Empty trailer shaking truck....

[Colorado04]

Here's the scoop...

Bought a used tilt boat trailer with old tires, bearings on the loose side and bent frame. Looked like someone overloaded it. I hauled it home behind the truck without issue. It tracked well and felt smooth.

So far, I have straightened the frame, moved the axle back 12" , put new tires and coupler on it. Haven't had a chance to tighten up the bearings yet.

I took it out for a test run last night and it shakes at +/-40 and +/-70 kph. It shakes so hard that if feels like the trany was going to fall out of my truck. It's like a harmonic vibration sort of thing.

The plan now is to tighten up the bearings and move the axle back to where it was and see if the shake goes away.

Anyone have any thoughts what might cause the shake?

 

[tashasdaddy]

Re: Empty trailer shaking truck....

would probably help if you balanced the tires. also empty trailers do bounce. you have no business towing a empty trailer a 70 anyway. the roads are rough, and there is no weight to keep the trailer on the ground.

 

[CATransplant]

Re: Empty trailer shaking truck....

Before you tow that thing again, pull the hubs and pack the wheel bearings, replacing any that are worn. You can't tell anything with loose or worn bearings. Once you do that, if the thing still shakes and vibrates, we can look for other causes.

Inspecting old wheel bearings, repacking them, and replacing any that are worn should be job one with any trailer, especially an old one with unknown history.

Other causes could be out of round or out of balance tires, bent tire rims, or loose lug nuts. An axle not square with the frame could also cause problems. Too light on the hitch could also add to the problem.

Still, if the bearings aren't good, then you won't be able to tell until you get them right.

 

[Colorado04]

Re: Empty trailer shaking truck....

Thanks for the input...

Will do on the bearings.

TD, do you really think towing a empty trailer at 70 km\h ( 44 mph ) is excessive? I have seen people towing empty trailers at speeds above 100 km\h ( 60 mph ) on a regular basis on the highways.

Just wondering...

 

[cgrooves]

Re: Empty trailer shaking truck....

Thanks for the input...
TD, do you really think towing a empty trailer at 70 km\h ( 44 mph ) is excessive? I have seen people towing empty trailers at speeds above 100 km\h ( 60 mph ) on a regular basis on the highways.

Just wondering...

I'm going to go out on a limb here and say that he read it as 70 mph.

tashasdaddy-
Feel free to tell me to stay out of it, if needed

 

[kenmyfam]

Re: Empty trailer shaking truck....

70kph should be O.K. if that is the case. Empty trailers sure do bounce around though.
Get those bearings packed and adjusted and try again.

 

[BMOLCHANY]

Re: Empty trailer shaking truck....

My first thought was the same as many others that empty trailers bounce like you would not believe. I am sure that once you put some weight on it that it will ride alot better.

 

[thunder219]

Re: Empty trailer shaking truck....

I know my old two place snowmobile trailer would about rattle your teeth out empty, but was smooth as can be loaded. I have only pulled my boat trailer empty once for a short distance and it also bounced a lot.

 

[reelfishin]

Re: Empty trailer shaking truck....

I had one trailer that would beat the truck to death when empty, a larger tandem axle Sea Lion. It bounced, shook and rattled so bad it was hard to see out of the mirrors. It was ok with a boat on but not great. The problem was that it was sprung to carry a larger boat and when empty it was like having no suspension. I sold it.

Check the obvious first, make sure you have some tongue weight when empty, make sure the bearings and tires are OK. Tire balance can help but they would have to be pretty far out of balance to be really noticeable. Make sure the suspension is moving and not seized up.

The worst trailer I ever towed was a home made boat trailer that came with an old flat bottom boat, it was made from the rear suspension of an old car, they used the torque tube as the tongue, which connected the tow vehicle directly to the trailers wheels, only the boat was on the sprung chassis. That thing nearly chattered my teeth out all the way from NC to NJ. The tires were tube type 16" nylon cord truck tires, which were flat spotted from being soft or flat for years. You could feel every last bump in the road that the trailer hit and every irregularity in the tires as well. To make matters worse, someone had welded each and every leaf spring together, in effect making it just about a solid suspension, then they built the boat trailer part on top of four coil springs. The boat was great but that trailer was destined to become a farm wagon, never to see road use again. The Massey red and Ford blue with John Deere green wheels were another special touch. It got lots of looks all the way home. It had no trailer lights, just two battery powered lanterns with their lenses painted red which had long ago died of battery leakage. The tags on it were from 1947, most likely just taken from the truck that donated the most parts.

 

[Colorado04]

Re: Empty trailer shaking truck....

Finally had a chance to get back to the trailer tonight. I did the bearings and put on known good tires from my utility trailer ( same size ). Then moved the axle back to where it was when I first got it. Took it out. No problems and no unwarrented shakes. Almost didn't feel it behind the truck. Got back to the house and moved the axle back 12 inches again to where I though might be good for when the boat is on there. Took it out again. Shakes were back. I'm no trailer expert, but as best as I can figure with the axle forward, the trailer suspension had more weight acting on it. With the axle back, there was more tongue weight transfering more force to the truck. I'm sure it will all change again when the boat gets on there.

Thanks everybody.

Donnie.

 

[ne7800]

Re: Empty trailer shaking truck....

would probably help if you balanced the tires.

aggred balancing the tires is the first place to start

 

[j_martin]

Re: Empty trailer shaking truck....

You must be running with very little tongue weight. It takes some weight to keep the ball centered in the hitch. If it walks, it'll shake back and forth like a dog with a rag doll as it hunts for center.

Rule of thumb is 10% of total weight on the ball.

hope it helps
John

 

[Colorado04]

Re: Empty trailer shaking truck....

How do you guys get your tires balanced. Do you use a static balancer or a machine that spins them like car tires?

 

[Gary H NC]

Re: Empty trailer shaking truck....

Balance them just like car tires.
Static is better than no balance but the spin type machines the tire shops use do a good job.Weights on the inside or outside of the rim is fine.

 

[guy74]

Re: Empty trailer shaking truck....

By chance is your trailer constructed from channel (C) iron, or is it tubing. It's kind of the nature of channel iron trailers to flex, and sometimes they get a wild ocillation to them when the boat isn't there to stifffen the trailer. My trailer is a channel iron frame, it really shakes and twists when the boat isn't on it. Channel iron frame trailers are strong, but not very stiff.

 

[Colorado04]

Re: Empty trailer shaking truck....

Yes it is made of C channel steel. Thanks for the "heads up". You guys are the best.

 

[DJ]

Re: Empty trailer shaking truck....

By chance is your trailer constructed from channel (C) iron, or is it tubing. It's kind of the nature of channel iron trailers to flex, and sometimes they get a wild ocillation to them when the boat isn't there to stifffen the trailer. My trailer is a channel iron frame, it really shakes and twists when the boat isn't on it. Channel iron frame trailers are strong, but not very stiff.

Yup. A big tuning fork.

Moving the axle back changed the entire frequency. You could probably eliviate it by strengthening the tongue.

 

[bassboy1]

Re: Empty trailer shaking truck....

Trailer doesn't have coil springs does it? I picked up a small 12 foot aluminum on a real light trailer (whole load with boat on was probably 200 pounds) that had coil springs in a 2500 series Suburban. Coming back at highway speeds, that trailer had some sort of harmonic vibration that shook that 6500 pound vehicle like you wouldn't believe. It was just a rumble felt in the steering column, or anywhere in the car. Kept stopping to check and see if a tire was going bad, or if it was a goofy road road surface. Only thing we could think of was the coil springs. Dad says it was significantly worse when we took 100 pounds of boat off.

 

[Colorado04]

Re: Empty trailer shaking truck....

The trailer has leaf springs. But I hear ya about the vibrations at certain speeds. Like DJ and Guy74 said....a big tuning fork.