Outer Limits 4x4 Board

Why don't more people put more work into the front end. Everyone goes for heaps of flex out the rear and get nothing out of the front. A real flexy front will feel heaps better then rear.

thanks for all the help guys

yeah seems to be that way that every one focuses on the rear but i was thinking about doing a 3/4 in the rear with longer shocks

and then drop shackles just in the front with a leaf taken out of the front for a bit more flex

correct me if im wrond but isn't the 3/4 design lwork like a drop shackle

or do you have more control over the 3/4

cheers

just cruizin' wrote:Why don't more people put more work into the front end. Everyone goes for heaps of flex out the rear and get nothing out of the front. A real flexy front will feel heaps better then rear.

Interesting related point. Ive never seen a 3/4 setup done to the front. It would be harder to setup I imagine due to the shape of the chassis, however it would still be doable. Maybe its because when standardish, they flex beter in the front anyway...

nick.gooding wrote:correct me if im wrond but isn't the 3/4 design lwork like a drop shackle

No. Drop shackles are just that, they drop out. 3/4 still has a spring rate, hence a level of stiffness (drop shackles when dropped out will have essentially no stiffness). Only thing they really share in common, is the ability to be pinned back. Ive never used either, but I would imagine that a 3/4 would feel allot better, and give the car vastly superior stability.

nick.gooding wrote:thanks for all the help guys

yeah seems to be that way that every one focuses on the rear but i was thinking about doing a 3/4 in the rear with longer shocks

and then drop shackles just in the front with a leaf taken out of the front for a bit more flex

correct me if im wrond but isn't the 3/4 design lwork like a drop shackle

or do you have more control over the 3/4

cheers

Dont put drop shackles in the front. Acutally just dont put them on a car at all. 3/4 in the front has been done. Many years back Sam from Aoverkill had this on the front of a suzuki. No real gains from memory and just made packaging it more hassle than it was worth.


Layto....

so does that mean that the drop shackles wont slowly flex
do you mean they will only drop when a wheel has come off the ground

because the impression i got from the replys is that there only good for showing off because they dont slowly flew they only drop when a wheel comes off.

cheers

nick.gooding wrote:so does that mean that the drop shackles wont slowly flex
do you mean they will only drop when a wheel has come off the ground

because the impression i got from the replys is that there only good for showing off because they dont slowly flew they only drop when a wheel comes off.

cheers

They will slowly open up. Imagine your suspension drooping with no shackles on at all (until after a certain period they get stopped), that is a pretty average way of explaining how they would work.

The reason people give you that impression is because they honestly believe that's all they are good for (myself included). Not for your given reason, but because they simply unfold and allow the wheel to drop, they do no apply any real force between the axle and the car/chassis, as they are a pin joint and cannot transmit loads until they are either fully closed or fully open.

yeah thats what i thought
well thats shit ill go with the 3/4

are any of you experts on drop shackles using bumpstops set up right??
i mean a bumpstop that FORCES the opposite (droop) wheel into the ground..
i just CAN NOT understand how your saying a drop shackle is so bad/ unpredictable as opposed to a normal shackle.
yes there is a few different way of doing it. the way im using mine is it operates like any other shackle untill the wheel starts flexing.
there is only so much movement you can get out of a spring and short shackle, same as disconnecting shocks, makes a difference but not earth shattering difference. a longer spring makes a difference but stuffs with your approch. a longer repositioned shackle helps but affects approch.

i no drop shackles are good for flex
but people are saying they its not flex its flop where the shackles just drops when the wheels off the ground

so if your wheels in the air spinning and the shackle drops like there sapose to i dont wanna wreck any diffs
and from what iv herd the 3/4 has upward travel as well where i herd the drop shackles dont

have you had any problems with yours

11_evl wrote:are any of you experts on drop shackles using bumpstops set up right??
i mean a bumpstop that FORCES the opposite (droop) wheel into the ground..
i just CAN NOT understand how your saying a drop shackle is so bad/ unpredictable as opposed to a normal shackle.
yes there is a few different way of doing it. the way im using mine is it operates like any other shackle untill the wheel starts flexing.
there is only so much movement you can get out of a spring and short shackle, same as disconnecting shocks, makes a difference but not earth shattering difference. a longer spring makes a difference but stuffs with your approch. a longer repositioned shackle helps but affects approch.

If you have the time and patience, do a detailed write up on how people should be seting up this type supension then. Allot of people will just go buy them and bolt them on.

No I am not an expert, but all the common sense and basic theory in the world tells me that having a joint in the suspension which can travel up and down freely with negligable force is a negetive thing. I think I gather what your saying about bumptops forcing the otherside down, my boring suspension does this, however does it add any sort of true roll stiffness to the suspension? For example could you walk up to your vehicle flexed and easily push down on the car body on the side that the wheel is drooping and hence compress the shackle easily, or does your bumpstop configuration in someway transfer the opposite side spring load to resist this behaviour?

I appoligise for my terrible written description of what Im trying to say. I dont want a shirt fight over for and against, a genuinly intelligent debate is a good thing .

nick.gooding wrote: so if your wheels in the air spinning and the shackle drops like there sapose to i dont wanna wreck any diffs
and from what iv herd the 3/4 has upward travel as well where i herd the drop shackles dont

If your wheel is in the air spinning and you hit the gorund whilst spinning, I think no-matter what type of suspension you have, you could damage something.
Drop shackles themselves wont allow uptravel (from the closed position), however the leaf spring its attatched to should, so long as its not way too stiff, or you are riding on the bumpstops.

The reason 3/4 works better is that all the extra travel has a spring rate, and this rate can be tuned and adjusted. with a 3/4 car you'll never feel the car coming on and off of the 3/4" leaf - it just acts the same as a normal sierra with more travel.

However, where are a 3/4 and a drop shackle are similar are when they are trying to deal with droop and power. Under these situations, they tend to unload with a lot of noisy slapping. and do weird things to the driveshaft angle -and in any case, that slapping/climbing effect of the unloading 3/4 or drop shackle is just lost traction and power at the wheels.


11_evl- I think some of the success of your front drop shackle is due to the very low rear roll stiffness you have. As the front end unloads on a climb, and the shackle unfolds, your front roll stiffness will go to almost nothing. In your case, that's probably creating quite nice balance. I don't think it's fair to apply that to every situation though. from memroy, your rear springs also unload at close to full flex, so in that way, your rear end is also behaving the same as a drop shackle rear too, but with a generally lower srping rate and better axle control with your coils/links.

I've built a shackle reversed 3/4 front. It was a waste of time. The shape of the chassis and the shortness of the 3/4 leaf makes it pointless.

nick.gooding - good on you for trying to understand why they don't work. It's not that they don't slowly unload, it's that they unload at all. uncontrolled travel is a bad thing unless you are crawling at idle or posing on a ramp. That's why there isn't ONE factory road vehicle that uses any form of uncontrolled travel. Less travel under good control is 100% better than more travel that's unpredictable.

Steve.

no i dont have time to do a write up

plus. if a drop shackle causes unstability by freely dropping away. what do you class a coil sprung car, it drops away with no effort at all.

11_evl wrote:plus. if a drop shackle causes unstability by freely dropping away. what do you class a coil sprung car, it drops away with no effort at all.

I dont know too much about coil suspesnion, but this is my understanding:
First of all a coil suspension would have to fully stretch the coil (to its free position at least?) before it could remove the coil from its seat, drop shackles do not need this, they may unfold before the leaf itself has drooped. Next of all because of this fact the coil suspension could be designed so that the shock absorber could actually prevent the suspension drooping further than the coil is designed for, hence making the coil coming off the seat a very unlikely occurance.
Last but not least, If the shock absorber cannot be the restrictive component due to its mounts being insufficient, then you could put spring retainers on both ends of the coil.

I am happy to be corrected about any of this, but thats how I understand it.

Highway-Star

Posted: Thu Apr 30, 2009 9:32 am

I dont know too much about coil suspesnion, but this is my understanding:
First of all a coil suspension would have to fully stretch the coil (to its free position at least?) before it could remove the coil from its seat, drop shackles do not need this, they may unfold before the leaf itself has drooped. Next of all because of this fact the coil suspension could be designed so that the shock absorber could actually prevent the suspension drooping further than the coil is designed for, hence making the coil coming off the seat a very unlikely occurance.
Last but not least, If the shock absorber cannot be the restrictive component due to its mounts being insufficient, then you could put spring retainers on both ends of the coil.

I am happy to be corrected about any of this, but thats how I understand it.

You could also fit a drop out cone on the top coil mount to retain the coil.

I have had a coil come lose from the rear of my car once. It was flexed fully
on the right side and hit a rock with the radial arm. I believe it was the impact that forced the spring out on the left side.

Ridge wrote:

Highway-Star

Posted: Thu Apr 30, 2009 9:32 am

I dont know too much about coil suspesnion, but this is my understanding:
First of all a coil suspension would have to fully stretch the coil (to its free position at least?) before it could remove the coil from its seat, drop shackles do not need this, they may unfold before the leaf itself has drooped. Next of all because of this fact the coil suspension could be designed so that the shock absorber could actually prevent the suspension drooping further than the coil is designed for, hence making the coil coming off the seat a very unlikely occurance.
Last but not least, If the shock absorber cannot be the restrictive component due to its mounts being insufficient, then you could put spring retainers on both ends of the coil.

I am happy to be corrected about any of this, but thats how I understand it.

You could also fit a drop out cone on the top coil mount to retain the coil.

I have had a coil come lose from the rear of my car once. It was flexed fully
on the right side and hit a rock with the radial arm. I believe it was the impact that forced the spring out on the left side.

Drop out cones might make the coil stay in, but it wont do anthing about the coil not supporting the body allowing the suspension to unload uncontrolled. If the spring is retained, it will reach its rest point, then if the suspension continues to flex the coil will acutally pull back. If you jsut have a cone, the suspesnion will reach teh rest point of the spring, then just unload further with no resistance from the spring.

Layto....

lay80n wrote: Drop out cones might make the coil stay in, but it wont do anthing about the coil not supporting the body allowing the suspension to unload uncontrolled. If the spring is retained, it will reach its rest point, then if the suspension continues to flex the coil will acutally pull back. If you jsut have a cone, the suspesnion will reach teh rest point of the spring, then just unload further with no resistance from the spring.

Layto....

is that a good thing or bad??

yeah same questions is it bad or good

i thought it was a bad thaing but thins bloke seems to get a heep of flex


http://www.outerlimits4x4.com/ftopic152891-0-asc-0.php

the sierra at the bottom

but thats clearly not standard

11_evl wrote:

lay80n wrote: Drop out cones might make the coil stay in, but it wont do anthing about the coil not supporting the body allowing the suspension to unload uncontrolled. If the spring is retained, it will reach its rest point, then if the suspension continues to flex the coil will acutally pull back. If you jsut have a cone, the suspesnion will reach teh rest point of the spring, then just unload further with no resistance from the spring.

Layto....

is that a good thing or bad??

Personal opinion. It is basically the same as a drop shackle, in that the axle can droop away with no spring influence. But on a coil spring it happen as the end of hte spring's travel, whre as with a drop shackle it can happen mid way through the sprigns travel. I would rather have correctly set up shocks and retained springs, but it comes down to personal opinion. Excessive flex can make a car sh*t house to drive expecially if its no well controlled or badly balanced front to rear. (that is not a negative comment on Mark's old MUD4B)


Layto....

nick.gooding wrote:yeah same questions is it bad or good

i thought it was a bad thaing but thins bloke seems to get a heep of flex

I assume you mean this car?


Yes, this is heaps of flex, but it's all coming from the rear. When this happens, the body and the front axle are at almost the same angle. That means there's lots of weight transfer and cars set up like this get really spooky on big compound angles as the body can basically flop over and take the car with it. that front tyre should be right into the guard and the body much more level IMHO.

Do a search for Roothy's Daihatsu rollover at Tough Truck last year. It's a perfect example of how uncontrolled rear flex and weight transfer makes for a hard to handle car.

IMHO if mud4b's car was limit strapped to keep the rear coils on the seat, the front would work much harder and the car would be more drivable.

11_evl - coils that unseat are not cool IMHO. They might be even worse than a drop shackle - at least a drop shackle has some travel limits set into it as the drop only has so much movementm but with an unloaded coil, only the shock limits travel, and that might be way beyond the added flex was doing anything to improve the cars behaviour. Anyway, show me a factory suspension that unseats coils to add flex under normal conditions (not when somethings unhooked or broken) and I'll happily admit it's a good idea.

nick.gooding You also need to consider that Mud4B's car has heavy wheels and tyres and heavy diffs. This lowers the car's centre of gravity a lot and helps it remain stable in this sort of situation. try that with sierra diffs and 31's and it's going to fall over.

The bigger issue nick.gooding is seriously, why you think added flex adds capability? Adding flex is probably the hardest and least effective way of making a car capable.

Steve.

i supose it really would depend on the situation. the pic after the one above on the link
http://www.outerlimits4x4.com/ftopic152891-0-asc-0.php (still need to learn how to post pics)
shows the car body almost level and everything else flexing well.

If you look closely the body is still pretty much in line with the axle, Its the front axle that is level not the suspension working

Josh

Thought you'd jump onto that photo. I deliberately didn't link that photo because I thought people would latch on to how the front appears to be working.

A) The car looks to be to be slightly nose down, theoretically loading the front. more heavily than the rear.

B) the body is still leaning to the right- and that's not right. compare the angle between the chassis and the front axle and the chassis and the rear axle. If those angles aren't within 10% or so of each other, the car isn't balanced.

C) the front end is still doing less than 1/2 of the flex.

It's possible to drive any car, regardless of where it's balance point is, to a point where the body is level and the car looks balanced - but that's not the case in that photo.

The relevant photo is the one I posted - that scenario is the one that is going to cause the car problems - not the flat ground or nose down position.

That car would look totally amazing backed up a ramp. I don't back up ramps on tracks very often though.

Flex is totally 1998.

Steve.

Gwagensteve wrote:Flex is totally 1998.

Steve.

thanks steve you should have posted that in 2007 so the build i started in 2008, and will finish in 2011 would still be in vogue. damn thing will be outdated by near 15years before it even gets its rego plates

badabing-badabam!

In fact, balanced flex might well be 2109 too.

Steve.

.

deleted by request

ahhh finally see some pics of CJs build

a good read and good bit of tech. steve, you have got me intrigued now about this balance thing your on about. i might have to have a play and see how my jalopy weighs up. i suppose if i put an equal tyre stack under the diagonally opposite wheels on level ground the body should sit level? if it does sit level but doesn't drive well, i'll see you in court

I'd prefer to see on level ground that the front works harder than the rear, so that with equal tyre stacks, there's either a back wheel a bit off the ground and the body level or the body slightly favoring the rear end but keeping the front wheels on the ground.

The real aim is to put the car up a ramp or with the front wheel up on a stack and have the front work much harder than the rear.

It's one of the great advantages of RUF IMHO - the front works crazy hard.

An example - Cj's flexless monster as photographed, flexed the front axle to 32˚, and the body to 18.˚ That's not 50% being done by the front, but it's close enough for me. There's more in it - it is unfinished and oversprung in the front in those photos.

An angle finder and a engine crane is what's required to get some hard data on balance. If the rear flexes more than the front when the front is lifted, you're moving away from ideal balance. Equal balance on flat ground might mean the rear is bit soft and front a bit stiff once the car is climbing.

The old safari-gard stage three suspension kit on land rovers was able to deliver more than 50% articulation to the front end on a ramp, and in subjective testing, was also amazingly capable on the trail. I'd love to emulate that with a leaf sierra and achieve the travel these guys were able to, but I'll settle for the balance with less travel.

Here's some powerful reading on balance:

http://www.yellowdefender.com/twist_off ... /index.htm

This is some of the best real-world theory on trail suspension behaviour ever. Funny, It's from 1999, yet there's still threads about whacky shackles on the rear and loose springs.

Steve.