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Old 02-18-2021, 10:25 AM   #1
2010 Georgetown
 
Join Date: Oct 2016
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thinking of making a two axle dolly

I have been from Alaska to Dallas and plan a return trip. On the trip down I towed a trailer and was glad that I had dual axles when I had a flat. Having tow axles gave me time to find a safe spot to pull over.

I want to use a tow dolly to tow our Pacifica. I have two 3000 axles and am thinking of making a dual axle dolly and add am considering adding on disk brakes.

I will include a pivoting platform to help with the fact that two axles are harder to turn.

I would like your thoughts on how practical this would be.
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Old 02-18-2021, 10:41 AM   #2
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Wouldn't it be easier and cheaper to add TPMS to the normal dolly that would give you a heads up to a problem?
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Old 02-18-2021, 02:24 PM   #3
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Quote:
Originally Posted by wilsonintexas View Post
I have been from Alaska to Dallas and plan a return trip. On the trip down I towed a trailer and was glad that I had dual axles when I had a flat. Having tow axles gave me time to find a safe spot to pull over.

I want to use a tow dolly to tow our Pacifica. I have two 3000 axles and am thinking of making a dual axle dolly and add am considering adding on disk brakes.

I will include a pivoting platform to help with the fact that two axles are harder to turn.

I would like your thoughts on how practical this would be.

Two axle trailers are harder to turn because the wheels are not free to align with the turning circle. Won't be any different with your dolly as the axles will still be in fixed relationship with each other. Same stresses will be present in the tires.

If worried about flat tires on a dolly I'd put my money in better tires and a TPMS monitoring the dolly tires. Might also consider adding some valve cap sensors from the same monitoring system to the tires on the towed vehicle that are down on the road.

Money far better spent.


In closing, "wheel alignment" in tandem axles is far more important than with single axle trailers. On a single you only have to deal with Camber and Toe in one axle. Add a second and you still have the same angles to worry about but in addition you have to worry about the Toe angles in relation to the other axle.

A tandem dolly will be a lot larger than a single axle and that could create problems fitting the towed vehicle on it with proper weight distribution.
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Old 02-18-2021, 03:05 PM   #4
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I thought Pacificas are AWD. Can you tow one with a dolly?
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Old 02-19-2021, 12:37 PM   #5
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I have a good tpms.
The problem I had was in a 33 foot rv and a 20 foot trailer there were few places to safely pull over and fix a flat. So by having two axles when I did get a flat I could slow down and have time to get to a safe spot to change the tire.

I had two flats and each time I had to go several miles before I could safely pull over.

With a single axle if you get a flat, you have little choice about where you stop,
If it is on the drivers side you may not have much space to safely change the tire.
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Old 02-19-2021, 12:44 PM   #6
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Originally Posted by tkarper14 View Post
I thought Pacificas are AWD. Can you tow one with a dolly?

The one I have is front wheel drive. The manual states that you can only tow on a dolly or on a trailer.

I have a trailer that would handle it, but then if I am in a RV park I have a 33 foot rv, 20 foot trailer, and if I take the car off I have to park it as well.

I also have a 2 wheel drive dodge ram 1500. I may have to take it on some trips and leave my wifes car with her. Again it has to be towed on a dolly but with the rear wheels on the dolly.

I could retrofit drive shaft disconnect on the Ram, but that would cost as much as building the dolly. (since I have 2 3000 pound axles. )

For the last trip I bought an enclosed trailer, but I did not trust the springs they were very pitted. I decided to upgrade the axles to 7000 each. That way they are very lightly loaded, and if I did get a flat the axle could handle it until I got to a safe place to change the flat.
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Old 02-19-2021, 12:53 PM   #7
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Originally Posted by TitanMike View Post
Two axle trailers are harder to turn because the wheels are not free to align with the turning circle. Won't be any different with your dolly as the axles will still be in fixed relationship with each other. Same stresses will be present in the tires.

If worried about flat tires on a dolly I'd put my money in better tires and a TPMS monitoring the dolly tires. Might also consider adding some valve cap sensors from the same monitoring system to the tires on the towed vehicle that are down on the road.

Money far better spent.


In closing, "wheel alignment" in tandem axles is far more important than with single axle trailers. On a single you only have to deal with Camber and Toe in one axle. Add a second and you still have the same angles to worry about but in addition you have to worry about the Toe angles in relation to the other axle.

A tandem dolly will be a lot larger than a single axle and that could create problems fitting the towed vehicle on it with proper weight distribution.

I plan to have a platform that is pinned so it can rotate to help with cornering. It will be set up to distribute the load between the two axles. I know that the two axles will be more stressed during turns. But the 33 foot rv has a pretty big turning circle. I will keep the same axle spacing that is recommended for a tandem axle trailer. I will have a pretty long tong to I do not hit the back of the RV with the towed vehicle if I have to back up or make a tight turn.


I saw plans for a single axle dolly that had a pivoting platform that also swung up so you could swing it up and the loading ramps then went down. When you pulled forward the whole platform came down and was pinned in place.

I will build in a place so the tires always stop at the same stop, ensuring that the load is balanced between the two axles.

Since the cars have springs I will not put any springs on the dolly.
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Old 02-19-2021, 12:56 PM   #8
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Quote:
Originally Posted by wilsonintexas View Post
I have a good tpms.
The problem I had was in a 33 foot rv and a 20 foot trailer there were few places to safely pull over and fix a flat. So by having two axles when I did get a flat I could slow down and have time to get to a safe spot to change the tire.

I had two flats and each time I had to go several miles before I could safely pull over.

With a single axle if you get a flat, you have little choice about where you stop,
If it is on the drivers side you may not have much space to safely change the tire.
Draw yourself a Plan View (top) of your proposed dolly. Make sure to include fenders and your towed vehicle in place.

With a single axle the pivot for the wheel supports will be directly over the axle.

On a tandem axle the pivot should be directly over the center point between the two axles. This will place the towed vehicle farther forward and create two serious problems. First will be the clearance between the ramps on the wheel support and towed vehicle chassis/frame/body. Second will be on turns such as pulling into a fuel station, entering a grocery store parking lot, etc. Since the front wheels will be farther forward your turn radius will be limited as the fenders can come in contact with towed vehicle's body.

It's a good idea but really unnecessary. If it was practical you'd see a lot more "tandem dolly's on the road. Only ones I've ever seen are on Heavy Haul trailers where they are necessary for the heavy loads that a single axle wouldn't be able to carry the load.

The IDEAL transport device for a TOAD would be the same kind of wheel lift/under-lift that is used by tow trucks from 1-Ton all the way up to the largest Heavy Wreckers. A boom extending from the rear of the chassis with wheel/frame lift adapters that are attached to the boom using a pivot. One less pivot point and you can actually back up without having to unhitch.

With a tandem axle you've really only increased your chance of a flat tire with two more on the road and still have the remaining rear tires on the towed vehicle on the road where one of them could go flat.

I still say the best way to prevent flats is to purchase good tires, inspect before every trip (and during long trips) and use a TPMS.

With a simple nail puncture a tire will usually lose air slow enough so when the TPMS warns you there's plenty of time to find a safe place to pull over (after you slow down to lessen the heating in the tire). If you are using "cheap" tires then the problem is their total failure due to poor quality/construction. THAT is very preventable.

To add:

If I were faced with a tire failure and didn't have a safe place to change it, and couldn't really drive any distance to one, I'd pull over as far as possible, put out my warning triangles (You do carry them don't you?) then call for a "Trooper" to provide safe "cover" while I changed tires. Chances are one will show up anyway.
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Old 02-20-2021, 01:15 PM   #9
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A dually will not work. I just ran the numbers and it will be to wide.


the extra 3500 pound axles I have would also have to be modified to be wide enough.
I am also thinking of tires and spares for the trailers that I have.
I am leaning toward a 7000 pound axle, that way I can use the same spare tires for my enclosed trailer. It would also put about 2300 pounds from the front axle weight on the dolly. That way the 7000 rated axles are very lightly loaded. So the tires are also lightly loaded as a percent of their rated load. This will help with tire wear, temp, and reduce the chance of a flat.

it would also let me use a more standard dolly plan with a rotating platform. I would probably go ahead and add disk brakes but I then have to add a brake controller to the rv. The towed weight is right at 5000 pounds.
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Ted Wilson
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1992 Rockwood (33 foot)
TST 507 TPMS
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Old 02-25-2021, 03:12 PM   #10
2010 Georgetown
 
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Changed things up
Bought a 2020 ram 2500 4 wheel drive that i will tow flat
It is pushing the tow capacity but there will be no tong weight and i am adding a remote brake to the truck so there will be braking at the truck
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TST 507 TPMS
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