trailer questions/concerns (1 Viewer)

[motormike73]

i have not done a ton of hauling/trailering and always got a little nervous when pulling something and so had some questions about a new project of mine. i had this little utility trailer and wanted to use it to haul a custom motorcycle i built. i upgraded to the 12" wheels shown and built a rail for my bike to go on. also added a longer tongue. the trailer is rated at 1000# and my hitch is rated at #2000. i am guessing the bike weighs between 700-800 and another couple hundred for the trailer...so getting pretty close to if not slightly exceeding the trailer rating. the tires are c rated/1880# (990 each). my questions are:

how concerned about the 1000# rating should i be?

even though the tires are well within the load rating, they just look "small" to me and should a beefier tire be used, or is the load rating what i should be concerned with? (again i am at only about have of what the tires are rated for)

i did take it out for a test run with the bike on it. drove around the neighborhood as well as got it up to speed on the highway. everything seemed fine other than i could "feel" the trailer back there and a sort of pulling sensation. i am just using a little chevy 2wd 6 cylinder crossover to pull it. i suppose thats somewhat normal being as i dont have a ton of power?

and lastly i have considered flipping the axle to lower it a bit to make loading a little easier. i know i would need to raise the fenders, but otherwise is this an okay thing to do? i have seen some posts where people dont recommend this, saying it puts too much stress on the u-bolts and relys on them to take the weight vs the axle itself.

i apologize for the lengthy post. any help would be greatly appreciated. thanks!

 

[greentruck]

Well, I'm not a lawyer giving you advice like this, but...trailer were made to be overloaded. Within reason, you'll be OK. Now, is the gross weight limited to 1000 pounds? In other words weight of load + trailer? In that case, you're only a couple of hundred over, which would be 20%. To me, that's reasonable. If the trailer has a capacity of 1000 pounds, i.e. not including the trailer itself, then you're OK anyway.

Keep things checked, especially air pressure, and service those hubs, which is where the stress goes. Bigger tires, by a size or two, can't hurt, they cut down on the revs per miles, which will help with that heavy load on the bearings.

Not seeing the bike mounted on the trailer with the rail, I'm not sure of your balance. You'll definitely have enough ahead of the axle. You want to be 60/40, with 60% of the weight in front of the trailer axle, but you may actually have more than that. This leads to excess tongue weight, which is harder on the tow vehicle and gives less than the best towing. You may want to try to figure this out before you get the rail mounted.

As for the suspension, I wouldn't, given this is one of those bolt together rigs. Unless you can figure out all the engineering that went into what they did and successfully rearrange it, you're taking unknown risks. And you're already asking it to do more.

 

[Rock_Hugger]

How far and how fast do you plan on hauling the bike? Me personally I wouldn't use that axle and tires that small. The problem is if you are planning on driving at any speed the tires are spinning so fast it will eat wheel bearings. I wouldn't put a $30,000 bike on a $50 trailer.

 

[motormike73]

Greentruck....any idea how to calculate the 60/40? I'm not sure how to figure that out. The way I have the rail mounted now puts the rear axle right on the rear cross member. I was concerned about having the rear wheel hanging too far off the back end so I chose to put it there. If you can visualize from the two pictures, it puts the motor/roughly the center of the bike about 12" in front of the axle. But I'm not sure how to figure out how the wight is distributed from front to back on the bike and trailer. I can try to post a better pic tomorrow.

As for the rest I was a little hesitant to mess with the axle but thought id ask either way. And I do understand the idea of not putting an expensive custom on an inexpensive trailer, but I likely won't trailer much and certainly not for any great distances. And fwiw the bike isn't that pricey. I built it in my garage as well with mostly used parts and stuff off eBay! And as far as the wheels it had 8" wheels initially and I got it up to hwy speeds when using the trailer to haul camping stuff. They got a little warm but nothing I was ever concerned about, but either way wanted to upgrade to 12" to be safe and so was just curious if they would suffice. Again they are rated at 990 each...and total weight is in the 1000 range.

 

[motormike73]

This might be stupid... But what do u think about hooking everything up to the tow vehicle, then putting the jack down on a scale and then unhitching from the vehicle therefore having the tongue/jack rest on the scale? Would that be an accurate way to determine tongue weight and thereby work backwards to approximate the weight distribution?

 

[greentruck]

That actually sounds better than I visualized as far as weight distribution. Probably give it a try in that case. So long as the center of weight is ahead of the trailer axle, you're generally OK. It's just that things ride and handle better if it doesn't end up with too much tongue weight.

Easiest method of checking tongue weight is to rest tongue of loaded trailer on a bathroom scale. You want it somewhere between 100 and 200 pounds. If it's over 200, it's probably got the weight too far ahead of the axle. If not, you should be OK provided everything rides level when hitched and loaded.

You'll likely be limited by what will bolt up to the present hubs in terms of tire size. Dealing with the fenders is not too big a deal, but trying to upsize bearings and hubs can get tricky and expensive.

 

[Rock_Hugger]

I wouldn't be overly concerned about the tongue weight ratio, it's more important that you just have some weight. You just do not want none or negative tongue weight. As for a 60/40 that doesn't make any sense to me. With a 1000lb trailer you would have 400lb of tongue weight? Travel trailers don't usually have that much.

 

[motormike73]

There is a CAT scale at a qt near me. Gonna take the bike and trailer to get weighed tomorrow so I have a more accurate idea of the weights. Will also check the tongue weight with a bathroom scale. Hopefully I'm good on all. Thanks so much for all the insight guys.

 

[greentruck]

I wouldn't be overly concerned about the tongue weight ratio, it's more important that you just have some weight. You just do not want none or negative tongue weight. As for a 60/40 that doesn't make any sense to me. With a 1000lb trailer you would have 400lb of tongue weight? Travel trailers don't usually have that much.

OK, I'm a historian, so all the math is a bit dicey for me...

Tongue weight is different than the need for fore and aft weight distribution. First, if we used your example, we need to turn it around and put the 600 pounds in FRONT of the axle and the 400 pounds behind it. But the tongue doesn't carry all that 600 pounds. Most of it is still carried by the trailer tires. It's only the balance between the difference that contributes to tongue weight...or something better worded than I can make it after just one cup of coffee.

Now I would say that if there was an ideal weight distribution of 60/40, then it would only be 200 pound tongue weight. The other 400 pounds would be balanced by the 400 pounds that are behind the trailer tires. However, IIRC, that's may be too simplistic a calculation for tongue weight, as I think there's some other factors that go into this if calculating. That's why I recommended using the bathroom scale -- no math involved.

 

[greentruck]

This might be stupid... But what do u think about hooking everything up to the tow vehicle, then putting the jack down on a scale and then unhitching from the vehicle therefore having the tongue/jack rest on the scale? Would that be an accurate way to determine tongue weight and thereby work backwards to approximate the weight distribution?

Missed this when replying last night.

Yeah, that's pretty much it. Have everything loaded and hooked up, then lift the trailer off the coupling and set the landing leg on the scale gently, ensuring it's free from the vehicle supporting the weight. Now if the landing leg is set back far from the coupling, then it won't be quite accurate, as it will be somewhat less than the actual coupling sees because of the extra leverage of it being further forward. But it will give you a good ball park number for tongue weight.

 

[Living in the Past]

How far and how fast do you plan on hauling the bike? Me personally I wouldn't use that axle and tires that small. The problem is if you are planning on driving at any speed the tires are spinning so fast it will eat wheel bearings. I wouldn't put a $30,000 bike on a $50 trailer.

I agree on wheel/tire size. Don't know how many times I've seen a full size truck with a lift hauling a tent trailer with tiny wheels. When you see them off to the side of the road most the time the hub has been pulled because it was the bearing that failed not tire.

 

[motormike73]

what would be a recommended tire/wheel size? i thought i was addressing that issue by going from 8" to 12"....but are 12" still not enough?

 

[Rock_Hugger]

It's has to do with your axle. That axle is an extremely light duty axle. Just putting different size tires doesn't solve the problem. It would be like using a 10 speed bike wheel hub with a motorcycle tire on your chopper. It works fine for what it's designed for but the bearings are too small for what you want to do. Again I would upgrade the axle to a REAL trailer axle not a garden trailer axle.

 

[motormike73]

Got everything weighed today. Bike was 600#, trailer as a whole was 310. Also checked the tongue weight...was getting 150. So I would think I should be pretty good...

 

[greentruck]

Yes, that sounds pretty good all around.

As for the wheels, if you've already bumped up to the next size, you may be about to the limit of what you can do with the bearings you have. You've already substantially cut down on revs per mile.

The key thing with bearings on trailers is that maintenance is often neglected. While it's true small tires and bearings have their limitations, if maintained correctly they'll serve you well. I also am in the habit of checking bearing temp whenever I stop when towing by placing a hand on the center cap of the hub. You'll learn how warm it usually gets -- shouldn't be much -- and that way will notice right away if it starts getting warm.

 

[motormike73]

awesome...thanks so much for the help everyone!

 

[ntsqd]

I wouldn't be overly concerned about the tongue weight ratio, it's more important that you just have some weight. You just do not want none or negative tongue weight. As for a 60/40 that doesn't make any sense to me. With a 1000lb trailer you would have 400lb of tongue weight? Travel trailers don't usually have that much.

OK, I'm a historian, so all the math is a bit dicey for me...

Tongue weight is different than the need for fore and aft weight distribution. First, if we used your example, we need to turn it around and put the 600 pounds in FRONT of the axle and the 400 pounds behind it. But the tongue doesn't carry all that 600 pounds. Most of it is still carried by the trailer tires. It's only the balance between the difference that contributes to tongue weight...or something better worded than I can make it after just one cup of coffee.

Now I would say that if there was an ideal weight distribution of 60/40, then it would only be 200 pound tongue weight. The other 400 pounds would be balanced by the 400 pounds that are behind the trailer tires. However, IIRC, that's may be too simplistic a calculation for tongue weight, as I think there's some other factors that go into this if calculating. That's why I recommended using the bathroom scale -- no math involved.

What you guys are talking about is called a "Shear-Moment Diagram" by Engineers. There are formulas already derived for point loads and for distributed loads on any kind of beam. The trailer frame is the beam. The supports are the axle and the coupler. In this case the loading is two point loads where the M/C's tires are.
Need to know the weight on the M/C's front & rear tires, the M/C wheel base, and the distance from the coupler to the trailer axle.
Then search "Shear-Moment Diagram" or "Shear-Moment Formulas"

 

[greentruck]

What you guys are talking about is called a "Shear-Moment Diagram" by Engineers. There are formulas already derived for point loads and for distributed loads on any kind of beam. The trailer frame is the beam. The supports are the axle and the coupler. In this case the loading is two point loads where the M/C's tires are.
Need to know the weight on the M/C's front & rear tires, the M/C wheel base, and the distance from the coupler to the trailer axle.
Then search "Shear-Moment Diagram" or "Shear-Moment Formulas"

Even after another cup of coffee, I think I'd still call the engineer for an answer on this one...

At least I know the name of now it for reference.

 

[ntsqd]

Its just algebra, and no equation manipulation required. Plug in the values for the variables and make Excel do the "heavy lifting".....

 

[Parsnip]

Just some other thoughts that you may consider. I'm no trailer engineer ok but I moved a 500# wet street bike a few times on a kit trailer from northern tool.

I found that, when loading, jack stands under the rear frame of the trailer took the trailer's suspension out of the equation and made it much easier to load/unload.

I sat on the bike for final tensioning of its tie-downs to compress its suspension to about half travel. I don't think you need to worry about this with a hard tail though.

I also ran a coated steel cable from the front wheel of the bike wrapped around the tongue and connected to the tow vehicle. (in addition to the normal safety chains for the trailer) I had this weird vision of some jackass clipping the low trailer unseen behind the big truck and sending the bike through some family's minivan window. I've never even heard of this happening but it was an easy thing to do and it made me feel better.

So post more pics of your bike or link us up to your build thread on another forum