Uncontrolled Bouncing

[rkymntsno]

Ok, I need some help. We have a 2019 355mbqs and a 2018 Ram 3500 LB SRW with Timbrens installed. On our way back from Pigeon Forge, TN (to San Antonio), we hit a rather large dip in the road on a bridge expansion joint. I was running about 67 mph and when we hit it, the backend of the truck started bouncing uncontrollably. Of course I hit the brakes and usually that will straighten things out. But it must've been a bigger dip than normal cuz it wouldn't stop, seemed like forever. It knocked stuff off the dash and when we finally opened the slides, everything was everywhere, fireplace front, sofa cushions, stuff in the cabinets over the sofa was on the floor.

Does anyone have a 2500/3500 SRW that had this happening but once they installed airbags, it didn't happen again? I'm wondering if airbags are the answer or it would continue to happen and the only option is to slow down or try to recognize the dips as you come up on them. I talked with my truck and trailer shop contacts and they said shocks probably would not help on the truck, that airbags may be the way to go. I remember putting airbags on my Ram 1500 towing 7k was still bouncy. Wondering what the best thing to do is?????? (and don't say get a dually cuz I already know that would solve the problem, lmao!!)

[Slurugger]

I had a F250 towing a 377RLBH (16k lbs) with air bags and it was bouncy at times. I know you don't want to hear it but going to the F450 was a game changer in terms of stability. Both from left to right and a bouncy perspective. When you hit rough spots the truck commands the trailer and keeps it in line with limited bouncing. I'm not an engineer so I can't explain the how, I can only speak on my own experiences.



Having said all of that, nothing can totally overcome the fact that our highways are falling apart in many locations...

[Jagiven]

I have no 5ver experience. But it almost sounds like the pin weight might be to light.

Have you ran across a CAT scale? Both fully hooked up road ready, and just the TV.

[TxLoser]

I’ve got a FW that’s just a bit lighter than yours and Chevy 3500 SRW. I’ve hit some bad dips and bumps, but usually it’s one oscillation and done. Yes, roads are terrible these days.

Could it be coming up off the Timbrens and then bouncing on them. I’d pull the Timbrens and find some rough highway for a test tow to see how it does. Depending on miles on the truck, it could also be time for new shocks if you’ve not already done this.

[rkymntsno]

Originally Posted by Jagiven

I have no 5ver experience. But it almost sounds like the pin weight might be to light.

Have you ran across a CAT scale? Both fully hooked up road ready, and just the TV.

Yes. Loaded the pin weight is around 3100# as I calculate it. All still within payload.

[rkymntsno]

Originally Posted by TxLoser

I’ve got a FW that’s just a bit lighter than yours and Chevy 3500 SRW. I’ve hit some bad dips and bumps, but usually it’s one oscillation and done. Yes, roads are terrible these days.

Could it be coming up off the Timbrens and then bouncing on them. I’d pull the Timbrens and find some rough highway for a test tow to see how it does. Depending on miles on the truck, it could also be time for new shocks if you’ve not already done this.

That's a good point about the Timbrens and yes that could be happening. The axle rides on the Timbrens when towing the 5'er as designed. I guess it's possible it's bouncing off the Timbrens and then back onto the Timbrens until it levels out. That could be a good test on my next trip to take them off and see the difference. I have a softer set of Timbrens also they sent me I could try. Shocks seem fine, 43k on the truck. Thanks for the info!

[RedHorse1]

I put Timbrens on my F350 and they’ve been great. Our 5th tips in at 13,000# with 3,000# of that on the pin and they help with the squat (I installed them for that reason). I’d suggest taking a peek at them loaded and unloaded to insure they have the prescribed gap when unloaded (I don’t remember what it is). I studied the install a bit before deciding whether to use the included spacer (may have been more than per side, jus don’t recall). I suspect mine may make contact when unloaded after hitting a big bump but not when on the usual “rough n tumble”.

[rkymntsno]

Originally Posted by RedHorse1

I put Timbrens on my F350 and they’ve been great. Our 5th tips in at 13,000# with 3,000# of that on the pin and they help with the squat (I installed them for that reason). I’d suggest taking a peek at them loaded and unloaded to insure they have the prescribed gap when unloaded (I don’t remember what it is). I studied the install a bit before deciding whether to use the included spacer (may have been more than per side, jus don’t recall). I suspect mine may make contact when unloaded after hitting a big bump but not when on the usual “rough n tumble”.

When I installed them it had the required gap unloaded, about an inch or more. Didn't need the spacers.

[herewego]

We have the 3500 Ram SRW never had a issue like that, but i don't tow over 60 anyway

[rkymntsno]

Originally Posted by herewego

We have the 3500 Ram SRW never had a issue like that, but i don't tow over 60 anyway

Looks like yours is a trailer, you wouldn't have 3100 pounds of kingpin weight.

[craigav]

I would go ahead and change out the rear shocks anyway. Once you start bouncing as you encountered, it is the shock absorbers that dampens the bouncing.

While you certainly may have shocks that are just as good as new, however almost every factory oem shock is a balance between being too firm vs being too soft, which relates to the weight that they are damping (more weight more inertia). In any case they mfgs compromise here to meet the most owner's needs. Also, the stock shocks most commonly have a single level of dampening which mean the same dampening on a smooth road vs rough road, loaded vs unloaded results in the same dampening.

If you go with a shock like this (there are likely other manufactures... koni maybe), then these can make a big difference as what these do that almost all oem shocks don't do, is these become much more firm (more dampening) when hitting a big bumps or other similar situations that would cause uncontrolled bouncing. Once those conditions no longer are occurring the shocks become less firm allowing for a smoother ride on a smoother road.

I will say though that the cause of the bouncing may still exist after installing new shocks so pin weights, tire pressures, and all other factors should be considered, but if such a bounce does occur again, having shocks that have more dampening capability will certainly be of value to stop the bouncing more quickly, especially considering that you would also have a smoother ride otherwise.

Also, disclaimer, I have used Bilsteins on my Ford E450 motorhome and my Chev 2500HD (which I pulled a ~30' 5th wheel with) and can report noticeable improvements on each and a much better ride overall, but I don't have any personal experience with a Ram pickup truck.

Bilstein 24-238533

https://cart.bilsteinus.com/details?...71853036048834

btw, just rambling, have you ever seen a road, highway, or interstate and right after a bridge sometimes you see a lot of oil stains on the road and then you hit a dip and up ahead maybe 30' another set of stains and you hit the next dip, followed by maybe another and another. All that oil indicates that many vehicles are hitting these dips and whatever they may have to drip off of the engine\transmission does so. In any case, with a 5th wheel sometimes the spacing of dips in a road could be at a frequency that makes it worse than would be otherwise. Better shocks could help a lot, but can only do so much, slower speed helps as well. ~CA

[Learjet]

Originally Posted by craigav

I would go ahead and change out the rear shocks anyway. Once you start bouncing as you encountered, it is the shock absorbers that dampens the bouncing.

While you certainly may have shocks that are just as good as new, however almost every factory oem shock is a balance between being too firm vs being too soft, which relates to the weight that they are damping (more weight more inertia). In any case they mfgs compromise here to meet the most owner's needs. Also, the stock shocks most commonly have a single level of dampening which mean the same dampening on a smooth road vs rough road, loaded vs unloaded results in the same dampening.

If you go with a shock like this (there are likely other manufactures... koni maybe), then these can make a big difference as what these do that almost all oem shocks don't do, is these become much more firm (more dampening) when hitting a big bumps or other similar situations that would cause uncontrolled bouncing. Once those conditions no longer are occurring the shocks become less firm allowing for a smoother ride on a smoother road.

I will say though that the cause of the bouncing may still exist after installing new shocks so pin weights, tire pressures, and all other factors should be considered, but if such a bounce does occur again, having shocks that have more dampening capability will certainly be of value to stop the bouncing more quickly, especially considering that you would also have a smoother ride otherwise.

Also, disclaimer, I have used Bilsteins on my Ford E450 motorhome and my Chev 2500HD (which I pulled a ~30' 5th wheel with) and can report noticeable improvements on each and a much better ride overall, but I don't have any personal experience with a Ram pickup truck.

Bilstein 24-238533

https://cart.bilsteinus.com/details?...71853036048834

btw, just rambling, have you ever seen a road, highway, or interstate and right after a bridge sometimes you see a lot of oil stains on the road and then you hit a dip and up ahead maybe 30' another set of stains and you hit the next dip, followed by maybe another and another. All that oil indicates that many vehicles are hitting these dips and whatever they may have to drip off of the engine\transmission does so. In any case, with a 5th wheel sometimes the spacing of dips in a road could be at a frequency that makes it worse than would be otherwise. Better shocks could help a lot, but can only do so much, slower speed helps as well. ~CA

I have had Timbrens before and never had this issue....I agree ^^^^ start with shocks on the rear axle of the truck.

[TWP723]

I've never had an episode like that with mine. I have airbags everywhere. lol

[norty1]

Never experienced that when I had Timbrens.

I installed mine and they have a very good Customer Service group. If you did not have that experience before, I would call them and explain what you describe.

[jetlag]

Our '21 3500 has the factory air ride, and so far, have not noticed anything like that. As someone else mentioned earlier, we tow slow as well, usually 65 and under.

[RJR]

We have a 2021 Pinnacle 36KPTS and tow with a 2021 Ford F350 SRW. We added Air Lift Air Bags to the rear with the onboard compressor and it tows like a dream. Been on many 2 lane rough roads with little to no bouncing.

[rkymntsno]

Originally Posted by norty1

Never experienced that when I had Timbrens.

I installed mine and they have a very good Customer Service group. If you did not have that experience before, I would call them and explain what you describe.

I did that and they are very helpful. They wanted to send me a softer pair of Timbrens, told them they had already done that when I bought them new so I asked them if putting the softer ones on might help. After talking with his engineering dept, he recommended doing that for now. So I added the softer ones thinking the stiffer ones kicked back too strong on the dip. Have a trip next weekend so we'll see. Figured I'd do this and if I still have problems, will end up putting air bags on.

Thanks for all the comments.

[Yooper906]

Originally Posted by rkymntsno

After talking with his engineering dept, he recommended doing that for now. So I added the softer ones thinking the stiffer ones kicked back too strong on the dip. Have a trip next weekend so we'll see. Figured I'd do this and if I still have problems, will end up putting air bags on.

Let us know how this works out, I'm interested.

[rkymntsno]

Originally Posted by Yooper906

Let us know how this works out, I'm interested.

Will do. I'll post an update when I know something, probably within a week or two.

[madmaxmutt]

It sounds like you are sure it was the rear of the truck. I would want to make sure it wasn't death wobble in the front suspension. I have heard that can feel like the whole truck shaking violently.

Short of that, I would be checking the rear of the truck and the trailer suspension for anything that looks amiss or loose. There have been several threads on here about broken suspension parts (hangers, springs, etc...), and one about a hub that sheared off the trailer.