single leaf springs

[Matt76]

Hi guys, I am about to order some bits and pieces to make a new boat trailer. The guys I got a price off recommended a single parabolic spring instead of a stack of leaves. They said they are less prone to rusting (makes sense). Are any of you guys using a single spring? My biat and trailer will be somewhere roughly around the 1 tonne mark, but the springs come in up to 1000kg each so surely should handle it ok. I'm just a bit unsure because all the trailers I see seem to use a multi spring setup.

Any advice?

Cheers
matt

[Dan5]

Don't buy singles if you intend on doing any offroad work........they are prone to breaking...Fine for sealed roads.

Dan

[Matt76]

Yeah I dont think it would ever venture offroad mate, I see your point though.

[Noelm]

try to find some good Aus made springs, the cheap crap ones (especially the single leaf parabolic) are weak as p!ss and will bend like buggery if you try to (say) reverse up a gutter, seen it a dozen times now, and the spring works near me has a pile of them you couldn't jump over that have been replaced.

[Willow1]

I run a dual axle trailer using Parabolic springs (single) and have had no problems. Mind you mine are 900kg springs and not as thin as the lower kg ones. Run up the coast on North Qld roads and use some pretty rough back roads at times but always take it easy when it gets rough. Easy to clean and less prone to rust out. Thats my two bobs worth, hope it helps.

[suzygs1000]

I have been using these galvanised parabolics on my trailer with a 20' tinny for the past three and a half years. Not a bit of rust, and I would never go back to multis. Don't know about the offroad tho. Mine are rated at 1000kg's each. Total weight of bmt is around 1500 kg's.

Dave.

[Mike Delisser]

Is rust that big an issue?
After my imported gal leaf springs cracked big time I got some home grown made up for me at Mayne Spring Works near Albion, about $70. I wash them when I get home and give them a spray of Inox every few trips, only a little surface rust after 2 years. I'll get 5 years easy then get another brand new set made up.

I would never get gal again as I've seen so many crack, it's got something to do with the acid they bath the spring in before it gets dipped in gal, I was told it changes the structure of the metal, makes it more brittle.


http://img809.imageshack.us/img809/5941/0016.th.jpg (http://img809.imageshack.us/i/0016.jpg/)

[murf]

Is rust that big an issue?
After my imported gal leaf springs cracked big time I got some home grown made up for me at Mayne Spring Works near Albion, about $70. I wash them when I get home and give them a spray of Inox every few trips, only a little surface rust after 2 years. I'll get 5 years easy then get another brand new set made up.

I would never get gal again as I've seen so many crack, it's got something to do with the acid they bath the spring in before it gets dipped in gal, I was told it changes the structure of the metal, makes it more brittle.


http://img809.imageshack.us/img809/5941/0016.th.jpg (http://img809.imageshack.us/i/0016.jpg/)

have seen electroplating destroy spring washers so is it the acid bath that does it?

I have towed a grossly overloaded boat to Fraser with the single leaf springs and it was my biggest concern all trip, they did last though

I have been told by trailer manufactures they won't put HDG springs on as they break too often

so far so good with my HDG multi springs with 3 trips to Fraser including the very rutted inland track up from Inskip Point

so how does a quality made non gal single leaf spring go?

cheers Murf

[FNQCairns]

Just 5 months ago I fitted some gal springs for the first time ever. Cracking was always the concern for me. This last time I thought stuff it all! if they crack then they crack, who am i to say one way or another. They will save me money and effort over time.

I did move up to the next higher spring rating to help me feel a bit better about it.

[finga]

Don't go too heavy in the springs though.
Are the springs rated for 1000kg per set or each?
There's gotta be some give somewhere and the springs is a better place then the trailer frame.

[Mr__Bean]

I have had galvanised parabolic springs on my trailer for the last six years.

They are rated at 1400kg per axle on a tandem axle trailer beneath an 8 metre plate ally boat.

They have been overloaded plenty of times and they have taken the boat all over the place (into South Australia, locations all along the Victorian coast, up to Brisbane and then north up to the Whitsundays).

No problems thus far.

Perhaps like many things, there are good quality items and there are cheap imported ones.

I think it would be wrong to say all parabolic springs will break and let you down.

- Darren

[FNQCairns]

I have had galvanised parabolic springs on my trailer for the last six years.

They are rated at 1400kg per axle on a tandem axle trailer beneath an 8 metre plate ally boat.

They have been overloaded plenty of times and they have taken the boat all over the place (into South Australia, locations all along the Victorian coast, up to Brisbane and then north up to the Whitsundays).

No problems thus far.

Perhaps like many things, there are good quality items and there are cheap imported ones.

I think it would be wrong to say all parabolic springs will break and let you down.

- Darren

Dead right, MQ patrols had them front and rear, i never heard of any breaking actually the opposite they where a superior spring as far as leaf springs go.

[tunaticer]

One point that needs to me mentioned about any springs at all. The U-bolts need to be 100% tight, if you have cracking at the centre bolt like in the above images, it is because there is some movement in the springs at the U-bolts. You need to make them tight, then after a drive of say 20km down a corrugated track or 100km on the blacktop, re-tighten them. All springs will work slightly loose after initial installation and all springs need to be re-tightened after a short drive.

Often times the plate supplied with the spring sets or the U-bolt sets is too light to effectively get a good tight connection. I make my own plated by drilling 12mm steel to the right centres for the bolts and the spring width to avoid the one fits all slots they usually supply. Slots effectively remove the chances of getting a good tight connection.

I run singles on my boat as well. 1000kg pair rated for a boat that weighs about 850kg fully loaded and they ride better than any of the three multi-leafs I have had fitted to this setup before.

[Mike Delisser]

Just 5 months ago I fitted some gal springs for the first time ever. Cracking was always the concern for me. This last time I thought stuff it all! if they crack then they crack, who am i to say one way or another. They will save me money and effort over time.

I did move up to the next higher spring rating to help me feel a bit better about it.

Hopfuly it's in a controlable situation.


One point that needs to me mentioned about any springs at all. The U-bolts need to be 100% tight, if you have cracking at the centre bolt like in the above images, it is because there is some movement in the springs at the U-bolts. You need to make them tight, then after a drive of say 20km down a corrugated track or 100km on the blacktop, re-tighten them. All springs will work slightly loose after initial installation and all springs need to be re-tightened after a short drive.
.

I agree but you couldn't have got them any tighter, 110%.

[Wayne_Red]

Had singles on my trailer for 6 years now, no problem. 445 haines
Wayne

[Matt76]

Ok thanks a heap guys.

[rooboy98]

Check your PM Box.

Cheers,
Roo.

[Noelm]

I think most are missing the point, the actual spring system is fine (parabolic) but the quality is the problem, good quality made springs will be fine, regardless of the system used, and even galvanised ones are OK, the drama is when cheap crap springs are used, doesn't matter if you have a single leaf, or a whole set on a duel setup, if they are cheap crap, they will give you grief, and usually sooner than later.

[toolman2810]

The old man broke a spring. Tandem wheels 2 tonne rated trailer maxed out in weight. He broke it turning into a marine shop doing 5km per hr. Its the first time I have ever seen broken leaf springs.
Made me feel sick deep down in my stomack. If that spring had broken on the open road, the only way it could end is badly.

There is something wrong with the trailer on full lock (turning circle) I suspect it loads up with side thrust.
Anyone know anything about it ?

[Noelm]

next time someone with a duel wheel trailer with a decent load is reversing into a driveway, take a look at the wheels, they are screwed at angles that will scare the pants off you, there is huge loads when turning, another often over looked thing is when a driveway has a "hump" when one wheel gets on top of the hump, it is forced up hard, and the spring is taking the full load instead of equal sharing, proper rocker tandem setups will help, but with double slippers, it is a spring/axle/bearing/tyre killer! couple this with cheap springs, and your in for some work and expense.

[cormorant]

Cheap soft axels and underinflated tyres don't help. See a lot of tyres get trimmed by guards ( or guards get rub marks from tyres) when all the weight goes on one tyre and axel twists and loads of lateral load on springs. Tyres then fail on the road later.