Looking for DIY independent trailer suspension information.

Louisd75

Adventurer
Build the trailing arms as strongly as you can as they take a lot of abuse off road. If you go with airbags make the upper mounts from 1/4” steel. If you go with coils adjust them for the load, if you don’t the results are not pretty. Do not link the airbags together, keep them independent. Do not for one moment believe that torsion axles, leaf springs etc. perform anywhere near as well as independent air or coil suspension. Your eggs will arrive in one piece and your beer will not explode when you open it. You will not feel the trailer moving behind the vehicle. Look at an old build Andre Shoumatoff posted on the forum on an independent trailing arm set up he made, I think it was one of the best set ups made by an individual.

Martyn,

Do you guys still do any trailer stuff?
 

ottsville

Observer
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Cheers,
Peter
OKA196 motorhome
In a parking lot, the math says that a trailer will follow the track of the TV given the right dimensions. That won't be the case in a place where you are worried about clearance because the trailer will slide/bounce/creep towards the low side of the trail or down obstacles.
 

Unholy

New member
Thank you all for the replies. Between full time work, college classes/homework for 20 hours a week, and house/vehicle repairs I'm a bit busy, it makes spending time researching and digging for information a bit hard right now.. My apologies for the slow response time.

I appreciate the wealth of information. The trailer, I'm wanting to build is a small single axle. Well, minus the axle. I'd like a flat bed, but, one that can be changed in order to be used as a expedition trailer. While this may seem not possible to most, I had made a 4x8 trailer a few years ago, that had a removable flat deck with extensions. When the deck was removed, it was just a frame. I had a set of Kayak mounting racks allowing for 4 to be loaded. I had a few other mounts for motorcycles and lumber. I had plans for a small camper pod that could be attached also, a teardrop style, however I never built it. The trailer was lighter duty than what I would want now. It also was very tall, while not a problem for my dodge ram, it would be way to tall for my subaru outback. It also, didn't perform well off road. I sold it about a year and a half ago.


My issue with normal axles is the very poor off road handling. yes, I have tried. I also find, that having to order a special size axle to be more costly than what it is worth, especially with the lesser performance. I'm not a fan of torsion axles either. I found pictures of many independent arm/coil suspensions and videos of how well they work off road. I'd like to think with this suspension, and a redesign of my original trailer coupled with some material changes, I can create a smaller, more useful better adapted trailer. As far as airbags, I've seen a few failures that keep me wanting something that is a bit more sound. It would be nice to be able to adjust the coil tension or travel to change load on the springs, but not sure that can really be done.

I am mostly looking to pull this behind my Outback, while small, it can tow 2700 lbs. I'm not looking to exceed 1,500lbs even. I figure a small trailer with a more rigid frame that can be reconfigured, with a small storage pod and either rooftop tent or folding hard shell sleeper would be the trick. A removable tongue that allows for a high or low one to be installed for the truck, or car. Just a month and half ago, I went to the UP in Michigan, I went down many trails to remote state camp sites. Some spots, even a small truck was to tall to access. I slept in my Outback, but, I had no toilet or shower. No stove/grill. Nothing but the bed, a spare tire, fuel packs on my roof rack, along with a winch, farm jack, shovel and boards. It was fun... but I'd like a bit more ability to be away from towns/cities.

Thanks to all who replied. - Unholy
 

billiebob

Well-known member
something like this should be a fairly easy home build..

the benefit of independent suspension is reducing unsprung weight, making it easier for a shock to control and giving a softer ride for all those expensive, sensitive items like refrigerators, cameras, solar panels.....

the benefit of air ride is adjustability according to the load.

50565316_2031043316944819_3318940483404693504_n.jpeg
 
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Thread resurrection.

I built my own independent trailing arm suspensions to replace a 3500# Dexter axle on an Aliner Ranger 12 trailer. I used Firestone airbags and the mounting plates that came with them for a F150 truck. I combined these with Monroe shocks. It has all worked great for many forest service/BLM road trips. Recently though I noticed the 1/4" airbag mounting plates are bent upwards on both sides. Is it possible I had too much pressure in them (70 psi) on the last trip? Or does this indicate there wasn't enough pressure and they bottomed-out? If the latter, I would be surprised since I monitored the pressure almost everyday (manually). Looking for answers for what could have caused this. Thank you.
 

slimtwo

Adventurer
Thread resurrection.

I built my own independent trailing arm suspensions to replace a 3500# Dexter axle on an Aliner Ranger 12 trailer. I used Firestone airbags and the mounting plates that came with them for a F150 truck. I combined these with Monroe shocks. It has all worked great for many forest service/BLM road trips. Recently though I noticed the 1/4" airbag mounting plates are bent upwards on both sides. Is it possible I had too much pressure in them (70 psi) on the last trip? Or does this indicate there wasn't enough pressure and they bottomed-out? If the latter, I would be surprised since I monitored the pressure almost everyday (manually). Looking for answers for what could have caused this. Thank you.
In my thinking, it sounds to me like the suspension bottomed out, causing the damage. Only way to really know for sure, is to mount a camera under there, or I guess you could have someone follow you and observe what the suspension is doing.
 
SlimTwo,
So, if I follow correctly, the shocks are compressed too much at neutral stance? Or do I just need to add bump stops?

Edit: bump stops, not dampner blocks
 
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billiebob

Well-known member
I noticed the 1/4" airbag mounting plates are bent upwards on both sides. Is it possible I had too much pressure in them (70 psi) on the last trip?
If the upper mounting plates bent.... I'd say you need to add gussets to triangulate and reinforce the plates. Even if things are overloaded and bottoming out the mounting plates should not bend.

PS a picture would really be helpful.
 

jwiereng

Active member
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Cheers,
Peter
OKA196 motorhome

, if you want the trailer wheels to take the exact same path as the rear axle of the truck the hitch must be exactly the same middle of the tow vehicle axle and the trailer axle. In most cases the trailer axle to hitch distance is longer than truck axle to hitch distance, causing the trailer to take a tighter turn than the truck, off tracking to the inside.

take out your Meccano and give it a try
 

billiebob

Well-known member
, if you want the trailer wheels to take the exact same path as the rear axle of the truck the hitch must be exactly the same middle of the tow vehicle axle and the trailer axle. In most cases the trailer axle to hitch distance is longer than truck axle to hitch distance, causing the trailer to take a tighter turn than the truck, off tracking to the inside.

take out your Meccano and give it a try
If you have an F250 they spec a 52" rear overhang so lets guess 52" from the hitch/ball to the axle centerline. With the pretty standard 48" tongue, you'd have 8" of trailer body in front of the axle, given the standard 60/40 ratio for the trailer body, less than 3" behind. Cool theory but not a practical contribution to the discussion.
 
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jwiereng

Active member
So if have a pickup, average distance of less than 60" hitch/ball to rear axle centerline, the ideal trailer would be 60" or less from the hitch/ball to the axle centerline. With the pretty standard 48" tongue, you'd have 12" of trailer body in front of the axle, given the standard 60/40 ratio for the trailer body, you figure there is a market for a 20" trailer ???? Cool theory but not a practical contribution to the discussion.

ps, I just guessed at a generous 60" number, axle centerline to hitch/ball on an average pickup. Pretty sure it is less than 48"...
which with a 48" tongue.... means it is not even a theoretical option.
I agree. Not practical. A little off tracking on tight turns will occurs. This is normal, and certainly desirable for backing up.

Just clearing up a point of misinformation from quickfarm.

Gooseneck and 5th wheel do more offtracking than “bumper” tows
 
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billiebob

Well-known member
I agree. Not practical. A little off tracking on tight turns will occurs. This is normal, and certainly desirable for backing up.

Just clearing up a point of misinformation from quickfarm.

Gooseneck and 5th wheel do more offtracking than “bumper” tows
In reverse, the trailer pin over the axle sure makes reversing smoother..... as does a loong trailer wheelbase.
Altho the negative of how fast a bumper pull and short trailer reacts to steering inputs while backing up can be an advantage.

wow, have we ever gone off topic
 
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Louisd75

Adventurer
In reverse, the trailer pin over the axle sure makes reversing smoother..... as does a loong trailer wheelbase.
Altho the negative of how fast a bumper pull and short trailer reacts to steering inputs while backing up can be an advantage.

wow, have we ever gone off topic

You could even say that we've gone ... off track




I'll see my way out now
 

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