stop the Bucking!

[MacMcCaskie]

On a recent trip we ran into a few spots on the highway when the rig started to buck violently (hitch moving up and down rapidly). The TV is a Toyota Tacoma Pre-runner with tow package, and the trailer's a star-craft popup. BTW, the tire air pressure was low on the trailer.

I'll be getting a lighter TT soon and wondered if I will need something such as a weight distribution hitch to stop the bucking. Or was it all due to the tire pressure?

[djsamuel]

KenNTennessee wrote:
I appreciate the responses. TomG2, I was not familiar with the Anderson hitch, so after reading about that, it sounds like a better investment than a new set of Blisten Shocks. I appreciate the comments about load and speed also. I do understand the harmonic issue, but when you need to make 600 miles in one day (getting home with the new trailer) you really do not want to drastically drop the speed for hours and increasing speed is out of the question due to fuel economy. I was driving between 60 to 65 mph, so to change the harmonic I would probably need to go 10 mph different one way or the other. Anyway, I think I'll look into the Anderson WDH a bit more as it seems to be the only one with anti-bounce.

Just made our first trip with our Andersen hitch (at the campground now). It was only a short tow of 30 miles, but so far I'm really impressed. I'll try a slightly different setting on our trip back, but the truck and trailer really tow well now.

[Jmactootall]

Had the bucking happen to me on I81 North bound near Scranton for about 20-30 miles of a 342 mile run that day. I stopped and checked my set up and it looked Ok. I was going to look for a dealer but it stopped. That was the only time it happened on a trip of about 3000 miles during 6+ weeks. South bound over same road was not a problem.

[easycamper]

For such a common problem, no one seems to have come up with a solution for bucking/chucking that works in all cases.

1. Definitely it's a result of resonance at particular frequencies, so adjusting your speed is an instant solution when driving over pavement joints, but it's less successful when driving over more random bumps.

2. Anything which stiffens the suspension helps. It might make bumps more noticeable, but that's usually less irritating than chucking. So this includes transfering weight to the front of the trailer or rear of the truck, higher tire pressures (within safe limits), tires with stiffer sidewalls, firmer shocks.

3. I've never tried one, but I think the special pin boxes designed to reduce chucking can be hit or miss. They work in some cases but not in others. In some cases they can make things worse.

So the best approach is to start with the cheap/simple fixes (adjust speed, shift weight, adjust tire pressures) and then progress to the more costly ones.

[JIMNLIN]

As the OP I get severe bucking with all of my trucks and a 20' bumper pull 12k flatdeck trailer if my 8000 lb tractor is loaded to far aft which causes light hitch weights. I move the tractor forward for more hitch weight and no more truck bucking.

[heavyodie1]

Had the same issue on concrete roads in Indiana. Slowed down, sped up no change. When we reached our destination I increased tire pressure and went to Walmart and bought six bags of water softener salt and put in the front compartment of the trailer. On the return trip the ride was a little bit smoother but still not great. I have since purchased an Anderson hitch but have not traveled the same stretch of road to see what the results are.

[KenNTennessee]

I appreciate the responses. TomG2, I was not familiar with the Anderson hitch, so after reading about that, it sounds like a better investment than a new set of Blisten Shocks. I appreciate the comments about load and speed also. I do understand the harmonic issue, but when you need to make 600 miles in one day (getting home with the new trailer) you really do not want to drastically drop the speed for hours and increasing speed is out of the question due to fuel economy. I was driving between 60 to 65 mph, so to change the harmonic I would probably need to go 10 mph different one way or the other. Anyway, I think I'll look into the Anderson WDH a bit more as it seems to be the only one with anti-bounce.

[goducks10]

1000lb bars are a bit much for 670lb TW. I know you were empty but more than likely once you get loaded up your TW will be 800lbs which is more in line with the WDH. With 670lbs you really don't even need WDH except to cover the receivers rating. Using the 1000lb bars probably made things worse. You could always load up 200lbs of stuff in the front and experiment.

SDcampowneroperator, has a good point also.

[SDcampowneroper]

Its not so much weight of rig, it is distance between tv axles and tl axles, weight distribution . At a given speed, there will be a harmonic resonance between the pavement expansion joints and your unit correlated to your speed. All you can do to minimize the effect is to adjust your speed faster or slower to negate the resonance.

[TomG2]

Most of us who use the Andersen No-Sway hitch benefit from the reduction in porpoising also. The compression of the bushings can be tuned to eliminate most, if not all of this irritating behavior.

[KenNTennessee]

Just bought a new dual axle TT, towed it empty (4950 lbs, 670 lbs TW =13.5% ) with my 2012 GMC Sierra CC Z-71 XLT with tow pkg rated at 9600 lbs. All tire pressures were correct, both the TT and TV were level using a WDH rated at 1000 lbs TW. When towing on I-65 in Indiana, we experienced severe porposing. Temp was -6 to -12 and expansion joints in concrete were buckled up. When we got on asphalt sections, it stopped completely.
I've towed our old dual axle TT (loaded was 4850 lbs, 487 lbs TW) over 15,000 miles with the same setup over some pretty rough roads and never experienced that before. It almost seemed that the WDH (EZLift) was aggravating the situation, but I can't prove that. This trailer is 6 feet longer and about 600 pounds heavier, and has a higher percent of the weight on the hitch. I need to solve the problem before setting out on a 8000 mile trip we have planned for this summer. The dealer helped me set the WDH tension which brought both the TV and the TT to level, so I'm assuming that's set right. Any help would be appreciated.

[mlts22]

When I hit 130 (a toll road that bypasses Austin made for the NAFTA trucks... but never used by them) with my TT, it is a cheap alternative to hitting a roller coaster. The length of the cement blocks has a resonance effect causing a pronounced up/down motion. That, I don't worry about (I just slow to 55 or so)... now, side to side motion is something scary that I don't want to see or feel.

[nolra]

A cheap set of air bags will work wonders, especially if you add some tongue weight and tires to match.

[mobeewan]

Porpoising is caused by not enough weight on the tongue. As you go over bumps the front of the trailer bounces up lifting the rear of the TV. The only time I ever had the trailer porpoise on me was not enough weight on the tongue after boon docking during hunting season. I was returning home with an empty FW tank in front of the axles and an over half full black tank at the rear of the trailer. I hit a section of uneven concrete a couple miles from my exit coming home and the bucking started. The next time coming home I moved weight forward to compensate for the back tank weight and didn't porpoise near my exit like before.

[goducks10]

I had bucking with a Heartland 26LRSS and towed it with two different trucks. 1st was a 2010 F150 MaxTow 2nd was a 12 Ram 2500 CTD. Used several different types of WD's. Never got rid of the bucking/proposing. I came to the conclusion it was a bad design by Heartland. The TT had the WideTraxx axle spacing but they were placed more towards the middle. Fresh water tank was behind the axles. I had a TW of 900-950lbs. Roughly 12%. Took everything I could do to get it that high.
The Ram has a 169"wb and the F150 had a 145"wb. Neither the trucks suspensions or WB had any effect on bucking. It bucked on small bumps or large bumps. After 2-1/2 yrs and 10,000 miles I gave up and went the 5'er route. That got rid of the porposing:)
If it were as simple as a WB issue then why do the similar WB/TT combos tow nicely. I think some frame makers (Lippert) don't build them as well and some TT makers don't do their home work enough with floor plans. Our TT had a 9% TW from the factory, as a newbie that didn't ring a bell. Live and learn I guess.

[JiminDenver]

There are a few stretches between Denver and where we boondock that cause bucking. It does it both ways with the fresh water being full on the way there and the waste tanks in the rear on the way home. We have stopped and tightened/ loosened the bars with little if any change. It just happens.