Outer Limits 4x4 Board

1. Does the length of the trackbar from where it mounts onto the diff to where it mounts on the crossmember between the chassi have much affect on its performance?

2. The shackle thats on the crossmember with the rose joint in it, does it make a difference if the shackle is mounted to the crossmember pointing up off the crossmember or if its pointing down??

reason i ask is i lose too much ground clearance if its pointing down

screwy

the shackle must be pointing down and it must be at 90 degrees to the track bar otherwise it'll all turn pear shaped

mine is at 90 degrees........

but its facing up

y must it be down?

Screwy_ScrewBall wrote:mine is at 90 degrees........

but its facing up

y must it be down?

as the rear compresses the diff moves backwards hence making the angle between the trac bar and shackle greater then 90 degrees. if you give it a bootful (which you like to do), potential the wrap from the diff would try and push the shackle down. if the shackle is pointing down to start with, when you give it a bootful the diff is then brought back into its natural positon.

STUMPY wrote:

Screwy_ScrewBall wrote:mine is at 90 degrees........

but its facing up

y must it be down?

as the rear compresses the diff moves backwards hence making the angle between the trac bar and shackle greater then 90 degrees. if you give it a bootful (which you like to do), potential the wrap from the diff would try and push the shackle down. if the shackle is pointing down to start with, when you give it a bootful the diff is then brought back into its natural positon.

thats not good news........
appears my trackbar is in need of changing.......

I assume by ur comment, u saw some of my drives at nissan trails..... im alittle more careful with a rig i actually care abit about

Screwy_ScrewBall wrote:

STUMPY wrote:

Screwy_ScrewBall wrote:mine is at 90 degrees........

but its facing up

y must it be down?

as the rear compresses the diff moves backwards hence making the angle between the trac bar and shackle greater then 90 degrees. if you give it a bootful (which you like to do), potential the wrap from the diff would try and push the shackle down. if the shackle is pointing down to start with, when you give it a bootful the diff is then brought back into its natural positon.

thats not good news........
appears my trackbar is in need of changing.......

I assume by ur comment, u saw some of my drives at nissan trails..... im alittle more careful with a rig i actually care abit about

how did that rig pull up after the trails? Loved it on the stairs

just chucked some grease in the steering, got a hammer to the panel damage and some touch up paint and sold her off
im happy

dumbdunce and carts saw it on the side of the road in blacktown. it had just been defected

screwy, this just my opinion, whilst i believe it to be correct, it my pay to have other input

cheers joel

ur shackle can face up or down

STUMPY wrote:dumbdunce and carts saw it on the side of the road in blacktown. it had just been defected

screwy, this just my opinion, whilst i believe it to be correct, it my pay to have other input

cheers joel

yeh, not my rig anymore

redzook wrote:ur shackle can face up or down

I didnt think it mattered either..........

IF its up its only gunna pull up on the crossmember its mounted to and push down on it....
rather than pull down on it and push up.
the shackle enables it to move regardless as long as its straight.

?????

screwy

STUMPY wrote: the wrap from the diff would try and push the shackle down.

Doesnt axle wrap try to twist the front of the diff UP?

Up by the looks of this pick of when it happened to me. But I spose it would depend on if you going forwards or backwards??

ausyota wrote:

STUMPY wrote: the wrap from the diff would try and push the shackle down.

Doesnt axle wrap try to twist the front of the diff UP?

Yes it does, so the shakel on a trac bar is best off pointing up and the longer you can have the bar the better.

Obviously the longer the bars the better and the further the two mounts on the diff are apart the better.
But what about things like shackle length? Does the length of the shackle matter? Should it be the same length as your spring shackles?
Do the angles on the bars effect its performance?
ie should the top bar be level or angled up etc?
Paul.

i was told that the top bar should try to be pretty close to parralel with the ground, which mine is

my shackle is point up

and my track bar is reletily long compared to others ive seen

does that mean i have a good trackbar

Screwy_ScrewBall wrote:i was told that the top bar should try to be pretty close to parralel with the ground, which mine is

my shackle is point up

and my track bar is reletily long compared to others ive seen

does that mean i have a good trackbar

OFCOURSE ITS IT .......



I MADE IT ! :finger:


the only thing I'd be suss on is ...as I said to you when I fitted it .... is the rear section on the diff mount, it "could do with some additional bracing" ...IE: a 6mm plate wraped around the trackbar mount from the top to the bottom of the mount .... around the BACK of the diff so to speak.
This additional plate would aslo be better if it was a triangle shape so to spread the load further along the axle tube and diff pumpkin.

But I did say to do it "IF" it looked like being a problem
Kingy

opps forgot .....

The question about the trackbar shackle connection to the cross member mount being better below or above the cross member....


It makes absolutely NO DIFFERANCE AT ALL ......

The force applied to the cross member via the track bar is verticle .....IE: UP or DOWN.
This load is transfered through the shackle and under acceleration or decceleration the force is either a ....
Compression Force OR a Tension Force.

Because the track bar applies force in BOTH directions during acceleration and decceleration then the shackle is placed in both TENSION & COMPRESSION. Ideally if we could obtain a single direction of force then I would say that the shackle would be better in the "Compression" direction rather than a tension direction. My ONLY reason for this would be that mild steel is slightly stronger in a compression state than it is in a tension state, mind you the differance would be itsy bitsy teeny weeny.... & definately not worth the worry !!!


Kingy

V8Patrol wrote:...mild steel is slightly stronger in a compression state than it is in a tension state...

what the? I am interested in hearing your scientific/engineering basis for this assertion. Although the steel itself is equally 'strong' in tension or compression up to yield, (where due to thickening in the compression case it can be argued it becomes "stronger" as it compresses and does not have an ultimate strength as in the tensile case), in the case of a shackle arrangement a compressive failure will always be a bending/bucking failure, never a pure compressive failure - compression tends to bend things long before yield stresses are present, tension always keep them straight right up to yield.

so as not to hijack the thread, I agree it does not matter whether the shackle goes up or down, nor is the length of the shackle greatly significant, it just needs to be long enough to compensate for the fore/aft movement of the axle due to articulation and travel, and strong enough not to bend. snappage is unlikely unless you make it out of paper clips.

the only test that matters for a track bar is - does it work? ie, does it prevent axle wrap, and does it induce any axle hop/tramp under load? if the answers are yes and no respectively, it's a good job.

from wot i have built and found out over the few uears of playing with the rear suspension in my luxy is that if u run the shackle pointing down from the chassis mount then the angle it sits at needs 2 b 90degrees 2 the angle of force, (not the tracbar or the chassis or the ground), because if its not wen u put load on it and the load isnt going thru the shackle at 90degrees then the shackle will want 2 snap forwards or backwards depending on the angle of the shackle if that makes sence.

just like holdin a peice of steel against a wall and u push on it, if u dont push on it at 90degrees then the peice of steel wil want 2 go in the direction of the force yeah??? make sence...

so basically wot im saying is build alot of adjustability into it so that u can get the shackle angle right, and also if u make it as flat 2 the ground or even have the front slightly lower(which i have had i one of my setups) it will b easier 2 adjust and make it work..........

this is just from my experience so yeah hope it helps

Cheers guys,

great feedback here.

very interesting to know.........


Im just happy it doensnt look like i have to change it much