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Uprated springs? what? how?
http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=342		 Page 1 of 4
Author:  Matt S [ April 29th, 2009, 4:08 pm ]
Post subject:  Uprated springs? what? how?
OK, so i want to theoretically sort out some uprated, lowered springs into some spare cans ive got here.

How exactly do i go about it (in a nutshell) is it cut old cans apart and weld up again or what? all help greatly recieved.
Author:  Russell [ April 29th, 2009, 7:00 pm ]
Post subject:  Re: Uprated springs? what? how?
Matt S wrote:
is it cut old cans apart and weld up again or what?



Yes.

Taking care not to mix the tie rods up (they are different front/rear) so that you re-install the cans the same way round. Front and rear springs are also different, so make sure you have it all marked up what's what when you come to reassembling it all and welding it back together.

Easiest to cut the end of the can where the cap is welded on.
Author:  Matt S [ April 30th, 2009, 8:42 am ]
Post subject:  Re: Uprated springs? what? how?
Thank you muchly Mr Russ, thats all i wanted to know :) :)
Author:  4x4 SuperFinn [ May 1st, 2009, 12:49 pm ]
Post subject:  Re: Uprated springs? what? how?
We have used Springcoil before to manufacture uprated springs:

http://www.springcoil.co.uk/

They have measured a set of standard 2CV springs before so you should be able to get a set made X% stiffer as they know the base value.

Prices are not too bad as well.

For the 4x4 we use upen springs with a guide plate. Very useful if you want to test springs before committing them back to cans as we can change a set of 4 springs in under an hour.
Author:  Harley [ May 5th, 2009, 4:47 pm ]
Post subject:  Re: Uprated springs? what? how?
Does anyone now the spring rates for a 2cv?
I have taken a set to a spring manifacture to have a set made 50% stiffer, but they still need to know the spring rate of the originals...?

or

They need to know how compressed the spring is when it is on the bumbstops. ( which will vary depending on what you have your ride height set at)

Or

They need to know how much weight/pressure is applied to each spring...

Anyone :?

Harley
Author:  subarupete [ May 5th, 2009, 5:39 pm ]
Post subject:  Re: Uprated springs? what? how?
An idea.
If you have corner weight scale or similar device, place it under a (front) wheel.
Record the kg or lbs. Then calculate the weight applied to the road spring. The front suspension arm ratio is 405.8mm to 108.6mm or 1:3.7 from the (2cvsnail site).
Eg 280Kg at the front gives 1036Kg.
Author:  ken [ May 5th, 2009, 6:55 pm ]
Post subject:  Re: Uprated springs? what? how?
@ subarupete.
That's a remarkable degree of accuracy, until you take into account that the ratio will alter depending on the ride height set and also the variation introduced by movement of an arm from its static position... ;)

@ Harley.
Weights as given in an owner's manual...
Kerb weight (unladen), front axle 340 kg & rear axle 240 kg
Gross vehicle weight, front axle 450 kg & rear axle 500 kg

Note that these are static loads and that dynamic loads will be _much_ higher, especially if the car is driven on rough terrain.

ken.


subarupete wrote:
The front suspension arm ratio is 405.8mm to 108.6mm or 1:3.7 from the (2cvsnail site).
Author:  subarupete [ May 5th, 2009, 9:31 pm ]
Post subject:  Re: Uprated springs? what? how?
Tried this Spring Calculator.

http://www.reliablespring.co.uk/calculator.htm
Used some values from AZ 2CV6 specs, others measured

Spring Material Option and Output Type - Plain Carbon Steel
Number of Active Coils: - 6 measured
Wire Diameter: - 0.6"
Outside Diameter of Spring: - 4.0" measured
Free Length: - 7.59
Compressed Length: - 6.0 quess

Spring Rate: 791 lb/ft or 800 seems to tally 800 as quoted by others/forums

Force at compressed length: 2048 ft/lbs !!!

Note.
Perhaps use spring cans either two halves when can is cut in the middle or cut end and use full length keeps the spring parallel.
Have seen 4x4 cars break tie rods and eye bolts because spring gets "spring bound" when unchecked due to lack of spring can.
Author:  Harley [ May 6th, 2009, 8:35 am ]
Post subject:  Re: Uprated springs? what? how?
Thanks guys, appreciated,

Next question, how much can the spring be lenghthened? To increase the spring rate a thicker gauge can be used at the same lenght to gain about 20% so to gain more the spring will need to be lengthened... how much play(?) is in an unloaded spring can?

Cheers
Harley
Author:  Matt S [ May 6th, 2009, 8:59 am ]
Post subject:  Re: Uprated springs? what? how?
silly question time............

why not just buy the uprated springs that 'normal' suppliers advertise.

i guess its more expensive to have some new ones made than to buy those ones?? i dunno.
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