Wanting softer suspension for my Thule trailer

bobholthaus

Observer
I have a small Thule utility trailer that I've added racks to and have upgraded the tires on. It's not exactly an expedition trailer, but gets used for a lot of things, including camping and hauling an ATV. It has a Knott torsion suspension that is not very forgiving at all; I've seen the trailer 6" off the ground after hitting big bumps. I'm willing to spend the money on a new suspension setup, but have no idea where to turn for design. I want a plush suspension, like on my Polaris Ranger. Something very soft that absorbs bumps (I'm thinking even softer than leaf springs, like a trailing arm spring and shock setup). Any ideas on where/how to design one? I asked Martyn at AT if he'd sell me one of his suspensions and he said they don't do that. Thoughts? Thanks.

https://www.dropbox.com/s/egv92ru36wuhzzt/20100611 - Door County 2010 020.jpg
 

Weeds

Adventurer
There are companies that make custom designed springs. Pohl Spring in Spokane, WA make springs for everything from mountain bikes to pickups to large construction equipment.
 

navigator

Adventurer
what air pressure are you running in your tires? You might be able to drop the air pressure down and get a better ride.
 

FredB

Observer
From the picture that I see, there is no room for the suspension to flex??? It looks like it is bottomed out. Which would explain why it bounces over bumps. Look for Old Man's trailer build, he is using trailing arms with air bags, which should flex pretty well.
 

navigator

Adventurer

bobholthaus

Observer
Gentlemen- yes, my tires are oversized, and I did move the plastic fenders up once already. Even if I took the fenders off the suspension still wouldn't flex unless loaded with 1000 lbs or more (the only time I've ever seen it truly flex was with a large load of mulch). A trailing arm with shocks/springs or air bags is what I'd like to see up close. Good idea on lowering the tire pressure, although my BFG All Terrains are very stiff/heavy tires. But I'm going to drop the pressure this morning as a start. I'm assuming I can search for "Old Mans" build? Thanks for the responses.

I just looked st the member list and "old man" has no posts. Any help in finding a thread you're talking about? Thanks.
 
Last edited:

bobholthaus

Observer
Okay, I found another post of a trailing arm setup, which looks pretty basic. But where can I buy the arm setup, or does the entire thing need to be custom welded? I'd like to buy the arms with pivot points attached that I can just have welded to my frame, and that have hubs on the other end (or ideally I could somehow have my existing axle/hub welded on so that I can reuse my wheels/tires/hubs, which are all metric). My tires alone were $500 for the pair. Then I just need some spring/shocks to support everything (I do not want to hassle with airbags if I don't have to).

Side note on tire pressure: anyone know what is the lowest I can go in pressure and still be safe? I've probably got 600 lbs in weight for everyday use. Thanks.
 

Philp100

Observer
As cool as the trailing arm suspension system is I wonder if you are over thinking this project. For your stated purpose I think it would be cheaper and easier to find another torsion axel with a lower spring rate that would bolt right in. Have you checked with your local trailer supply dealer for one?

Phil
 

bobholthaus

Observer
I'll take some pics tomorrow. Yeah, I'm not looking for the cool factor of a trailing arm setup, just looking for a more plush ride. Thank you for the feedback thus far.

Btw, I moved the fenders up and then a few months later oversized the tires. It looks like there is no up travel because I really need to move the fenders again but just never got around to it. In fact, on one side, the tire has worn a little hole in the corner of the fender, so I know for certain I'm getting some up travel.

Okay, just found an old pic. This was before I upgraded/up sized the tires. I will take additional pics tomorrow.
nume4yzu.jpg


Here's another one showing the minuscule amount of clearance between the sidewall and wall of the trailer. I had to use spacers to make these tires, which are the smallest/only 14" AT tires I cou,d find.
ydu5u7a2.jpg


I could easily use the bracket of these axles and bolt them to a solid crossbar for a non-independent trailing arm setup like Old Mans. So that would save me some money.
 
Last edited:

bluejeep

just a guy
Air Bag it. You'll never regret it. And you'll never hear your trailer bouncing around behind you - adjust the pressure to the load and it's smooooooooooth
 

bobholthaus

Observer
As much as I want to buy a Manley ORV trailer (www.manleyorv.com), I think it will be less expensive to have a new frame welded for mine with a trailing arm setup. I've already replaced the deck on mine with diamond tread aluminum, and I spent a small fortune on the wheels and tires. I've got about $4000 in mine. So I'm going to over-design a sweet frame, lengthen the tongue so I can swing open my tailgate all of the way, and figure out the suspension. I'll likely just keep my solid axle and torsion setup and bolt it to the arms, that way I can reuse the wheels/hubs, etc. It's going to be pretty high, so I'll go with a receiver hitch setup on the trailer like Manley so I can change the tongue as my vehicles change. Any advice on where to get airbags, appropriate shocks, and the pivot points and brackets for a trailing arm setup? Also, I'll leave the placement of the axle where it is; but how do I know how long the trailing arms should be, which would dictate their bracket placement? Thanks guys.
 

Forum statistics

Threads
185,535
Messages
2,875,636
Members
224,922
Latest member
Randy Towles
Top