suspension

[P. A. Schilke]

@HotShotOffroad normally, I'd tend to disagree with the idea that adding a rear anti-roll bar would REDUCE oversteer, but for some reason I can't help but entertain this thought.

Maybe one way a rear anti-roll bar would help this situation the OP mentions is if the skitteryness and "stepping out" is caused by an axle tramp (the left and right sides hopping out of phase relative to one another) resonance. The rear ARB would only help if the shift in "tramp resonant frequency" is enough to keep it well higher than the "input frequency" of the washboards AND the shift in roll stiffness bias isn't enough to make the truck an oversteery handful. I suppose the soft inboard mounted dampers aren't really helping to damp axle tramp, either...

But... I'm wrong a lot. @P. A. Schilke how does that grab you?

Either way, running dirt roads in 4hi or going slower or faster might be easier to try before OP gets out the parts cannon. (don't get me wrong, I love screwing with thoughtfully engineered stuff)

Hi Terra,

Okay...the end of the vehicle with the suspension with the stiffest rate in roll generates the highest slip angles meaning tires slip at a greater angle than the tire is pointed. So, a rear bar will cause the rear to kick out at a increased angle from a non rear bar truck. There is a metric called roll stiffness balance between front and rear and if you change just rear, that changes the balance. Most people like Understeer as it is comforting to them...Oversteer is not... ie back end out in a turn dynamic.

Now...this only occurs in a turn where there is a twist in the suspension between inside tires and outside tires/suspension. Straight up and down...bars have little to no effect. Twist the truck and bars come into play for vehicle dynamics....

You are correct about inboard shocks...and this was the bugger for prior generations of Rangers that were prone to skate/dart.... The damping of the shocks was minimal due to what we call motion ratio...the amount of shock travel up or down relative to the wheel....more inboard the shocks the less effective they are in roll. So tune for roll and the damping up and down is worse, so you have to compromise in straight up and down vs roll where one wheel is up and one down... Since Shocks are velocity devices, there are opportunites with sophisticated valving, to a degree. This is where $ enters the equasion for the cost benefit ratio and most folks will never press a truck to its limit...so soft controlled ride is the objective. FX4 is tuned for offroad and unfortunately folks call it bouncy for on road in some cases. It is doing its job, JMO, but off road more than on road. Add a rear bar, and aftermarket shocks might not be the ticket for tuning..

Welcome to the world of vehicle dynamics.... tuning this trade off. I am a proponent of Big Bars and soft springs.

Okay....Retreating to the flameproof bunker.... let the pundits pontificate....

Best,
Phil

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[RBMAN]

OK, Lots of good info to study on. Maybe I should drive slower! or maybe I need to add about 1000 lbs in the back to equal the weight of my F-150 before I spend $ on new shocks or sway bar!

 

[TerraMechE]

@RBMAN

I grew up going too fast on Iowa gravel roads. I now encounter Colorado washboards in my Ranger. In stock form, my truck was sometimes intervening with traction control and sometimes stability control on such surfaces. I blame ecoboost and lightness, which are great things, really.

Running in 4HI on particularly rough road sections killed the sideways drama for me.

2 dirtbikes in the back also seemed to help a little.

Dampers can theoretically help. In practice, good luck finding what you like. I like Bilstein. For me and for the money, they suck at everything more or less equally, which is a compliment.

I thought the stock Hankooks were more than fine for a stock tire. However, in the past, I've run stock size AT tires with more tread depth or slightly more tread void (usually LT load ranges vs SL) and they usually offer more grip in gravel, even over washboards. It is hard to find a good gravel tread in the lighter load range, but they do exist. I can't recommend them, but the new Mickey Thompson Baja Boss A/T in the SL/116 load ranges look like good gravel tires for lighter trucks. I now run Cooper AT3/XLT's to get the size I want. They are great on gravel and highway, but they do ride a bit harsher as they are an E load rating. I also had Duratracs in the SL trim. I didn't care for how loud they got, but they were a great gravel tire besides that.

Good luck

 

[TheBadger]

Aw man, you got 5160s. How do you like them?
They've been out of stock for ages and I got impatient, just grabbed 5100s.

 

[Dr3wDrop]

Throwing in my 2 cents for what its worth. I ran a Hellwig rear swaybar on my 2 door lifted Jeep JK to help with daily driving. It helped plant the rear end and completely removed the feeling on windy days that the Jeep was being was blown around driving on the freeway.

Now I did suffer some articulation offroad and could have installed some disconnects if I felt it was necessary. However, daily driving was much more of a pleasure reducing body roll and the feeling that the back end was doing what it wanted in a push comes to shove scenario.

If my Tremor ever starts acting up I wouldn't hesitate installing a Hellwig rear swaybar to see if it helped.

 

[jcru1017]

What tires are you running? The old hankooks are decent for grip but I don’t think so great on washboards. I would suggest upgrading to a bigger size and more aggressive. Maybe a c rated tire and definitely let some air out.

 

[TerraMechE]

Aw man, you got 5160s. How do you like them?
They've been out of stock for ages and I got impatient, just grabbed 5100s.

Those are 7100's. I swapped the spherical bearings for rubber. The guts started with 360/80 shim stacks but they've been through a few revisions. I like them, lol.

I also liked 5100's on other vehicles. I doubt you are missing much.

 

[Bluestem]

I grew up going too fast on Iowa gravel roads.

Oh man, this brings back memories. We did the same thing. Sliding around corners in my buddy's Escort, ramping the occasional intersection in my other buddy's old 72 Buick Lesabre. I'm surprised we're still all alive.

 

[RBMAN]

@RBMAN

I grew up going too fast on Iowa gravel roads. I now encounter Colorado washboards in my Ranger. In stock form, my truck was sometimes intervening with traction control and sometimes stability control on such surfaces. I blame ecoboost and lightness, which are great things, really.

Running in 4HI on particularly rough road sections killed the sideways drama for me.

2 dirtbikes in the back also seemed to help a little.

Dampers can theoretically help. In practice, good luck finding what you like. I like Bilstein. For me and for the money, they suck at everything more or less equally, which is a compliment.

I thought the stock Hankooks were more than fine for a stock tire. However, in the past, I've run stock size AT tires with more tread depth or slightly more tread void (usually LT load ranges vs SL) and they usually offer more grip in gravel, even over washboards. It is hard to find a good gravel tread in the lighter load range, but they do exist. I can't recommend them, but the new Mickey Thompson Baja Boss A/T in the SL/116 load ranges look like good gravel tires for lighter trucks. I now run Cooper AT3/XLT's to get the size I want. They are great on gravel and highway, but they do ride a bit harsher as they are an E load rating. I also had Duratracs in the SL trim. I didn't care for how loud they got, but they were a great gravel tire besides that.

Good luck

Thanks for the info. I don't drive on country roads as much as I used to, but I will try putting it in 4HI to see if it make a difference!

 

[McLeadslinger]

A level is a waste of money IMO. Go with a full adjustable shock replacement or adjustable coilovers. All the effort doing a spacer level literally requires just a much time and effort as replacing the junk factory shocks and struts with new quality pieces.

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