Wheel hop, axle wrap...

[TwinStick]

My truck had the bad wheel hop since it was brand new. Deep dense good packing snow & sand will do it every time. It is a byproduct of a flexy suspension with no ladder bars/link bars/traction bars. No one has come out with ones that will not be a hindrance when off road.

[adeluca73]

So u vibrate like a 12v diesel. I like this adeluca fellow. We will keep him round a bit longer

In my mind though they should have done a modified version of this. Maybe a 4 link but it removes the trac bar and rides very well yet is flexy

Copy. It's really simplistic in theory of application, the math is a giant pain in the ass because, with cars, the applied external force is, well completely unpredictable. The force transmitted to the suspension can take on the form of a purely harmonic (think washboard road w/fairly evenly spaced humps from a plow or road grater) or periodic force (from some type of rutted dirt road, rock climbing, etc), or random excitations (potholes, stumps, roots, curbs etc), all change the solution to the ODE, the solution is in terms of vertical displacement of the rear end, and for a forced input, is best conveyed in the frequency domain, as a function of excitation frequency. That is something very difficult to identify, because no one drives on the same roads, and thus, no two truck owners will see the same vibration profile because we all live in different areas and drive different roads and more importantly, off-road differently. add to the varied road conditions, the tire type/size/wear/pressure/temperature, suspension system state of degradation, not to mention all us PW guys getting in there and changing shit for Carli/Theuren parts makes the system response completely unpredictable. But the concept is easy--the rear end as a total vibratory system has to be designed so the driving of the "most" avoids exciting the system's natural frequency. IT's impossible to account for all these variables and everyone's intended or unintended use of the vehicle. To change the axle vibratory response, especially the frequency, you have to changed the stiffness of the system, which comes from changing either the spring equivalent rate (Keq), or the system equivalent mass (Meq), or increase the dampening. The system stiffness is globally computed as the square root of (Keq/Meq)....they're inversely proportional, and therein lies the engineering trade space.

You can change the stiffness of the system by adding or removing mass, or change the spring rate by changing the mass of the sprung weight, or the size and/or number of springs. In general, the spring rate (K) is calculated by Force/Displacement. If you set the number and size of the springs (coils), say Dodge fixed them for articulation and on road ride, then a way to change the response is by either addition of mass (which the fuel mpg guys and marketing people will freakout over), removing mass (which the structural and safety people will freak out over), or add in another dampener, hence the center shock.

In my humble opinion, of course...

[nts007]

Vibratory system...... Love it when you talk dirty....with science

[olyelr]

Holy geez all mighty wheres my geomatriganomacalculus book to follow up with all of that STUFF. Well stated adeluca... I think!

All the mumbo jumbo aside, I am pretty certain there is no way in hell the rear end (axle nst007, I mean axle) has any WRAPING issues. The design of a 4 link simply cant allow it. But the dreaded HOP... now that may still come into play. Adeluca, are those long paragraphs stating that the added horizontal shock is there to help with the hop?

[nts007]

[nts007]

Sry I'm in a good mood. My truck is finally alive today since it went down on Boxing Day so

[TwinStick]

[2wagons1driveway]

Wow. Good write up. I also now feel a whole lot dumber haha

haha me too! So what your saying is it helps axle wrap?! Lol


To add to this I've been running 18-20 psi in the rear during outtings with little no no wrap. I've noticed since the 37's are on even with the bfg's (ko2) at street pressures (not towing) in the winter at 35psi little to no wrap at all! I do have aftermarket leafs however.


Sent from Canada

[olyelr]

Wow. Good write up. I also now feel a whole lot dumber haha

haha me too! So what your saying is it helps axle wrap?! Lol


To add to this I've been running 18-20 psi in the rear during outtings with little no no wrap. I've noticed since the 37's are on even with the bfg's (ko2) at street pressures (not towing) in the winter at 35psi little to no wrap at all! I do have aftermarket leafs however.


Sent from Canada

Hey 2wags you have that old outdated flinstones leaf spring type suspension. Your input dosnt mean anything, this is about the new linked rear so get your Carli/Thuren tuned mind out of this thread

[Will]

[MoparToYou]

I went exploring in the snow today in my 2016 Power Wagon, and for a truck that has a suspension that is designed with "a 4 link that simply cant allow it", this truck does indeed have a horrible case of axle wrap. Those great big 3" diameter rubber bushings on the rear control arms allow for a lot of flex, which also creates a lot of axle wrap. This truck is even worse than previous trucks I've owned with leaf springs.

I had to climb a modest 20% grade on a dirt road that had 8 to 10 inches of snow on it, and the Power Wagon was absolutely incapable of climbing it, largely due to such a severe case of axle wrap. I've been four wheeling for a long time, and have done it with several different vehicles, and this truck performed pretty dismally today. I tried 4-hi with traction control on, with no luck. I tried 4-hi with traction control off, with no luck. I tried 4-low with no lockers, with no luck. And I tried 4-low with both lockers, with no luck. Nothing made a difference. That hill wasn't much of a hill, and I've owned several prior vehicles that would have went right up it. But that hopping, bouncing, chattering, axle wrapping, spinning Power Wagon was just about useless today. I almost couldn't make it back up the small hill we had come down, to get back out again. That's great, performance so good that it is almost life threatening.

So, Ram puts a bandaid center shock on the truck because they knew it had axle wrap with those huge soft bushings. How do we fix it? Has anyone replaced the center shock with a shock that has Conan the Barbarian valving in it? Has anyone replaced control arms with custom arms from Synergy, or other companies, that have better bushings (Johnny joints, etc.). Then again, if you get rid of those huge soft bushings, are you left with unacceptable noise, vibration, and harmonics?

Axle wrap on this truck is a joke. Very unimpressed with Ram's engineering job on this one. Yes, I may sound a bit upset about this, I just got back from a very disappointing four wheeling trip

[nts007]

Another bandaid fix but maybe just put the lower control arm from a 3rd gen to replace that shock. Looks bout right length

[TwinStick]

"Axle wrap" is just that, meaning the axle wants to rotate. The banging is the axle twisting up or down & then letting go. There are really only 2 ways to fix it. Coils & leafs so stiff that it wont do it anymore---which = a crappy ride & limit articulation. Traction bars, which lower ground clearance & will get destroyed off road & also limit suspension travel. Shocks can certainly help alot but also only so much. What i do in snow that seems to work well for me, is to use 4 LO & 4th or 5th gear (but mine is a G-56 manual shift). I get those tires spinning good & have at it. I have also used 1st gear Lo & just let the truck drive itself, with no skinny pedal at all.

[Colibri]

Damn mopartoyou thats ridiculous! I'm sorry to hear that your new truck performed so poorly. I can't speak for the new trucks suspension specifically but over the years I've replaced a lot of factory control arm bushings with Johnny Joints and never been sorry. They really don't effect NVH to any appreciable degree, only give better handling and longevity/serviceability. I don't know what's available for you rear arm wise but if you can get jj arms back there it will definitely help

[MoparToYou]

Has anyone had that center shock off of their truck yet to see how stiffly it is valved? It might not have much damping in it. Maybe we could find a Rancho RS 9000 the same length, and install it with the damping dialed all the way up.

[adeluca73]

Has anyone had that center shock off of their truck yet to see how stiffly it is valved? It might not have much damping in it. Maybe we could find a Rancho RS 9000 the same length, and install it with the damping dialed all the way up.

I have not had it off. When my truck was about 2-3 months old last November, I went on a week+ hunting trip in N. Mich, & it never stopped snowing, 20"+ easily in some spots & I traversed some very steep hills, so steep I couldn't see over the hood, up or down, & the PW handled it every day w/o any issue, no spinning, no wrap or no hop, very sure footed. My cousin was getting a little concerned about some of the remote spots I was exploring, and the snow was evvery bit near the wheel well in drifts and in some shallow swallows, I'm curious as to the difference

[MoparToYou]

Snow is not always the same. I've had similar experiences with other vehicles, namely, being able to drive almost effortlessly through snow that is deep enough that it is at times coming up over the hood of a Jeep. Yet at other times, in that same vehicle, not being able to drive through snow that is even differential deep without spinning and struggling. It has to do with the density, moisture content, temperature, etc, etc, etc. The snow from yesterday was just the wrong kind of snow. This truck can't be that bad all the time.

[Will]

Another bandaid fix but maybe just put the lower control arm from a 3rd gen to replace that shock. Looks bout right length

It's got to have a slip joint in it, get's short as the axle moves up.
I'm still curious if this is truly axle wrap, I imagine you can't have much wrap when the tires grip and slip, but still something is torquing up and then turning loose. A go pro back there would tell the tale. I know the guys with mustangs fought wheel hop and changed all sorts of suspension parts until they finally discovered it was the subframe torquing, all the suspension mods you could have done would not have cured it because all of the suspension was mounted to the part that was moving. I surely hope the actual frame is allowing this to happen. Can you tell if both tires are hopping in unison or is it a left then right then left then right, etc.... If so, could be the frame itself, I know Dodge has one of, if not the strongest frames but I can't help but to think about a video that shows a Tundra going over staggered bumps and the rear jousting back and forth with the frame twisting, this may be similar but a much smaller, faster scale... thinking out loud here...

[2wagons1driveway]

It's still the same issue as the 3rd and 4th gens and every truck with a lot of power a high gear ratio and leaf springs experienced before. Play with the tire pressures and if possible try locking up the rear also. If the truck is in full spool in the rear it won't want to hop as much either. JBMs wagon is a 5th gen radius arm truck and he airs his 35's down to 20psi and has no wrap whatsoever when he's with us either in the snow or the dunes

Sent from Canada

[nts007]

I have the cure. It's currently in my truck. It's a secret. But I've pushed through bumper deep snow in the fields many times. And only gotten a little bit of wheel hop.

[Will]

I have the cure. It's currently in my truck. It's a secret. But I've pushed through bumper deep snow in the fields many times. And only gotten a little bit of wheel hop.

Well I know it's not the CTD It has to be the tires!! Honestly, probably is the tires and air pressure. A four linked drag car will hop with the wrong tires and psi..

[nts007]

Lol. The answer is more power!!! Obviously. I once chatted with skyd and he was asking how bad my axle hop is and truthfully it's not really bad. And I have pw leafs. But I actually have the pipe in the box my truck and the flat stock to build this as I've been planning it for a bit. I've seen a few designs. I plan to do one right close to the carrier and have a double hinge joint farther up the line. I've just been procrastinating on doin it as it really hasn't been a problem.
Here's a link http://shop.broncograveyard.com/Black-D ... nfo/13605/

[GunniPWguy]

Seems like an easy fix. Nothing worse than trying to stomp on it in some deep snow or sand only to get denied by the dreaded shudder of axle hop. embarrassing.

[2wagons1driveway]

I dunno about more power being a fix lol once te wheels are spinning fast enough your fine but you also have to remember your running a 37" tire with a much larger sidewall then most people on here that are having wrap issues. You probably don't run your pressures at 60psi all the time either


Sent from Canada

[TwinStick]

Seems like an easy fix. Nothing worse than trying to stomp on it in some deep snow or sand only to get denied by the dreaded shudder of axle hop. embarrassing.

Not to mention that u-joints are the weakest link when this happens.