TOPIC: trailer balance

Hi all, I haven't been on this forum for quite a while. I've been a member since before the big V came the logo and have lurked out here often but haven't posted anything since the new site. Anyway, I have bought a 1984 Larson Citation 5500 that sits on an old 1967 tandem wheel trailer. When dragging it the 59 miles home, the trailer really beat the car up with vertical vibrations. I thought for awhile I was having engine misfire because the vibrations felt like a cylinder was missing. However, I ruled that out by revving the engine up or coasting down hill and the vibrations stayed the same. The boat weighs about 2000 lbs. and the trailer has good tires. I'm wondering if moving the boat forward or backward would have any effect. It seems overly heavy on the tongue but I don't want to put so much weigh on the rear that it sways. Any suggestions?
Dan

Just a thought ? Are you sure you are using the proper size ball ?

Welcome back, Handydan. The boat looks to me to be properly positioned on the trailer, but weighing it out would confirm. You generally want slightly more than half the weight transferred to the tongue to get a stable tow, 55 to 60% sticks in my head for some reason.

Even though the trailer tires look good, have you had them balanced and check them for "out of round"? I noticed on a recent long road trip one of the trailer tires would start vibrating at about 66-68MPH, so I held it at 65 or under for the rest of the trip. (Probably plenty fast with 12" wheels and tires anyway!) To check for out of round you can jack up each wheel individually, place an object very near the tread, and rotate slowly watching the gap between the object and the tread. For balance, you'd have to take it to a tire shop unless you have access to a balance machine.

Wheel bearings and spring bushings etc. should also be checked out, but I think you'll find the answer above. Just my opinion, mind you.

Well, I decided to bite the bullet and got new tires. Had them balanced. As the tires were off the trailer I checked the hubs to see how well they turned and for any play in them. The front left was very stiff and hard to turn. Either the previous owner tightened that one too tight or the bearings are shot. Either way I'm changing out the bearings. I'll see if that helps. Bringing it home from the tire shop showed a little improvement in the vibration but it is still there. I'll see what happens after I change the bearings. Thanks for the suggestions. I appreciate the encouragement.
Dan

Do you have a way to take the tongue weight? The weight that is pushing down on the ball. Mine is no more than 40 lbs and rides wonderful. My Tee nee with the 59 winner with engine takes about 10 lbs to push it down to hook it up. Without an outboard the weight is maybe 50 lbs. Does your tow vehicle squat with the boat on?

The trailer is extremely heavy on the tongue. I can't lift it by myself. The tow vehicle is a 1999 GMC Suburban so the weight doesn't show as much as on a smaller car, but I can sure feel it. I'm pretty sure that is what the real problem is. Changing the bearing helped a little but it still feels like I'm driving over a rutted road. I haven't had the boat on the water yet but I'm headed for the lake this weekend. I'll be pulling it with my old motorhome (It's the one in the background). Once the boat is off I'm going to move the front stop back about two inches. The wheels can be moved but I don't know if that is necessary, yet, but something to consider.

Once the boat is off I'm going to move the front stop back about two inches.

Can I make a suggestion / warning here? Measure the amount of trailer bolster you have sicking out behind the transom, and don't move it back any farther than that. You really want to keep support under the hull where the transom intersects, even with an I/O, in my opinion. The gang can better explain why, (the hull may develop a "hook") but I wouldn't go any farther back with the boat than that. Just my two cents.....

Is it possible you have waterlogged foam in the front. Was it stored nose down? I would entertain all possibilities. It looks like she is sitting OK. Most trailers I've seen have a way to move the wheel gear forward thus putting more weight on the wheels.

Most of the trailers I have worked on were adjustable axles. By that I mean there were multiple holes in the frame that you could actually jack up the trailer and move the axle/wheel setup either forward or back. Might help to move the wheel a notch or two forward to take some of the weight off the tongue without having to move the boat on the bunks/rollers.
My .02 worth.
Cal

I dont think it should ever be so front heavy that one person cant lift the tongue. Either the boat, or the axles need to be moved.

Remember that even a full size tow vehicle with capacities over 5000# may have a tongue weight of less than 500#.

Even if the scale shows the tounge at 300#, thats dead weight. Now imagine the forces down and forward when you hit the brakes.

I appreciate your replies. I have a few inches of bunks left. Excuse the tidiness of the pictures. I took these photos when I went to look at the boat. After replacing the bearings and putting on new tires I still wasn't satisfied with the way it pulled. I took the trailer to a local trailer dealer and asked them to look at it. They said they had never seen a trailer setup like this one. Usually on tandem wheels there are two sets of springs. This trailer has one spring set that has one bolt in the middle that acts as a pivot point. The trailer tech agreed that there is too much weight on the tongue. He suggested turning my receiver on my trailer hitch over so the ball is two inches higher. He thought that might help some until I can get the boat off the trailer and see what my options are. I can move the boat back about two inches or move the wheels forward. No matter what, I'm dragging it to the lake next Monday.

Is that six leaves I see piled up there? Wow never seen anything like it. Is it a homemade job?

To maintain the dynamic stability of a trailer the tongue weight should be 5-10% of the towed load.The target spot is 7.5%. The two preferred methods are moving the axle or to reposition the boat.So if you had a load of 1000lbs the tongue weight sweet spot would be 75lbs.

Doing more research and Sherline,who sells scales, rec.are single axle 10% Min/15%Max...
Tandem axle 9% Min. and 15% Max. So that sweet spot may be closer to 10% than the 7.5%. Two different mfgs and web sites and two slightly different formulas.Get her close to that 8-10% and you should be good to go.

Maybe I'm a little late to the party here, but anyway...

A trailer that is light on the tongue will not vibrate, it will swing side to side. Very dangerous but will only result from very light or negative tongue weight. Heavy on the tongue would not cause vibration unless it's so heavy that the wheel bearings in your truck start to come apart. When in doubt heavy on the tongue is always better until you can find the sweet spot as described above.

Bearings and tires are a much more common source of vibration. Wheel bearings are cheap and easy to replace. I've cooked my share along the way and you'll be a lot happier if you replace them early instead of on the side of the road at 1 in the morning. Put bearing buddies on them when you do.

Is that a factory spring setup or something pieced together by a thrifty previous owner? A new suspension isn't free but it's cheaper than another boat.

Replace the tires or get them balanced if you haven't already.

HandyDan wrote:

I appreciate your replies. I have a few inches of bunks left. Excuse the tidiness of the pictures. I took these photos when I went to look at the boat. After replacing the bearings and putting on new tires I still wasn't satisfied with the way it pulled. I took the trailer to a local trailer dealer and asked them to look at it. They said they had never seen a trailer setup like this one. Usually on tandem wheels there are two sets of springs. This trailer has one spring set that has one bolt in the middle that acts as a pivot point. The trailer tech agreed that there is too much weight on the tongue. He suggested turning my receiver on my trailer hitch over so the ball is two inches higher. He thought that might help some until I can get the boat off the trailer and see what my options are. I can move the boat back about two inches or move the wheels forward. No matter what, I'm dragging it to the lake next Monday.

That was my thought as well. There is something really goofy with that spring set up. I'm wondering if that might be the cause of the vibration. Does it have a shackle on both ends of the spring? If not, I can see where one wheel hitting a bump might set up a tension battle between the 2 axles. (vibration)

At any rate, snap a photo while the boat is off so we can see how much the springs, spring, and how they are mounted to the trailer.

Todd

Trailer vibrations are most often caused by tire problems. Look very closley for a squirm in the tread If a belt has let go in the tire you won't notice it till the tirelets go. If you could get someone else to pull the trailer at speed and follow you'll be able to tell which tire is causing the problem.

Should have 10 percent of tounge (sp) weight. on hitch

Well, I spent the last week at the lake. After having the springs and hubs inspected and fixed at the local trailer store, I hooked the trailer on the back of my old Holiday Rambler and never even knew it was back there except when I looked at my rear view monitor. The ball on the trailer hitch is 4 inches higher than on my Suburban. I think that makes all the difference. While the boat was off the trailer I moved the forward stop back 2 inches. I didn't notice any difference when pulling it home, but I tried it on my car with the ball raised up 2 inches and it worked beautifully. It's all in the balance. I also learned a few things about my boat. It runs a lot different than my old MFG Beachcomber with 85hp Johnson outboard. Thank you for all your replies. I appreciate all that took the time to offer advice.

Glad you got it all worked out Dan, looks like the vacation at the lake was a big success too! Nice catch.

I'm glad it worked out. I'd still keep a good eye on that spring set up. Never seen anything like it.