Choosing your Offroad TD AXLE

[wlivesey]

I went with a swing arm/coil with standard shocks .

I imagine thats a custom fab job??? Looks nice, I'd like to have that setup on the build I'm planning but I don't know anything about the geometry. I'd be afraid it just wouldn't perform well.

[PaulC]

I use the KISS principle with my offroad builds. The heaviest rated axle with leaf springs. The only trailers I've seen starnded in the Outback, down here, have been those with the "Tows beautifully" independent suspension. IF, and only IF, you have the misfortune of breaking a leaf, it's amazing what you can do with a lump of wood, some fencing wire and a slightly lower pressure in the affected tire.

[wlivesey]

Agreed. It's easy to get caught up in "cool".

I apply the same principle in my day job as a software engineer.

[CaBowhunter]

I don't do cool I do functionality , The system could not be more KISS proof then the archaic straight axel is . Lets see I have 2 shocks it has 2 shocks , I have 4 attach points it has 4 attach points . It uses leafs springs my uses coil springs . OK I give were is it over complicated? And mine uses a 3500 lbs rated axle with the right bolt pattern to match my FSJ.


Randy

[wlivesey]

I don't do cool I do functionality , The system could not be more KISS proof then the archaic strait axel is . Lets see I have 2 shocks it has 2 shocks , I have 4 attach points it has 4 attach points . It uses leafs springs my uses coil springs . OK I give were is it over complicated? And it uses a 3500 lbs rated axle with the right bolt pattern to match my FSJ.


Randy

I definately like the idea of an independent suspension setup. No doubt it can be kept simple. Again, I'm just not a familiar with the geometry required to make such a setup work well. The build I'm planning will be used for long highway hauls (Texas to Wyoming) as well as off road trips locally so whatever suspension setup I choose, it must work perfectly. Straight axel setups can be easily purchased and installed. Indenpent setups seem like they must be custom fabricated. Do you, Randy, have any recommendations or insight into making a custom independent setup work correctly? Thanks for any info you can offer...

On a side note, I'll post some info about my planned build shortly...

[PaulC]

I don't do cool I do functionality , The system could not be more KISS proof then the archaic straight axel is . Lets see I have 2 shocks it has 2 shocks , I have 4 attach points it has 4 attach points . It uses leafs springs my uses coil springs . OK I give were is it over complicated? And mine uses a 3500 lbs rated axle with the right bolt pattern to match my FSJ.


Randy

What could me more functional than a leaf set up. Sorry Randy, you do cool. Tell me you hate when people look underneath and say, " hey, Independent suspension, that's cool"
Leaf- no pivot points so less strain.
Leaf- no need for something to stop anything from falling out.
Leaf- no need for shocks, if that's the way you want to go.
Leaf- no need to figure the geometry with camber etc

[brian_bp]

...Leaf- no need to figure the geometry with camber etc...

The fully trailing arm geometry is very commonly used (in trailers, this is usually the rubber-sprung system), so I don't think there's anything to work out if that experience is to be accepted: just mount all four pivot bushings in a straight horizontal line across the trailer, yielding a fully trailing geometry, which in turn means no camber or toe change except due to bushing deflection; the spindles are just parallel to the pivots, yielding zero camber and toe. That appears to be Randy's setup.

If anyone does want to play with geometry, I think a slightly semi-trailing geometry with some initial negative camber would likely handle better at highway speeds, but the plain upright fully trailing arm setup will work, so I don't think that any "figuring" is required.

(For those interested in the semi-trailing arm option, the Al-Ko Kober Delta axle is an example; it is likely only available in Europe, and their description isn't very good, but it shows that this type of geometry has been proven.)

Ironically, leaf spring axles do have geometric considerations: I believe that they should have the front eye lower than the rear eye to produce a favourable steering response to roll, or at least to eliminate the adverse response. This is usually not considered in trailers... almost everyone just mounts them in the most convenient fashion despite the geometry. This is, of course, just my view of leaf-spring suspensions... opinions vary. For somebody else's opinion, try AFCO Racing's RRM Tech Net Article: Leaf Springs, or Multi-Leaf Spring and Hotchkiss Suspension; CAE Simulation, or any book on racing chassis setup which includes leaf-spring suspensions.

[stomperxj]

Unless you find a bolt on independent setup, it is more complicated to build than just buying a leaf sprung axle and welding perches onto the frame... Plus, I can find leaf springs pretty much anywhere that I can make fit in a pinch if there is a failure...

[PaulC]

Unless you find a bolt on independent setup, it is more complicated to build than just buying a leaf sprung axle and welding perches onto the frame... Plus, I can find leaf springs pretty much anywhere that I can make fit in a pinch if there is a failure...

BINGO!!

Well Said.

[deepmud]

I have a bolt on(4 bolts), trailing arm, soft riding suspension. When I first built it I had no welder, only a hack-saw, and grade 8 bolts, and some big C-channel for a frame. It grew a few years later, when I had a welder, and need for more room. It's only really good to about 1500 pounds gross on a long trip, tho' I've loaded 2300 pounds palletized flooring on it once. It is inexpensive, and you can get parts easily, tho' mine has been trouble free for over 15 years, and at least one 15,000 mile trip.

It's a Subaru 2wd Station wagon suspension, early 80's era. A lot like the VW suspension mentioned earlier in the thread.

My trailer is not a Teardrop, but could be made into one, if my wife didn't hate small spaces. The Deck on it is about 6'x8'.


It's light too - less than 300 for the frame, axles, tires, shocks. I tipped it on it's side for the underside shot with one hand.




As you can see - gobs of clearance. And it handles a load. I participated in a trail clean up and hauled a subaru wagon carcass out. It was lifting the hitch UP so transferring weight from the tow rig to the trailer. Easily 1000 pounds on the axle with all the mud and gravel that was washed into it.






I posted up on the Expedition board in their trailer section - but not much response. Maybe this forum, with the more homebuilt style, will be more interested

Here's the box I built to travel from Alaska to Washington D.C. and back with my family of 5 (we tented out of it and our AWD Aerostar).



The trails I have towed it on are no joke - I've hauled it loaded with logs across downed trees, and under water loaded with junk.

Sometimes I use my big Suzuki to haul stuff, not just the little one




PaulC - I hear you on the "KISS" idea of leaves - but for a counterpoint I've seen leaf suspensions break too - and I've seen too-heavy suspensions beat the heck out of trailers, especially campers, with stuff like post/pans/lanterns/stoves taking a beating to the point stuff starts to break, while a smooth riding trailing arm might keep things together longer.

The Lone Wolf Expedition was a good example:
http://www.lonewolftransglobal.com/LoneWolf.htm
( and a heck of an interesting ready if it's new to ya )
- he really traveled some miles in some really remote places - and multiple times he broke the heavy leaf suspension on his trailer - and he was not a self-fixer, spending quite a bit of time and effort hunting down welding/repairs in Pakistan and Thailand(or was it Laos? whatever) . I kept wondering if a well built, softer suspension might have held up better - my own experience would say "yes".

Oh - and sorry to barge in without an intro - I've like Teardrops "forever", and have lurked here once in awhile in the past ( I didn't see the offroad trailer section then ) but ....my wife ....small spaces....lol

[Miriam C.]

Goodness the things I almost miss. Deepmud tell the wife a td isn't much smaller than a tent when your laying down. Sleeping bag keeps it all in prospective.

and to the playground. Thanks for the pictures.

[PaulC]

Deepmud, Welcome to the Forum. Lots of interesting reading and backed by pics to boot.
Let me clarify one thing though, at no time have I said that leaf spring susp. won't break. What I have said is that, if it does, you can normally
jury rig it easily to get you out of a spot. As for leaf springs beating the cr4p out of stuff. Any trailer, leaf spring or trailing arm, with the wrong combination is capable of doing that.

[brian_bp]

...It's a Subaru 2wd Station wagon suspension, early 80's era. A lot like the VW suspension mentioned earlier in the thread...

Thinking about this earlier, I could only come up with three fully trailing arm completely independent non-driven rear suspensions off the top of my head, and Subaru was one of them; however, I didn't know anything about the details of the design or the years or models which used it. Thanks for the photo.

Are the springs in this design torsion bars inside the cross-tube?

[deepmud]

True enough that leaves can be made to work pretty well, they do tend to be less progressive than coils or torsion. Most people buy a 3500 pound axle and you get maybe 3 or 4 leaves - unless you start to spend real money. I do agree that the 3500 pound axle is going to come with heavy duty bearings - that alone is a great investment.

You mentioned bolt-on suspension - this is has been a great one for me - it's been REALLY reliable and REALLY abused, and the way the axles swing back with the bumps and hits of the road seems to make them more forgiving than any leaf suspensions out there - making the "repair in the field" option sort of moot. Unless you have "skills" it seems that either style is going to take some sort of professional assistance - like the wolf expedition needing to find welders/fixers in the remotes locations he was in. Me, if I go around the world, I'm bringing a Ready Welder, lol.

The http://www.adventuretrailers.com/suspension.html Adventure Trailer Site has a pretty good argument for their trailing arms, talking about evolving from leaves. to rubber torsion. to their latest, air-sprung trailing arms. Their design can be bought and bolted on, I just could never justify the kind of money they require. Given a choice between leaf springs and their system I'd buy leaf-springs every time, 'cause I'm CHEAP, lol. But I'd buy rubber torsion before buying leaf-springs too. They are pretty simple. AT says they can wear out but I think I could jury-rig them to stay together in all but the most catastrophic failers, like a snapped spindle or something (which neither style suspension is immune to).

As for my Suby trailer - it's only drawback has been when I really load it up. The 13" Suby tires have a limited load capacity, and the torsion spring is so soft (yes, contained in the cross-tube) that by 2000 pounds on the trailer, it's pretty much out of suspension travel. Keep in mind when I built this I has almost NO fab skills, yet it held up to many years travel before getting reworked and even then, I ignored the suspension, just getting it a quick bearing grease before setting out.

The wheels are getting swapped to 15" 6 on 5.5 Toyota/Chevy/Nissan pattern - mostly so I can get a wider, more floatatin-type tire - this is an easy swap because the Subaru pattern is 4 on 5.5 - I just knock out 2 studs, and use the new rim as a pattern to drill the 4 new holes. The torsion springs I'm going to give a little help to with some cheap JC Whitney air-shocks. Another option is the JC Whitnet "helper coils" that clamp on normal shock tubes - but I like the air shocks cause I usually have less than a few hundred pounds of crap on the trailer and it rides great.

And finally as for getting my wife to use a Teardrop - lol - logic has nothing to do with her reaction to the small space.
We rode by motorcycle across Europe a few years (ok over a decade now eek!) ago - she's a great, calm passenger even at 130 mph on the autobahn and the amazing roads in the Alps - and we used a really small, 2 man tent - but I can't even get her to LOOK INSIDE a small trailer, hehehe.

[Dave Nathanson]

Well, We've been out doing materials testing again!

We did a 2002 mile trip through Baja Mexico in Oct. It was a really great trip, even though we broke a leaf spring on the trailer in the last few days. I was shocked, but no stranger to trail fixes. I had it all strapped back together in less than 2 hours. Luckily, the spring broke behind the axle, so the front half of the spring held the axle on. If we had a torsion axle, I don't know what I would have done. We were 400 miles from home, deep into a very remote area of Baja Mexico. It seemed that few others were brave enough (or foolish enough) to tread there.

I blame the breakage on hundreds, no, thousands of miles of washboard roads. The shocks were wasted long ago, so they were not helping dampen anything. The road was rough, some of the worst washboard I've seen, but it was also very rocky. The shorty leaf springs that come with Trailer axles are apparently not designed for enough vertical travel to absorb dropping the trailer from a height of 16 inches.. Which is pretty much what were doing, even when we didn't mean to. (We never mean to bounce it like that).

There were 3 springs in the leaf spring pack, and it would seem that the bottom one must have broken first, and some time ago. Because it was already sort of rusted on the end. The other 2 broke that day, and with vigor on the road to Puertecitos. (some 80 miles south of).

Anyway, this validates my opinion that if I ever broke a leaf spring I could fix it on the trail and drive it home. Which we did, being ever so careful not to stress it any more than absolutely necessary. We even headed for the nearest (and only) paved road and took paved roads all the way home after that.

If you ever need to repair a broken leaf spring, or even a torn frame (another story) here's how. Jack up the trailer a little, so you can jam 1 or 2, maybe 3 pices of 2x4 between the frame and the axle. You want enough wood there so the axle will not travel away from the frame. Then strap it up, all around the frame & axle. Use several straps if you have them. You really don't want this to let go. The "motorcycle straps" with the hooks on them are more difficult to get tight in such a short area, so use a ratchet strap with 1 end free (no hook). Medium duty worked for me. Consider tying a strap from the axle to the front of the trailer to prevent the axle from moving backwards at all.

Oh! This reminds me. I'm REALLY GLAD that our trailer has a frame cross-member exactly above the axle. That has turned out to be important! Or else it would not have been there to tie the axle to! Important 4x4 Frame design tip!

(Actually took this photo the next morning in camp).

When we got home, I replaced both springs, and saw that the drivers side spring was about to break off too! Just made it! =:-0

Now that I have a new pair of springs, and time to think, I'm wondering if longer leaf springs from a Jeep might work out better. Or better shocks. Or maybe that fancy trailing arm suspension...

Here is the View from the back. Notice the missing leaf spring!



And here is the view from the front:


Here are a very few (29) photo highlights of the trip
And Here are ALL 601 of the trip Photos



(Update: 7/15/2015: fixed photo links)