Anti-Sway Bars with RTT?

[Stryder106]

Many thanks for the pics.

 

[davescott]

Coil springs are just like a Slinky toy. Once they start to go over they keep in going. A Jeep Rubicon is a very capable off-roader. Has coil springs. Also has a sway bar disconnect, but only on the front.
When I use to off-road extreme lifted Samurais one ofthe tip offs to an impending rollover was a banging of the leaves in the leaf springs. A pop or two was ok, but after more than a couple plan on being in your side

 

[Stryder106]

Coils don't have friction inherent to them like leaf springs do so they are prone to hysteresis when disturbed. That means prone to resonate or carry momentum forward from one cycle to the next. This can lead to sudden and unexpected loss of stability at higher speeds.

Additionally on a vehicle with solid axles at both ends in particular, there's almost nothing about a coil sprung vehicle (without sway bars) to tell the coils how to share the weight. If your springs are 100lb/inch and you put 200lb on two of them, the springs themselves don't really care if that's 200lb on one (taking two inches of compression) and 0 on the other, so the load - the vehicle chassis - leans, compounding the incentive to lean even further. Sure, the geometry of the links, stiffness of the bushings etc tend to offer some means of detent but really not much, and little enough that it gets eaten up quickly under the worst conditions.

A (dual) live axle, coil sprung vehicle should have at least one small sway bar at one end to provide detent even off-road. Any live axle vehicle with coil springs should have sway bars connected on-road.

I run sway bars at both ends on both of my 4wd vehicles (IFS/solid rear) and disconnect the front bar when the terrain calls for it. I did take care to extend the rear link attachment points (not the links themselves) when lifting so that sway bar geometry remained neutral and would not bind. The sway bars do not hinder me off road and yes, I'm going where you're going

Cool thanks. My Av is a T-Bar IFS front / Live Coil rear. On the front, the sway bar links are a straight bolt through - so a bit of a pain to connect and disconnect. The Warrior Products quick disconnects have a pin in the middle - so wondering if those are a viable solution? I don't do rock crawling and typically stick to stuff that would be rated 5 or less in the Backcountry Adventures books - I may push it beyond that 5 rating a bit if I was with multiple vehicles and had someone more versed at this than I am.

 

[rayra]

better check that the loose front sway bar will pivot / swing clear of the upper and lower control arms, before you spring for the link disconnects. If the bar is constrained by the control arms anyway, you may not get anywhere near the freedom of motion you expect / want, as the free bar contacts the lower arm on one side and the upper arm on the other. I didn't test that motion arc either time that I was working on my front end and had the sway bar loose or out altogether. But looking at my pictures it doesn't appear it will pivot clear in either direction.

 

[Scoutn79]

Since your full size I wonder about the possibility of swapping in a late model Power Wagon front disconnect swaybar system Dis/reconnect form the cab.

Darrell

 

[RoyJ]

I feel everyone has a different level of tolerance for sway.

On my 4th gen Explorer (coils, IFS/IRS), I've got both sways permanently removed, and feel perfectly fine. In fact, it sways less than my 100 Series on stock AHC suspension.

You just have to be realist on handling expectations. If you want to swerve at 70 mph to avoid something, then leave the sways on. But if that's the universal standard for handling, every motorhome, bus, and heavy truck would fail miserably...

 

[Stryder106]

LOL - true Roy.
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Rayra - are you still coming out later this week? We can take a look at it.
//

 

[rayra]

probably postponed a couple weeks, still not settled will PM you

 

[RoyJ]

Things that would make you swerve don't tend to give you the choice of whether want to be in that situation. Sometimes it seems people are coming at this from a "Cigarettes are fine I've been smoking them 30 years and haven't got cancer yet" perspective.

Can I drive to the store without sway bars? Sure if it came down to it any of us could manage to get our vehicles down the road in all sorts of tragic barely roadworthy condition - I just can't get behind the idea of entirely deleting safety equipment which has an objective purpose.

So where's the cutoff? How much "swerve-ability" is safe for road travel? What about a built Unimog camper? A 6x6 MAN?

My truck without sways is still much safer than a heavy truck (5 ton+) WITH sways. And my truck with sways is still much more dangerous than my Z06 or Mini Cooper with no sways.

Again, where do we draw the line?

What about suspension lifts? Big tires? Heavy RTT? They're all examples of "deleting safety equipment", yet most of us are willing to make that trade-off for better off road performance. So why not sway deletes?

 

[Meili]

Depending on your age, today's pick up trucks would out handle 95% of the car from the 1960s on down. Suspension and tire technology has advanced quite a bit.

Unfortunately cars/trucks handle so well now people have never learned to drive.

RoyJ makes some good points, I really comes down to what you can handle and are comfortable with.

Again, in my case going with smaller bars that articulate better.

It still will handle better then my old tail happy 78 F150, 56 VW swing axle that would "jack" in a sharp turn, 67 Dodge Coronet 440 that would plow (understeer) in a turn etc etc etc.....

 

[Stryder106]

I appreciate all of the info offered up. I can drive - I've been doing so since I was 13, learned how to drive in Walker Evans race truck, raced pro mx, am an NHRA licensed advanced ET drag racer, and have been driving in various forms of dirt most of my life. Now, I will say this - I am learning and have a lot to learn about the more technical aspects of trail driving - but if you want to bomb a desert, let go of a trans-brake button at 5600 RPM launching hard enough to suck the eyeballs back in your head while the horizon rotates and then grab a shift, or skim whoops - I'll go there. But, I am seriously learning how to do the slow thing and do it correctly (no interest in rock crawling though - I'll just turn around - LOL).
//
My main point of this topic is that I have a 2002 Chevy Avalanche - it has been extensively modified: shocks, arms, brakes, tires, wheels, track bar, steering components, etc. It is a Torsion bar front and coil spring rear. I have the Z71 front bars and I've swapped to Hummer rear coils. It is leveled with CST keys but it does not have a lift kit (could not find any that I thought were actually stout enough for offroad). I have my stock sway bars - connected front and rear.
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I have been considering ways to get a bit more articulation offroad (particularly the front given the limited travel of T-Bar suspension), but I'm also in the process of adding a RTT. Hence me asking, if anyone with a RTT (and that higher weight) actually disconnects their sway bars. If so, what is the experience? Good, bad, meh? I'm not a big fan of removing my sway bars given the street use (it is my daily driver as well).
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Another idea I'm considering is going to a stiffer T-Bar. Wondering if the stiffer T-bar would allow me to disconnect the front sway bar and get an overall stiffer (more stable) ride and simultaneously allow the front IFS to articulate a bit more offroad? I'm not sure how that works - hence me asking. Thanks again for any and all input. I want it safe and capable.

 

[Bear in NM]

maybe I can convince Shovel to come back and perhaps answer this question. I have the same Av as Stryder, with the same Eibach Hummer rear coils. My difference is that I added airbags to my rear coils. Would the addition of inflated airbags help with the issues associated with unswayed coils? And thanks, Shovel, for taking the time to explain things with coils. makes total sense. Just wondering out loud whether bags would fit the criterion for spring damping? Not sure if they would conversely limit articulation?

I was wondering about this after rereading this thread, and as I had my off road trailer out this last weekend (and two weeks ago) for the first time with the new rear upgrade. I was amazed at how well the back of my Av handled the tight paved mountain road curves, with a fair amount of tongue weight. Did fine off road, but my trailer does not have shocks, so I tend to creep.

And Stryder, I am with you. I also felt that my key lifted stock front torsion bars could really stand to be a bit stiffer. With my rear airbags and no trailer droop, I have enough rake to be able to crank a little more on the front keys. Not ready to try that yet, as I have a heaver trailer that needs to see some off road time.

Craig

 

[RoyJ]

None of this will convince you of course but I've said my piece. See ya out there (with my sway bars on).

And I don't plan on convincing you either, but I will respond just so readers can see both sides.


I agree with a lot of what you said, but why do you not classify sway bar removal as an "upgrade" like you do for a suspension lift?

You're placing too much emphasis on the sway bar itself. It's not a black magic device that suddenly makes road travel safer. It's simply ONE METHOD engineers use to dial in roll stiffness.

The engineer could've just easily used stiffer springs to begin with. Exactly what Dodge engineers did with the 3rd gen Ram HD - rear sway bar removal due to stiffer and wider spaced springs. Is it dangerous compared to a 2nd gen?

If a vehicle with a "high quality long travel suspension" actually rolls more (less roll stiffness) than an OEM suspension with sways removed, which one do you consider unsafe? Have you seen how much a Baja trophy trucks rolls on tarmac? Do you not consider their suspension "high quality"?

When evaluating what's safe and unsafe, we need to measure in absolute terms: inches of COG gain, lb-ft per degree of roll stiffness lost, roll center shift, etc. vs gain in travel and articulation. And not: this is suddenly unsafe because a bar is removed...

 

[RoyJ]

I have been considering ways to get a bit more articulation offroad (particularly the front given the limited travel of T-Bar suspension), but I'm also in the process of adding a RTT. Hence me asking, if anyone with a RTT (and that higher weight) actually disconnects their sway bars. If so, what is the experience? Good, bad, meh? I'm not a big fan of removing my sway bars given the street use (it is my daily driver as well).

I think this is where you have to try it yourself, and see if the amount of roll is acceptable. Every truck will respond differently.

In my case, it's a 2006 Explorer with OEM suspension. I have a Tepui RTT and feel the sway is perfectly ok. You have to also consider what else you're carrying. A full load of passengers may raise the COG higher than an empty truck with RTT.

But I also load very low to offset my COG. My 130 lbs of batteries, 24 gal of water, fridge, and fuel all sit within 20" of my floor.

On the other hand, my old Ram 2500 carries a 2500 lbs Bigfoot camper. I leave both of my sways on because a load that heavy and tall is definitely outside of MY comfort zone for no sways.

Another idea I'm considering is going to a stiffer T-Bar. Wondering if the stiffer T-bar would allow me to disconnect the front sway bar and get an overall stiffer (more stable) ride and simultaneously allow the front IFS to articulate a bit more offroad? I'm not sure how that works - hence me asking. Thanks again for any and all input. I want it safe and capable.

Difficult to guess if the stiffer springs would offset the OEM springs with a sway bar, without exact specs.

If you do have the specs - in-lb for springs, lb-Ft/deg for sway bars PLUS the ratio of the sway bar endlink to tire contact patch, you can do an RTi test and calculate as follow:

Total spring force = bump travel (of tire on ramp) + (degree of twist of bar x stiffness of bar) x bar endlink ratio X sway bar moment arm length.

Let's say you get something like 2500 lbs of force. Then look at your new spring constant and see if your new suspension travel is greater or less than what's measured during your RTi session.

Then to calculate which one rolls less (on the highway), you'll have to go through roll stiffness calculation taking into account your new COG and roll center (stiffer springs likely ride taller).

In summary - not worth it! Easier to just buy the springs and try it out.

 

[Regcabguy]

I've got a 3rd gen 2500 Ram with Thuren valved Kings,Carli minipaks and Kore front coils. Suspension mutt for sure that works pretty well. My Hellwig swaybar greatly improved road handling without increasing spring rate or shock valving.