[JrZook]

alien wrote:

theres more clearance with this setup than if you were SPUA, and the bars are 4130 solid bar with 12mm thread on the rose joints... its pretty tough =) i've knocked them a few times and not done any damage.

Mine only hangs ~2.5". What's your hang?

This was measured from the bottom of the diff tube to the lowest part being the heads of my u-bolt nuts.

[boostedbrick]

JrZook wrote:

alien wrote:

theres more clearance with this setup than if you were SPUA, and the bars are 4130 solid bar with 12mm thread on the rose joints... its pretty tough =) i've knocked them a few times and not done any damage.

Mine only hangs ~2.5". What's your hang?

This was measured from the bottom of the diff tube to the lowest part being the heads of my u-bolt nuts.

Mine was around that measurement as well, and i bent several ubolts catching them on god knows what(that was with 31s and 33s). I drive minimal rock, mainly just hard packed dirt. I would like something like that, mounted on top of the axel/spring. To work with a u bolt flip.

You seem to drive alot of rock alien, i would have thought you would have had alot of issues.

[alien]

i just measured diff housing to the bottom of the rose joint and its 80mm down. Don't forget though its only 15mm wide and its rounded, then the bar is about 25mm wide and again rounded - so it slides over whatever it hits anyway.

i've found more that because of its position i dont get hung up on them, and usually what i do scrape them on is just that before the back wheel hits whatever im going over.

i certainly wouldnt say that they've ever held me back.

[alien]

these pics give a better idea of how it sits under the zuk...
this one shows better how the rear tyre hits before the bars do:


this is a better profile shot:

[jmd-247]

yeah no clearance issues there huh. and as you said spua clearance is no difference..

i might think of a way to work this set up of yours out alien..

do you suffer from much axle wrap on the front? without the trac bars???

i was thinking of only doingthe back atm.!?

[alien]

nope - i get none at all from the front... but i don't do all that much high speed 4wd... most i've done in 4wd is around 80km/hr rally style and its not wrapped at all.

infact i've replaced 1 rear uni 4yrs after the SPOA, and the front is still tight as a tiger. but i ran no trac bar for about 6 months after the build so that wont have helped.

as for copying it - try this: http://www.hotrodsandhemis.com/Traction.html

[jmd-247]

yeah well it wont be going on straight away.

i have a spoa with standard rears up the front n longer shackles.. it has only had test drives and back for more mods so will be interesting to see how much i actually get when i am out on the track once finished.. i want to put longer springs on the rear today but its raining here!!
so this is the reason i want the trac bars.. i like that explination tho.. website is good.. will no doubt use it!!! i still have the old spua perches off the bottom of the house so may be able to incorporate those into it...

[alien]

yeah mine uses custom made square u-bolts to hold everything in place. the u-bolts are also thicker than standard sierra (not by much).

[jmd-247]

yeah i seen those. and i like.. if i use the old perches to fab something up i wont have to change my u bolt. i may go the 323 or 808 springs in the back so the trac bars will be a must after that. i like they two of them rather than the diff centre housing way. . u didnt notice a restriction in flex and movement at all????

[alien]

i didnt notice it, but there would have been a minor loss in flex due to the solid bushing pressed into the fixed end of the spring stopping the bush giving a few mm of twist... but thats all. it never binds up so can't limit flex through binding.

[jmd-247]

yeah too true.. and losing a few mm's of flew is alot better then unis every second weekend i guess

i like either your set up or something similer but on the top of the spring.. and too the top of the perch plate.. did u make your or have them fab'ed up??

[alien]

mine were custom made by sj performance (who make the oztracs system in australia for drag cars). he's since moved from perth to vic i believe.

[jmd-247]

i want this bit done properly.. hahha as i am no man of precision.

might have a dig around sydney for someone to make them at a reasonable price..

cheers..

[4wheeljive]

mnemonix wrote:

http://www.pirate4x4.com/forum/showthread.php?t=922156
This thread over on Pirate shows a few design options.

Personally I like this one:

Not a perfect solution, but it should be more than ideal for what I need.
Building one out of 15NB medium pipe and some 3/4heims when I get a chance.

Is there any more info on this idea or video of it in action I'm keen on making something like this cause I don't have a real lot of room near my diff

[mnemonix]

Only info is in the thread link you quoted.
The owner posted that image in it, with his opinion. Check the link to Pirate.

[shane1992]

do those track bars above the springs stop wheel travel?

[atari4x4]

i was stuck next to a RTV Falcon Ute in traffic yesterday & the rear end runs a leaf sprung set up with a track bar very similar to the green thing mnemonix posted, tried googling for a pic of the suspension in the falcon but found nothing. if i see another one, i'll grab a pic.

[rpmwrx]

One of my mates has a ford rtv, i'll have to check it out and post some up some pics...

[4wheeljive]

Ok I've decided im going to build the bars I quoted above and I'll report back how well it works or dosnt work

[jmd-247]

Nice pick up atari..
i am going to check one out today! wooo

[4wheeljive]

Can you post a pic as well

[just_cruizin]

The one in the pic above have very little mechanical advantage, I think you would be better off moving it inside the chassis rail and raising the mount on the diff up. But to do all that work on two sides you may as well just do a centre one. ideally when crawling the centre point of the diff doesn't move to much unless you hit your bumpstops therefore the trackbar pivot point on the diff would just move side to side with twist rather then up and down. Only when you compress both springs at once does the centre point of the diff move up and down.

[31zook]

3/4 heim joints and 45OD 8mm wall thickness hollow bar. I plated the top of the dff and where it mounts to the car. It's a lux axle btw....



When I was spua with 29s I would get a bit of wrap, and spoa felt the same as spua, then I fitted up the track bar and it is a whole heap smoother power delivery.... No lurch or slight hang up as I took off or stopped....

[sogone]

Why do the americans carry on about needing two points on the diff and a shackle set up on the cross member. I've been trying to wrap my head around it and it's lost me. I'm gonna make something like yours Josh, But the americans swear it won't stop the wrap unless it has two contact points on the diff?

[Bucket]

I'm going down the same path as 31zook. I can't see how that wouldn't work.

[Gwagensteve]

I'm not American and you need two points at the diff. They reached that conclusion after many, many more years running more cars with more power and more tyre than we have.

A single bar results in the axle trying to drive forward under the springs. The point the axle wraps from moves from the axle centreline to the diff end of the traction bar. You still get wrap and the thrust force on the single bar is enormous. You'll bend springs, and normally the body mount crossmember breaks, if it doesn't break off the diff first. Generally, the car won't launch straight either. The torque favours the driver's side so that's the side the spring winds up further on and the car pulls right.

These single bars also tend to "lock out" suspension movement when you are under power because as the axle is being forced to try and push forward, it basically forces the spring into arch.

The whole point of a traction bar is that it should take load off the the springs, not re introduce it in a different plane.

By adding a second connection at the diff end, the pivot point stays the same as stock (rolling around the axle centreline) but at the chassis end the force is now up-down rather than fore-aft. There's no thrust load being applied to the springs.

Caltracs as per Alien's set up are the best solution, but the ground clearance loss would be unacceptable for victorian conditions. I still think it's possible to run them upside down/back to front so they sit above the axle and run to the rear shackle to avoid loss of clearance.

Traction bars are a minefield.

Bear in mind too that once you lock out axle wrap, all the force is transmitted into diff gears, unis and the transfer case. Axlewrap softens the hit the driveline sees.

Steve.

[Locks]

sogone wrote:

the americans swear it won't stop the wrap unless it has two contact points on the diff?

makes sense to me. that traction bar on the hilux diff above would work better if it were attached at the bottom and the top of that square section welded to the diff.

at the moment it can still rotate if the springs wrap enough.

[Locks]

steve it seems that you have read my thoughts. only you were able to translate them into words.

[sogone]

Thanks steve. That makes sense. I'm running Spoa at the moment. I don't drive rocks. I just drive mud and dirt tracks and maybe some hills with ruts(barely). Will a traction bar setup benefit me? I'm running standard springs and extended shackles with shocks to suit.

[Gwagensteve]

Axlewrap is a function of traction - so it's often worst on the street. From what I've seen a well engineered traction bar is a good idea. On a spoa, it might allow you to run a softer spring to approach the ride quality achievable with a SPUA. SPOA's generally require a stiffer spring to fight axle wrap.

Steve.