# Trailer bounce problems



## moopups (May 12, 2002)

Its a 16 foot bed, tandum, Dexter axels, converted travel trailer frame, decked with 2 by 6's. Loaded its fine but empty it bounces, in a repeated pattern of 3's. I think its a tire balance problem.

I know how to check the heavy side, spinning the tire, chaulking the bottom for rechecking; but how do you know how much weight to install? This is for an 'at home' request, I am moving and funds are not pleantiful.


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## agmantoo (May 23, 2003)

I do not have the answer as to how to determine the size of wheel weights. I would check the following however, tongue weight, a few hundred pounds of tongue weight will make the trailer behave better. tire inflation, when empty too much air will make a light trailer bounce. out of round tires and bent rims, this you can check when you spin the tires/wheels. Any chance that you can rig a means to spin the tire/wheel at a higher speed than by hand? This would possibly identify the wheel(s) with the problem.


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## Guest (Dec 13, 2005)

I have a similar problem with a little single axled 10' trailer. The axle is directly centered in the middle of the bed and it has a short tongue. Loaded or Unloaded, it pulls alright until you reach about 45 mph and then it starts teter totering back and forth from one side to the other. Really scary, it makes you think the trailor is going to flip over onto one of its side. It's a bummer to have to drive so slow on the highway to keep from wrecking. I think I need a longer tongue on it, but not sure if that is what the problem is.


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## agmantoo (May 23, 2003)

Check the trailer to see if there is any toe in. The front side of the tires should be closer than the back side. I think the wheels are set exactly parallel which is incorrect.

Edit....I was unclear with this response, it was intended for RH above


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## ace admirer (Oct 5, 2005)

ok, on tag along, two axle trailors, 200 lbs min. on tongue. when loaded, 10% of load should be transfered to hitch. example: 4000 lb load, 400 lbs + 200 unloaded total 600 lbs. deflating tires helps with trailor bounce when unloaded, (carry a compressor to reinflate tires before loading). the bounce may just be a factor of sprung weight vs stiffness of the springs.

my guess is that balancing in not a factor, or not much of one. if the wheels are the type that use wedges, care has to be exercised to keep wheels both concentric and aligned as the lugs are tightened. 

tow in problems will make a trailor sway as one side hits bumps, so will caster and camber. but i think his problem is bounce not unstablility. the three bounce thing is something i hear when i pull my trailor unloaded with tire pressure above 60 psi. if it were tire balance the trailor wound continously bounce (worse at certain speeds)

and finally, all combinations of truck/trailor/load will become unstable at some speed, even when properly loaded. 

Abook written by M. M. Smith (Trailers, how to design and build), northern tool, gives a lot of information of trailor basics.


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## moopups (May 12, 2002)

The running gear is factory original, the frame was a travel trailor, not modified any way. Factory specs. About 25 years old - Dexter set up - still bouncing when empty. Feels like a 150 mile horse ride.


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## Janon (Aug 25, 2002)

Since its a tandem axle - you may want to remove the wheels from one axle at a time, and take the trailer for a short test run. This may help isolate the axle/wheels which are causing the problem. All of this is assuming that its safe to pull the trailer minus two of the wheels.

cheers,


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## foxtrapper (Dec 23, 2003)

Drop your tire pressure when empty.


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## agmantoo (May 23, 2003)

Moopups, do you think the trailer axle position was calculated as to the position of the load when it was a travel trailer and now the center of balance has shifted due to the modification?


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## ace admirer (Oct 5, 2005)

I think thats a good observation, Agmantoo,. in a way the trailor has been "highly modified" by changing its whole purpose. i would think that a travel trailor is lightly and fairly consistantely loaded. while an equipment trailor is very variable in its loading. but again it bounce not laterial stability that he is complaining of....i still think bounce is a function of spring rate (both tire and steel)

also Dexter sells over 158 combinations of hubs, axles, springs and suspension systems so again not sure of wheel mounting or trueness. i do know that i have never balanced a trailor tire and i've got trailors out the.....well i've got a lot of trailors.


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## twohawlks (Oct 14, 2003)

If it only bounces when the trailer is empty I would think that the springs are too stiff, you said this is made from a travel trailer which probably was fairly heavy and you are using the same springs.Taking a leaf out of the springs might help.


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## Jack Parr (Sep 23, 2005)

r.h. in okla. said:


> I have a similar problem with a little single axled 10' trailer. The axle is directly centered in the middle of the bed and it has a short tongue. Loaded or Unloaded, it pulls alright until you reach about 45 mph and then it starts teter totering back and forth from one side to the other. Really scary, it makes you think the trailor is going to flip over onto one of its side. It's a bummer to have to drive so slow on the highway to keep from wrecking. I think I need a longer tongue on it, but not sure if that is what the problem is.


You need to move the axle rearwards. I would go to about 6' of the trailer deck IN FRONT of the axle at least. There should be an accurate formula somewhere on the net. Do a Google.

Is your trailer homemade? 

Yours is a very dangerous situation. I have been there. In fact just a few weeks back. My trailer is a 16 footer and is axled OK but I loaded some 25' lengths of steel on it and had to drive 35 mph or else the trailer did as you described. I knew that would happen so I was prepared and drove accordingly. 

Trailers can be dangerous if improperly loaded also. A trailer loaded too haevy behind the axle can do the same even if it is properly axled.

Take care and good luck.


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