90mm vs 100mm shocks

[TacoCrawler]

^ links purdy much sum up what I was trying to explain.


Tho' the explanation of compression fails to mention some minor detail.

Considering droop...
the drive shaft (universal) angle is critical for it's full drop potential...
and is what will limit max droop.

A similar rule can be noted regarding compression...
as there are some components that will demand compression limitation.

ie:

Besides the drive shaft alignment and body/wheel wells causing tire compression interference...
if the rig is leaf sprung those too can become a limiting factor.

reason being...
the leaf springs do not survive long when inverted past flat, constantly.

So if leaf sprung...
the leaf pak(s) compression deflection need be considered.

Coil Springs will also settle...
but they do not invert like a leaf spring might.
So generally speaking...
a coil spring should survive longer then a leaf spring might.
But gravity and constant compression forces will still wear them out.

My leaf springs on my Tacoma axle becomes slightly inverted when compressed fully.
Yes it's hard on my leaf pak(s)
but the trade off is worth it IMO.

The leaf paks on my 1:1 are not the originals
but custom built 9 lf progressive high flex springs.
Deaver is the mfgr if that rings a bell with anyone.

Some folk add taller bump stops to limit that leaf inversion.
But I do not
I prefer the maximum allowable compression.

When a leaf spring gets tired... (settles flat)
simply rebuild, re-arch and go do it again ;-)

btw... gravity is a bitch...
and even if you never drove yer rig...
In a matter of time... the vehicle's weight
would cause the springs to settle some.

Wheeling and flexing those springs hard...
just makes it happen quicker ;-)

My RC crawler sits on a stand when not in use...
that ignores gravity... and insures the tires don't get flat spots.

I think those links you posted
should help you and anyone else whom cares
to garner a better understanding regarding.

I should have googled those for you
instead of using my own words in explanation

 

[DowntownScience]

For those of you that would like to read right here. This first article is actually for 1:1's but all of the information is still very relevant to what we're trying to do on the rocks with our crawlers.

Do Your Wheels Hang Low? Compression vs. Droop for Rock Crawling - Auto Trends Magazine


Do Your Wheels Hang Low? Compression vs. Droop for Rock Crawling

There are countless ways to customize a 4×4: lifts, tires, shocks, light bars, armor – and that isn’t even touching on what you can do under the hood. With many modifications, a cursory Google search will turn up some ideas on the best build for a specific type of wheeling. This is not the case with the argument of compression vs. droop — not even close.
This is despite how important droop and compression are in any off-roading vehicle. As Dylan Peterson, content specialist at 4 Wheel Parts puts it, “Proper droop and compression ratio is just as important to a 4×4’s setup as lift height and tire size, but it’s usually just an afterthought once those parts are already installed.”
Every forum member has a different idea of what the best compression and droop ratios are and half of their opinions consist of “Well, it depends.” It is important to know that neither compression nor droop are the “most” important for wheeling: the truly optimal ratio would be 50-50.
However, a true 50-50 compression to droop ratio is virtually unachievable. Instead, for rock crawling, a 60 percent compression to 40 percent droop ratio is the number to aim for. Based on personal preference, there is plenty of wiggle room, of course. Generally speaking though, a crawler wants more compression than droop. Here’s why.

Compression, a/k/a “Stuff”
Compression, or how far up a wheel can be “stuffed” into the wells, is not only important for smooth riding, but also vital for an even distribution of weight.
Consider a Jeep JK attempting to crawl over a large rock, left front tire on the rock, right front tire on the ground. Having 60 percent compression means the body of the JK will remain almost straight while the axle tilts, stuffing the left front tire into the wheel well. This insures the JK’s center of balance remains stable, decreasing the likelihood of a roll or flop.
A high percentage of compression also means maximum traction while wheeling. If a wheel droops down, while it may be able to reach the ground, it may not be able to gain any traction because of uneven weight distribution.
Mike Finch, content specialist for 4 Wheel Parts says, “A stuffed tire has more traction than a drooped tire. By the nature of a vehicle, it takes a lot of psi to force a tire up into the well. That force is transferred into the traction patch. Any time you droop a tire away from the rig, you lose psi on the traction patch.”
With plenty of compression, all four tires are more likely to stay on the ground with the weight of the vehicle evenly distributed amongst them. Even if a tire were to lift from the ground due to extremely uneven terrain, with a good set of lockers (or even using the emergency brake to force the free wheel to stop), there will still be enough weight distributed amongst the other three to pull the vehicle forward.
Without the right exterior accessories, a high compression ratio does mean too much upward motion would mash bits together, bend metal and rapidly wear down parts. However, there are aftermarket accessories to prevent damage like this, such as bump stops, which work very well to protect precious parts.
Aftermarket fenders and a small to medium lift kit also serve to increase the amount of upward travel available to a 4×4, while a high percentage of compression decreases the likelihood of jamming an axle against the bump stops and losing control.
Additional benefits of a high compression ratio include a smoother ride and a decreased likelihood of bending or breaking an axle on whoops, drops and other obstacles.

Droop
Droop is downward motion – how far the suspension will allow a wheel to reach down below a vehicle, and it’s important for reaching into dips or crevices and maximizing axle tilt.
Without enough droop, the axle does not have enough room to move and the obstacles a 4×4 can take on will be severely limited. Without droop, a 4×4 wouldn’t be able to climb onto an obstacle on one side and keep its wheels on the ground on the other – they just wouldn’t be able to reach.
Without droop, the axle would compress excessively, sacrificing ground clearance.
Consider the same Jeep JK as before, crawling over the same rock. Without sufficient droop, as the left wheel climbed the rock, the right would be very quick to lift entirely off the ground. Even on relatively flat terrain, if the JK went through a dip or crevice on one side, not having enough droop would mean leaving at least one tire to dangle in space.
Droop helps with crawling obstacles and managing rough terrain. It increases a 4×4’s reach, so that at extreme angles of terrain the body can remain relatively level. However, droop in and of itself is not enough, just like compression would not be much use alone.

60-40
With too much droop over compression, a 4×4’s center of gravity climbs as the wheels climb, putting it at risk of a roll. Weight will not be evenly distributed, disrupting traction, and every bump and hiccup in the trail would be jarring.
“The farther up your axle can travel without disturbing the weight patch of the tire on the low side, the more stable your Jeep or truck will be and the more flex you can get before pushing the center of gravity of the rig higher,” says Finch.
With too much compression over droop, the vehicle’s reach would be severely compromised, meaning wheels may not be able to reach the ground on rough terrain and ground clearance would be sacrificed with every obstacle.
A rock crawler needs to be able to make the most out of the amount of static travel its axle has. A 60-40 compression-to-droop ratio does exactly that by ensuring weight remains evenly distributed and the greatest amount of traction is achieved. This ratio decreases the likelihood of a roll, makes for a smoother ride which is less likely to damage parts, maintains good ground clearance and increases driving control.

The Gist
Lowering compression to less than 50 percent of total travel sacrifices traction and evens weight distribution. It would be the equivalent of someone trying to walk down the stairs while only being able to bend their knees part of the way. It would make him uncomfortable, put him off balance and more likely cause this individual to go tumbling down the more his range of motion was limited. No matter how far his other leg might be stretched to reach the step below, he would be hindered by not being able to bend his knees completely.
Having less than 40 percent droop means sacrificing tire reach. Like someone walking down the stairs while only being able to extend their legs halfway, hopping step to step. They are only one wrong hop away from slipping and sliding down the steps on to their backsides because no matter how far their knees can bend, they cannot reach the next step with their other leg only partially outstretched.
Droop and compression work in tandem and optimally in equal amounts. However, not living in a perfect world means 60 percent compression, 40 percent droop is the most realistic way to maximize static motion and crawl the rocks like a pro.

 

[TacoCrawler]

now you need search shock valving - fluid viscosity to complete your understanding.

 

[DowntownScience]

Ok...just looked for some more information on droop and I definitely wasn't understanding it properly.

I wasn't aware of the main concept which is to keep the shocks closed using internal springs which are under the piston.

That changes things a bit. Still wrapping head around concept.

So then do you need special shocks for this or can you use a traditional adjustable coil over with a thin spring in side?

Still not understanding the benefits of this full droop setup with the spring under the piston and no compression. From what I'm reading the whole point of droop is to allow for the shock to extend from ride height when needed over an obstacle. This setup is actually making it harder for that to happen. Without compression the weight of the truck is going to push the piston into that position anyway so why the spring? Might as well just connect a link up to your shock tower. :ror:

 

[TacoCrawler]

This setup is actually making it harder for that to happen. Without compression the weight of the truck is going to push the piston into that position anyway so why the spring? Might as well just connect a link up to your shock tower. :ror:

IMO there are a lot of things posted here that aren't right...
that's probably one of them.

Converting your shocks to a pogo stick isn't really helpful IMO

But I have seen where others added a spring internally to their shocks
in support of excessively soft leaf springs.

Still not the right fix... but not my problem.

 

[DowntownScience]

Here is the other link for those that want to read it here...

The deal with droop - RC Car Action

Suspension tuning is not a simple thing. A typical RC car has more adjustments than you can shake a hex driver at, and choosing the right thing to adjust in the right way in the right situation takes years to learn.

One of the more subtle tuning attributes on a car is droop. A lot of people think they understand droop (and some of them actually do), but plenty of others have never even heard of it. In both cases there is a surprising amount of confusion around the topic, which is why I’m writing about it.

The first thing to understand is that droop is not a setting; it’s an attribute. It is affected by other settings, each of which have their own unique names, but at the end of the day droop is a result of the way your car’s suspension has been adjusted. Droop allows (or limits) weight transfer from one side of your car to another – a factor that can drastically alter handling. Adding droop on one end of your car will generally increase grip on the other end, although this is not always the case. Running a lot of rear droop, for example, allows more weight to transfer to the front wheels during braking, which may or may not be desirable depending on what type of driving you’re doing. I won’t go into the nuances of tuning with droop, largely because the effects differ greatly depending on vehicle, surface type, driving style, and more. Just know it is one of many options open to you, and adjusting it can have profound effects.

Ok, let’s get down to exactly what droop is. Put your car down on a flat surface and let the suspension settle; this is your car’s ride height. Now, slowly lift up on your car’s chassis until the wheels just begin to leave the ground; the distance your suspension is able to extend downwards before the wheels leave the ground is the droop value. Put more simply, droop is the total amount your chassis is able to rise above its natural ride height.

Many cars feature screws in the chassis or suspension arms that limit suspension travel. Although often referred to as “droop screws”, these are more accurately described as downtravel, downstop, or drop stop screws. Although downtravel adjustments affect droop, they don’t define it.

Confused? Ok, here’s an example. Let’s say that your sedan’s chassis is 5mm off the ground at rest. You lift up on the chassis, and at a height of 10mm the wheels leave the ground. This means you have a 5mm ride height and 5mm of droop. Easy.

You want to reduce the amount of droop your car has, so you make an adjustment to limit the downtravel of your suspension by 1mm. The ride height of your car remains 5mm, but now as you lift up on your car the tires leave the ground when the chassis is at 9mm, which gives you 4mm of droop. So far so good.

You now decide that you want to raise the ride height of your car, so you add 3mm of preload to the shock springs. Your car now has an 8mm ride height. So far so good, right? You lift up on the chassis, and because of the downtravel adjustment you just made, the wheels again leave the ground at a height of 9mm. But wait… That means you now only have 1mm of droop. Clearly then, both preload and downtravel are unique and independent settings, but both affect droop.

For the most part, any time ride height is changed droop changes as well. This includes spring changes, weight distribution adjustments, shock angle adjustments, and so on. It is worth noting, however, that unsprung ride height changes (e.g., tire and rim changes) do not affect droop. Additionally, any adjustment that limits suspension travel will also change the droop value. Along with downstop screw adjustments, travel limiters can be added to shock absorbers to reduce the amount they are able to extend. Before suspension-mounted downtravel screws became common on RC vehicles, shock travel limiters were pretty much the only way to adjust droop.

This concept can sometimes be a bit confusing, but that’s ok – nobody was born knowing this stuff. Just give it some time and practice and you’ll be a pro before you know it.

 

[TacoCrawler]

guess I'm on ignore

I'm gone

 

[DowntownScience]

guess I'm on ignore

I'm gone

Huh?

 

[cotyhamlett]

We have an ignore button?


Sent from my iPod touch using Tapatalk

 

[DowntownScience]

 

[Eric0424]

We have an ignore button?

You have the option to put people on an ignore list, it's in the User CP (Control Panel). It can really help clean up your view of the forum sometimes.