Shock absorbers / Dampers?

[Robmc]

Coming back from the far North of Scotland yesterday, as I yet again slowed down for sections of road that would not be out of place on a farm track, or trying to keep the wheels out of the crumbling shoulders (main roads / not single track), I got to wondering if anyone had ever fitted shock absorbers / damper to a boat trailer.

They seem to be a pretty common retrofit for caravans ( am putting a pair of Alko shocks on our van later this month) but I can't see any article on the web about boat trailers.

The trailer is a Degraff with a knott axle. Just interested if anyone has had some experience of doing this.
Ta

[spartacus]

Interested in this myself. I agree some of the roads in the north are in poor condition, but by all accounts that's the same for the rest of the UK!

I just got the tracking done on my car, and I'm convinced that's down to pot-holes and years of neglect, basically because councils are strapped for cash. Road verges crumbling won't be helped with a shock set-up, but I take your point.

I looked at the caravan conversions and they have the necessary holes drilled on the chassis and/or bungs for the hub arm for the fitting kit.

With single or double-axle trailers, braked or unbraked then it will have to be a fitting kit. I've found a Polish company called Lorries - so they have a couple of YouTube videos showing installation.

I have what I assume is an Alko torsion axle on a Rapide 750kg unbraked trailer - but I don't see how I could retro-fit without swapping the axle.

https://www.youtube.com/watch?v=_mxHSmgPu2M

[Steve509926]

Originally Posted by spartacus

Interested in this myself. I agree some of the roads in the north are in poor condition, but by all accounts that's the same for the rest of the UK!

Not Wales! The roads in Pembrokeshire where like billiard tables when I was there even the single track country lanes. Coming back home the difference when you passed from Wrexham into Cheshire was palpable, you could clearly see a line where maintenance of the road finished and the pot holes began.

[Robmc]

Yes - seen that vid while hunting for info - it looks to be a different kind of swing arm as it has a hole for the fitting of a bracket.

One thing puzzles me is that the units seem to be in a position forward of the wheel, so if the damper is attached to the bottom of the trailing arm it can only act when it's being "pulled" as opposed to being compressed which is how I'd usually consider a damper to work. But this would mean the damper being position above the training arm?

I can't find any info explaining how these work - if someone knows maybe they'd care to share!

[Robmc]

I'm away up to Nigg next week to Fraser Brown Engineering with the caravan axle which is being overhauled as it's lopsided.

They seem to be quite interesting people up there and rather knowledgeable so I thought I'd pick their brains about what improvement they might be able to suggest to a boat trailer suspension and I'll post back here with their views.

[Fenlander]

>> it can only act when it's being "pulled" as opposed to being compressed which is how I'd usually consider a damper to work.

As the shock is basically a piston moving through oil it shouldn't matter which way it's moved by suspension compression as long as it is valved for that use.

[Robmc]

Originally Posted by Fenlander

>> it can only act when it's being "pulled" as opposed to being compressed which is how I'd usually consider a damper to work.

As the shock is basically a piston moving through oil it shouldn't matter which way it's moved by suspension compression as long as it is valved for that use.

Thanks - makes sense

[beamishken]

I'm wondering what your trying to achieve by fitting dampers? Dampers are there to reduce body roll & prevent the tendancy for the vehicle to bounce on its springs which makes for an uncomfortable ride, neither of which I've found to be a problem on trailers with rubber torsion axles they just dont oscillate like steel springs

[beerbelly]

Originally Posted by Fenlander

>> it can only act when it's being "pulled" as opposed to being compressed which is how I'd usually consider a damper to work.

As the shock is basically a piston moving through oil it shouldn't matter which way it's moved by suspension compression as long as it is valved for that use.

its called re bound damping to stop the spring returning to full length too quickly can be more vital than compression damping