Changing a single axle to a tandem

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cannonman

Petty Officer 3rd Class
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Jun 20, 2010
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92
I have a 20' bowrider that rides on a single axle trailer without brakes. I have always felt it would be better off on a tandem axle trailer with brakes. After losing the tread on a tire and damaging a fender pretty badly I am considering a new trailer or modifying mine. My trailer looks and works great now that I have added guide on posts and a spare tire carrier. A new trailer will cost in the neighborhood of $3,500.00-4,000.00. I could possible buy a used trailer, reset the bunks to fit my boat, then have to paint the trailer, but how hard would it be to change mine to a tandem axle with brakes on the new axle? I could do most of the work myself. Any thoughts?:confused:
 
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ufm82

Master Chief Petty Officer
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Jul 29, 2003
Messages
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Re: Changing a single axle to a tandem

It's not a big deal if you are mechanical. My current trailer's undercarriage is simply u-bolted to the main frame so it wouldn't even require welding anything. You would need to move your existing axle forward and add the rear assembly. My single axle that I used to have would have taken a second axle easily. I could have done it for under $400 but I bought a used tandem for $500 and wound up with a better trailer anyway. Why not hunt for a good used trailer? $2K will get you a nice trailer. Since you are mechanical you could even find a cheaper tandem and "fix it up" as my BIL would say. LOL
 
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rbh

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Re: Changing a single axle to a tandem

I would not, and heres why.
The MFG of the trailer uses steel of a certain gauge to achieve the desired GVW.
(you have seen the tag that shows the GVW of your trailer???)

Although in part you will be increasing the GVW of your trailer by adding another axle, it has not been engineered into the frame and liability will be yours if there is an accident.
 
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Struc

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Jul 27, 2011
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409
Re: Changing a single axle to a tandem

I picked up a good+ condition EZ Loader roller tandem trailer with brakes and a parts boat (my exact boat 1 year newer with blown engine & trashed interior) for my 1988 Sea Ray Seville 20' for $600. If you go looking for a trailer, you will be disappointed in the pricing. Look for a combo with a trashed boat, and it will be 1/4 to 1/2 the price. It doesn't make sense, but it's true. Craigslist is your friend.
 
bruceb58

bruceb58

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Re: Changing a single axle to a tandem

rbh said:
Although in part you will be increasing the GVW of your trailer by adding another axle, it has not been engineered into the frame and liability will be yours if there is an accident.
Click to expand...
He said nothing about increasing the gross vehicle weight he would be carrying. He is just adding the reliability of the second axle and using it under the same exact boat.
 
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rbh

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Re: Changing a single axle to a tandem

bruceb58 said:
He said nothing about increasing the gross vehicle weight he would be carrying. He is just adding the reliability of the second axle and using it under the same exact boat.
Click to expand...

This may be a cheezie reply, but he would be changing the configuration of the trailer (regardless of the GVW), and you know that if there ever was an issue due to an accident, he could swing for it.

How you ask?
Probably because he does'nt have a P-eng stamp for the the work done on it.
 
JB

JB

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45,907
Re: Changing a single axle to a tandem

Take a look at www.championtrailers.com. If I recall, they have anything and everything you would need, plus how-to help.
 
bruceb58

bruceb58

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Re: Changing a single axle to a tandem

rbh said:
Probably because he does'nt have a P-eng stamp for the the work done on it.
Click to expand...
If the work is done by someone competent, should not be an issue. All that wil be changed will be the spring hanger locations. If anything, the load is now distributed over a larger portion of the frame. If he is really concerned and the OEM of the trailer is still in business, they could be contacted for advice.

I was at Trail Rite trailers in Santa Ana CA and observed the difference between the tandem and single axle trailers. No difference in the frames for same length trailer.

STD-2999-Sin.jpg

STD-5000Tan.jpg
 
mnypitboat

mnypitboat

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May 31, 2010
Messages
1,091
Re: Changing a single axle to a tandem

ufm82 said:
It's not a big deal if you are mechanical. My current trailer's undercarriage is simply u-bolted to the main frame so it wouldn't even require welding anything. You would need to move your existing axle forward and add the rear assembly. My single axle that I used to have would have taken a second axle easily. I could have done it for under $400 but I bought a used tandem for $500 and wound up with a better trailer anyway. Why not hunt for a good used trailer? $2K will get you a nice trailer. Since you are mechanical you could even find a cheaper tandem and "fix it up" as my BIL would say. LOL
Click to expand...

I had exactly the same experiance. When my Tahoe trailer rusted and broke in half I had to get a trailer. I bought a single axle trailer to get my boat so I could move it. I quickly realized it wasnt gonna cut it. I was gonna take my old trailer axles, but they turned out to be rotted too. So I just bought a tandem trailer for $250 and threw hubs on it and a light kit and was into it for about $450 total. Then I replaced the tires a couple years later.

So I would take a bit of time and try to find a trailer that is already a tandem.
 
Sharp Shooter

Sharp Shooter

Petty Officer 1st Class
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Jun 5, 2008
Messages
293
Re: Changing a single axle to a tandem

I've done this upgrade before. It's doable but as stated above you might be able to find a used tandem trailer on the cheap....
 
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