leaf springs

Submitted: Friday, Aug 15, 2003 at 18:25
ThreadID: 6603 Views:2040 Replies:5 FollowUps:1
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How do leaf springs compare to coil springs? Is it true that leaf springs are alot stiffer than coils? When it comes to getting alot of suspention travel can it be done with leafs and how?

Just a man with to much time to think...

thanx
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Reply By: Dennis (Brisbane) - Friday, Aug 15, 2003 at 20:46

Friday, Aug 15, 2003 at 20:46
Chalk and cheese really...

Leaf generally can carry more weight as standard, coil is (as a rule) more supple and comfortable.

Leaf springs can be soft and supple, but then you can't carry much weight.

The trade off has to made somewhere between weight bearing ability and comfort. This dependent on the number, type and 'set' of the leafs.

Leaf sprung vehicles can get more lift (and travel) by adding specially designed leafs and/or longer shackles.
AnswerID: 28053

Reply By: Eric - Friday, Aug 15, 2003 at 22:13

Friday, Aug 15, 2003 at 22:13
Dave.
There is a lot of misinformation about springs out there, the is no reason that leafs have to be stiffer than coils, the reason coils are prefered is because they can move side ways so that one wheel can be up and the other down. If you try to get big travel with leaves the leaf has to bend side ways to allow for the fact that the axle is diagonal across the chassis. leaves can be made progressive, coils can not even though many manifacturers try to. Eric.
AnswerID: 28066

Reply By: daviiiMQ - Saturday, Aug 16, 2003 at 07:28

Saturday, Aug 16, 2003 at 07:28
Thanks guys this has cleared up a lot of confusion in my mind.

what would adding coils to your leafs do? as i have seen pictures of cars with both on?

dave
AnswerID: 28080

Follow Up By: Old Jack - Sunday, Aug 17, 2003 at 17:54

Sunday, Aug 17, 2003 at 17:54
This has been cone on a number of "cars" over the years to increase load carrying capability without modifying the axle locating ability of the leaf spring. sometimes coil over shock absorbers are used to do this but the shocks themselves must be very good quiality & the damping rate appropriate for the spring rate. In the past I have used coils in the back end of leaf spring rally cars, you use 2-3 leaf's then add a coil. it reduces the amount of axle tramp and you can increase/decrease the spring rate quicker to suit conditions in a shorter period of time than having to pull the leaf's out and re-setup the rear end alignment all the time.
all leaf spring vehicals suffer this to some extent due to the long flat spring curling as torque is applied on a 4WD all four wheels get torque so you can get all four wheels "tramping" up and down on the spot!)
If you ever get to see an army jeep (yes the old ones!) with its leaf spring suspension & spring steel ladder chassis or for that matter an old landrover, dont laught they go places simply because they get to keep the wheels on the ground you will see what wheel articulation is all about.

happy motoring
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FollowupID: 19517

Reply By: Slunnie - Saturday, Aug 16, 2003 at 23:18

Saturday, Aug 16, 2003 at 23:18
What makes the leaved juddery is the stiction that occurs between each leaf. It neads to break this then move and so the ride becomes a little sharp. You can get a fair amount of travel from leaves, though you can probably get a lot more from coils with the same effort.

You can get more travel by removing a leaf or some leaves from the pack which will help with compression travel. Unclipping the clamps that hold the spring pack together may also help with droop travel. You will also need to sort the shocks and brake lines to allow these to reach.

or you can get expensive and start reengineering with new bits.

The leaves with coils as far as I know is a change over from using the leaves to support the vehicle to using the coils to support the vehicle, but the main leaf is used for axle location. I'm not sure how these go with axle wrap though or if they have some extra links to prevent it.

Regards
Slunnie
AnswerID: 28137

Reply By: Fred - Sunday, Aug 17, 2003 at 22:39

Sunday, Aug 17, 2003 at 22:39
Leaf springs are commonly known as "cart springs". They are aptly named as they give a ride similar to a horse and cart. Good for trailers and caravans but not up to the requirements of a modern 4wd.
AnswerID: 28254

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