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05-24-2021, 02:11 PM
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#1
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Junior Member
Join Date: May 2021
Location: Jackson
Posts: 2
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porpoising
We are towing a Bullet 258 (55k empty 30') tt with a Ram 2500 6.7 Cummins diesel as our tv. We use an Andersen wdh. We originally had a Sierra 1500 as the tv and thought the porpoising may have been due to that tv. The Ram sure pulls much more efficiently but we are still experiencing what I feel is unacceptable bounce especially on concrete highways. We just returned from our first trip with this setup and while traveling Rt 27 near Montauk NY we thought our teeth were going to come loose. I have not actually taken any weight measurements but have tried many different positions and tensions with the Andersen. Any recommendations on setup or a better wdh? Would adding airbags help?
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05-24-2021, 02:48 PM
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#2
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Senior Member
Join Date: Oct 2014
Location: Germantown, TN
Posts: 6,327
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Bzinky, first, welcome to the forum. You have a great plenty truck to tow that RV and no, air bags will not do the trick. I am more experienced with 5th wheels, but I believe you should start from scratch and take your rig across your friendly CAT scale. You will need to take three passes, one for $13.00 and 2 reweighs for $3.00 each. First pull up and put steer axle (front wheels) on the front concrete pad, your drive axle (rear wheels) on the second concrete pad and your RV axles on the third (last) concrete pad. Have that weighed and get your slip. Then remove your bars and tell them to weigh again. (another $3.00)
At that point, tow your RV to a handy dandy empty spot and return and just weigh your truck, steer on the first pad and drive on the second pad.
If you will, post those tickets for us to read and I can assure you there will be a minimum of four members here who can pinpoint your problem. I guarantee...
__________________
Jim in Memphis, Wife of 51 years is Brenda
2019 F450 6.7 Powerstroke
2018 Mobile Suites 40RSSA
2021 40' Jayco Eagle
2001 Road king w/matching Harley sidecar
2021 Yamaha X2 Wolverine 1000
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05-24-2021, 04:00 PM
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#3
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Site Team
Join Date: Oct 2011
Location: Joppa, MD
Posts: 11,741
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As suggested visit the scales. Too little tounge weight can contribute to what you are describing. The tonmgue weight should be somewhere between 10-15% of the total trailer weight.
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Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
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05-25-2021, 01:27 PM
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#4
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Senior Member
Join Date: Nov 2012
Location: Fruitland
Posts: 3,357
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My take may be different so I am up to listening to others. I have experienced both porpoising and bounce. Poster mentioned both.
Porpoising has happened to me with a full size truck in bed camper, pulling a large boat and driving into strong head winds. It feels like the front axle is to light as the front of the truck keeps going up and down. Slowing down until it stopped porpoising stopped all that. In my case it was a 1 time event. Dropping to 45 from 65 was the trick.
Bounce I get is due to the roadway empty or loaded driving over the same road the back of the truck bounces. Here it is the cement joints between the wore out cement surface that is the cause. I do not feel the bounce in my wifes small car nor the H3 at same speeds on same road.
So, just saying it may not be RV related.
__________________
2013 24RKSWE (27ft TT) Cougar 1/2 ton series SOLD 10-2021
2013 Ford F350 4x4 CC 6.7 engine, 8 ft bed, 3.55 rear end, lariat package
Retired from Oregon State Police in 2011 than worked another 9.5 years as a small town traffic cop:
As of 05-2020, I am all done with 39 years total police work. No more uniforms for me.
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05-25-2021, 02:41 PM
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#5
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Site Team
Join Date: Feb 2014
Location: W. Texas
Posts: 17,669
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Like Ken mentioned, maybe it's the road surface and not the truck/trailer setup? You said your previous truck did it and now this one does it. Have you ever been over the problem road before when it didn't happen? "Porpoising" leads me to think a rhythmic type of undulation like concrete/asphalt joints. I've had what you describe happen to me a few times, to the point of literally felling like my teeth were coming loose as you describe. The worst was pulling with a 1/2 ton but I still felt it in a 3/4. Nearly always it's on a concrete highway. When it is happening have you looked at the highway to see if there are joints as you feel that porpoise motion?
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Danny and Susan, wife of 56 years
2019 Ram 3500 Laramie CC SWB SB 6.4 4x4 4.10
2020 Montana High Country 331RL
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05-25-2021, 03:20 PM
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#6
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Senior Member
Join Date: Aug 2020
Location: Upper Chesapeake Bay
Posts: 4,819
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I hope you all can forgive me .. all I can think about when you mention porpoising ...”it’s not a porpoose”!
__________________
2020 Cougar 315 RLS
2020 Ram 3500 6.7HO 4.10 Dually Aisin
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05-25-2021, 03:36 PM
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#7
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Senior Member
Join Date: Jan 2013
Location: Indiana
Posts: 2,705
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There is a country road near my home where the speed limit is 45 mph. No one ever drives 45 on this road, more like 60. I'm no exception... until one day.
Driving in the traditional SUV I never noticed anything unusual about this road. Oh, it seemed a little "bouncy" but it also has lots of slight dips in the road which made driving the road a lot of fun... especially at faster speeds.
Now one day I had the travel trailer in tow and turned on the same road accelerated to speed. 45 - 50 - 55 and then ... OH MY GOSH! The truck started bouncing up and down and the trailer hitch was actually banging on the asphalt road. I slowed way down and then realized WHY the speedlimit was posted at 45. At 45 I could safely tow. There was some roller coaster up-s and down's at 45, but nothing made contact with the road.
I think that is the reason for the porpousing? (however it's spelled). The road conditions get the truck and trailer into a rythem, cuasing the up and down pattern to the point it becomes near impossible to control. The only solution is to slow down.
That is different than hard hits at bridge transition joints. Those will just tear your truck and trailer up. You don't feel it in the family car, the suspension is just too soft. Attach a trailer and everything get's heavy. And the basic law of physics, the harder the object, the harder the hit! (or so it feels). Nothing gives... like in a softer suspension on the family car. Again, the only solution is to slow down.
__________________
2019 Montana High Country 375FL
2014 Chevy Duramax HD 6.6 - 3500 Diesel Dully Long bed Crew Cab
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05-25-2021, 04:26 PM
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#8
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Senior Member
Join Date: Aug 2020
Location: Upper Chesapeake Bay
Posts: 4,819
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Could a problem with trailer tires or trailer suspension cause this? A broken belt in a tire or tire out of balance ? Proper air pressure ?Not sure of age of op’s trailer
__________________
2020 Cougar 315 RLS
2020 Ram 3500 6.7HO 4.10 Dually Aisin
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05-26-2021, 04:02 AM
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#9
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Junior Member
Join Date: Apr 2019
Location: Laquey
Posts: 20
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My truck was bought used and the struts were well worn as well as the rear shocks. Replacing them helped to reduce this effect and made my setup more stable and reduced this effect.
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05-26-2021, 02:54 PM
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#10
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Junior Member
Join Date: May 2021
Location: Jackson
Posts: 2
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Tt is a 2021. Tv is 2019. I did check tire pressure so I think I'm good there
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05-27-2021, 05:14 AM
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#11
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Senior Member
Join Date: Sep 2019
Location: Florissant
Posts: 698
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Everything “elastic” has natural resonance. Tires, metal frames, weight distribution bars, etc. There is a such thing as additive resonances (like 220 voltage). This is the purpose of shocks on the tow vehicle — to dampen the motion. The joints in the concrete may be at the interval where at a certain speed, it is causing the porpoising. Just a little theory here, no solutions.
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Skids
2019 Bullet 248RKS
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05-27-2021, 05:49 AM
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#12
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Senior Member
Join Date: Nov 2012
Location: Fruitland
Posts: 3,357
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The easy test as suggested by 2 posts, drive on the same road in a passenger car/suv. I did a little research and found 1 company that makes balancing devices that go on each wheel to reduce rear end bouncing. But my opinion is they might work if it's the trucks problem. Not sure they would do a thing with a wore cement roadway.
__________________
2013 24RKSWE (27ft TT) Cougar 1/2 ton series SOLD 10-2021
2013 Ford F350 4x4 CC 6.7 engine, 8 ft bed, 3.55 rear end, lariat package
Retired from Oregon State Police in 2011 than worked another 9.5 years as a small town traffic cop:
As of 05-2020, I am all done with 39 years total police work. No more uniforms for me.
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05-27-2021, 11:21 AM
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#13
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Junior Member
Join Date: Mar 2012
Location: Atlanta
Posts: 14
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I had the same problem. I dropped the trailer tire pressure from 80 to 68 psi. That has helped a great deal. There are still spots were I have to slowdown but not many and I do not have to slow as much.
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05-27-2021, 12:02 PM
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#14
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Senior Member
Join Date: Nov 2017
Location: Picacho, Az
Posts: 6,809
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Quote:
Originally Posted by STLCG
I had the same problem. I dropped the trailer tire pressure from 80 to 68 psi. That has helped a great deal. There are still spots were I have to slowdown but not many and I do not have to slow as much.
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The issue with that solution is that you've created another one possibly causing more expensive issues than just a bad ride. By lowering the psi of your rv tires you've also reduced their load carrying rating by several hundred pounds increasing the risk of a blowout due under inflation.
__________________
Full-timed 10+ years
Sold '13 Redwood FB
Traded '13 GMC Denali DRW D/A
Replacement undetermined
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05-27-2021, 12:06 PM
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#15
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Member
Join Date: Aug 2019
Location: Houston
Posts: 74
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Try a set of Timbrens on the truck. Really helped in pulling our 35' TT behind the F-250.
Griz
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05-27-2021, 12:11 PM
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#16
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Site Team
Join Date: Mar 2011
Location: Gaylord
Posts: 26,979
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Quote:
Originally Posted by STLCG
I had the same problem. I dropped the trailer tire pressure from 80 to 68 psi. That has helped a great deal. There are still spots were I have to slowdown but not many and I do not have to slow as much.
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Quote:
Originally Posted by travelin texans
The issue with that solution is that you've created another one possibly causing more expensive issues than just a bad ride. By lowering the psi of your rv tires you've also reduced their load carrying rating by several hundred pounds increasing the risk of a blowout due under inflation.
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Sort of like saying, "I shot myself in the foot so my broken arm doesn't hurt any more".....
__________________
John
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
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05-30-2021, 07:32 AM
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#17
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Senior Member
Join Date: May 2017
Location: CT frontier
Posts: 154
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As you can see from my sig I’m towing a Cougar 21rbs with a 3500 Ram. I also have the Anderson wdh. It’s the only travel trailer I’ve ever owner, so I have no frame of reference with other hitches. I think the Anderson does an excellent job with sway, but I’ve never been totally convinced of the weight distribution part of the equation, because of the chains instead of bars. I sometimes get a little more bounce on concrete sections of interstates than I think I should. But the hitch is easy for DW and I to hook and unhook, and like I said I think it’s great at preventing sway.
__________________
2017 Cougar XLite 21 RBS
2015 Ram 3500 SLT 5.7 Hemi
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05-30-2021, 11:45 AM
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#18
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Senior Member
Join Date: Oct 2018
Location: Fort Collins
Posts: 125
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I am also towing a Cougar 21RBSWE using a Anderson wdh but with a 1/2 ton. I was experiencing porpoising on uneven roads particularly over bumps. I put a bit more tension on the Anderson hitch chains and that has helped. I am also a bit light on the tongue weight at 740lbs when loaded at a 6,600lb TT weight, which may also be contributing to the problem.
__________________
2012 Cougar 21RBSWE
2018 GMC 1500 5.3L, 4x4, crew cab, max tow pkg
Andersen Hitch
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05-30-2021, 02:26 PM
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#19
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Senior Member
Join Date: May 2018
Location: Markham, Ontario
Posts: 1,942
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When I had my TT and the 1500 Sierra I found that if I tightened up my Blue ox by one link and ran air bags at 30 psi there was no issue. It took some time to dial it in. I started at 20 psi, and 8 links. Went to 9 links and was better. Added 10 psi and was non existent.
My fresh water tank was at the front of the trailer and usually had around 10 gals.
__________________
Dan & Serena
2019 GMC SIERRA 2500 HD SLE
2015 Cougar X-Lite 29 RET
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05-30-2021, 05:33 PM
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#20
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Junior Member
Join Date: Jul 2014
Location: Salina Ks,
Posts: 7
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I have a 39' Outback trailer and Anderson hitch. It took me a while after scaling the truck and trailer several times to figure out different configurations of water storage, and stuff in the trailer to get the tongue weight in the sweet spot. I also will tighten up the hitch when the tongue gets heavy and it really quiets the bouncing down.
I always keep my trailer and tow rig tires at the maximum recommended pressure.
You will see it recommended here and on most forums to keep the tongue weight between 10 to 15% of your trailer weight, and keeping the trailer level or slightly "nose" down. These factors will allow your suspension to do its job like it was designed and make for a better ride.
Having said that, some roads just will kick your butt, and you have to slow down.
__________________
Erik Clark
2021 Outback 340BH, 2015 F350srw 4X4 6.7
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