Half Torsion Axle Mounting Question

[BillInTampa]

Hi all. A newbie here with what's probably a silly question. I'm been bitten by the Teardrop building bug and am in the process of considering designs. One I'm particularly interested in is Angib's Superleggera (http://www.angib.pwp.blueyonder.co.uk/t ... tear32.htm). I'm interested in this one primarily due to it's light weight, as I'd like to tow it behind my Scion xB. I really like the style and simplicity too. I've priced out having the steel frame constructed (got a trailer shop right around the corner) and am now looking into the suspension/axle units. The plans call for what looks like a half torsion axles. The ones I've been able to find at outfits like etrailerpart.com look different than what's on the plans. Angib's drawing shows a unit that's fairly compact - I suspect it's spring powered. The unit's I see on this side of the pond are all kinda long - the 550 lbs axles I need are 7" long with 3 pairs of mounting holes along the length of the body plate. So my question is, how are these axles secured to my 2" axle tube? The guy at the trailer shop said that they just U bolt onto the square tube. Is that right? Or do I need to have the shop weld mounting plates to the trailer's axle tube. Any guidance would be appreciated.

Thanx,

[SteveH]

Bill,

Are you looking for something like this: http://www.northerntool.com/webapp/wcs/ ... 27&R=25127

If these are what you have in mind, they bolt to the frame and the frame needs to be designed for their use. IMHO they are the type to use on a teardrop where weight is of main concern.

Ane, welcome to the form.

[BillInTampa]

Hi Steve,

Yep, that's the type I'm looking at. The trailer design I have in mind has a 2" square steel tube welded across a pair of longitudinals, sorta like an "A". The ends of the cross bar/axle extends past the long pieces and the torsion units bolt to these axle stubs. On the plans they bolt to a plate, but when I mentioned that to the guy at the trailer shop, he said they are just strapped to the axle tube with U bolts. So when you say the trailer's got to be setup for these and bolted down, do you mean a mounting plate or the U bolt setup.

Thanks for the input.

[SteveH]

Bill,

The frame for sub tortion axels must have either a plate, or members stategically located of sufficient strength to support the stubs and the torque they will apply to the frame. They are bolted on to the frame.

The one the link takes you to is just one of many the Northern Tool carries. Other trailer supply companies will also sell them, so shop around for the style and weight rating axels you think would work best.

Southwest Wheel is another supplier that I know handles stub axels: http://www.southwestwheel.com/

[angib]

Bill,

I'm not sure using U-bolts would be a great idea, as you'd have to cut holes in the floor ply where the tops of the U-bolts passed over the cross-member. It would work, but it wouldn't be pretty and it could leak.

The plates shown on the drawing also include 'ears' that stick out the front and back - these carry the ends of the (longitudinal) framing under the floor ply, where this is interrupted by the cross-member.

Andrew (angib)

[BillInTampa]

Hi Andrew,

First off, let me say how much I like your designs. If I can work out the issues with the steel chassis, I'll definitely be building the Superleggera.

I came to the same conclusion regarding the U bolts and started tinkering with the chassis design to get the half axles I can find here to fit. See this site, the 250kg units are near the bottom:

http://www.etrailerpart.com/halftorsionaxles.htm

I increased the cross member from 48" to 49" and reduced the spacing of the longitudinals to 42" at the back. This freed up the 7" I needed on the cross member outboard of the longitudinals for the suspension units. I added a 4" wide roughly 7" long 1/4" steel plate with the ears that will be welded to the underside of the cross member and to the adjoining longitudinal. I'll drill this for the half axles and to bolt to the wood frame where it's interrupted by the cross member. Do you see any problems with what I propose? Should I beef up any of the scantlings?

Thanks Much,

[DoWopBox]

I'm interested in this one primarily due to it's light weight, as I'd like to tow it behind my Scion xB. I really like the style and simplicity too. I've priced out having the steel frame constructed (got a trailer shop right around the corner) and am now looking into the suspension/axle units.

Hi and welcome to the forum. I also have an xB and am building a teardrop based on the Harbor Freight trailer. I upgraded the axle to a Flexiride, I ordered from Southwest Trailer, so I can put larger wheels/tires on it than the 8" ones that came with it.

I got my hitch from www.hitchsource.com via ebay and it works great.

[BillInTampa]

Hi DoWopBox,

Did that hitch bolt on with no problems? Did the receiver come out under the rear skirting or did you have to cut an opening in it? Lastly, what design are you building and what do you think the all-up weight of it will be? I'm trying to keep mine light as I'll be dragging it through the mountains of Tennesee, Georgia, and North Carolina.

Thanks,

[angib]

Should I beef up any of the scantlings?

No, I think that's OK - I don't see that you've increased the stresses significantly by the changes you've made.

Andrew

[DoWopBox]

Hi DoWopBox,

Did that hitch bolt on with no problems? Did the receiver come out under the rear skirting or did you have to cut an opening in it? Lastly, what design are you building and what do you think the all-up weight of it will be? I'm trying to keep mine light as I'll be dragging it through the mountains of Tennesee, Georgia, and North Carolina.

Thanks,

Maybe this will help. The Hitch went right on, took me about a half hour to install it. It uses the original factory shipping-hook boltholes that are already threaded. It goes underneath the rear pan.

(Click for larger pic)




I'm going to try to keep it under 900 pounds. I still haven't decided on a final design, I'm still gathering the materials and tools. I'm thinking a modified Benroy at this point tho.