Question to the brains trust on suspension.

Saturn 5
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Question to the brains trust on suspension.

Post by Saturn 5 » Sat Nov 30, 2013 7:21 pm

Today has been a sit and think day, I have lots of them but I did drill out for and fitted the hitch. Oh and I did have a little more tint added to the liming stain as the first sheet I coated dried paler than I expected. The clear coat to go over the top should be now just right.
Moving the 50x50 solid axles about, the heft becomes more apparent and so I start to think ahead before they are installed. The reality is, I doubt I'll get to do many OB dirt roads but one day somebody else will own this van so I'll make it the best I reasonably can.
On a corrugated road I imagine the axles would start to wobble something like a guitar string, affecting the whole ride of the van and contents if it is not controlled. And so my question to those with prior experience.
If I was to under sling a heavy strap or webbing holding the axel at the centre point and in a straight line, would this be as effective as I think it should be? To phrase that a little better, would it stop what I think would be a kind of harmonic?
Someone must have tried this before, and does anyone on the forum use this strap at the moment?

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Old Techo
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Re: Question to the brains trust on suspension.

Post by Old Techo » Sat Nov 30, 2013 8:53 pm

50 mm axles seem overkill for a 5.1 metre van. I think a single 45 mm is good for 1400 kg. How heavy will the van be?

I'm guessing a tad but I reckon the resonant frequency of a 50 mm axle would be quite high, in terms of corrugation induced vibrations to the suspension in general. Also the amplitude of any axle resonant vibration would be bugga-orl. In other words, absolutely no axle natural resonance suppression modifications are needed, in my estimation.

Note, we are discussing just the bare axle as a guitar string - and nothing to do with shockers, which will be needed to control the springs.
Regards, Old Techo
2007 Prado Grande Diesel Auto
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Saturn 5
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Re: Question to the brains trust on suspension.

Post by Saturn 5 » Sat Nov 30, 2013 11:25 pm

Oops I should have written 45x45 mm. The comparison with the guitar string was wrong of me too OT. I'll try again. Meaning to say, a rock lifting a wheel on one side with force, say at 80 kph, would send down the axle some kind of energy which on rebound of the spring would need to be controlled. So if I'll spit it out, would a single centre strap as described, be a useful alternative to a shock on each side? If that is, the strap was taut when axle was in a line same as when at rest.
I hope I clarified that mud a little.

George W.

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Old Techo
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Re: Question to the brains trust on suspension.

Post by Old Techo » Sun Dec 01, 2013 6:45 am

Saturn 5 wrote:So if I'll spit it out, would a single centre strap as described, be a useful alternative to a shock on each side?
George, I'm still not quite getting the strap picture but suffice to say there is NO, I say again, NO alternative to a shock fitted as close to each spring as practicable.

Secondly, simple solid or beam axles are not intended to carry any loads i.e. be subjected to any forces at their mid point or thereabouts.
Regards, Old Techo
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dieseltojo
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Re: Question to the brains trust on suspension.

Post by dieseltojo » Sun Dec 01, 2013 8:35 am

Hi Saturn 5,
That bit about brains trust pretty well excluded me , but I am interested in the
"If I was to under sling a heavy strap or webbing holding the axle at the centre point and in a straight line" question.

I can only envision some thing like I drew in the pic, but that would negate any axle movement at all and can't be what you mean. So I am having a problem visualising your idea.
The thing is ,If you don't see it on other vans , it probably is not a good idea.

I reckon the axle would be held by the spring hangers and the centre bolt bracket placement. Bounce would be handled buy a good set of shocks and also restrain axle tramp.

Please let us know (via the user control panel) what city you live and some one may be able to refer you to a good van repairer or supplier of parts. :D
Estimated weight of the van and its expected ATM will help to decide a good suspension.

I like JRs set up, and if my van was worth it I may have gone that way myself.



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Old Techo
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Re: Question to the brains trust on suspension.

Post by Old Techo » Sun Dec 01, 2013 8:50 am

DT, you are describing the centre of the spring.

I thought George was describing the centre of the axle (meaning halfway between the 2 wheels, i.e. where the diff is in a car) and confirming this by referring to a shock on each side. Quote... 'would a single centre strap as described, be a useful alternative to a shock on each side?'

A pic is always worth 1k words :)

By the way, the only sense I can make out of the drawing is it's showing axle wind-up under the torque of engine power.
Regards, Old Techo
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Saturn 5
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Re: Question to the brains trust on suspension.

Post by Saturn 5 » Sun Dec 01, 2013 10:02 am

Thanks fellers, it was just something that crossed my mind as I sat visualising what I have to do when installing the suspension. A 'what if ' kind of thought. I was thinking that when that heavy beam axle gets excited when one or both wheels jump, there would be some kind of movement both up and down that a strap, would quickly quieten on the downward movement which I would say is the rebound moment which all suspensions try to control.
When I get the welder out this week I think I'll make provision for both a strap and shocks. As an exercise I'll try the strap first as I'm sure it will have a calming effect.
DT, as you have drawn but as OT explained supported at the diff point.
If I had the requisite skills I'd draw it up but as you may have already guessed I'm not flush with computer skills. I'm waiting for my son, who is moving home again tonight, to help me post up some pics of my build this far. I'll do my best to show the important details of my build but I'll fall short in presentation compared to some of the previous builds.

Cheers
George.

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Re: Question to the brains trust on suspension.

Post by rusty69911 » Mon Dec 24, 2018 2:47 pm

The problem I can se with a strap is if you hit a dip and the van goes down as you exit it will raise up again, this would lead to a solid stop on the straps, doesn't sound good to me,
a small swaybar off the rear of a live axle car would be a more soft option as that seems to be what you are trying to control.

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Gerry M
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Re: Question to the brains trust on suspension.

Post by Gerry M » Mon Dec 24, 2018 5:55 pm

Hi Rusty,

Now this is coming from a use a bigger wrench ex-plumber.

How would a 63mm going axle go if you had the ends machined for your hubs?

I know when I had my suspension upgraded they turned an axle to suit the requirements, on the spot.

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Gerry
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Old Techo
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Re: Question to the brains trust on suspension.

Post by Old Techo » Mon Dec 24, 2018 7:07 pm

Saturn 5 wrote:
Sun Dec 01, 2013 10:02 am
I think I'll make provision for both a strap and shocks. As an exercise I'll try the strap first as I'm sure it will have a calming effect.
G'day George,

It's not having a calming effect on me :(

In my several posts I thought I gave enough clues to it being a bad idea. I'm only one opinion of course ;-)
Regards, Old Techo
2007 Prado Grande Diesel Auto
2004 Roadstar Limited Edition

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