Choosing your Offroad TD AXLE

[deepmud]

Good job fixing the axle on the trail. The pics are great - and I especially liked the cliff paintings - how cool. I'd love to do a trip like that some day with my lifted Samurai and a TD or tent-trailer.

Ratchet-straps are great. I repaired a broken transfer case mount with one on my Suzuki once, lt looked like your axle repair did, and lasted a couple months until I could get new mounts.

[marcovgv]

here is the link for my new trailer. its a one tone but the axle looks like it will hold up to much more than 2000 pounds. below is a descrition of the sellers ad
http://www.auctiva.com/hostedimages/sho ... 0&format=0

1988 Turtle Mountian Military trailer. The trailer is an M116A3 which is not common. This is a USMC Equiptment trailer that was used to haul generators in Iraq. It is 1 ton, most are 3/4. It can handle up to a 37 X 12.50 X16.5 tire and 2pc 8 lug wheel. it has hydraulic surge brakes with toledo actuator using silicone brake fluid, 8 lug 1 ton axle, shock absorbers, 1 ton springs with lubricated shackles that have grease fittings, parking brakes to keep it wherever you put it, removeable equiptment mounts, brand new RADIAL 8ply 235/80/R16 HEAVY DUTY trailer tires mounted and balanced with new bolt in high pressure valve stems, built in pivoting stand, lift shackles, and retractable load leveling stand to keep the trailer level during loading. This trailer is built tough and has the clearance and suspension for off road use and tows well behind a 4X4. It has an 11000lb capacity lunette eye for towing and has a new military 12pin electrical connector that is heavy guage which can be wired for auxillary power to the trailer as well as reverse lights. The possibilities are limitless.

[deepmud]

nniiiiiiiccccce super-beefy. You could carry loads of concrete across boulder fields and never begin to stress that beasty.

[Russ in California]

Lot's of food for thought and great ideas.
My guide will be Larry and Diane Sorensen's Outback TD design.
This could, should be the bible site for anyone wanting an off road TD.
If nothing else, it's a great place to start or for reference on great ideas for comparison.
There you go...


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[Dave Nathanson]

If I had known it was available, I would have ordered my TD axle with a PARKING BRAKE. It's not much more money. That would be a lot better than always messing with wheel chocks. You can run a parking brake cable up to the front & have a parking brake lever there, like the military trailers do. Easy!

And considering that TDs are mostly full of air, you really don't want the short stiff leaf springs that typically are used for a utility trailer. Those are designed for carrying a heavy load on smooth asphalt roads. A leaf spring that is softer and longer would be a lot better.

Anyway, before you get your axle, give this some consideration.

[aggie79]

Based upon his testimony, this is what I'm considering on my next build: http://www.tnttt.com/viewtopic.php?f=35&t=57134. My build won't be for off-road, but I like the independent design of the Timbren. Per the poster, you can get the 3500# axle with the 2000# "springs".

[angib]

.... but I like the independent design of the Timbren.

I can't see what benefit the Timbren provides - unless you intend to put some structure in between the two suspension units (like a dropped floor) which you can't with a torsion axle, or you want the clear space between the suspension units (like for an off-road trailer).

Functionally, the Timbren units and a rubber torsion axle are just the same. The torsion axle has the advantage that it comes with the geometry and strength of the central tube.

[alaska teardrop]

.... but I like the independent design of the Timbren.

I can't see what benefit the Timbren provides - unless you intend to put some structure in between the two suspension units (like a dropped floor) which you can't with a torsion axle, or you want the clear space between the suspension units (like for an off-road trailer).

Functionally, the Timbren units and a rubber torsion axle are just the same. The torsion axle has the advantage that it comes with the geometry and strength of the central tube.

Interesting comparison. By geometry, Andrew, I am assuming that you mean, is information available as to predetermined ride height according to load? Also, can the width/track be adjusted to the build in regards to such issues as tire width/body clearance ect.?

Another thought, Tom. Will your trailer come to a weight that a 2000# suspension is acceptable? i.e. by comparison, a torsion axle can be tailored more closely to the load requirements.

Fred

[angib]

By geometry, I was thinking of toe-in and camber that doesn't have to be worried about with a one-piece torsion axle (or with a pair of Timbrens with a tube between them - but then that's just a homebuild torsion axle). Admittedly here in Yurp where using two separate 'half-axles' is common, we know that this alignment isn't actually a problem, but it does seem a concern in North America where they aren't that common.

There are circumstances where the Timbrens would be wonderful, but I think a pair of Flexiride half-axles would usually be more wonderful.

[Toyotamike]

I'm going to swap in an 80's Toyota rear axle so it can be spares for my rig. Will need to build a sub frame for the harbor freight trailer but then I can use Toyota leaf springs too.

[eamarquardt]

Why is there no mention of SPARE parts. "Parts is parts" and having some u-bolts, nuts and bolts, spring, shackles, etc would make things go much easier in the event of a failure. I think a spring suspension system would be easier to carry spares for and service in the hinterlands than a torsion axle.

I used to sail and offshore there are no parts stores so I carried a few essential items. Occasionally they came in handy.

Hope this helps.

Cheers,

Gus

[Dave Nathanson]

Hi everybody,
As you may recall, I've been complaining that the suspension of my TD is too stiff, the trailer bounces, and we broke a couple of leaf springs 80 miles down a washboard trail in Baja Mexico. I've been theorizing that longer YJ Jeep springs might be the answer. Well, today I took the TD over to Off Road Evolution in Fullerton, CA and talked with Mel. He is good with off road suspensions.

I have to say I was surprised at his advice (but I like it). He pointed out that you can see almost 2 inches of travel on the shock shaft. It is shiny there. So we would not want to add much more travel or the trailer will be bottoming out all the time. We could use YJ jeep springs, but he's not sure that would be better. Actually, he recommended against that.

Or we could do a spring over axle lift to create more room for travel, but if we make the jeep too tall there is a serious danger of it tipping over or rolling over on the trail. He has seen that happen several times. So he didn't recommend that either.

The best solution is to use bigger tires & lower pressure (especially on the trail). He said no reason not to use the exact same 32" tires on the trailer as the Jeep already has. Might need to raise fenders to make room for larger tires. But it's only three bolts, so no big deal. He also thought it would be perfectly okay to bolt a full-size 32" spare tire to the side of my trailer, since the trailer walls are 1 inch thick plywood.

He suggested a trail tire pressure of as low as 10 PSI in the trailer tires (if they are bigger). And back to the normal 35 PSI when on the highway. Same as the Jeep.

And as for the history of leaf spring breakage.... He said to carry an extra spring! That makes sense to me, so I bought a pair at Carson Trailer on the way home. I plan to find a place to affix it under the TD so I will always have a spare leaf spring.

TD leaf Spring axle travel 2014b.jpg (79.52 KiB) Viewed 9477 times

[Dave Nathanson]

This being the Offroad TD Axle & Suspension thread, I have to report that I broke 2 more leaf springs on the last trip to Baja Mexico. For a total of 4 broken leaf springs over 4 years. It was rough going, and those springs broke going very slowly. I think the wheel fell into a hole, or dropped off a rock then compressed the leaf spring until it snapped.
I'm going to tell you WHY my leaf springs keep breaking, and what I'm doing about it.

If you look closely at the photo in my previous post you can see that the shocks are mounted wrong. You don't see that? Don't feel bad. In 13 years, I didn't see it either. What is wrong is that the shock mounting bolts are not parallel to each other, not pointing the same way. One is twisted 90 degrees. It seemed ok at the time. But if you think about it, in addition to getting longer & shorter, part of what a shock does is to pivot on the mounting bolts. Fine. But not possible when the mounting bolts are not pointing the same way.

So what was happening was that everything was FINE when the shocks were broken off. And they were broken off for years. But I replaced them before the "big Baja off road trip" and that is when the shocks would restrict the motion of the leaf spring, putting all the forces on just half of the leaf spring. SNAP! When it broke we were hundreds of miles south of the border, and hadn't seen pavement or civilization in days. But that's a story for another post.

A DIRECT FIX
If I just left off the shocks or mounted them differently (bolts pointing same direction) I think the leaf spring would not keep breaking. That is certainly an option and a direct fix.

THE OTHER PROBLEM
These short utility trailer springs are intended for much heavier loads so they are way too stiff for a little teardrop trailer. Stiff means a hard ride, which means it bounces easily, especially when empty. Bouncing - and I do mean getting airborne 6 inches to 12 inches - means the whole trailer is being pounded and this is after all, a mostly wooden trailer and pounding like that can't be good for it.

WHAT I AM DOING ABOUT IT
I bought a Timbren "axle-less suspension" . Part number ASR1T-HDS02 == 3500 # suspension (strong metal very thick), 1500# rubber spring (soft), & offset spindle for Offroad tires (8.5"), then down rated to 2000# for offroad use. Offset =hub face to frame = 8.5".
HOWEVER if you are an offroader, you probably want the 4" lifted spindles part number P025. I don't know what the part number for the whole kit is when it includes the lift spindles, but you can get that. Alternately, you can weld on some good square tubing under the frame to lower the frame, then bolt the Timbren to that. I'll get a build thread together.

I've taken only 2 trips with the Timbren, and it is much smoother riding than the leaf springs ever were. I feel this will prevent my trailer from getting so pounded by repeated bouncing & slamming. This is an important step forward for my offroad TD, so I wanted to mention it here. Search TNTTT for Timbren, or search for my posts and you'll find more mentions, plus I'll eventually get up a bunch of photos, measurements & findings about this suspension. In the meantime, the Timbren looks like a serious contender for an off road teardrop trailer suspension.