Trailer spring load ratings

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Trailer spring load ratings

Postby mr_grumble » Tue Nov 06, 2007 7:48 pm

Need some input on a dilema in which I've found myself in.

When I was designing my CT, I only invisaged that I would need springs rated up to 1000kg.

Typically, as most backyard engineering has it, I've over engineered most of my trailer and the end result is that when loaded, it weighs approx 1100kg :(

I have ALKO, 'outback' 5 leaf springs which are rated at 1200kg.

Can these be reliably used on the trailer being so close to the rated values of the springs ?

If I have to upgrade to 7 leaf springs, how much difference in trailer height can I expect coming from 5 leaf ?

Cheers,
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Postby Kramer » Wed Nov 07, 2007 12:00 am

5 leaf to 7 shouldn't be too much of a difference, do your springs sit on top of the axle or underneath? I am thinking at the most it will be a 20mm difference. Running a trailer that weighs 1100kg with 1200kg springs shouldn't be too bad but dosen't leave you anymore room to put anything else in it in the future.
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Postby mr_grumble » Wed Nov 07, 2007 9:19 am

Axle sits on top of the spring, so I guess no matter what number of leaves there are in the spring, the axle should stay relatively in the same verticle position.

Not so worried about adding extra's to the trailer later, got no more room anyway :***
More so, that off road conditions may require more of a gap between actual load and the springs ratings.

Think it's worth replacing the springs ????

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Postby Kramer » Thu Nov 08, 2007 4:09 pm

oops sorry for the late reply, but yes as you said you might need a little gap incase of bad offroad conditions eg potholes etc.

Edit you have the old springs for sale already good choice.
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Postby BrettC » Thu Nov 08, 2007 5:27 pm

I don't know much about trailers but I have built a couple of cars.
Are you sure on the rating of these springs?

Don't forget you will have 2 springs carrying half the weight each and that springs are rated by weight Vs compression. eg Ibs per inch.

It is not uncommon to have a springs which are rated half or even a third of the static load they carry.
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Postby mr_grumble » Fri Nov 09, 2007 8:54 pm

Absolutely positive about the load rating.
5 leaf 1150kg (pair)
7 leaf 1500kg (pair)

Kramer,
Good estimating on the height difference of 20mm.
Was exactly 20mm :+
Don't have much room to spare, the tent top is already damn tight when I peg it down.

Do new springs sag slightly after they've been used a little ?
Think 20mm sag is likely ? Damn I hope so :(
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Postby Kramer » Sun Nov 11, 2007 4:43 pm

Yeah they will sag maybe not 20mm but a little and also your tent might stretch a little :)
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Postby Cruzin » Tue Nov 13, 2007 6:51 am

You can also reduce the profile (diam) of the tyres or the size of the wheels. Which is my dilema at the moment
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Postby mr_grumble » Wed Nov 14, 2007 8:14 pm

Cruzin wrote:You can also reduce the profile (diam) of the tyres or the size of the wheels. Which is my dilema at the moment


Ahhhhhhh...Cruzin, BITE YOUR TONGUE :booty

I had a hell of a time findin a good set of wheels and when I did they were 15" instead of 16" (as on Pajero), and then the added task findin a set of tires to match the 15" wheels to give me the same rolling radius of the of the 16" Pajero wheels.
If the springs don't sag, I might be digging a couple of holes in which to park the CT in :armsup
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Postby Cruzin » Thu Nov 15, 2007 7:08 am

Well Mr Grumble

it amazes me how the world works

My CT came with 2x 16" x 6 Stud Pajero wheels and Dunlop Tyres - Suits Landcruiser etc
I also bought 3 new x 16" x6 Stud Rims (7JJJ, I think) that are sitting out in the shed because they were a good buy (From Challenge CTs)

Now I need to swap all of them to end up with 3 xTyre & Rim combos of either,
a) 16" x 6 stud with smaller profile tyres to suit height of tent or
b) 15" x6 stud with appropriate profile to suit height of tent or
c) a shovel to dig holes in the ground under the wheels.

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Postby mr_grumble » Thu Nov 15, 2007 7:18 am

Yup, sounds familiar :)

Luckily I only have two 16" wheels/tires left over.

As for the tires, theres a tire shop just down the road that stores all the old tires out in the vacant lot. I went down one Saturday afternoon, parked the car in the lot and started going through the pile looking for 31x10.5xR15 AT's.
I was ammazed just how many good (50%) tires were in the pile. I ended up with a pair of Yokahama AT's with a good 8mm of tread still on em :armsup
Might pay to scope out the local tire shops your way ?
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