Single Axle versus Double Axle Enclosed Trailer?

[Dick R.]

Are there significant stability or other disadvantages to a single axle enclosed trailer compared to a double axle. Assume size, load rating, etc. are all OK.

If the 1100 lbs additional weight of a 16 foot double axle enclosed trailer compared to my current SA open trailer is too much for my tow vehicle another option for my FF is a 14 foot single axle enclosed.

Dropping down from a 7 X 16 DA Pace Cargo Sport to a 7 X 14 SA saves almost 500 lbs.

Since the tow vehicle is a 1 ton camper van I don't know how significant the 500 lbs would be going over the "mountains" in North Carolina, etc. I'm currently at about 2000 lbs below the van's gross combined vehicle weight with an open trailer. A 16 foot DA will add at least 1100 lbs.

Thanks,

Dick

[Brian]

I personally wouldn't choose a single axle enclosed trailer over a tandem axle, just the potential damage when the tire blows out would sway me. The main advantages of a tandem axle trailer are better brakes (on 4 wheels instead of two), better handling (far less sensitive to loading and balance, and less sway) and payload. The tandem axle trailer has just about dead on triple the payload compared to the single axle version. Trust me on this, you will find things you need to bring with you, and a payload of 1700 or 1800 lbs isn't going to cut it for long.

What I find is that the aero drag of the box is a more significant factor than the ultimate weight of the combined vehicle, at least while you are in sight on the GCWR, and you say you would be under. I can load my trailer at 6K lbs and 8K lbs and aside from getting away from stops a little slower I don't notice a whole lot of difference.

Brian

[Doug FST 5]

I've towed both and think that a double axle trailer is less prone to sway (properly loaded). I also think there is a safety advantage with a double axle in the case of a trailer tire blowout. A 1 ton tow vehicle should be able to handle any trailer you are considering without a problem. I pull a tall and wide 20' enclosed trailer with a 1/2 ton Avalanche. We slow down a little on big hills but overall its just fine.

Doug FST 5

[Tom Valet]

Doug, if weight is an issue and you dont want to buy another tow vehicle, get yourself an aluminum enclosed trailer. We tow our FF and all our spares in a 7 x 16 foot CargoPro aluminum trailer, double axle. The trailer weighs only 1,800 pounds. An aluminum trailer costs a bit more but not as much as buying another tow vehicle. They also hold their value really well.

[Jim Garry]

The responses above make a lot of sense. Ya can't argue. I'll just give my experience towing a 15', single axle, enclosed trailer since 1998. Towed for 10 years with a '92 Buick Roadmaster and now with a GMC full sized van. Except for hills, it tows the same.

With the correct tongue weight and the anti-sway device attached I've never had any sway problems. The trailer tows like it's not even back there.

Knock on wood I haven't had any tire problems on this trailer so I can't give my experience of a blow out. But back when I had a single axle open trailer I did experience a blow out and was very surprised at the lack of drama. But that trailer was about half the weight of my current one and that may have been a factor in the benign behavior experienced during that blow out.

My trailer deck height is a lot lower to the ground than most race car trailers seen on the road today. That may have something to do with my experience. It's also got a very low roof.

One reason for my single axle ownership is that the only place to park the trailer at my home is in a very tight spot. Two axles would make maneuvering it into this tight spot difficult.

[formulasuper]

Ditto on the tire blow out advantage for the dual axle. On a recent return trip thru a major city I had a blow out at 65mph on my dual axle open trailer while in the fast thru-lane of a 5 lane interstate & was happy to be able to continue on to the next exit and change the tire in a parking lot.

[EYERACE]

agree that not only is the double axle enclosed the smart idea [go with the 16 foot] - and agree that your tow car can handle it [unless you like to tow at something like 75 to 80 mph which is a guarantee to buy tranny after tranny for your tow car] - but also agree that the aero tug you will feel will seem different - because you'll be towing with a van, you will break the air nicely in front of the box - but you will notice the sideways push of 18 wheeler air passing you a little bit more - have the brakes on your van serviced if they've got a few miles on them already - make up a tapered end block wider than a tire and about four plus feet long and tall enough too to lift the other trailer tire off the ground, it has a ripple in the top to accept the radius of your tire across the top of the block - in the event of a flat you can quickly back up the nonflat tire onto the block to change a flat tire, keep the block near your spare - i hope that the prior passage is understandable, i reworte it about four times - this works more quickly than digging out your jack and probably boards too when you're on the road - I tow a 18 foot box CargoMate with a F-250 Diesel Crew Cab and short bed, probably heavier than your van, i do not use a sway bar with the hitch and things go smoothly - think about the sway bar partly because you might not weigh as much - what sort of brake controller are you using presently?

[Dick R.]

Great info! As usual from ApexSpeed!!!

Eyerace, how are you doing? I understand what you are saying about the block under the good tire/wheel being used as a jack for the flat tire. I've heard/seen that approach before.

Is the consensus that as long as I'm within the GCVW of the van that 500 lbs of additional weight is only a minor impact on acceleration and hill climbing and maybe stop and go gas mileage?

Edit to add: I'll get a good brake controller since the one I use with the open trailer won't do the job. Also, I'll use an equalizer hitch mostly since the van's rear tires are already close to their Load Range E limit and I'll need to shift some tongue weight to the front tires.

Thanks,

Dick

[Paul LeCain]

I'd never use a single axle trailer. The blowout/catastrophe potential is way too high.

I don't even like double-axle trailers. I've had three tire failures with them and didn't like the experience one bit. If one tire fails and you're anywhere near the GVWR, the other tire is instantly overloaded. (So is the axle.)

So, I have a three-axle trailer. Its GVWR is 18,000 lbs. I'd have to load it with bricks to get anywhere near that weight. It runs around 9,000 lbs most of the time. Even if I blow one tire, I'm still way under the limits of the other two axles and tires. Seems like overkill to most people, I suppose, but I worry a lot less while towing.

[PCalhoun]

A large percentage of the additonal weight is obviously due to the second axle assembly, however, on dual axle trailers brakes are also mandatory per the DOT. Where in most states on a single axle trailer brakes would be optional. NY is an exception to this rule, as anything over 1000# GVWR I believe is required to have brakes in NY.

On some makes & models 14" wheels will also be the norm on single axle trailers, esspecially spring-axle equipped models w/ bias tires.

[Dick R.]

Peter,

I'm "assuming" a Pace American Cargo Sport 7 X 14 SA which has the Torflex you recommended and electric brakes included in the specs with the weight. This is only if weight saving is needed because I would prefer to have the additional 2 feet of the 7 X 16 as you recommend. a 7 X 14 DA saves about 150 lbs compared to the 7 X 16 DA.

I'm basically researching what my "reasonable" options might be if necessary but really don't want to go to SA with an enclosed normal height trailer that I plan on using well into my 70's. (i.e. as long as I can get in and out of the car and walk autocross courses). I don't mind going a little slower up hills . . . I'll be retired then and have plenty of time.

Thanks again

Dick

[PCalhoun]

Peter,

I'm "assuming" a Pace American Cargo Sport 7 X 14 SA which has the Torflex you recommended and electric brakes included in the specs with the weight. This is only if weight saving is needed because I would prefer to have the additional 2 feet of the 7 X 16 as you recommend. a 7 X 14 DA saves about 150 lbs compared to the 7 X 16 DA.


Dick

Dick-
The curb and payload capacity weights listed on the Pace website are based on base models w/ no additional options. On an SA model; i.e. single axle this would not include brakes, on a TA model (tandem axle) it would. The base weight would also not include the additional weight of a ramp door vs rear cargo style doors.

Yes, the CargoSport has Dexter Torsion axles as standard, though the 22.5 degree upstarts to lower the platform would be a small upcharge. Torsion axles are also available on the Journey model as part of an option pkg. Tim can explain this all to you when you visit his store.

In general 150# for every two addtional feet is a good estimate on a 7w trailer, but as stated before in your case it will be the van/RV punching the hole in the air and the trailer should hide pretty well behind it.

[brownslane]

Dick, regardless on what you decide is the best (I have a dual axle 28-footer), BE SURE AND TEST DRIVE IT.

My 28-footer used to be towed behind my full size Chev 2500 van. What a PIG!! I have proper torsion swa bars, loaded with tongue weight, had proper tires on the trailer (THAT is very important) and on the truck. Still the thing was always a handful, and wanted to bite you when it was hauling empty. Then I changed to a full-sized "high-top" conversion van.

TOTAL DIFFERENCE!! Now the trailer is a "two-finger" drive down the highway. The extra two feet of height on the van made all the aero difference. Now the hauls are easy-peasy.
I also know people who have had the exact opposite experience. So the only true way to determine if the trailer works for you is to test drive it before you purchase.

Here are basic requirements:

The tow vehicle has to have 6 ply truck tires. The soft-sidewalled regular SUV tires will contribute a lot to sway.

The trailer must have proper trailer tires. I know this sounds redundant, but if you look at a lot of used trailers they have car tires on them....if they do, guaranteed you will have tire failures and a lot of sway

Dual axles are a lot more stable and safer in cases of tire failure. Everyone has already said all there is to say on that point.

Buy the best torsion bar set up you can get. The ability to "load level" between the trailer and the tow vehicle is great, and the added sway reduction will make you much more relaxed when you get to the track...or home at the end of the weekend.

Make sure the car fits on the trailer. Again, pretty simple, but you need to consider beaver tail versus regular drop door. I have used beaver tails and would never use a regular trailer again. For me, low ground clearances mean I need to work hard on eliminating any rapid inclination changes on the loading ramps.

Always buy the extra two feet in length. A trailer is like your garage; no matter how big it is, you will always need to carry 110% of its available space! But also, the extra couple of feet add to stability, do not really wiegh much, and once the trailer is moving 80% of the effort is overcoming aero drag...longer trailers are more efficient aerodynamically.


I tow over 17,000 # when loaded. With a half ton van with all the "conversion van" stuff like leather seats, air conditioners, TV sets, etc....and I am way over my limit....but all I did was add great shocks to the truck, use the load levellers on the trailer, and an extra leaf on the rear suspension. And I can haul from Detroit to Chicago on one tank of gas at 65 mph. So your van can do it!

All the best, Tom

[Dick R.]

Peter and Tom and others (and the private message from another guy),

Thanks for the additional info from all of you. Obviously it is time for a test pull.

FYI Peter, the online specs for the SA Cargo Sport 7 X 14 "claim" electric brakes are included. Good to know that is questionable since there is no way I will buy without brakes. Even my single axle open trailer has brakes. (I'm a safety engineer).

FYI Tom, my camper van is even taller than a conversion van and due to an overhang over the windshield and an AC on top it has the aero of a very lumpy brick and should be punching a big hole. Hopefully it is more like a wake since the trailer would be wider than the van.

Dick

[Dick R.]

I finally actually towed an enclosed trailer today with our van. Piece of cake, even on a somewhat windy day with no weight distribution hitch or sway control.

Question: I test towed an 8 X 16 V-Nose which is taller than the 7 X 14 flat nose. Would the drag be similar? It was fine but I don't know how good the test was.

Pic of the combo and Pic of what I would love to do attached. I can use some sort of hitch extension to support the gooseneck on the longer trailer, can't I?

Attachment 21129

Attachment 21130

Dick
CM 85

[Daryl DeArman]

On the topic of tires.....make certain the trailer you buy has "trailer tires" and not some standard Passenger car or Light Truck tire. There is a difference in their construction and weight load specs.

Many of the "big brand name" lower end models use junk LT or P car tires. Many of the off brand trailers do the same.

Heck my cheap-o Carson single axle open utility trailer even came with proper tires.

[Dick R.]

Daryl,

Not to worry. Trailer tires for sure. Almost for sure radial trailer tires even though some models come with bias as standard even when upgraded from springs to Torflex axles.

I have radial trailer tires on my single axle open trailer.

Thanks,

Dick

[Dick R.]

Bump after the weekend.

The question is whether test pulling a 8 X 16 V-nose is a reasonable approximation of towing a 7 X 16 flat nose. Also the actual trailer would be about 6 inches lower but would have a longer tongue to clear the van's spare tire.

Thanks,

Dick

I finally actually towed an enclosed trailer today with our van. Piece of cake, even on a somewhat windy day with no weight distribution hitch or sway control.

Question: I test towed an 8 X 16 V-Nose which is taller than the 7 X 14 flat nose. Would the drag be similar? It was fine but I don't know how good the test was.

Pic of the combo and Pic of what I would love to do attached. I can use some sort of hitch extension to support the gooseneck on the longer trailer, can't I?

Attachment 21129

Attachment 21130

Dick
CM 85

[Mark_Silverberg]

V nose trailers are not necessarily better than flat nose trailers. While the V "cuts" the air it does not make the trailer any more aerodynamic as it can cause some low pressure areas on the side of the trailer where the air comes around the front edge. This is not a large issue unless you have side winds or a running near a vehicle causing turbulence. In that case it can make the trailer much more squirrely.

I addressed this issue on my 17x6 TA v-nose by adding air tabs on each side of the front where the trailer is not in the shaddow of the tow vehicle.

You vehicle is so tall that this may be less of an issue.

[Bob VanDyke]

I would agree with Mark. I have had an 16X8 flat trailer and a 16x7 V nose and that V nose was much more prone to get squirrelly when a tractor trailer would pass me. It also would suck the lift gate of the cap open unless I strapped it shut. I towed with a Ford F-250 SuperDuty diesel so neither trailer was difficult to tow, but the flat trailer seemed more stable.

[DanW]

http://www.apexspeed.com/forums/show...Improvement%22

[Dick R.]

Thanks Mark and Bob.

My question was in regard to whether test towing with a wider and slightly higher v-nose would be at least as much drag as the narrower/lower flat nose. I don't want to fool myself into thinking that just because the v-nose was fine that a slightly smaller flat nose would also be fine. I don't plan on getting a v-nose.

However, it is good to get more input regarding the turbulence sensitivity of the v-nose. I had heard that before but you guys provided more detail.

Dick

[Mark_Silverberg]

The V nose is not going to create much if any drag reduction. Most of the incremental drag is caused by the exposed frontal area (area above the tow vehicle) and the low pressure area behind the trailer. Neither of these have to do with nose shape.

the best way to address trailer drag is by airtabs

http://www.airtab.com/en/

[brownslane]

I am a real believer in Air Tabs. I tried them out on my 26 foot tag, and found a real improvement in cross winds and passing/being passed by tractor-trailers. No more 'tail wagging the dog' syndrome. I also saw a (slight) increase in fuel economy.

But when I added the air tabs to the motor home!!! WOW! Incredible change in characterisitcs. More than two mile-per-gallon increase and a much more stable ride.

I also installed them on my high-top Chev van and found a similar improvement.

Highly recommended.

Comment regarding slope nose, "flat" nose and V-nose trailers. I would NOT recommend a V-nose. Due to their shape, they tend to "seek" direction changes when towed behind a vehicle that is lower than the nose of the trailer. The longer the trailer, the worse it will wander... I have a slope nose on my trailer and it seems to work great with the motorhome (it has NO aero exposure on the front of the trailer) and my high-top van (minimal exposure)...

But, as I had said in an earlier post, when I towed with a "regular" height van, the same trailer was a diabolical hand full to tow. I am not sure why, but the extra height of the new van (and of course the motor home) seemed to virtually eliminate any tail wagging.

I would NEVER again purchase either a tow vehicle or a trailer without first test driving them as a pair...at least then I can be assured that the drive to and from the track are less challenging than the racing itself.

Regards, Tom

[Nardi]

Could one use something like a gurney flap at the end of the trailer in lieu of the air tabs?

[Mark_Silverberg]

No, the purpose of the gurney tab is to help energize the flow coming off the bottom of the wing. There is no "bottom" to the side of the trailer.

Air tabs are a boundary layer device, they generate multiple vortexes to fill in the low pressure area behind the trailer - the smaller low pressure area makes the trailer more resistant to side winds.

[Nardi]

Any rough ideas of what the airtabs cost?

[Paul LeCain]

$220 here:

http://www.buyairtab.com/result.php?catid=1