Trailer Sway, any thoughts?
- Thread starter fctadam
- Start date
- Views: 4965
755inNY
Platinum Member
- Joined
- Jul 4, 2003
- Messages
- 530
- Tractor
- JD 4310, ehydro, 4WD, R4s
I agree with the other responses. Not enough tongue weight. You mentioned that the truck hardly squats at all. With your estimated 7500 pound total load you should have 750 to 1100 pounds of tongue weight. Add a couple of hundred pounds to the tongue (strap down something heavy on the front of the trailer or in the bucket of the tractor) and make a few test runs.
I recall trying to haul long lumber on a snowmobile trailer resulting in negative tongue weight. I threw a few concrete blocks on the front to weigh it down but it still was not enough. At 25 mph or below everything was fine but as soon as I went over 25 the trailer started to sway almost instantly and quite severe. Fortunately I was on a back road posted at 35mph and did not have to go far.
Jeff
I recall trying to haul long lumber on a snowmobile trailer resulting in negative tongue weight. I threw a few concrete blocks on the front to weigh it down but it still was not enough. At 25 mph or below everything was fine but as soon as I went over 25 the trailer started to sway almost instantly and quite severe. Fortunately I was on a back road posted at 35mph and did not have to go far.
Jeff
surfran
Platinum Member
It sounds to me like not enough tongue weight. I would try loading it with the rear of the tractor on the front of the trailer.
You want 10-15% of the weight in front not exceeding your max tongue weight.
My BX doesn't weigh as much, but how I determined the place to park it was to step on the bumper of my truck with the trailer empty and measure the drop with my weight so I have an idea of how much 220 lbs tongue weight will drop it.
I do this by using my adjustable rollers for my miter saw and set them to the bumper height before loading. Then I drive tractor on the trailer and watch the drop of bumper relative to the stand. When it equals my weight I know that I am good (in my case for the BX, yours would probably need more than the 220 so maybe add some known weights like sand bags and yourself one time to get an approx. measurement).
Anyhow you do not want to be swaying and end up wrecking your trailer. I did it ONCE and NEVER want to do it again.
As for resizing your pics, you can use a free ware program called Pix Resizer. Below is the link. It works really well.
Pix Resizer Website
You want 10-15% of the weight in front not exceeding your max tongue weight.
My BX doesn't weigh as much, but how I determined the place to park it was to step on the bumper of my truck with the trailer empty and measure the drop with my weight so I have an idea of how much 220 lbs tongue weight will drop it.
I do this by using my adjustable rollers for my miter saw and set them to the bumper height before loading. Then I drive tractor on the trailer and watch the drop of bumper relative to the stand. When it equals my weight I know that I am good (in my case for the BX, yours would probably need more than the 220 so maybe add some known weights like sand bags and yourself one time to get an approx. measurement).
Anyhow you do not want to be swaying and end up wrecking your trailer. I did it ONCE and NEVER want to do it again.
As for resizing your pics, you can use a free ware program called Pix Resizer. Below is the link. It works really well.
Pix Resizer Website
Joe1
Platinum Member
Inadequate tongue weight is most likely the problem, the second possibility is uneven trailer tire pressure from side to side. I assume the trailer is loaded evenly side to side, so that should not be a problem. I would also recommend backing the tractor on.
The sure way to find out the problem is to weigh the truck/ trailer in total. Pull forward and weigh only the weight on the trailer wheels, then weigh the truck by itself. Total truck/trailer weight minus the truck weight alone, minus weight on trailer tires alone equals tongue weight. You might be able to weigh the total trailer on the scale then just the tongue weight, but that takes some time, and the scale operator might not want to take that much time. Tongue weight should be a MINIMUM of 10 - 12 % of total trailer weight on the tongue, up to 15 % would be OK, not to exceed the capacity of the hitch.
A long bed truck places the trailer ball pretty far back from the axle. The greater the distance, the greater chance it will sway. If you're just using a ball hitch and no equalizer bars, it will have a tendency to sway more.
Adding weight to the truck bed might help but is a band aid approach. The truck rear tires must also be adequately and evenly inflated to prevent sway. I doubt the truck is the problem; I'd bet it's inadequate tongue weight.
Good Luck
Joe
The sure way to find out the problem is to weigh the truck/ trailer in total. Pull forward and weigh only the weight on the trailer wheels, then weigh the truck by itself. Total truck/trailer weight minus the truck weight alone, minus weight on trailer tires alone equals tongue weight. You might be able to weigh the total trailer on the scale then just the tongue weight, but that takes some time, and the scale operator might not want to take that much time. Tongue weight should be a MINIMUM of 10 - 12 % of total trailer weight on the tongue, up to 15 % would be OK, not to exceed the capacity of the hitch.
A long bed truck places the trailer ball pretty far back from the axle. The greater the distance, the greater chance it will sway. If you're just using a ball hitch and no equalizer bars, it will have a tendency to sway more.
Adding weight to the truck bed might help but is a band aid approach. The truck rear tires must also be adequately and evenly inflated to prevent sway. I doubt the truck is the problem; I'd bet it's inadequate tongue weight.
Good Luck
Joe
hfd376
Bronze Member
Just for grins, and not to highjack the post, would mismatched tire pressure have any effect on trailer sway?
Doug
Doug
GregJ
Platinum Member
- Joined
- Oct 8, 2002
- Messages
- 708
- Location
- Washington
- Tractor
- Kubota B2301/LA435FEL/BH70 ; John Deere X350
I had the same problem with a boat trailer about 30 years ago. In fact, you could classify it as a "religious experience" /forums/images/graemlins/crazy.gif one time on the way home from a fishing trip. This "inspired" /forums/images/graemlins/blush.gif me to do a lot of research on sway. From the experts I talked with, you should have no less than 7-10% of the total weight of the trailer and load on the tongue. I found that the only way that you can accurately measure this is to go to a truck scale. I have done this with all of the boats I have owned. I measure the weight, while hitched to the car and the car is not on the scale. Then I unhitch the trailer and measure the full load. With a boat trailer, you can move the axle forward or backward to adjust tongue weight. I always make sure to have at least 7-10% of the weight on the tongue and then I am also very careful how I load the boat so that I don't make the tongue light. My current boat weighs 5,000lbs empty. I have not experienced any sway since I have taken this approach. Hope this helps.
Greg
Greg
Gary_in_Indiana
Elite Member
- Joined
- Apr 22, 2002
- Messages
- 3,373
- Location
- Fort Wayne, IN
- Tractor
- John Deere 4200 MFWD HST w/ JD 420 FEL w/ 61" loader bucket & toothbar & JD 37 BH w/ 12" bucket
Add my voice to the chorus. Not enough tongue weight would seem to be the problem.
Generally speaking, too little tongue weight creates a 'tail wagging the dog' effect while too much squats your tow vehicle and points your headlights at passing aircraft. Steering gets squirrelly and braking becomes adventuresome, too.
Since I added a weight equalizing hitch I've found a little wider tolerance in my trailer for how it's loaded. I've become a big fan of those hitches for towing heavier loads.
Generally speaking, too little tongue weight creates a 'tail wagging the dog' effect while too much squats your tow vehicle and points your headlights at passing aircraft. Steering gets squirrelly and braking becomes adventuresome, too.
Since I added a weight equalizing hitch I've found a little wider tolerance in my trailer for how it's loaded. I've become a big fan of those hitches for towing heavier loads.
DavesTractor
Elite Member
Not enough tonque weight. Set the backhoe bucket down on the deck.
With the backhoe up, the rear tires are the fulcrum and your weight center is moved rearward. Have someone lower the hoe to the deck and watch your truck, you'll see it squat a little.
Let us know if that makes a difference.
With the backhoe up, the rear tires are the fulcrum and your weight center is moved rearward. Have someone lower the hoe to the deck and watch your truck, you'll see it squat a little.
Let us know if that makes a difference.
TOMDUALLY
Silver Member
The most common reasons for trailer sway is as tongue weight and tire pressure, tire pressure.tire pressure!!! when hauling tractors across country the trailer tires must be at least 50 psi as well as the rear pick-up tires. the way I measure tongue weight of a strange tractor is while the trailer is empty and hooked up measure the distance from the ground to the top of the rear bumper of the truck and then again after loading , the distance after loading should be 1,5" to 2"inches less. after doing all this check the tire pressure again.
Joe1
Platinum Member
Doug:
Uneven tire pressure would be much more pronounced on a single axle trailer than a tandem. The softer tire has more rolling resistance and tends to pull the tire to that side. The effects of wind and the drawbar pull eventually overcomes the drag and the trailer heads off in the opposite direction where in the tire drag effect repeats itself. The larger the differential in tire pressure, the more pronounced the problem. Add inadequate tongue weight, and it exascerbates the problem.
The problem of inadequate tongue weight is also greater if the trailer is not level. If a trailer hitch has 100 lbs of weight on it, as the trailer tongue is raised, the center of gravits shifts and the tongue gets lighter. Drop the tongue below level, and the hitch weight increases.
My .02
Joe
Uneven tire pressure would be much more pronounced on a single axle trailer than a tandem. The softer tire has more rolling resistance and tends to pull the tire to that side. The effects of wind and the drawbar pull eventually overcomes the drag and the trailer heads off in the opposite direction where in the tire drag effect repeats itself. The larger the differential in tire pressure, the more pronounced the problem. Add inadequate tongue weight, and it exascerbates the problem.
The problem of inadequate tongue weight is also greater if the trailer is not level. If a trailer hitch has 100 lbs of weight on it, as the trailer tongue is raised, the center of gravits shifts and the tongue gets lighter. Drop the tongue below level, and the hitch weight increases.
My .02
Joe