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
Your not the average, you have more skills and ability.... not to mention a parts supply that probably dwarfs mine
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
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
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 more than 13" of travel and that rate 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
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 and all to give a progressive suspension rate
Have a look at score racing rules there is a leaf sprung class but it is an entry one
You have pointed out where leaves suck 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