very heavy leaf springs - estimate rating?

Submitted: Saturday, Dec 11, 2010 at 12:51

ThreadID: 82991 Views:3296 Replies:4 FollowUps:2

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Suspension

There is an unfortunate but realistic fact about purchasing a new 4WD - it won't come fitted with a suspension system designed to carry the kind of load you'll pack for a serious outback trip.

wortgames

Hi everyone, I am restoring an old caravan, and will be replacing the axle but I'd like to retain the original leaf springs as they are still in excellent condition. The van has been up on blocks for years with no load on the springs.

Each leaf is 2 inches wide (51mm) and there are 11 of them in an 80mm stack, making each leaf about 7.3mm thick. Eye-to-eye distance is 84cm. This seems insanely over-engineered by today's standards but then the van is probably on the heavy side for a single axle and it'll be even heavier when I'm finished with it, so I'm keen to know what sort of weight these springs would have been built to handle.

I'm sure there is a rule-of-thumb way to calculate a load capacity but all I can seem to find on Google are spring rate calculators which aren't what I need.

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Reply By: Member - mazcan - Saturday, Dec 11, 2010 at 13:24

Saturday, Dec 11, 2010 at 13:24

hi wortgames
my old 1969 16ft viscount suppreme had 9 leaves in the spring packs but they were soft riding and also looked like over kill
mine was 1280kg on road total
but actually were'nt it would carry it's load really well
but always rode with out bumping along even on corregations
you havent said what the van is or it's lenghth
mine had a crank axle so i rotated it down so the van was lifted 40mm to match the 4wd towing height

i think from memory when i rotated the axle i had to unbolt back plates and put them on the opposite sides so the hand brake cable lever was then pointing forward again
if yours is say 18 ft it might well be a simular system they used softer spring rates with more leaves
cheers

AnswerID: 438540

Reply By: wortgames - Saturday, Dec 11, 2010 at 17:02

Saturday, Dec 11, 2010 at 17:02

Hi Mazcan, it's only 6m long but it's a fairly heavy construction and I plan to kit it out with some serious solar, battery and water. I reckon it'll weigh around 1500kg in normal use so I might as well go for a 2t axle & ATM as long as the springs are up to it.

AnswerID: 438561

Reply By: Trev6 - Saturday, Dec 11, 2010 at 17:52

Saturday, Dec 11, 2010 at 17:52

Hi wortgames,

Have you pulled the spring pack appart to see what sort of condition the leaves are in. I overhauled the old springs on my trailer that I take camping, when I pulled the pack appart I found that the center bolt was half rusted through and the leaves were corroded (rust) and were pitted quite badly thus reducing the leaf thickness at that point.

Could I suggest that they are at the least checked out by someone as it's the only thing keeping your newly restored van and the wheels in partnership together.

regards
Trev6

BTW, I replaced my springs cost $220/pair + new U bolts

AnswerID: 438563

Reply By: Member - peter f (VIC) - Saturday, Dec 11, 2010 at 18:21

Saturday, Dec 11, 2010 at 18:21

wouldn,t it be better to go an talk to a caravan repair shop or trailer
manufacturer . someone who knows
mechpete

AnswerID: 438568

Follow Up By: disco driver - Saturday, Dec 11, 2010 at 19:54

Saturday, Dec 11, 2010 at 19:54

As a follow up, Peter, wouldn't it be even better to go to a spring manufacturer with the details of the c/van (gross intended weight, distance between spring centres, distance from towpoint to axle centre).
This would allow any competent springmaker to manufacture a set of springs to suit your purposes.

Disco.

FollowupID: 710348