Axle selection for homemade trailer

[jeep4x4greg]

Hi all,

I'm new to the forum. I was wondering if someone could point me toward some good axles for consideration in my trailer project. I'm not sure if I should go with a tube axle with leaf springs, or if I should get the torsion style that attach directly to the frame with no typical springs.

the trailer will be about 4.5x8.5ft enclosed like a camper but will do double duty when I need to haul the riding mower, sheets of plywood, lumber, etc.

I have found two leaf sprung options from Northern Tool....one is 2000lb, the other is a 3500lb. NT also has a few torsion axles but they seem to be all rated for 2000lb.....

It will get pulled behind my Subaru Forester until I get around to replacing the project Jeep I got rid of a while ago. It will see some mild terrain for now, but I want it to be rock-ready for when I get a new trail vehicle.

Let me know if there's a benefit for one or the other type of axle....I've never built a trailer but I've gotten some good inspiration on here and should be swell


thanks!

 

[Hill Bill E.]

I've never had a torsion axle set up, so I can't speak to how they work.

I have an M416 with a RTT, and did a spring over on the axle, to fit up to 33" tires.

I'm running 31" tires on it now, and have never had a problem with hanging the axle up on rocks or stumps. I figure the CJ has to go first, and with the pumpkins and bigger axle tubes, it'll get hung up before the trailer! :elkgrin:

I may end up pulling a couple leaves out of the springs, to soften the ride (still has stock Military springs under it) but am very happy with the solid axle/leaf spring set up.

 

[ntsqd]

For years I've maintained that the rubber torsion axles work fine for all but the most extreme off road uses. The caveat is that they must have shocks attached to them, which they are not set-up for.

Adventure Trailers disagrees with this and have moved away from this design in favor of their own Independent Trailer Suspension. In their experience the rubber eventually allows the trailing arm to walk out of the housing. That is a hard failure to field repair. http://www.adventuretrailers.com/suspension.html

My position has been based on a trailer, currently in my possession, with the rubber torsion suspension that has thousands of off pavement miles on it. A large percentage of those miles have been Baja washboard roads. It has had shocks from the very beginning and has not shown any sign of the trailing arms wanting to walk out. My theory is that w/o shocks the rubber overheats and allows the movement. By putting shocks on some or all of the heat is dissipated by shocks rather than absorbed by the rubber.

Martyn, of AT, recently posted that the trailing arms are not vulcanized in, but rather simply force-fitted (in some manner or other) into the housings. This has led me to re-evaluate my own thinking. I am still convinced that a rubber torsion trailing arm suspension has no business being off pavement without shocks, but it may not be quite as good of a solution as I used to think.

HTH

 

[uk trailer guy]

Hi there,

The torsion axle is pretty common over here in the UK, certainly more so than leaf springs nowadays. The reason (over here anyway!) for using leaf springs was that most trailers' running-gear was based on vehicle wheel PCD's and suspension springs. Things like Ford Escorts, from the 1970's, that used rear leaf springs, were chopped about and made in to trailers. During the late 70's trailers started getting bespoke suspension systems - hence the rise of the torsion system.

It's horses for courses really. It depends on the use you're going to put it to - and you have to be honest with yourself! I made an 'overland' trailer last year, but realising we (unfortunately!) don't have the beautiful trails you do over in the States, I didn't need the really heavy duty set-up of the leaf spring system; I opted for a torsion system.

I've been in to building and selling trailers, in the UK, for nearly 20 years (so maybe not as long as some on here! :sombrero and the main differences I've found are:

• Leaf springs give a 'harder' ride than the torsion style
• A single axle torsion system is limited to around 1800kg (circa 3960lbs)
• Leaf springs are much easier to fix, if you're in a jam (can be welded etc)
• Once a torsion system fails you generally have to replace the axle
• Comparatively a torsion system gives a much smoother ride, especially when unladen, where as leaf springs need a degree of 'load' before giving a more forgiving ride
• A torsion beam axle can be used to significantly strengthen the trailer's chassis

There's probably more 'pros and cons', but it's getting late over here and I've been servicing trailers all day, so I'm tired! Below is a couple of pic's of the overland trailer I built using a torsion axle (with a close-up), to give you a bit of help. It still needs a bit of finishing off - but paying customers come first!!

All the best.

 

[njtaco]

Recommended reading...

http://www.adventuretrailers.com/suspension.html

 

[ex m38a1er]

Went to a local junk yard.Picked up a rear axle from a Citroen.
Kind of torsion axle with shocks

Bolt on ,tows great,

nice clearance

 

[jeep4x4greg]

I like the air bag set ups.....but if I were to do an air bag suspension.....I'd need an onboard compressor like a truck right? My subaru doesnt have this and I would like to make the trailer able to be used with any vehicle....regardless on on board air setups.

i imagine I could have an electric on board air system built into the trailer, but I'm not sure this is the most practical thing.

I have a set of Stock jeep TJ suspension coils...I wonder if i could get those to work. Maybe use a trailing arm suspension similar to thier Gen 2 design, but then replace the air bag with a coil spring.... They may be a little stiff with an empty trailer but I'd think they would be fine when I carry a full load..

thoughts?

 

[ntsqd]

Buy one of the MV-50 or MV-1050 or similar air compressors. Search those names for more info. Then you can deal with flats, airing up tires, and setting the air spring pressure without the compressor being tied to any particular vehicle.

 

[wjeeper]

I really liked the idea of a trailing arm/ air bag set up......in theory anyways.

The more and more I looked into it was not a viable solution for me. Its more expensive to set up, onboard air is pretty much a necessity. More parts + more complex = more stuff to go wrong.

In the end I am going YJ leafs and a standard off the shelf 3000 lb axle. Yeah its not adjustable, and it might ride rougher but what it all boiled down to was $$. I would rather spend an extra weekend or two out in the hills having fun not in the garage fabricating. Plus you can spend the price the difference on a few extra trips.

As my grandpa always tells me Keep It Simple Stupid.... just my $.02

 

[chubbydude]

Could you not cut the leafs of behind the axle, but retain the main full leaf. That way you are using the leaf spring for location, and then use the airbag over the axle for weight carrying duties.

 

[mcneil]

Recommended reading...

http://www.adventuretrailers.com/suspension.html

Ironic.. I just saw one of these yesterday. It was on a flatbead, headed south from Independence, CA, with a busted suspension. One wheel was at ~30 deg toe and 45 deg camber. Looked like one of the A-arm mounts broke.

My own experience with commercially available torsion axles went about the same way. The rubber failed to control toe, and the added drag from more toe broke the radius arm.

My second rev at this expedition trailer will have a straight axle.

 

[wjeeper]

Could you not cut the leafs of behind the axle, but retain the main full leaf. That way you are using the leaf spring for location, and then use the airbag over the axle for weight carrying duties.

Sounds like you are thinking of a quarter elliptical suspension set up of sorts. You would have locate the axle laterally as I it would walk side to side. A simple panhard bar would control the side to side.

Some rock buggies use to run this set up back a few years ago. There is next to no resistance when the axle droops out. Looked good on a ramp but

http://www.rocky-road.com/quarterelliptic.html

http://www.bluetorchfab.com/how-to/quarter-elliptic-suspension-intro/

EDIT.......just noticed you mentioned leaving the whole main leaf, my concern would be the main leaf bending where the remaining leafs were cut off

 

[ThomD]

I've been wondering about the practical differences in suspensions. AT makes a very good case for the air bag system, but if one is buying a trailer from other than AT, air bags are not an option, so that had me looking around at the range of options.

I don't think anyone has discussed the system from Mor-Ryde yet. Their system uses rubber springs with a shearing force. They may not be available in ratings for things as small as an off road trailer because they are primarily geared toward 5th wheel units.

http://www.morryde.com/php/products/suspensions/towables/IS.php

 

[Springhilljeep]

Axle

I did the same as an earlier Person.

I purchased a straight 3500 lb axle and kept the leaf springs with new shocks and did the leaves over the axle. I am also running 33 inch tires on my M416 and it handles any type of terrain and tows real well. The like the leaf springs an shocks as set up is very simple and very reliable.

 

[R_Lefebvre]

For years I've maintained that the rubber torsion axles work fine for all but the most extreme off road uses. The caveat is that they must have shocks attached to them, which they are not set-up for.

Adventure Trailers disagrees with this and have moved away from this design in favor of their own Independent Trailer Suspension. In their experience the rubber eventually allows the trailing arm to walk out of the housing. That is a hard failure to field repair. http://www.adventuretrailers.com/suspension.html

My position has been based on a trailer, currently in my possession, with the rubber torsion suspension that has thousands of off pavement miles on it. A large percentage of those miles have been Baja washboard roads. It has had shocks from the very beginning and has not shown any sign of the trailing arms wanting to walk out. My theory is that w/o shocks the rubber overheats and allows the movement. By putting shocks on some or all of the heat is dissipated by shocks rather than absorbed by the rubber.

Martyn, of AT, recently posted that the trailing arms are not vulcanized in, but rather simply force-fitted (in some manner or other) into the housings. This has led me to re-evaluate my own thinking. I am still convinced that a rubber torsion trailing arm suspension has no business being off pavement without shocks, but it may not be quite as good of a solution as I used to think.

HTH

Agree with this.

I love the torsion axles on my Seadoo trailer. Super smooth riding on road.

On my camping trailer... I'm less convinced. It's super smooth riding on road. But it also seems way underdamped. I think it makes a difference because the CG of the trailer is relatively high, compared to a Seadoo trailer, utility trailer, or car hauler. It's not unstable, but... I often do a "wiggle test" to check the stability of my setup while rolling, and the trailer oscilates side to side several times after I stop sawing on the steering wheel.

I've also driven over some bumpy rail road crossings, and it's pretty rough. I'm not sure if something is bottoming out, or the trailer is getting air, but there's a lot of banging around. I haven't had it seriously off-road yet, but when I do, I won't be able to go too fast.

So I agree, dampers are mandatory, which I do not have, because they are not set up for it.

I will either make the changes,or just change the setup for a leaf spring with shocks. I have my niggling doubts about the durability of the torsion axle from AT, but those are countered by testimony from ntsqd. I am going to build a small car-hauler trailer at some point, and I could just reuse the rubber axle on it so it doesn't go to waste.

I recommend to all the home builders, just stick to the axle with leaf springs. It's easy, it works, and anybody with a hammer and a welder can fix them.

Edit: Make that solid axle with JEEP leaf springs, not trailer leafs!