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Leaf spring design
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Rdover



Joined: 26 Nov 2007
Posts: 413

PostPosted: Mon Feb 02, 2015 10:58 am    Post subject: Leaf spring design Reply with quote

I was doing some re-assembly on my Alldays when I noticed that the rear offside looked a little low and when I measured it I found, to my horror a 4" difference in the height of the chassis rails left to right!

Not only has the right hand one collapsed but eh left hand one does not look happy either. They're not 100 years old but they are certainly at least 30 so probably due for a change. Add to the current problem that they've proven to be too weak to cope with the weight of the new body and passengers by bottoming out far too easily.

So, I need to have new springs made but I have no idea of how to measure the capacity or rate. I can't move the car so I need an smart idea on how to weigh the back end to calculate the capacity (probably not the right word) and then I need to figure out how to calculate the rate (ie resistance to compression). Add into the mix that the car does not have shock absorbers and the ride height is set by aesthetics.

Anyone suspension experts out there?
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Richard


Last edited by Rdover on Mon Feb 02, 2015 11:43 am; edited 1 time in total
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Rdover



Joined: 26 Nov 2007
Posts: 413

PostPosted: Mon Feb 02, 2015 11:42 am    Post subject: Reply with quote

Just found this link

http://www.turbosport.co.uk/showthread.php?t=153066

great cheap way to measure corner weight!

4 x argos basic mechanical sales are being bought today so I can measure everything and then take the springs off to use as a pattern.
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Rdover



Joined: 26 Nov 2007
Posts: 413

PostPosted: Mon Feb 02, 2015 12:33 pm    Post subject: Reply with quote

A bit of rapid research found me speaking to a helpful chap at Owen Springs in Rotherham who gave me loads of information.

The information he requires is:
Spring camber height - sit the car body at the height you want then measure the distance from top of the centre of the spring pack to an imaginary line drawn between the the 2 eyes of the leaf spring.

Unsprung weight - weight of everything attached to the springs, ie complete axle

corner weights - each side and combined weight unladen with driver and then with maximum expected weight (eg with 2 bloaters and a large picnic basket and extra fuel

From this he'll be able to calculate (with a touch of inspired guesswork) the correct spring strength for the ride height and spring rate especially given the lack of damping. They also have developed a way of coating the springs with flexible powder coat over chrome that will not affect the spring (ie the heat involved would affect the spring).

Compared to the monkey in Coatbridge who'd simply copy the knackered spring they were very helpful and knowledgeable.
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