Trailer suspension problem

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norfolk heron

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I have a Mirror and Heron - both light dinghies which I trail. I have used a Snipe trailer for years - lovely soft ride on a transverse spring, then I bought a newish trailer with torsion rubber suspension - A well known make - The suspension was rubbish and barely deflected at all even with all my weight on one side of the axle. I have examined a lot of other rubber suspension types and they all suffer the same problem - unless your boat is heavy (ie more than 400lbs) they dont do much and you might just as well have no suspension at all (fixed axle). The problem with this is that it damages the bilges of the boat due to a rough ride (I spent a good deal of time fixing mine after I realised the problem and quickly got rid of the trailer which caused it). The trailer supplier actually admitted to me that 'unless the trailer is fully loaded there will be virtually no deflection and that its impossible to get units which deflect for under 400lbs' - what sort of industry is that (actually many of the units seem to be Chinese so there you are)?

My Snipe is comming to the end of its life and as far as I can see there are no other dinghy trailer/suspension manufacturers who make any other suspension types (there used to be torsion coil spring units as well as transverse leaf spring things). Do you know of any though? I would be happy to make up a trailer if I could get non-rubber suspension units or a simple leaf spring of the type Snipe used. In the meantime checkout the bilges of dinghies and see what I mean - loads of crazing and stress cracks on a hell of a lot of them caused by useless suspension that is quite wrong for the job.
 
I had a Heron which I restored and when I sold it the guy who bought it punched a hole in each bottom near the chine by driving over speed bumps too quickly. This made me aware of the problem and for my clinker dinghy I got some units rated at 250kgs the pair. The trailer rides beautifully. The dinghy "floats" along behind.

From Here
Look for parts FG250 or FE250 depending on stub length.
Great people to deal with.
 
I used to build trailers for a living way back. The modern rubber twist units are absolute rubbish, except (as you say) when loaded near their operating limit. There is a legal requirement to have suspension and they satisfy it.
If you can make your own frame and axle, there is a guy near Cambridge who is the agent for Aeon rubber springs, now a devision of Timbrin industries. Rubber is somewhat self damping, so less bouncy than steel.
Recently I built two trailers. One for my 300lb Oughtred double ender and one as a general purpose box. Both used Seat Marbella rear axles. The boat one is a T frame with the wishbones fabricated from the Seat bits and sprung with Renault Clio rear coils, very satisfactory. The box uses the leaf springs and Seat rigid axle, helped by Aeon springs to up the carrying capacity for fire wood and building sand. Cost of an axle, springs and wheels (as new tyres) about 60 GBP. Also both hydraulic and cable brakes, plus if the bearings go, cheap aftermarket bits.

PM me if you want the Aeon agent.
Andrew
 
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tinkicker0 said:
The peugeot 205 has torsion beam rear suspension I believe.. Have a look for at the scrappies for the arms and torsion bars if you are not opposed to a little tinkering.
Click to expand...

Takes me back to the late 60's early 70's when I was designing torsion bar trailer axles, we supplied Snipe, SBS,etc, infact about 70% of the total trailer market.

Back to to-day, re Peugot, the Partner range has the same type torsion bar rear axle, may have a better capacity. you can use the handbrake system if you need brakes.


Brian
 
Old Renault 4/5/6 and others have usefull torsion bars as well. Common trailer around here is to bolt/weld the whole assembly off a small Pug/ Renault to a steel frame. Bit overkill for a small boat. I built a very light one with bars of a Renault 4 van to use behind a 2CV. Rode very smoothly, later added shocks (Bendix washing machine!!) to cure the bounce. Still in use over 30 yrs later. About 400kg cap. wheels were 8x4 standard trailer.
A
 
I have that trouble too. I have a tiny little trailer for an 8' fibreglass tender which (if I had a roof rack) would be light enough to be car-toppable. Even with those 250kg units that Lakesailor mentioned, it rides like a skateboard! I have opted for supporting the boat in as many places as I can and then making sure it's really tightened down hard on the trailer with ratchet straps so that it can't bounce. Even then, it's far from ideal.

The problem with using the torsion springs off a current car is that they will be similarly rated - the maximum rear axle weight of a Peugeot Partner will be pretty enormous compared to your boat and trailer. The Renaut Kangoo is another one with torsion bars at the back, if you're looking for one.

If you can find one (they're very rare now), the Triumph Herald had a single transverse leaf spring. You could take a couple of leaves out for your trailer. Also have a look at any of the Reliant rear axles - they were conventional solid axles on leaf springs and Reliants were very light. Finally, a more modern unit would be the Fiat Doblo. That has an extremely simple tube for a rear axle and a single leaf spring on each side. Might still be far too stiff for a dinghy though! Finally, have a look at a Citroen BX or Xantia. They had that tricky hydraulic suspension but they used traling arms at the back and instead of rubber bushes, they are mounted on taper roller bearings so they keep their alignment well. You'd then just have to find some conventional coil springs to replace the hydraulic cylinders and spheres.

Worth just checking out the NTTA's site for trailer brake requirements. The maximum weight of unbraked trailer that any car can tow is given in the handbook - generally between 500kg and 750kg. I don't know if you need auto-reverse brakes if you fit them to a trailer that doesn't need brakes though. Car ones won't do that!
 
Avocet said:
The problem with using the torsion springs off a current car is that they will be similarly rated - the maximum rear axle weight of a Peugeot Partner will be pretty enormous compared to your boat and trailer. The Renaut Kangoo is another one with torsion bars at the back, if you're looking for one
Click to expand...

There is also the old one, mini rear sub frame, trailing arm rubber cone, lighter body weight, comes with dampers as well. Little rare there days though.

Brian
 
halcyon said:
There is also the old one, mini rear sub frame, trailing arm rubber cone, lighter body weight, comes with dampers as well. Little rare there days though.

Brian
Click to expand...

I have had a couple of these. The trouble is the cone can drop out if the travel is not limited.

My Finn trailer uses the trailing arms off the early mini 850. Instead of the rubber cone I welded a support and use the rear coil over shocks off of a Suzuki 650 motor bike to the shock absorber bolt on the end of the trailing arms. The tower for the coil overs double as the support for the mud guards [ss beer barrel cut to width].

Finn weighs about 150 kilos with a bit of gear and it travels well, done a couple of 1000 kilometre trips at speed, don't even know its there.

Looks exotic too, I get people asking me about it all the time.
 
Lakey,
Out of interest, how much travel do you get from those units? With the Renault 4 torsion bars and 8x4 wheels I fabricated shorter trailing arms than the van had. This decreased the travel for a given load, but was plenty as the R4 had loads of it. As it was used for lots of diferent jobs, a useful feature was that when the arms were parallel with the road it was at max rated load.
A

I like the idea of beer keg mudguards:-)
 
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Very hard to say. As I'm driving when the maximum travel occurs. Just jumping up and down on the loaded trailer can't replicate a big bump on the road.
However I used to have mudguards which were about two inches above the tyres at rest and they certainly got zizzed by the tyres during a journey.
It's not so much the travel as the nature of the deflection. In my mirror I can see the dimghy gently bobbing up and down as I travel over bumpy roads.
I can see that some custom built suspensions may be softer still, but at £90 or so a pair these were a bolt-on replacement and so a very good compromise.
 
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That would be the same as the units I linked two which were 250Kg a Pair
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I think you will find that the units Philip linked to are 125kg per pair. Indespension units have always been rated "per pair" I guess these are the same as the ones in my old Indespension Trailer manual rated at 2½ cwt per pair. A sensible choice for a Mirror which as a hull weight of 100lbs.

They used to publish technical test data that showed deflection vs load but the older manual, containing test data, that I still have was published before they added the 2.5 cwt units to the range. However looking at the test data for other sizes I would estimate that the deflection at full load for the 2.5cwt units is approx 0.6 " The stub axle is at a radius from the centre of the unit of 3" and at zero load is 45° to the horizontal
 
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That would be even better for him then. Not forgetting the weight of the spars, rudder, oars and other guff you put in the dinghy, plus the trailer (less unsprung weight) weight.
He would probably end up, like me, with 30 or so Kgs in hand.
Stick an outboard in as well and there you go.
 
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