ridden in multiple AEV equipped rams, and in a few Thuren equipped Rams, and stock and spacer lift, I don't know that most people would notice a huge difference between the AEV suspension and a spacer lift. To be honest, I don't think most people are sensitive enough to notice most of the little details about how their truck rides, so there is that.

I'm curious what others think about the suspension design AEV choose for their HD platform. It seems to be, according to AEV, very misunderstood. To be honest, I think the majority of guys that have bought into the AEV suspension design aren't doing much beyond mall crawling and camp sites anyway, and I see very few guys using their trucks in any way that necessitates anything near 37-40" tires or a winch, but it's cool and if you've got the cash why not, who am I to judge how anyone spends their money. I'm sure that most Carli equipped trucks haven't ever seen anything but pavement also, so no brand is immune.

Anyway, what does everyone think? What am I missing? What made you choose your setup? When will someone release a power wagon winch conversion for the cummins trucks? These are the questions I've got (I'm not holding out for the last one until someone figures out a non mounted winch option that doesn't have me manually wrenching a hi-lift…)

 

[Trail_Wagon]

Spacer lifts are often looked down upon. I think people put way too much stock in the "full lift" concept of changing springs. A spring has a very simple job, it just needs to hold up the vehicles weight. If you increase or decrease that weight you will need to change the spring to compensate. Past that, there are two considerations. The spring needs to be short enough when fully compressed that the coils don't bind or bunch up. It also needs to be long enough that the spring doesn't fall out when the suspension is unloaded. As long as those criteria are met, there is no reason to change to a "better" coil.

This next part is hard. Its nearly impossible to get people to accept this, but springs have very little to do with ride quality. A 10-20% change in spring rate will have no impact on ride that you can feel. Shocks are responsible for how a car, truck, train or bus handle bumps. This is knowledge earned though piles of old coil springs and shocks.

 

[Crusty old shellback]

Here's my take.
Using a spacer to lift a vehicle will do just that, only lift it the distance of the spacer. Nothing else changes with ride quality, load carrying, or suspension travel.

But if you use a good quality of lift spring, you accomplish a lot more besides lifting the vehicle.
1. You can increase the suspension travel.
2. You can change the ride quality to stiffer or softer.
3. You can change the load carrying capacity.

You dont see lift spacers or blocks on vehicles built for certain performance/handling/capabilities.

If you are just street driving and occasional driving down a dirt road, then yes, a spacer is probably fine. But if you are going to use the vehicle for more than that, then use the right suspension parts.
Shocks and springs work as a package deal

 

[Trail_Wagon]

Here's my take.
Using a spacer to lift a vehicle will do just that, only lift it the distance of the spacer. Nothing else changes with ride quality, load carrying, or suspension travel.

But if you use a good quality of lift spring, you accomplish a lot more besides lifting the vehicle.
1. You can increase the suspension travel.
2. You can change the ride quality to stiffer or softer.
3. You can change the load carrying capacity.

You dont see lift spacers or blocks on vehicles built for certain performance/handling/capabilities.

If you are just street driving and occasional driving down a dirt road, then yes, a spacer is probably fine. But if you are going to use the vehicle for more than that, then use the right suspension parts.
Shocks and springs work as a package deal

How do springs increase suspension travel?

 

[Crusty old shellback]

By the way they are built.

This is leaf springs, but the same concept applies to coil springs
I had a '85 K5 and a '73 K5.
Basically same trucks, just different suspensions. The K5 didnt really change fro. '73 to '90
The '85 had stock springs. 2 leaf reverse bend in front, 4 leaves in the rear.
'73 had Deaver springs and King shocks.
12 leaves in front, 14 in rear. But the leaves were thinner than the '85s
The '85 had maybe 4 inches of travel and 35" tires.
The '73 had 12" front/18" rear travel and 35" tires. The '73 had maybe 4" of lift.
The '73 rode better on road than the '85. And you could "bomb" it off road at 70MPH and even jump it. Even with gear packed in it.

It has a lot to do with the springs.
Even on my Yamaha 450 quad. Stock coil over shocks have 1 spring. Aftermarket coil covers have 3 springs on the shock, each one is a different rate.
That's why I say for a daily driver that only sees fire roads on occasion, then yes, a lift spacer is probably ok. Anything more and you want a good spring.

 

[UglyViking]

How do springs increase suspension travel?

If you look at an OEM coil vs a Thuren coil for example, you'd be amazed at the difference in height. Their +1" rear coil for example is probably 3+" taller than the OEM coil. That additional height means you can get a lot more extension out of it before you risk the coil popping out.

 

[Trail_Wagon]

By the way they are built.

This is leaf springs, but the same concept applies to coil springs
I had a '85 K5 and a '73 K5.
Basically same trucks, just different suspensions. The K5 didnt really change fro. '73 to '90
The '85 had stock springs. 2 leaf reverse bend in front, 4 leaves in the rear.
'73 had Deaver springs and King shocks.
12 leaves in front, 14 in rear. But the leaves were thinner than the '85s
The '85 had maybe 4 inches of travel and 35" tires.
The '73 had 12" front/18" rear travel and 35" tires. The '73 had maybe 4" of lift.
The '73 rode better on road than the '85. And you could "bomb" it off road at 70MPH and even jump it. Even with gear packed in it.

It has a lot to do with the springs.
Even on my Yamaha 450 quad. Stock coil over shocks have 1 spring. Aftermarket coil covers have 3 springs on the shock, each one is a different rate.
That's why I say for a daily driver that only sees fire roads on occasion, then yes, a lift spacer is probably ok. Anything more and you want a good spring.

The shock is the determining factor for suspension travel.
Shocks have a compressed and extended length. Lets use an off the shelf fox remote reservoir. 19" fully compressed and 31" Fully extended. So 12" of travel. Nothing the spring does can make the shock shorter than 19" or longer than 31". The travel is locked in by shock length.

 

[Rockcrawlindude]

If you look at an OEM coil vs a Thuren coil for example, you'd be amazed at the difference in height. Their +1" rear coil for example is probably 3+" taller than the OEM coil. That additional height means you can get a lot more extension out of it before you risk the coil popping out.

Correct. You need much longer shocks to run thuren rear coils. You can “unlock” more suspension travel with new springs.

But, there are always trade offs. You simply cannot make one aspect of a vehicle better without sacrificing something else.

 

[Rockcrawlindude]

The shock is the determining factor for suspension travel.
Shocks have a compressed and extended length. Lets use an off the shelf fox remote reservoir. 19" fully compressed and 31" Fully extended. So 12" of travel. Nothing the spring does can make the shock shorter than 19" or longer than 31". The travel is locked in by shock length.

There is always a limiting factor for suspension travel. You’re always going to run out of something if you start making other components longer. Could be spring, could be shock, could be brake line, eventually it’ll be driveshaft. That’s why people run limit straps

 

[UglyViking]

Correct. You need much longer shocks to run thuren rear coils. You can “unlock” more suspension travel with new springs.

But, there are always trade offs. You simply cannot make one aspect of a vehicle better without sacrificing something else.

Agreed, and I think I may have claimed such at the first post that everyone has different needs and desires for their truck and so on. There is a reason that a truck designed to tow rides stiff and a trophy truck rides soft. Different goals.

 

[Crusty old shellback]

The shock is the determining factor for suspension travel.
Shocks have a compressed and extended length. Lets use an off the shelf fox remote reservoir. 19" fully compressed and 31" Fully extended. So 12" of travel. Nothing the spring does can make the shock shorter than 19" or longer than 31". The travel is locked in by shock length.

But if the spring will not compress or stretch to those lengths, then the shock does not matter.
It's a package deal.
And you never want to bottom out or fully compress you shocks except on a occasional extreme condition, not on a regular basis.

When I was talking with Carli about a suspension setup for my Power Wagon and not really wanting to lift it any, their recommendation was to use their 1" lift front coils, but keep my stock rear springs because they gave a better ride than their springs. And they would tune their King shocks to match the spring rates of the springs.

 

[Trail_Wagon]

But if the spring will not compress or stretch to those lengths, then the shock does not matter.
It's a package deal.
And you never want to bottom out or fully compress you shocks except on a occasional extreme condition, not on a regular basis.

When I was talking with Carli about a suspension setup for my Power Wagon and not really wanting to lift it any, their recommendation was to use their 1" lift front coils, but keep my stock rear springs because they gave a better ride than their springs. And they would tune their King shocks to match the spring rates of the springs.

I thought we were talking about coil springs. leaf springs will limit down travel. coil springs just fall out if your extended shock length is too long.

 

[Trail_Wagon]

There is always a limiting factor for suspension travel. You’re always going to run out of something if you start making other components longer. Could be spring, could be shock, could be brake line, eventually it’ll be driveshaft. That’s why people run limit straps

In these application, its usually the shocks, The highly modified crawlers that we are used to are exceptions. You would need a very very very long travel trailing arm rear suspension to bind the driveshaft on a truck this long. Not saying its not possible.

 

[Crusty old shellback]

Uglyviking
"Furthermore, why even lift for the prospector truck? If the goal is to simply clear 37s, you can do that with the correct offset wheel and some very minor trimming. I'd argue that the truck would perform better by simply switching wheels and tires rather than adding the AEV suspension if your plan is to keep 37s."

Their goal in lifting to clear 37s may have been that they didnt want to change rim offset and move the tire out from under the fender covering.
In a lot of states, if the tire sticks out past the fender, then you have to have big mud flaps to cover it, that's to protect others from rocks and such the tires throw up
And then there are people like me who dont like the look of their tires sticking out like that.
If you are doing it to widen the track, then also widen the fenders like the Raptor and TRX did.

 

[Crusty old shellback]

In these application, its usually the shocks, The highly modified crawlers that we are used to are exceptions. You would need a very very very long travel trailing arm rear suspension to bind the driveshaft on a truck this long. Not saying its not possible.

Purpose built off road trucks are running up to 30 inches of rear travel. Just saying.

 

[Trail_Wagon]

Purpose built off road trucks are running up to 30 inches of rear travel. Just saying.

"You would need a very very very long travel trailing arm rear suspension to bind the driveshaft on a truck this long. Not saying its not possible."

 

[Crusty old shellback]

I thought we were talking about coil springs. leaf springs will limit down travel. coil springs just fall out if your extended shock length is too long.

If the coil spring is not built correctly and matched to the shock, then it can go into coil bind way before the shock is fully compressed.
And you use limit straps to keep the shock from topping out before the coil spring is full extended.

 

[Trail_Wagon]

If the coil spring is not built correctly and matched to the shock, then it can go into coil bind way before the shock is fully compressed.
And you use limit straps to keep the shock from topping out before the coil spring is full extended.

Totally agree, but it would take a very poorly designed spring. Per Carlie, the factory PW rear coils can handle 11" of travel that comes on their pintops. Coil bind wouldn't be an issue.

But for the sake of argument, Yes, its possible to design a coil spring so badly it can limit suspension travel more than the shocks. It makes me think of the metalcloak rear springs for a TJ. They were so long compressed that you needed something stupid like 4" of bumpstop extension to stop them from binding.

 

[Trail_Wagon]

I also think this is a perfect opportunity to share this informative video where Dave does a great job explaining details associated with the AEV suspension upgrade:

Great vid. I've actually never looked that closely at the AEV stuff for the RAMs, but they did some clever things.

 

[Rockcrawlindude]

In these application, its usually the shocks, The highly modified crawlers that we are used to are exceptions. You would need a very very very long travel trailing arm rear suspension to bind the driveshaft on a truck this long. Not saying its not possible.

Oh yes. I was just saying we can’t just upgrade one part and expect more travel.

I built a leaf sprung crawler out of junk yard leaf springs and it would droop enough to pull the slip splines out of the driveshaft on the trail. It gets very expensive to have long slip spline driveshafts made. Of course, linked/coil suspension follows a very different arc through its range of motion.