Soft vs hard suspension regarding body roll?

[Cañonero]

I feel scared with sideways inclinations an the chance of ending up with the roof in the floor, specially on dune driving, when you can't go slow or you get stucked, so sometimes you get some scary sideway intertia in the side of a dune.

Of course I'm planning some kind of rollcage, but that's another story.

First of all, thinking about minimizing the chances, I installed the biggest negative offset wheels I could, forgot about any roof rack or roof tent and decided to keep the lift under 3", although I was looking for more. Also chose a quite hard suspension (more than I expected, to be honest, and quite uncomfortable when empty).

So the thing is, discussing about this with a friend, he told me that, unlike I would have thought, the harder suspension doesn't help much to keep the body roll away, more likely the opposite.

He says that a softer suspension would absorb the inertia of the body tending to roll while with a harder suspension, the truck would "pivot" on it and roll.

I still don't see it clear, what's your opinion on it?

 

[kidglove13]

I would think that a harder suspension would have a tendency to unload harder on you than one that is softer.
I would think that something progressive would be nice.

Im no expert but the 80 is already top heavy as it is.

 

[Ebag333]

A softer suspension will tend to have more body roll than a firmer one.

I used to have the OME shocks in my truck, switched them for the Pro Comp ES9000's. As an example in a hard high speed corner, the OME's would slowly roll over, then slowly return back to center after the corner. The Pro Comps feel more like they "snap" over, then hold the same angle through the corner then "snap" back to center.

The Pro Comp's get to the max angle much more quickly than the OME's, but they seem to not go as far over.

If you think about it, it's the same basic reason that race car suspensions (and "sport" suspensions) are very firm. A firm suspension will not want to roll but hold the vehicle upright. The down side to a firm suspension in a rock crawler is that a softer suspension will cycle easier. It might not achieve any more flex than a stiff suspension, but it'll get there with less work.

It's a balancing act. I very much like the ride and feel of the OME Medium springs with the stiffer Pro Comp shocks. I disliked the soft feel and ride of the OME springs with the OME shocks.

 

[Filmpros]

I am going on 15 months now of suspension testing with one of my trucks ... a 7,600lbs (empty) 97 Lexus LX-450.

I also just started testing on my other truck, a 1996 Lexus LX-450 which weighs about 1,000lbs less.

This is what I have learned so far.

1997 Lexus

* Softer suspension will give you much more roll and dive than a stiffer spring will.

* A softer spring tends to cause what I believe is referred to as "over steer" ... especially on sharper turns and while making sudden maneuvers.

* In addition, if the shock damping is too light, you will get very poor recovery and a lot of wallowing and porpoising.

* The combination above will force you to make repeated steering corrections in an effort to get the truck under control.

* In general, you will experience many OH **** moments when driving on unfamiliar roads. I found it difficult to control the vehicle and was not comfortable driving with this setup.

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* Going to a stiffer spring will reduce that roll and dive to a very large degree. However, depending on how heavy the truck is, you may still get some minor leaning but it is exactly as descibed above ... it leans a little and then only to a point. The truck then seems to settle and hold its angle at a point. It takes some good speed and more aggressive maneuvers to make the truck lean any further.

* Also, properly damped shocks are critical to getting the best ride and stability. Good shocks that are well matched to the vehicle weight and spring rate will make a huge difference in handling.

* Once you get the springs right, spending time tuning the damping is probably the best tweak I could think of for ride quality and stability.

* I am comfortable driving a truck with this setup and I had much greater control of the vehicle.

* I think we have the shock damping very good or at least very close right now.

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* I am tempted to increase my spring rate a little bit. It is very close to being right on the money but seems like it could use just a tad more support.

* However, my concern is with the off road ride quality ... which is superb at this point.

* I do not want to go too stiff on the spring rate and lose my ride quality .... which is also excellent on road given the "slightly more than I would like" lean angle on faster turns ... running 50mph in a turn marked 25 for example.

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1996 Lexus

* The 2nd Truck has stiffer springs and under damped shocks right now.

* This struck does not lean much at lower speeds and reacts similar to the 97 as far as lean in turns.

* It does very well, better than anything else we have tested so far on one of the test roads we use.

However, the under damped shocks are an issue. This truck does not ride as well as the 97 on the same test road

* I think the springs on this truck are at maximum spring rate for this truck ... and perhaps just better damped shocks will dial it in.

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* We are doing some more testing on a Snow Run with the Yankee Toys Group on 2/20.

* Soon after this testing, I will have revised springs & shocks for both of the above vehicles.

* I believe we will be as close as we can get for the "Medium" and "Heavy" designs we are working on.

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I will post more after the Snow Run if you are interested in hearing more about this.

 

[Nay]

Body roll and flopping on a side incline are not the same thing. I would never engineer an offroad suspension to stiffness for off camber considerations, because suspension geometry considerations such as roll axis are far more important than spring stiffness on a coil sprung suspension.

I think what you need is an inclinometer, because what you are talking about here isn't really the suspension at 3" of lift, it's the driver.

 

[IdahoDoug]

Canyonero,

I disagree with your friend regarding side hill stability in the static (nonmoving) sense. However, an unduly stiff suspension on a side hill while moving can indeed "toss" the truck if the uphill springs hit a bump that should have been largely absorbed by a softer spring. In that situation with the proper factory springs, the downhill springs would compress some also, the uphill shocks would have the proper rebound damping and the end result would be no drama.

As has been said, the most important thing of all to NOT end up on your roof in any on or offroad situation is to have springs and shocks engineered as a pair and sold together. To my book, that means only stock Toyota spring/shocks and OME suspensions which have matched sets. Everything else is a total crapshoot despite common offroad industry lore. Nobody, and I mean NOBODY in the shock business matches their shock absorbers to the vehicles they are sold for. They are sold to FIT the vehicle and some level of generic valving is done for vehicles of that FIT that weigh in certain weight groups. Such as from 4500-5000 use shock A. 5000-5700 use shock B and so on. These rough cuts miss the more important vehicle aspects such as track, wheelbase, roll center, rebound damping, compression damping, and so on ad nauseum - the stuff the factory does.

So your best bet to have an 80 that will retain one of its biggest advantages - that of doing everything very well - is to use stock suspension parts from Toyota. If you have to have a lift, look at Old Man Emu as the only aftermarket maker that carefully calibrates and tests their spring and shock rates for proper emergency handling.

DougM

 

[Dave 2000]

I think what you need is an inclinometer,

Yeh they are real great when you are standing still! The problem with an inclinometer is (and we are assuming it's accurate) that it tells you the angle of incline right? But only when you are at the angle and not what angle is ten feet further on? Let's assume your close to the limit, and you roll forward dropping a wheel into a pot hole adding enough degrees to put you into a roll over situation and it's all over. Also while you are watching the meter you are not watching where you are going i.e. straight down a pot hole....ad infinitum!

IMHO a meter is more of a gimick than an aid,

regards

Dave

 

[Ebag333]

* A softer spring tends to cause what I believe is referred to as "over steer" ... especially on sharper turns and while making sudden maneuvers.

Actually it depends on front and rear. A stiff front end will be more likely to cause understeer. A stiff rear end will be more likely to cause oversteer.

understeer / oversteer corrections


The has had a chance to drive my truck more than usual this past week, and she commented to me that she just liked the way it drove much more than hers. She said it just felt better, more stable, and would do what she wanted it to. Keep in mind that my truck doesn't have corrected caster (yet) and so the steering is more twitchy, something she very much did not like when she drove it with the OME shocks on it.

As has been said, the most important thing of all to NOT end up on your roof in any on or offroad situation is to have springs and shocks engineered as a pair and sold together. To my book, that means only stock Toyota spring/shocks and OME suspensions which have matched sets. Everything else is a total crapshoot despite common offroad industry lore. Nobody, and I mean NOBODY in the shock business matches their shock absorbers to the vehicles they are sold for. They are sold to FIT the vehicle and some level of generic valving is done for vehicles of that FIT that weigh in certain weight groups. Such as from 4500-5000 use shock A. 5000-5700 use shock B and so on. These rough cuts miss the more important vehicle aspects such as track, wheelbase, roll center, rebound damping, compression damping, and so on ad nauseum - the stuff the factory does.

So your best bet to have an 80 that will retain one of its biggest advantages - that of doing everything very well - is to use stock suspension parts from Toyota. If you have to have a lift, look at Old Man Emu as the only aftermarket maker that carefully calibrates and tests their spring and shock rates for proper emergency handling.

Sorry Doug, but I gotta disagree with you here.

First, I don't believe that OME "carefully calibrates and tests their spring and shock rates for proper emergency handling." They match their shock to a specific spring, true, but that's not matched to the vehicle specifically. They simply manufacture a spring/shock combo that happens to fit a particular vehicle.

If it was so carefully calibrated why did they change their (new) shocks to be firmer? By your arguement that'd throw everything out of wack.

So, how does it handle? Compared with the OME classic NitroCharger, the NitroCharger Sport is slightly firmer and no longer has the soft wallow, providing better control at low speeds making it more stable in the corners. At high speeds, the shock will still allow you to feel the subtleties in the terrain for reactive handling, while offering better traction and stability. It handles in a Euro-Sport style with excellent cornering and extremely reactive handling.

I somehow doubt that they stiffened the shocks to "a Euro-Sport style" but I haven't actually used them, so I can't say for sure.

And do you honestly think OME fully tests every vehicle that they make springs/shocks for?

IMHO there's no substitute for butt-in-seat-behind-the-wheel. I can say that my truck handles 100% better in every situation I've thrown at it than the OME's did. There's less nose dive when braking (or worse braking and cornering hard), the suspension is far more stable, and the truck doesn't want to understeer badly as it did with the pure OME setup.

Now that's a setup that works very well for me, but involves my setup. Change the springs, change the vehicle (weight/wheelbase/etc), change the equipment (armor/expedition setup/etc), change the desire (softer/firmer rid)...and you'll change your needs.

 

[Nay]

Yeh they are real great when you are standing still! The problem with an inclinometer is (and we are assuming it's accurate) that it tells you the angle of incline right? But only when you are at the angle and not what angle is ten feet further on? Let's assume your close to the limit, and you roll forward dropping a wheel into a pot hole adding enough degrees to put you into a roll over situation and it's all over. Also while you are watching the meter you are not watching where you are going i.e. straight down a pot hole....ad infinitum!

IMHO a meter is more of a gimick than an aid,

regards

Dave

Agreed, but my guess is he is starting to freak out at 15 degrees when it will take over 40 to go over. The inclinometer helps regulate what you "feel" with reality, and this area is probably the hardest thing to get used to in wheeling and one of the most important so you don't make a mistake in your head to hands to foot that could lead to a roll that would otherwise not happen.

The issue is getting comfortable with a lot of lean, not trying to "stiffen" your way out of it.

To Idaho Doug's point, OME is not the only manufacturer putting out a "kit". FOR has put together a very high end spring and a custom tuned shock to go with it, and the result so outperforms OME across the board that it is kind of a joke. You have to start actually using some of this stuff to retain this type of opinion about the various aftermarket providers.

 

[Filmpros]

x2 on FOR verses OME

Agreed, but my guess is he is starting to freak out at 15 degrees when it will take over 40 to go over. The inclinometer helps regulate what you "feel" with reality, and this area is probably the hardest thing to get used to in wheeling and one of the most important so you don't make a mistake in your head to hands to foot that could lead to a roll that would otherwise not happen.

The issue is getting comfortable with a lot of lean, not trying to "stiffen" your way out of it.

To Idaho Doug's point, OME is not the only manufacturer putting out a "kit". FOR has put together a very high end spring and a custom tuned shock to go with it, and the result so outperforms OME across the board that it is kind of a joke. You have to start actually using some of this stuff to retain this type of opinion about the various aftermarket providers.