added a second axle

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raycarlson
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Re: added a second axle

Post by raycarlson » Tue May 12, 2015 7:05 am

If you stayed with a torsion axle, its very simple to reclock your wheel hubs to increase tire to fender clearance, also both wheel hub lever to torsion bar angles should be equal when trailer is level or adjusted for hitch ball height,

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Tomfoolery
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Re: added a second axle

Post by Tomfoolery » Tue May 12, 2015 7:39 am

Three Gypsies wrote:We loaded the Gypsy on her modified trailer , last week .
All is well ! She seemed to load easier and she definitely towed a 100% better !

We had the "MacGregor Bump " so the Gypsy wasn't snug in the bow chuck . Usually this makes her a little fish taily at anything around 60mph , BUt Now ! No fishtailing ! I was on two lanes roads so I couldn't get faster than 50 or 60 mph , but
I don't usually pull much faster than 60mph , anyway .
I calculated the location of the center of mass for a Mac X and standard single-axle trailer, overloaded as usual at 4000 lb, with a 10% tongue load of 400 lb. That's a bit more tongue weight than I actually measure on mine. My 2-axle modified trailer, with the midpoint between the axles right where the original single axle was, has the same tongue load, since nothing has changed. The CG location calculates to about 22" forward of the axle center.

If the trailer guy moved yours ahead 6", that puts the midpoint between the axles quite a bit further back. Assuming the typical 30" axle spacing, you get an increase in tongue load, with all other things being equal, to around 540 lb, or around 13.5% or so of total boat/trailer weight, though I didn't take into account the additional weight of that one axle, so call it 13%.

That additional tongue load should, by itself, help it track nicely. Mine tracks very well, and the CG didn't move when they added the axle (they moved the original forward about 15"). So between the higher tongue load, and the additional axle, I would think yours would track like a dream.

But I would be careful about that pole tongue, as they tend to rust and get thin, especially back where the bending is greatest - where it meets the channels. You might want to bang around on it with a hammer and listen for it to ring (good) or thud (bad), especially the bottom of it. But now you don't have to worry quite as much about putting heavy stuff in the bow to keep the tongue load adequate for safe trailering. 8)
Three Gypsies wrote: I only have brakes on the original axle , but braking seemed to fine , I never felt the boat pushing the tow vehicle . I didn't have to "slam on " the brakes in an emergency on our short tow , but I think she will stop as well as ever .
You'll probably find that it stops the same, since it weighs the same, and the brakes are the same. But with half the wheel load now, it may lock up in a panic stop. I found that to be the case on mine (disc brakes), but only when I hit it hard for the Mac Bump. And my brakes are on the back axle, which on an equalized leaf spring suspension system, actually sees an increase in tire load when braking (the front axle sees a decrease in tire load at the same time). I'm thinking about adding brakes to the front axle, too. Required in some states (Maryland, for one), but also because I've experienced the joys of hot brakes and long stopping distances in a former life (trailer driver), and there's nothing like the feeling of mashing the brakes to the floor and slowing like you're driving a freight train. :o

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u12fly
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Re: added a second axle

Post by u12fly » Tue May 12, 2015 8:16 pm

jasonsjwou wrote:Recently bought my 26M, came with the factory original aluminum trailer. (2007 26M)
I towed it behind a GMC Savana 1500 for 120 miles. It drove alright.
But I've been thinking about adding a second axle.
Does the factory original aluminum trailer use torsion beam suspension?
Should I just add 2nd axle without brake? Should it be also on a torsion beam?
This mod has been done by more than a few folks here on the site, it is pretty popular and easy to accomplish. I wrote up an overview in the Mod section a few years back. http://www.macgregorsailors.com/modt/in ... ?view=1832 My :macm: with all its modifications, fully loaded with gear weighs over 5000 lbs on the trailer. We have been towing with a 1998 Ford Expedition and have never had an issue. Several 400+ miles trips.

I pretty much copied the factory for supporting the boat piece by piece and bolted it together, over a second axle. Take your time marking and drilling the axle mounts, you'll want these exactly square or you'll be eating tires. 8)


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Three Gypsies
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Re: added a second axle

Post by Three Gypsies » Wed Jun 17, 2015 10:14 am

After writing the above , we towed the heavily loaded boat from Montgomery Alabama to Indiantown Florida . A distance of 900 miles .

We were loaded to the gills as we don't plan on going home anytime soon .

The boat pulled beautifully ! She was still the usual headaches of towing a long top heavy trailer , but compared to the single axle days , I couldn't ask for better .

As someone else wrote , she is hard to back up , with the dual axles she doesn't want to turn , but that's a small price to pay for the safety and secure feeling on the highway .

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RussMT
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Re: added a second axle

Post by RussMT » Wed Jun 17, 2015 11:36 am

Three Gypsies wrote: As someone else wrote , she is hard to back up , with the dual axles she doesn't want to turn , but that's a small price to pay for the safety and secure feeling on the highway .
I've never had a problem turning the dual axles. Backing with the surge brakes can be an issue if you don't have a 5th wire or lock out the compression with the brake key.

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Mac26Mpaul
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Re: added a second axle

Post by Mac26Mpaul » Wed Jun 17, 2015 8:05 pm

Three Gypsies wrote:W

The only problem is as someone else wrote , very little clearance between the new fenders . There is only about 3 inches of clearance . I am touching one fender and barely off the other .

!
I would not be driving too far if your tyres are rubbing on the fender..

The answer as suggested by Ray (thanks again Ray), was to take the arms off the axel and move them a few clicks.

I finally got to try mine out last weekend after doing this months ago. I don't know if it was just me not having towed the boat anywhere since last September, but we kind of felt the boat was bobbing around a bit back there (feeling less stable).

Also the boat doesn't slide on the trailer as easy from the water if you try and drive it on. Mind you the fact that after raising the torsion arms, I also had to invert my tow hitch to get a level load, means that the front of the trailer and also quite a bit higher.

Might lower them a click I think, and may have to start dunking my car wheels a bit which I don't really like doing..

korn_kid_12
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Re: added a second axle

Post by korn_kid_12 » Tue Dec 15, 2015 4:34 pm

I have a single 8 lug 7500lb axle on my x trailer. Kind of interesting deal. Tows decent parks nice.

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