Driveline issue...Jeep bouncing

[Mtpisgah]

I had some bouncing on my Mojave after a 3” lift AluCab canopy Camper install. Installing Fox 2.5 adjustable shocks and Dobinsons HD coils fixed it 95% of the time.
It took a while to get the shocks dialed in. I tried the valves all open, all closed, half way, one open and one closed. Finally got it to drive right. How much have you played with the Falcons?

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[hickman785]

@chorky touched on it with this =


Let me ask too, what type of road are you driving on the experience the bounce? My truck has always done this on concrete (or expansion joint roads) from about (50-60mph). Asphalt roads are never an issue. I've been in bone stock Gladiators that do the same thing. Sometimes it's just about the road surface and a "truck thing" that you can't get away from. There's a stretch of highway here in CO where both my JTR and friend's Tacomas all "buck" until you can achieve the correct speed to make it stop.

AEV always touts their "frequency tuned" springs for a front > rear balance but I've never personally ridden a JT with these to know if they control the "bounce/bucking" any better.

It happens on paved and concrete roads. Back roads, highways, freeways and interstates. The concrete interstates are definitely worse than paved.

 

[hickman785]

I had some bouncing on my Mojave after a 3” lift AluCab canopy Camper install. Installing Fox 2.5 adjustable shocks and Dobinsons HD coils fixed it 95% of the time.
It took a while to get the shocks dialed in. I tried the valves all open, all closed, half way, one open and one closed. Finally got it to drive right. How much have you played with the Falcons?

I had them in every setting possible and nothing ever changed, other than the jeep road rougher and rougher even in the softest setting. I replaced them with the factory shocks and now it rides a million times better, except for the bouncing.

 

[FitfulGoat]

Yeah, when I asked AEV about this a while back they said (paraphrasing) that they "tune" the springs so that by the time the rear end hits the same bump that the front just went over the Jeep is in "tune" to that hit as a whole (scientific explanation right?) I've had both Clayton springs and now Synergy springs and I can tell you that the same stretch of road still yields the same "bucking". Albeit, the Syngery springs are way softer and more road compliant IMO. My next endeavor (when my Falcon SP2 3.3's are done) would be trying new shocks to see if that helps. I just think that the wheelbase of both my JTR and my buddy's Taco don't play well on some of these concrete roads. I have 600lb constant load on my JTR and I thought that would've actually helped to "tame" the rear end but it obviously does not.

Again, this only happens on concrete roads and asphalt is perfectly fine.

Sorry OP, back to you

I experience this on a stretch of interstate 40 that is expansion joint/concrete. It’s only about two miles but my Jeep “bounces”. Otherwise drives fantastic and has done it with both my stock rubicon suspension, then with a leveling kit, and now with a full Clayton lift.

To the OP, crazy thought. Install your wheels and tires on another gladiator and drive the same stretches of road. (This is obviously assuming a lot in that you have access to another gladiator)

 

[Tosterman]

Any updates from the OP? I have the same trouble with my 21 sport. I have a similar load and have gone through a few of the same things. New springs, new shocks, adjusting the load. My bounce starts at 35 and ends around 40, peaking at 37mph. At times, it even makes it hard to carry on a conversation due to the noise, especially on concrete. There always seems to be an additional bounce or vibration after hitting small bumps too. I also noticed tire pressure changes the frequency of the bounce. For some odd reason, it seems worse in cold weather. I suspected it was a drive line issue or my JLU Rubi wheels and BF KO2 tires. I had an off road shop suggest my frame was flexing under the load. It’s to the point I hate driving it unless I have to.

 

[hickman785]

Any updates from the OP? I have the same trouble with my 21 sport. I have a similar load and have gone through a few of the same things. New springs, new shocks, adjusting the load. My bounce starts at 35 and ends around 40, peaking at 37mph. At times, it even makes it hard to carry on a conversation due to the noise, especially on concrete. There always seems to be an additional bounce or vibration after hitting small bumps too. I also noticed tire pressure changes the frequency of the bounce. For some odd reason, it seems worse in cold weather. I suspected it was a drive line issue or my JLU Rubi wheels and BF KO2 tires. I had an off road shop suggest my frame was flexing under the load. It’s to the point I hate driving it unless I have to.

You are experiencing exactly what I've been dealing with for over 2 years. In the winter it's worse because the tire pressures are lower. If my pressures are below 33/34 pounds it bounces horribly. Are you carrying any weight on the truck? I also had a local shop suggest that the frame is flexing.

 

[Tosterman]

You are experiencing exactly what I've been dealing with for over 2 years. In the winter it's worse because the tire pressures are lower. If my pressures are below 33/34 pounds it bounces horribly. Are you carrying any weight on the truck? I also had a local shop suggest that the frame is flexing.

I have a constant 400-500 lbs. I just ordered a rear driveshaft bushing drop. I can keep you posted. this summer, I plan to pull my weight and lower the rear a bit if needed.

 

[hickman785]

I have a constant 400-500 lbs. I just ordered a rear driveshaft bushing drop. I can keep you posted. this summer, I plan to pull my weight and lower the rear a bit if needed.

I have a carrier bearing drop bracket, it didn't help. The only thing I've found that helps with the bouncing is to remove weight or increase the tire pressures. I had 600ish pounds on mine and dropped down to around 200 and now the bouncing only happens on a couple of roads.

 

[ShadowsPapa]

I also had a local shop suggest that the frame is flexing.

That's a joke, sorry. I carry 280 pounds in the back of the bed of my truck in the winter and a 300 pound plow on the front, along with front receiver, power steps and other stuff. My truck is very loaded down, especially on the ends. No bounce, no flex or twisting. Smooth and even as ever.
Anyone checked the shocks? Make sure they don't bounce when doing a jounce test?

 

[hickman785]

That's a joke, sorry. I carry 280 pounds in the back of the bed of my truck in the winter and a 300 pound plow on the front, along with front receiver, power steps and other stuff. My truck is very loaded down, especially on the ends. No bounce, no flex or twisting. Smooth and even as ever.
Anyone checked the shocks? Make sure they don't bounce when doing a jounce test?

Well 280 pounds had no effect on the ride. I had over 600 pounds when the bouncing started. I've had 4 sets of shocks, from factory to Falcon 3.3s, none of them made any difference. I've 3 sets of springs, none of them made any difference. The only thing that helped is removing weight, which pisses me off because I bought the truck specifically to build an overland rig and now I can't.

I've had this truck in 6 different shops and I've spoken to probably 20 other shops around the country and no one has a clue what is wrong. I haven't dug into the flexing theory, but it's definitely not a joke. Everything else that should have helped or fixed the issue has had 0 effect so far so I am open to any idea at this point.

 

[DailyMoparGuy]

Wow. This may take the cake as the biggest head scratcher on the forum…at least that I’ve seen.

You’ve already had a lot of opinions and exhausted A LOT of options - coils, shocks, sway bar links, sway bar, track bar, etc….looks like you’ve replaced the entire suspension already which didn’t help. Driveline or frame issue maybe but idk how you prove that.

It really doesn’t seem like there’s solution for this on the horizon OP. Just my very humble and non-expert opinion from the outside looking in. However, I hope you can figure it out.

 

[Tosterman]

I am so glad I found this thread as my experience is very similar to the OP. I am lifted 3”, 400-600 lbs carry, three sets of springs, new Bilsteins. Helwegg rear swaybar, two shops have looked at it. One suggested frame or bed flex. I have taken numerous videos of the relationship between the cab and bed while in motion and several videos of the suspension. The only thing I have seen that is concerning is the amount of movement of the axle on acceleration. I still have factory control arms. The pinion flexes up several inches increasing the shaft angle. I’m just not sure how much rotation, if any, is normal.

 

[Dickster]

Have you had your tires force balanced? KO2s can be a pain to balance. Try switching wheels and tires to oem from the dealer...

 

[hickman785]

Wow. This may take the cake as the biggest head scratcher on the forum…at least that I’ve seen.

You’ve already had a lot of opinions and exhausted A LOT of options - coils, shocks, sway bar links, sway bar, track bar, etc….looks like you’ve replaced the entire suspension already which didn’t help. Driveline or frame issue maybe but idk how you prove that.

It really doesn’t seem like there’s solution for this on the horizon OP. Just my very humble and non-expert opinion from the outside looking in. However, I hope you can figure it out.

You are 100% correct about it being the biggest head scratcher. I have dealt with around 20 shops all over the country as well multiple parts manufacturers and none of them have ever heard dof this and none of them have had a clue as to how to fix it.

Naturally when I contacted Jeep and they sent an "engineer" to inspect it at the dealership, he said it wasn't bouncing at all and it drove 100% normal (even though the service department manager and service techs disagreed)

I've also had the driveshaft and rear axles replaced and the rear differential taken apart and inspected. Nothing helped.

 

[hickman785]

Have you had your tires force balanced? KO2s can be a pain to balance. Try switching wheels and tires to oem from the dealer...

I've had Falken 285/70/17s and KO2s both on factory wheels...no difference between the two, as far as bouncing

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