Many of you know of my caravan built last year and we did a lap. Apart from a drawbar crack and reweld at Cloncurry it went well for my first van build. We are nearly home from our second trip Victoria to Bundaberg and this 10'8" van is on the cramped side. So we want to sell it and build another, a 15' long 6'8" wide one with mechanical override brakes.
Our current van has a steel frame and many lightweight ideas to achieve a low low 450kg tare, 748 loaded meaning no brakes needed. But as my tug is now a JBA roadster the max I can tow is 850kg. Result, tare up to 550kg from 450. That extra 100 kg will include brake component weight say 30kg. So the extra size of the new van has to add up to no more than 70kg. So that is my justification to seek out more ways to reduce weight.
We checked out polystyrene products that double up as internal surfaces, varnish not lino, lightweight floor ply, water 84litre down to 65,...even balsa as laminated bench frames. I'm confident its doable but the suspension is the challenge.
The current van has stock leaf spring, 40mm round solid axle. The 10" alloy boat wheels might seem small but each weighs 8kg with tyre whereas a 13" unit weighs 18kg. X3 (one spare) means 30kg extra weight. As you can see ANY added weight is crucial to this project. One cant afford to allow weight to creep in.
The springs, axle assembled unit weighs 45kg...quiet heavy. The alternative is torsion suspension straight axle available from a number of suppliers but it seems 13" wheels is the minimum with brakes, lose weight on axles and springs -gain on wheels. The tug wheels are 14" cortina 4 stud so not easy to have those on the van and eliminate the spare.
I once had a motorcycle camper trailer with the same 10" wheels as I have now and it had magnetic Electric disk brakes. So I could, for the new van, use the 10" wheels with brakes but I'd need to stick with springs and solid axle. I'm happy with the workings if the springs set up.
Have you any thoughts on this. Is it worth pursuing the torsion with larger wheels? Will larger wheels result in better rolling ability? Do you have mote information?
Im finished surfing the net and waiting for return of calls that never come.
I'm leaning towards springs,, 10" wheels and disk brakes mechanical or electric.
What do you think?
Thanks.
Hey Jim said
09:34 PM Aug 16, 2017
Hey Tony,
Have you looked at a trailing arm ( coil ) spring rear set of a Toyota corolla, 14 inch wheels, complete with dis calipers and an over ride hydraulic hand brake from a Wrecker. I was doing our shopping carts rear brakes on Sunday . Took all of 15minutes to service. And got to thinking independent trailing arm off road box trailer. Food for thought. A set of Repco rear pads $44.20 with a 33% discount docket.
Jim
How I love the extra time now, to put one's brain into over drive.
Eaglemax said
10:36 PM Aug 16, 2017
Hi jim
"How I love the extra time now, to put one's brain into over drive." You must have retired!!
I'll have a look at that set up. Likely no car unit will be wide enough for a 2 metre wide van though.
Thanks for posting mate.
Diane1 said
10:51 AM Aug 17, 2017
Hi.
Look at the Alco swing arm rubber bush system. Light and WELL proven. Phoenix used it on some of their models. And i.ve hsd/Seen plenty o boat trlrs, Wheels to suit your choice.
Eaglemax said
04:17 PM Aug 17, 2017
Hi Diane, thankyou for replying
Alko systems wont take wheels under 13 inch. Resulting in 30kg extra weight (3 wheels) Trojan are the same. It defeats the purpose
Footprints said
01:40 PM Aug 18, 2017
Hi Tony,
I have a suggestion that may appeal, it is a suspension system that I have fabricated and used very successfully in my manufacture of cross country Competition Carriages which are designed to be as light as possible, simple in functionality and very robust. Employing the engineering concept of the triangle and circle e.g. tubing being the strongest form for strength and lightness I will try to explain. Firstly do away with a solid axle and weld stub axles of your choice at each end, probably 50 x 50 RHS. now using similar size RHS for the draw bar assemble and weld to form a triangle with the coupling located at the apex of the triangle and the other two corners of the triangle will be inboard of the stub axles at the desired location. Instead of using two springs use one only transverse spring mounted or attached behind the axle. By using a single transverse spring you eliminate any road shocks direct to the chassis and the result is a soft compliant ride over rough or corrugated surfaces. A couple of light shockers could be attached at axle ends if so desired.
To suspend the body simply weld a chassis cross member across the pre fabricated triangle at the location where the front of the body will be, to this I attach two Nolathane bushes ( as used for front torsion bars on cars) this now in effect hinges the front of the body and the transverse spring supports the body rearward of centre. With this method it becomes similar to the suspended cabs on Semi Trailers.
The above is my own design that has stood the test adequately for me, I hope it gives you some food for thought thinking outside the square. Weight reduction gained, eliminate one spring, lighter axle, less material as the base of the body frame can be of lighter products as it is fully "floating" suspended therefore only requiring a partial chassis as opposed to a conventional style trailer. Another advantage is the body height above ground can be set at any required height irrespective of spring or suspension as with other systems.
If you have any concerns about the robustness and simplicity of the transverse spring reflect on the Model T Fords and all Fords up until 1948, Buggies for over 100 years, and speedway Sprint Cars.
I hope this is of some help to you, Cheers Allen.
Eaglemax said
10:05 PM Aug 18, 2017
Allen, you explained it well. Ive got the concept in my head and its certainly plausible. I'll draw it up and get back to you. Thankyou
Ps with a central spring if one side of the van was heavier than the other wouldnt it lean?
Tony
Footprints said
01:25 PM Aug 19, 2017
Tony, no leaning shouor not be an issue noting that the body is hinged (attached) to the unsuspended draw bar Which remains constant with the axle regardless. With your application I would consider a full width shaft and tube hinge with lube points. If you wish to discuss the idea PM me. Cheers Allen.
Hey Tony,
Have you looked at a trailing arm ( coil ) spring rear set of a Toyota corolla, 14 inch wheels, complete with dis calipers and an over ride hydraulic hand brake from a Wrecker. I was doing our shopping carts rear brakes on Sunday . Took all of 15minutes to service. And got to thinking independent trailing arm off road box trailer.
Food for thought.
A set of Repco rear pads $44.20 with a 33% discount docket.
Jim
How I love the extra time now, to put one's brain into over drive.
Hi Tony,
I have a suggestion that may appeal, it is a suspension system that I have fabricated and used very successfully in my manufacture of cross country Competition Carriages which are designed to be as light as possible, simple in functionality and very robust. Employing the engineering concept of the triangle and circle e.g. tubing being the strongest form for strength and lightness I will try to explain. Firstly do away with a solid axle and weld stub axles of your choice at each end, probably 50 x 50 RHS. now using similar size RHS for the draw bar assemble and weld to form a triangle with the coupling located at the apex of the triangle and the other two corners of the triangle will be inboard of the stub axles at the desired location. Instead of using two springs use one only transverse spring mounted or attached behind the axle. By using a single transverse spring you eliminate any road shocks direct to the chassis and the result is a soft compliant ride over rough or corrugated surfaces. A couple of light shockers could be attached at axle ends if so desired.
To suspend the body simply weld a chassis cross member across the pre fabricated triangle at the location where the front of the body will be, to this I attach two Nolathane bushes ( as used for front torsion bars on cars) this now in effect hinges the front of the body and the transverse spring supports the body rearward of centre. With this method it becomes similar to the suspended cabs on Semi Trailers.
The above is my own design that has stood the test adequately for me, I hope it gives you some food for thought thinking outside the square. Weight reduction gained, eliminate one spring, lighter axle, less material as the base of the body frame can be of lighter products as it is fully "floating" suspended therefore only requiring a partial chassis as opposed to a conventional style trailer. Another advantage is the body height above ground can be set at any required height irrespective of spring or suspension as with other systems.
If you have any concerns about the robustness and simplicity of the transverse spring reflect on the Model T Fords and all Fords up until 1948, Buggies for over 100 years, and speedway Sprint Cars.
I hope this is of some help to you, Cheers Allen.
Tony, no leaning shouor not be an issue noting that the body is hinged (attached) to the unsuspended draw bar Which remains constant with the axle regardless. With your application I would consider a full width shaft and tube hinge with lube points. If you wish to discuss the idea PM me. Cheers Allen.