How to measure dampening

[highfructose]

Is there a way to measure the dampening capacity of a suspension system?

Like how does our ahc compare to the dampening potential of the stock suspension? An aftermarket fox or king with remote reservoirs etc?

Are we in between them? Do we have more dampening than the aftermarket remote reservoir suspensions?

How does tire psi/volume of air in a tire…and sidewall stiffness/springiness fit in?

I’m not an engineer…just wondering whether there’s a way figure this kind of thing out…maybe it’s like total volume of fluid in the accumulators and shocks vs total volume of fluid in stock suspension or the aftermarket with remote reservoirs?

I’ve heard that the remote reservoir raptor suspension floating on 35’s is, ironically, an ultra luxury like ride…wondering whether going full floaty 34.5” tires on our rigs would sort of maximize that for our platform as well…or does our suspension coupled with some 32-33 psi passenger tires get to that same ultra luxury float.

Any engineers care to pontificate?

 

[linuxgod]

I have a buddy that has a raptor. Yes the suspension in 35s feels very compliant, almost car-like soaking up of bumps and washboards. It’s got quite a bit longer wheelbase though and that also helps

Lower tire PSI will make the ride feel more plush, but the trade offs will be handling (and if PSI is too low, eventually tire failure). If I’m spending a lot of time on washboards and off-road at lower speeds I’ll drop my tires from 38 to 25PSI (or less depending on speed) and it makes the ride much more plush, at the trade off of turning like I’m driving on giant gummy bears

If you want more plush than stock suspension then a well tuned progressive shock with remote resi would help. In practice the remote resi probably isn’t necessary TBH unless your goal is to really push the suspension on trails and bounding through the desert. C-load 35s or 37s might help a bit though bigger tires are heavier and come with their own compromises

 

[lx200inAR]

I don't think damping "capacity" is a thing. Or at least not the way you are trying to imagine it. The damping part is just fluid running through a valve at a controlled speed. Too much damping would be bad and too little damping would be bad. The idea is finding the sweet spot.

The reason people go to "fancier" shocks (as it pertains to damping) is to gain adjustability, so the damping can be configured to match the spring rate better. Also, you can then get into the outboard reservoirs which do better to control heat, becaause hot suspension oil will flow differently through the valves than cool oil. It's all about control more than it is about capacity.

As far as tires go, the raptor is a 35" tire on a 17" wheel. Sidewall is the key here. I can say going from stock LX wheels/tires to a 34" tire on 17" RW made a huge difference in my ability to control how stiff/soft my over all suspension felt based on modifying tire pressure. But changing tires is more about adding extra springiness, (undampened springiness at that), but the more volume of air there the more the tire can absorb without actually flinging the truck like a basketball. (i'm sure i'm muddling some of this concept)

I would say AHC lands somewhere in between. It has adjustibility, but the driver doesn't get to control the adjustabilty to an extent. The AHC ECU is doing all that. The driver can only change the 1 setting that gives the option between 3 different "curves" of damping that the ECU adjusts based on speed and direction. AHC has tons of fluid though, so heat is not really an issue in that system.

I'm not a mechanical engnieer, so maybe none of this makes sense, but that's how i understand it.

 

[turbo8]

You can use a shock dyno to get some data. You would need a full chassis one for the AHC system equipped vehicles. AHC equipped vehicles also output a lot of data that you can read using techstream.

 

[bloc]

A major factor in raptor suspension compliance is the amount of travel. Our cruisers are no slouch at 9 & 9.5" of travel front/rear.. for such a vehicle this travel with either KDSS bars or AHC doing similar allows for impressive articulation and stability off-road, mostly on slower trails.

But a raptor does 14 & 15.. that is a huge difference.

Now keep in mind the extra width and length of a raptor means those 50%+ higher numbers won't necessarily translate into hugely improved articulation, but when simply driving along and hitting a given size bump, you are using a much smaller percentage of the total available travel. It is going to feel much more plush and compliant. And, the width and length will allow it to maintain some stability despite these large travel numbers. Put the same suspension on something as short as our cruiser, and the dive under braking would be flat-out scary.

But to more directly answer your question, characterizing suspension is actually pretty complex. You have low medium and high speed damping, tire spring rate, wheel base, roll center and CoG.. and dozens if not more other factors. All on a vehicle engineered to be nearly impossible to roll onto it's lid by a stupid 15yr old.

All of it is a compromise. Stock suspension is very impressive for a stock vehicle. AHC takes this up a few notches, but introduces some complexity. For some of us, for varying reasons, kings make sense.. in my case it was the ability to buy parts and rebuild them in my garage. Others like BP51s and the internal bypass and dual adjustability. Others have learned their lesson with Icons falling apart on-trail (twice).

And, bigger is not necessarily better. I forget who posted that king told them their (awesome) 3" setup wouldn't work well for them, because the system needs the heat of being pushed hard to work correctly, and their intended use case wouldn't get them there.

So no, a 35" tire will not make our vehicles ride like a raptor. As @linuxgod points out you can gain some suppleness over smaller/sharper bumps by lowering tire pressure, but you can't run around like this on the street if you don't want to resemble that 15yr old. And a raptor is better at far more than just small/sharp bumps. You could consider a Tundra front end swap, maybe even some total chaos long travel parts.. but even then you will have trouble emulating what a raptor does, specifically because the raptor was designed to do it from the outset.

 

[bloc]

All of that said.. it seems like with the accelerometers and processing ability of a modern smart phone, we have the tools to learn some stuff with a decent app. But then I guess you'd need some kind of course to drive the vehicle through with given features and speeds to make it scientific..

 

[OregonLC]

Damping capacity from the perspective of force and rate are a function of the valving. Damping capacity from the perspective of endurance is a function of heat dissipation. You can have adequate road dampening from a small-diameter, non-reservoir shock but lose that capacity on the trail. This happens on my Power Wagon with stock Bilsteins in about 30 minutes. A 10,000 lbs truck will rapidly heat the shock to the point of being hot to the touch. The result is shock fade where the ability to dampen motion is dramatically reduced.

While I don't have an LX, my guess is the heat capacity is good. The system is essentially a giant remote reservoir system. When the shock body is full of fluid, rather than fluid + nitrogen, it has a better ability to manage heat. Perhaps not as much surface area as a 3" RR, it's still of good volume. And while the LX may not have a fine level of adjustment, any adjustment that is used is better than one that is not. I suspect most aftermarket adjustment systems end up being 'set and forget'.

From the perspective of comfort, it's the total suspension system working together. Tire pressure, spring rates, travel, and dampening. If you have 14" of travel you can absorb the hit over a longer period than with a system that has 8" of travel. This is a big part of what's going on with the Raptor. [Edit, looks like @bloc and I posted this at about the same time].

 

[TeCKis300]

Is there a way to measure the dampening capacity of a suspension system?

Like how does our ahc compare to the dampening potential of the stock suspension? An aftermarket fox or king with remote reservoirs etc?

Are we in between them? Do we have more dampening than the aftermarket remote reservoir suspensions?

How does tire psi/volume of air in a tire…and sidewall stiffness/springiness fit in?

I’m not an engineer…just wondering whether there’s a way figure this kind of thing out…maybe it’s like total volume of fluid in the accumulators and shocks vs total volume of fluid in stock suspension or the aftermarket with remote reservoirs?

I’ve heard that the remote reservoir raptor suspension floating on 35’s is, ironically, an ultra luxury like ride…wondering whether going full floaty 34.5” tires on our rigs would sort of maximize that for our platform as well…or does our suspension coupled with some 32-33 psi passenger tires get to that same ultra luxury float.

Any engineers care to pontificate?

One of my closest off-roading buddies is big into Raptors and we've been on more trips than I can count. His is particularly beastly with top shelf everything including King 3.0s and 37s. He often leads Raptor run groups here in the southwest where they like to do Raptor things running wild in the open desert. So maybe I can help compare.

I know you're trying to objectively quantify parameters, but damping is complex and not really possible to capture in single metrics. Especially in mixed use.

Dampening capacity - where high end shocks earn their keep is the ability to generate higher damping forces with the ability to perform and stay cool for longer periods at that higher level of use. Adjustability to suit build or conditions is another. Being able to tune is good, but for street, rock crawling, and other lower speed activities, won't generally tax the damping capacity of higher end systems.

AHC compared - AHC is well beyond most standard OEM suspension. It's dynamic nature. Wide bandwidth and the ability to actively engage higher levels of damping (16 steps). Remote valving that is not just remote reservoir, as it has true remote components and large surface area to absorb heat. I've run 30 miles in the desert at high speeds and the shocks are just warm. Most normal use has it barely over ambient, as confirmed by the AHC dashboard over OBD-II. Higher level active functions to manage and constantly tailor the overall system. The damping management is very active and you can see it over OBD-II. What this means is that not only does it have the damping faculty to perform, it is constantly adjusting and dialed for a wide span of uses and conditions.

Tire and pressure - Offroad, tires are a huge part of the suspension itself. Larger sidewall tires aired down to say 18 PSI (depends on tire size), and they'll basically absorb much of the small features in the road allowing the suspension to focus on the larger hits. Upgrading to big tires in and of itself is a huge upgrade to the suspension. 35s with AHC, running harsh corrugations at higher speeds, few things will touch the ride quality.

Including my buddies Raptor. We've ridden in each others trucks. Kids always with us and they easily prefer the LX for comfort and ride quality off-road and I often become the luxury off-road schoolbus.

Don't get me wrong, when the desert really opens up to drive 8/10ths and beyond, and expose vehicles to risks most wouldn't in unknown tracks, the Raptor by virtue of its huge suspension travel, longer wheelbase, can and does perform at a higher level. I've been continuing to build my LX however, adding suspension travel (11" F and R, from 9" F and 10" R), and my buddy is frankly shocked at the speeds it'll keep, and possibly envious for it's better all around capability. To the degree that when he was ready to replace his Raptor (reliability), he seriously considered the LX.

He replaced his 2016 Raptor with a 2022 Raptor and is currently building that. Interestingly, the newer Raptors switched to a 5-link rear suspension (like ours), from rear leafs, and is more accurate and rides better. The newer gen factory Fox Live Valve suspension are pretty dang good and I've encouraged him to keep that and put in a small lift. As he won't be going back to all the aftermarket stuff on his previous Raptor, because as fun as it was, it biased the truck too much for off-road. Something that AHC excels at because it is dynamic and biased tuning is not a thing. Frankly he said his top shelf Raptor wasn't great around town, with ride compromises and tows poorly. Some of this was due to more extreme offsets. Some due to biased tuning including firmer spring rates. He almost wants to leave his new Raptor stock. Then again, after our last few runs, his stock Raptor is not keeping up with the LX when it comes to clearance and all around capability so he at a minimum needs to lift some.

TL;DR - Slap 35s on the LX and enjoy.

Raptor getting saved by the LX.

 

[OregonLC]

This discussion would be remiss to not mention valving progression. My guess would be that the AHC is linear while the Kings on the Raptor are probably on the progressive scale allowing those big flows over moderate hits. That seems to correspond with the description above of poor behavior in-town or when towing.

I could probably search for it, but can anyone confirm the shape of the AHC damping curve? And I'm probably in error on this, but does the AHC setting just offset the curve up and down the scale or does it change the shape of the damping curve as it moves from soft to firm? We Land Cruiser pilots are luddites with things AHC.

 

[TeCKis300]

This discussion would be remiss to not mention valving progression. My guess would be that the AHC is linear while the Kings on the Raptor are probably on the progressive scale allowing those big flows over moderate hits. That seems to correspond with the description above of poor behavior in-town or when towing.

I could probably search for it, but can anyone confirm the shape of the AHC damping curve? And I'm probably in error on this, but does the AHC setting just offset the curve up and down the scale or does it change the shape of the damping curve as it moves from soft to firm? We Land Cruiser pilots are luddites with things AHC.

AHC damping curve is algorithm based. That is to say it's neither progressive nor linear, as it has many software maps (for control of the various functions in the table above) for strategies to best control suspension and body motions for use at hand.

 

[lx200inAR]

This discussion would be remiss to not mention valving progression. My guess would be that the AHC is linear while the Kings on the Raptor are probably on the progressive scale allowing those big flows over moderate hits. That seems to correspond with the description above of poor behavior in-town or when towing.

I could probably search for it, but can anyone confirm the shape of the AHC damping curve? And I'm probably in error on this, but does the AHC setting just offset the curve up and down the scale or does it change the shape of the damping curve as it moves from soft to firm? We Land Cruiser pilots are luddites with things AHC.

The system definitely isn’t a sliding scale. In fact.. driving in a strait line the damping is almost the same between Comfort and Normal, and a little “stiffer” in sport, but during dynamic maneuvers the damping varies more greatly depending on mode.

 

[Maxwell]

Damping not dampening.
0) Do what most folks do and just go by feel. Ultimately that is what you will likely be trying to achieve through any adjustments you make. If it feels good, it's good.
1) The fastest, cheapest, easiest is to use a GoPro to film your suspension in action.
2) The next option is some sort of data acquisition product such as Motion Instruments although I don't know if any such product exist specifically for trucks as they are typically only used in situation where your dampers/springs support rapid and frequent adjustments.
3) If you take the dampers/shock off your vehicle you can have them "dyno" tested. Basically they run through a bunch of cycles of varying speed, frequency and power to produce a plot of your dampers performance ...this is probably only useful if you have a large database of similar vehicles operating on similar terrain to which you can compare your settings.
4) Buy a system that attempts to make adjustments for you on the fly such as Fox Live Value(?). Expensive and not even sure it is available for the LC200

I've done all 5 on bikes and if there is one thing I have learned ...there is not a perfect setting, so every spring/damper setting is a compromise between comfort, speed and traction.

 

[TeCKis300]

I’ve heard that the remote reservoir raptor suspension floating on 35’s is, ironically, an ultra luxury like ride…wondering whether going full floaty 34.5” tires on our rigs would sort of maximize that for our platform as well…or does our suspension coupled with some 32-33 psi passenger tires get to that same ultra luxury float.

Pulled a video from my archive. 35s, normal AHC height, sensor lifted by .75", ~1000lbs of camping gear, water, fuel

 

[linuxgod]

You really need to slap it on the fender behind the front wheel so you can see close up how much the wheel moves but not the body. Somewhere I've seen a video of that and it's hella-impressive

 

[TeCKis300]

You really need to slap it on the fender behind the front wheel so you can see close up how much the wheel moves but not the body. Somewhere I've seen a video of that and it's hella-impressive

Yeah, would be neat to get one of those suction cup mounts.