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why am I bouncing so much?

ashman

ashman

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I'm having a reoccuring problem with bouncing on obstacles and I keep having to take bypasses, or break stuff. I'd love to figure out the problem.

In the video, you can see @72gmck5 and I on the same climb and without the bouncing, he walked right up it.

View attachment bounce.mp4

My wheelbase is a little smaller than his, but we are running basically the same axles and tire size (37").

are my tires just that much worse than his?
Did he just do a better job picking the line?
Do I need different shocks, more or less stiff?
I'm running a hard top, is the extra weight making the difference?
I'm running ORD custom springs. Ryan has longer springs. The springs shouldn't be a problem. right? @Stephen
 
Oh, I am SOOOOOOO considering links, but if I have other issues, I'd rather solve it without going that route.

I don't remember specifically how much air I was running that day, but I'm usually actually running less air pressure than him. I was probably about 10psi that day. sometimes I run as low as 8psi though.
 
20240913_192908.jpg
37" cooper discoverer stt pro load range D.

of course while climbing, there isn't much weight on the front, so that may be part of it.
 
I watched the video you uploaded on YouTube earlier and when I saw the bouncing my first thought was shocks. What shocks do you have on there?
2nd thought for both trucks on the climb was too much air pressure. Sounds like you were both running low pressures.
 
To me it looks like super stiff lift springs but I wouldn’t think that would be the case with ORDs..I know the back of mine had terrible hop with rough country rear leafs, switched to pro comps and it was like I added a traction bar…hop was gone.
 
HankScorpio said:
I watched the video you uploaded on YouTube earlier and when I saw the bouncing my first thought was shocks. What shocks do you have on there?
2nd thought for both trucks on the climb was too much air pressure. Sounds like you were both running low pressures.
Click to expand...
I'm running bilstiens. I'm wondering if better valved shocks would help.

Afa my springs go, they are actually super soft. :dunno:
 
Not sure if you have one, but wouldn't like a raptor or something similar prevent that?
 
I’ve got the same problem and I have nailed it down to weak shocks. Both shock position and performance are not helping on my truck. I haven’t fixed it yet but fingers crossed that takes care of it.
 
I can see stiffer shocks reducing the hop, but the root cause is probably spring wrap or squat. You should be able to reproduce it on flat ground by torquing it and seeing if the back end raises or lowers. The difference on the climb is that most of the weight is on the rear axle and the traction is intermittent.
 
The forces that produce the hop are the loading and unloading of spring forces, as well as loading and unloading of the chassis. Spring forces are the leaf springs, tires, and chassis flex.

Kind of the standard deal. Next step is anti-wrap bar. After that it's links. There can still be a bit of hopping with links too as the tire loads and unloads.


Leaf springs can definitely get down and can do amazing things. Links can to. To fix the problem you've got a whole bunch of solutions which can help.
-Different springs and shocks can help.
-Anti-wrap bar
-Links
-Driving style

Different springs and COG height can help, mainly to give more comfort and hit that obstacle with a bit more momentum to get you up. With that you need the right spring combined with damping to soak up some of the bumps and keep the traction. As a driver you need to look at the line and determine how much momentum you need to get up it. Enough to get up, but not too much to upset the chassis.

If it was mine I'd be playing with the leaves and a anti wrap bar. You can take leaves out. Go to the junkyard and grab some packs, play with ride height, and play with cheap shocks. All of this can be done cheaply. If you're spending a bunch of money might as well link it. After that you can make an anti-wrap bar cheaply too. If you design it correctly and read about it you'll learn about instant centers, AS values, and how it all works.

I'm editing as someone said they're Stephen's springs. I'd leave the pack as is, focus on shocks, driving style, and anti wrap.

On my old 64's I used a chevy pack, overload and one other leaf taken out, then an S10 spring to keep the pack from W'ing, even though it wasn't the same arc. I used to do well with that pack. Experiment.

All of the above will hop if you as a driver let it get to hopping. So don't do that, hopping breaks shit.
 
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We were discussing this on our wheeling recent trip. I don't have much issue with hopping. This has been true with both ProComp lift springs and ORD custom springs. I have off the shelf Bilstein 5125 shocks in the rear and they are both angled toward the front at the top. I couldn't fit the shocks in a straight vertical orientation so I figured angling them both forward at the top might help with axle wrap. I do have air bags and we were wondering how much they contribute. I keep them at the minimum PSI Firestone recommends which is 5psi.

I've had a couple of different tires. I've always run around 14psi on the trail, not particularly low compared to what many run.

I wonder how much shackle angle might contribute. I aim to have the shackle at a 90 degree angle to a line drawn between spring eyes. This allows the springs to move freely in compression and extension. The angle I see on a lot of trucks works great for axle droop, but maybe not so much for compression. One of the best things about the ORD springs is they are designed to handle negative arch for up travel, so I want to take advantage of it.

I'm also sure wheelbase is a factor as well. Unfortunately there's not much you can do about that without getting radical with body mods.

@ashman if I had your truck, I would try doing something with your shackle angles. I know this might not be easy to do, though. I think you'd have to look at making a different front hanger for the front springs. I notice your springs have quite a bit of arch in them which means for them to compress towards flat, you need to have room in the shackle to swing back because as the spring flattens the distance between the spring eyes gets greater. With the top of the shackles angled forward you're starting at a disadvantage.

It would be interesting to drive the truck up an RTI ramp and see what happens to the arch of the spring. I have it in my mind Stephen told me the springs can handle 5" of up travel. On an RTI ramp, you could see how much up travel you're getting. You might be able to tell if you could benefit from moving the shackle hangers around if the shackles are limiting how much the spring can flatten out. I just think with the arch in your springs, the angled shackles might be a detriment.
 
Scott brought up a good point on wheelbase and shackle angle. The wheelbase on Scott's rig will change alot of things. The moment between the two axles is very different so force transfer from the rear or front hopping then affecting the other axle is not the same between the two trucks.

Is there a good pic of your leaf springs from the side @ashman ?
 
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