Coil vs Leaf discussion

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De-Ranged
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Coil vs Leaf discussion

Postby De-Ranged » Thu Jul 14, 2011 9:54 am

I've started this to stop a hyjack of another thread

turoa wrote:Why would you have to push the axle back? it can stay in the same place :?

I put that in becouse Jessy I mean Gotflex mentioned a new D/S it was aimed at him... your dead right you don't have too

Btw, I put a 4 link in the back of my hilux for less that what it would cost to replace the broken leaf (links.... zip zero nada) and it performed way better offroad. Can calculate and tune squat easily and changing the spring rate consists of buying new coils :roll:

:lol: Your not the average, you have more skills and ability.... not to mention a parts supply that probably dwarfs mine :mrgreen:

buying leaves - same cost as buying a set of coils

Yes but you get it wrong coils too stiff your up for a new coil but with a grinder and a couple of spanners and some spare leaves you can tune leaves :wink:

Im not sure what you're getting at by saying soils are linear? Do you mean linear spring rate? because thats incorrect given that the more you compress a spring the more force it has pushing back.

The rate is linear a coil spring with have a rate eg 80lb per Inche its how coils are sold that means it takes 80lb to travel its first inche, if the spring has 800lbs on it (10" of compression) and you add another 80lb it will compress 1 more inch
A leaf spring by virtue of its multiple leaves will flex first the top leaf as this gets to a certain point it will start to bend the leaf under it increasing its rate and so on progressive rate :wink:

Getting down travel is no problem, it consists of either capturing the spring top and bottom (which forces the axle to articulate and alllows it to be stable) or of course you could try buying the correct, long length coils!

Your dead right, you can get a set of scales weigh your sprung weight (the weight that is sitting on the coil) then you work out travel, I'll use my Zuk as an example... Its front end sprung weight is 280kg's per side I have a 13" travel shock as a rule of thumb you want the suspension to bottom out at near twice the weight, this way you wont be hammering the bumpstops, so 280 x 2 =560 divide this into your travel, 560 / 13 = 43 so 43kg/inche
yea I know mixing metric and imperial bs but you get the picture
Good luck finding this coil :roll: more than 13" of travel and that rate :lol: I looked long and hard, I've got a database of coil data after spending days going through wreaking yards and I couldn't find one
Anyway thats off the point there is more to this.... I'm betting you want more down travel than up, setup at the above rate your right in the middle of the shock travel @ 6.5"s so say we want only 4"s of up travel so that means 9" down
So we work off the sprung weight 280 / 9 = 31kg's per inch all good till you work out what its going to take to bottom out 4 x 31 = 124kgs .... hmmm
Now there are ways round this like those big long bumpstops you see on american trucks or fancy air bumps or multiple coil coilovers where your tender spring bottoms out before the full travel of your shock upping the overall rate for the last bit of travel, you can also control it with hard dampening, but this has the side effect that on road becouse of the shocks are slowing the spring down your wheels don't follow the road surface as well.... your old man races you ask him about excessive dampening

Ive tried leafs and found that they are complete and utter shit. Yes they can flex great (I can upload a pic showing this) but man they're uncomfortable (not to mention not being able to handle the bumps)! If they were so epic then why aren't all of a) the racers running them (ie koh, offroad racing, xrra etc) b) anyone that doesnt take half a million years to drive 100m

:lol: you come from a family that races and you can't see the money holding up each corner
KOH trucks most of these are on Air shocks... a progressive rate gas spring add to that a set of air bumps
The offroad racing trucks.... lets start with the coilover first 3 possibly 4 coils these are designed so they bottom out increasing the rate, then there is the triple or quad bypass shock and finally the air bump ..... one corner worth more than my whole custom zuk is going to be worth :shock: and all to give a progressive suspension rate
Have a look at score racing rules there is a leaf sprung class :wink: but it is an entry one

You have pointed out where leaves suck :lol: speed they rub as they work and this means they don't react as well at speed
Add to the fact that they are used as a link as well and this adds to the problems at speed you don't want any movement in your axles having them anchored by springs especially soft ones means there is movement, side to side, twist
That makes controlling the vehicle and getting the power down or braking harder, the opposite of what a racer wants

I've often wondered what they would be like if the pack was seperated by teflon and they were just used as a spring on a set of links.... if they could be made race worthy, I'm thinking along the lines of 1/4 elliptical to save some weight

Cheers Reece

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Re: Coil vs Leaf discussion

Postby Fakey » Fri Jul 15, 2011 11:48 pm

Image

But seriously, interesting stuff :wink:
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Re: Coil vs Leaf discussion

Postby haynzy » Sat Jul 16, 2011 7:03 am

if they were good enough for crumpy they good enough for me,
go the leafs :mrgreen:
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Re: Coil vs Leaf discussion

Postby Suza » Sat Jul 16, 2011 7:39 am

Having had leafs, i much prefer coils. Most of what I do is touring with the family and the ride comfort is much better on leafs

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Re: Coil vs Leaf discussion

Postby ClassicCruiserSpares » Sat Jul 16, 2011 9:28 am

Suza wrote:Having had leafs, i much prefer coils. Most of what I do is touring with the family and the ride comfort is much better on leafs


If the ride comfort is much better with leafs, Why do you prefer coils?
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Re: Coil vs Leaf discussion

Postby Suza » Sat Jul 16, 2011 10:32 am

ClassicCruiserSpares wrote:
Suza wrote:Having had leafs, i much prefer coils. Most of what I do is touring with the family and the ride comfort is much better on leafs


If the ride comfort is much better with leafs, Why do you prefer coils?

:oops: Meant to be is much better on coils

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Re: Coil vs Leaf discussion

Postby crazyclark31 » Sat Jul 16, 2011 7:13 pm

have to say i prefer coils myself . I like the control you get from the multi links setup when at speed.

concerning leafs though. How would say a 5 link setup like a safari go with a 1/4 elliptic leaf running the same length as the bottom arm. Would have to have the mounting points beside each other or set so they follow the same arc.

Feel free to rubbish this theory :)

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Re: Coil vs Leaf discussion

Postby DaveM » Sun Jul 17, 2011 9:34 am

I've always preferred coils, which is probably why I never bought a hilux.

One thing I've always been confused about is making the coils "captive" if you run longer shocks. Surely this does nothing other than make the vehicle look like it has huge travel? I would have thought once your coil is past its "free" length, there is no longer downward pressure on the wheel, therefore offering no extra traction? Also, surely making top AND bottom captive is worse, would you be stretching the coil, in which case it will be trying to compress itself anyway?

Obviously I'm no tech head, I just buy and fit off the shelf parts and hope they work, but I'm always keen to learn more if it doesn't get too technical :mrgreen:

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Re: Coil vs Leaf discussion

Postby De-Ranged » Sun Jul 17, 2011 10:24 am

crazyclark31 wrote:have to say i prefer coils myself . I like the control you get from the multi links setup when at speed.

concerning leafs though. How would say a 5 link setup like a safari go with a 1/4 elliptic leaf running the same length as the bottom arm. Would have to have the mounting points beside each other or set so they follow the same arc.

Feel free to rubbish this theory :)

:D :D I was thinking more along the lines of a dual triangulated linkage for the rear... you get the fixed axle, tuneability of the suspension (AS, under/oversteer & rollcenter) and your spring rate can be made progressive and easily tuneable
hmmmm something for the next truck

Effectively you are right dave but that captive spring will help in a sidling where the body has tipped by pulling on the axle, it is also a requirement for road going (cert) as the spring can't come out or reposition on a nasty bump(I have heard of some certifiers allowing a screw down captive setup on the axle and a spring location cone on the truck, my local guy wont :roll: )
You can get a bit more out of your springs on down travel or up travel by setting up your bumpstop placement & spring rate, if they are setup with the bumpstop outboard of the spring under full bump the spring will leverage the axle down on the drop side.... imagine your bumpstop is the pivot point and the spring is inside this so it pushes the axle down :wink:
the spring rate has to be less than twice the weight of the corner its supporting for this to work otherwise you wont get the weight on the bumpstop to make this happen
Be carefull the further inboard from the wheel the spring is the greater the leverage ratio on the spring.... making the truck tippy

Cheers Reece

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Re: Coil vs Leaf discussion

Postby niblik » Sun Jul 17, 2011 10:32 am

i tried both methods of coil retension in the back of my fawdy..

when tested with coils free at top, it travelled well.

when tested with coils contained at both ends, no artic was lost.

then when on compression if you had a location cone to try and relocate the coil it would be a hinderence when being on the compression side and would lose out on upwards flex as the cone gets in the way.

what i'm tryin to say is poo poo to that theory of a coil being captive at both ends being not as good.
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Re: Coil vs Leaf discussion

Postby tomsoffroad » Sun Jul 17, 2011 1:30 pm

I was thinking more along the lines of a dual triangulated linkage for the rear... you get the fixed axle, tuneability of the suspension (AS, under/oversteer & rollcenter) and your spring rate can be made progressive and easily tuneable
hmmmm something for the next truck



This is what Im up to with the cruiser but with a single triangle. I'm making my 1/4 ellipitc springs hinged at the chassis with locating bushes which will be pinned for road use and unpinned for off road. Should allow stupid amounts of down travel :wink:
Personally I like leaves for tunability and reliability and ease of construction. Why I've done exactly the opposite with the Cruiser.......... Well why not!!!!! :lol: :lol: :lol:

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Re: Coil vs Leaf discussion

Postby DaveM » Sun Jul 17, 2011 1:45 pm

niblik wrote:what i'm tryin to say is poo poo to that theory of a coil being captive at both ends being not as good.


Why not run a coil that doesn't need to be held captive? I'm assuming a coil that length would bind on full compression?

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Re: Coil vs Leaf discussion

Postby Lynx » Sun Jul 17, 2011 1:54 pm

DaveM wrote:
niblik wrote:what i'm tryin to say is poo poo to that theory of a coil being captive at both ends being not as good.


Why not run a coil that doesn't need to be held captive? I'm assuming a coil that length would bind on full compression?


Sure would.

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Re: Coil vs Leaf discussion

Postby crazyclark31 » Sun Jul 17, 2011 2:33 pm

tomsoffroad wrote:
I was thinking more along the lines of a dual triangulated linkage for the rear... you get the fixed axle, tuneability of the suspension (AS, under/oversteer & rollcenter) and your spring rate can be made progressive and easily tuneable
hmmmm something for the next truck



This is what Im up to with the cruiser but with a single triangle. I'm making my 1/4 ellipitc springs hinged at the chassis with locating bushes which will be pinned for road use and unpinned for off road. Should allow stupid amounts of down travel :wink:
Personally I like leaves for tunability and reliability and ease of construction. Why I've done exactly the opposite with the Cruiser.......... Well why not!!!!! :lol: :lol: :lol:


How does the axle end work? Does the spring slide or is it fixed at that end too?

Have seen a 3/4 elliptic set working and was pretty impressive. Was average at anthing faster than say 30km/h but when doing the tech stuff would out prefom most trucks.

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Re: Coil vs Leaf discussion

Postby De-Ranged » Sun Jul 17, 2011 4:00 pm

tomsoffroad wrote:This is what Im up to with the cruiser but with a single triangle. I'm making my 1/4 ellipitc springs hinged at the chassis with locating bushes which will be pinned for road use and unpinned for off road. Should allow stupid amounts of down travel :wink:
Personally I like leaves for tunability and reliability and ease of construction. Why I've done exactly the opposite with the Cruiser.......... Well why not!!!!! :lol: :lol: :lol:


:lol: yea well I can hardly talk going to the trouble of making coilovers for the zuk
Not so certain about the free drop by hinging the truck end.... its something I'd expect to create issues on sidelings, you could set the suspension for a high roll center to offset that tho
I was planing on running a longer spring that is hard mounted to the chassi won't be as much drop but should give me good handling

crazyclark31 wrote:How does the axle end work? Does the spring slide or is it fixed at that end too?

Here's a pick of a 1/4 elliptical
Image
Look at the front of the leaf pack you'll see its on a hinge.... the other way is to clamp the spring to the chassi with U bolts
As for the average performance of the 3/4 part of that is the axle isn't as securely mounted as you get from links, 3/4 systems unload in corners the inside can lift easily with body roll not a good system for road use, the other issue is when doing extreme climbs the back can gain Anti Squat jacking the rear till it looses traction then dropping then it gains traction again... that really scary bounce :lol:

Cheers Reece

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Re: Coil vs Leaf discussion

Postby darinz » Mon Jul 18, 2011 3:20 pm

Air bumpstops are virtually not used anymore. They went out of favour and most have gone hydraulic for one simple reason. With an airbump it would stop the big hit on compression but then it bounced the truck as it is just a high rate spring. Hydraulic bumpstops are the only option and work extremely well. (and should be fitted to anyone pushing hard offorad and any speed)
KOH trucks / buggies do not use air shocks anymore as they can't handle the high speed and had huge fade. Some did in the first couple of races but the first thing they now do is swap the airshocks for coilovers. (and fit bypass shocks depending on budget)

I do not understand why anyone would build a truck and would use leaf springs? (even 1/4 eipticals) With a coil spring and link system you basically have no design constraints. And unless you are going to do endurance races then a large coil over and a bumpstop is all you need. The coilover, hydraulic bumpstop and twin spring will cost less than $1,000 per corner for my truck and that will have 24"travel at the rear and 18"ish at the front. It will also have adjustable anti-squat (from 35% to about 100%) and adjustable hieght. Not sure what the actual articlation will be as it will have an adjustable swaybar as well. (obviously a high speed truck not a crawler)

Coil spring and links are going to cost more and be more complicated than leaf springs. It has more moving parts and more things that need to be designed correctly. It has more to go wrong with it but it is lighter, it is more tunable and will work better in most circumstances.
Leaves are easy to fit and easy to change to get the truck to handle better. The leaves rubbing on each other is extra shock absorbtion BUT ultimately they have limitations that make coils a better option in MOST applications.
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Re: Coil vs Leaf discussion

Postby rokhound » Mon Jul 18, 2011 5:27 pm

I tend to agree with Darinz on this one. Of course if you get people who have not studied how a link suspension should be set up to perform, then the leaf idea is the way to go. Obviously if you already have a leaf set up then tuning that is the easiest thing to do, even if it involves fitting much longer spring packs, this is a relatively straight forward job of relocating a spring perch or 2.
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Re: Coil vs Leaf discussion

Postby De-Ranged » Mon Jul 18, 2011 8:09 pm

:lol: yea sorry you are right they are using coilovers etc

Darinz you are not the norm, if you find adjusting coils easy... I'm not being smart but my experience has been that bugger all people know how to work out spring rates and how to apply em....
a leaf spring on the other hand you can with a grinder and a few vice grips pull apart and change the rate for f all in cost and some trial en error
For me the technical side of leaf springs is superior to a coil when used with a link setup, I get the progressive spring rate that I can tune for a fraction of the cost of coilovers and bumps and suspension I can tune ..... think outside the sqaure :wink:

By the way darinz could you pm me where your getting your suspension I maybe keen on a set of bumps for the zuk if they are that cheap

Cheers Reece

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Re: Coil vs Leaf discussion

Postby rokhound » Tue Jul 19, 2011 8:23 am

De-Ranged wrote::

By the way darinz could you pm me where your getting your suspension I maybe keen on a set of bumps for the zuk if they are that cheap

Cheers Reece



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Re: Coil vs Leaf discussion

Postby turoa » Tue Jul 19, 2011 11:43 am

De-Ranged wrote:
I've often wondered what they would be like if the pack was seperated by teflon and they were just used as a spring on a set of links.... if they could be made race worthy, I'm thinking along the lines of 1/4 elliptical to save some weight

Cheers Reece


Redzukis done the whole teflon between leaf packs. It makes the packs really supple but I think hes had problems with axle tramp

I think you're missing the core point though deranged. Your initial statement was that leafs are better than coils. Ill give you the fact that leafs are cheap and easy to set up but in my opinion they are far from superior.

darinz pretty much said it all. Its cheap to buy good quality suspension parts now, to me its much more economical than trying to make my owncoilovers (by the time a billet of alloy was bought + the shock it wasn't that cheap, not to mention they are completely rebuildable).

btw deranged,I didnt come from a racing family and my dads never raced. He has a race car tho (which gets moved around the yard every once in awhile).

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Re: Coil vs Leaf discussion

Postby GotFlex » Tue Jul 19, 2011 1:51 pm

Leaf setup isnt that cheap, buying a 2nd hand set is getting up there and a new set is far from cheap, they are time consuming to set up, speaking from exprience after we did rears up front i pulled my spring pack out 7-8 time getting it to sit right, they snap when pushed hard (pruggydore) bushes flog out if used hard, wheel alignment can be hard and caster wedges aint cheap, work well when flat but then they invert quickly as typically at the end of their life, terrible flex when they have a big arch. sometime require require anti wrap bar.

wish i had read a thread like this before i leafed my truck as coils would have been far better.
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Re: Coil vs Leaf discussion

Postby De-Ranged » Tue Jul 19, 2011 2:41 pm

Thanks for the heads up Tu's about Redzuk I'll have a chat to him

I was halfway through typing up the same pionts you guys seem to miss but I thought I've better stuff to do :lol:

As wise pruggydore said "why bother, nobody gives a f...."

Oh and sorry for the mix up Tu's over the racing thing

Cheers Reece

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Re: Coil vs Leaf discussion

Postby DieselBoy » Tue Jul 19, 2011 4:58 pm

De-Ranged wrote:

I was halfway through typing up the same pionts you guys seem to miss but I thought I've better stuff to do :lol:

As wise pruggydore said "why bother, nobody gives a f...."

Cheers Reece


Its a bit like that on hear from time to time eh.

I get were your coming from. Others do also.

Though there are some that will just never get it :lol: :lol: :lol: :lol:
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Re: Coil vs Leaf discussion

Postby doddzee » Tue Jul 19, 2011 7:08 pm

De-Ranged wrote:As wise pruggydore said "why bother, nobody gives a f...."


I give a #### and I'm sure I'm no the only one with not much to offer but am reading with interest.

Finally a good tech thread comes along, don't stop now. :wink:
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Re: Coil vs Leaf discussion

Postby crazyclark31 » Tue Jul 19, 2011 10:58 pm

doddzee wrote:
De-Ranged wrote:As wise pruggydore said "why bother, nobody gives a f...."


I give a #### and I'm sure I'm no the only one with not much to offer but am reading with interest.

Finally a good tech thread comes along, don't stop now. :wink:

ME TO :D :D :D
This is giving me the kinda info i'd never get unless you guys in the know have these kinda disscussions. Enables me to apply a little bit more knowledge when i finally get to biuld me a trailer queen :D.

Apologies in advance for my dumdass questions

Would a good shock help stop the axle tramp when using teflon between leaves?

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Re: Coil vs Leaf discussion

Postby De-Ranged » Tue Jul 19, 2011 11:03 pm

:lol: all good guys.... I'm not pissed, I was just real busy, the qoute was a bit of a dig at pruggador, me and him shear a shed :wink:
Sorry guys sometimes its hard to convay tone
I'm not pissed, I enjoy it when people challange me.... it forces me to think about things look at things from a different dirrection and I learn thiings, hell sometimes I'm wrong :lol: it does happen the guys at the shed love to remind me when it happens

Going to be down south for few days, will continue this when I get back

Oh considering changing the suspension on the zuk to a version of 1/4 eleptical

Cheers Reece

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Re: Coil vs Leaf discussion

Postby De-Ranged » Tue Jul 19, 2011 11:25 pm

This is giving me the kinda info i'd never get unless you guys in the know have these kinda disscussions. Enables me to apply a little bit more knowledge when i finally get to biuld me a trailer queen :D.


:lol: I thought I was just having a good argument.....

Apologies in advance for my dumdass questions

yes there are stupid guestions but its only the stupid that never ask :wink:

Would a good shock help stop the axle tramp when using teflon between leaves?

It will help a small bit..... its not going to stop the twist movement of the axle due to the flex of the leaf springs...
a link off the top of the diff would be better or something like this
http://i671.photobucket.com/albums/vv76/zukiscott/SUZUKI/AZALEA008.jpg
its a truck off pirate runnign these links on both sides

cheers Reece

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Re: Coil vs Leaf discussion

Postby muddyhilux » Wed Jul 20, 2011 7:26 pm

that's not a bad idea at all,keeps things out of the way ae,like as in not in the centre of the vehicle
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Re: Coil vs Leaf discussion

Postby De-Ranged » Thu Jul 28, 2011 3:40 pm

I'm back, got stuck in Dunner's in all that snow

I've been reading back through the posts and those that have bag'd leaf springs saying that coils are better only had these three points

Coils arn't dearer to buy
Yep, you have me there.... but :wink: if you get your spring rate wrong you can only shorten a coil (shortening travel and upping rate) a leaf spring on the other hand can be softened by removing leaves or shortening them, you can cheaply by other sets to add leaves to stiffen.... hell I have a collection of rat'd packs don't I Gotflex, Oh and did I forget that doing this dosn't shorten the spring and its available travel

Coils are better because you can tune the links
Got me there again, Long travel soft leaf springs do suffer from axle tramp (where the axle twists under power or brakes)hmmm this is lame so you add links so you can do coils why not add the links to a leaf spring.... guess what we got then tunable suspension with a tunable spring :wink: add just a track bar and a panhard bar to a leaf sprung truck and its a whole different truck :wink: ask gotflex how well his truck goes I've done that to his truck ( and be honest Jessy :lol: ) this is a very lifted Mu on leaf springs that out handles all his mates on road and out flex's them 8)
Now thats not starting to think outside the square and running a full link setup with a leaf spring

Now this is the one that is a very valid point
Coils are better used in race and there is more information out there for them
There are two issues with leaf spring's and racing the weight and stiction of the leaves as the spring flex's
I'll counter part of this by pointing out first the weight issue isn't really one for us, saving a couple of Kg's dosn't mean that much to us... my personal view is weight on my truck below the CoG is a good thing its what keeps me on the side of a hill
The stiction between the leaves is a problem especially with road going trucks and is part of the harsher ride (along with the fact that most factory standard leaf springs are made to carry loads not ride comfort :roll: )
And yes there is alot more information about spring rates and setups for coil because of the race development
The information for leaf springs is also alot harder to work with as calculating the stiction between leaves is very difficult in fact I have 3 different calculations from 3 different books (all reputable) that even use different variables that can be used to approximate the rate of a leaf spring pack :roll: :lol: oh and just to make it interesting they all gave me slightly different results on the same pack

This still dosn't change the point I have been repeating that coils suck when you have less up travel than down something that leaf springs are very good at, as they have a progressive rate and I'm still waiting for somebody to give me a good argument

Just to put my views on the line I've decided to put the coilovers aside and go 1/4 elliptical in my Zuk

Cheers Reece

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tgaguy1
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Re: Coil vs Leaf discussion

Postby tgaguy1 » Thu Jul 28, 2011 5:09 pm

De-Ranged wrote:Just to put my views on the line I've decided to put the coilovers aside and go 1/4 elliptical in my Zuk

Cheers Reece


Now that is cool 8) . Someone willing to risk it all. Definitely enjoying this tech thread. Has been a while since a thought provoking tech thread has appeared on ORE. Thanks to all of the tech guys that are willing to share their knowledge and experience.

One question though Reece, You mentioned putting a Teflon layer between the leaves of a spring pack to alleviate friction. What effect would that have on a road going truck? Would it improve road handling and would it improve off road performance?

Thanks

Jase.

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