Traction Bar (1 Viewer)

[Jetboy]

Thanks for your reply Jetboy, sounds good ... what do you guys mean by a 'shackle' would this be a Jonny joint or the same mount as the ring end of a shock absorber - or something else ???

No, it needs a shackle, just like a spring shackle on the front to allow the foreward and aft movement of the axle. as the springs compress the rear axle should move rearward while under droop it will move slightly foreward. With your current set up it will just twist the axle a little. with a lader bar style it cant do that and will bind. Essentially what you have now is the same, it just looks different. The fixed "tower" you have on your axle will now be much longer and pointing foreward instead of up. The bar you have now acts as the shackle. The new trac bar is much longer which is why it works better. More leverage against the axle. The only forces you care about are up or down at the end of the trac bar. A shackle keeps that movement under control while allowing natural foreward to back movement. BTW the shackle needs to be verticle.

If you search for trac bar there are lots of pictures of them floating around.

 

[matt the sign]

Thanks mate I appreciate your comprehesive reply, is there a particular bar you've seen on a specific FJ40 that you would point at and say 'thats the one' ???

 

[mdjohnsen]

Whew! I was wondering when someone would ask that? Thanks Matt.

 

[Jetboy]

check here https://forum.ih8mud.com/showthread.php?t=75246&highlight=trac+bar

The only thing I would change about the one in the first pic is to allow for the shackle portion to change length like tie rod style. This will allow you to fine tune your pinion angle if you have driveline vibes. ALso I like that design because it would protect the drive shaft pretty well. My next one will probably look like that, but I will add two or three rings on the side surrounding the drive shaft so that if it breaks it will be contained and not flop around and damage other stuff.

 

[Vitesse_6]

Whew! I was wondering when someone would ask that? Thanks Matt.

Now you gone and done it

 

[mdjohnsen]

 

[-XXX-]

ok so my friends who have been running their setups for over a year and haven't busted a pinon since are dumb then? before they used trac bars running below the centerline they all broke pinions (more than one apice).

Where did I say your freinds your friends were dumb?

and yes a rigid traction bar does transmit one hell of a shock load to the pinion, period. you can tell me that one mounted high or low changes any shock load on the pinion, but it doesnt at all. not being able to wrap up and move while the pinion is climbing the ring gear does increase the chance of breaking.

one disadvantage with no traction bar is the u-joint is able to point up when the pinon is under enourmous torque and bind.

if your friends were breaking more than on a peice while running traction bars that proves my point, but changing the location will not make the load any different.

 

[lowtideride]

Where did I say your freinds your friends were dumb?

and yes a rigid traction bar does transmit one hell of a shock load to the pinion, period. you can tell me that one mounted high or low changes any shock load on the pinion, but it doesnt at all. not being able to wrap up and move while the pinion is climbing the ring gear does increase the chance of breaking.

one disadvantage with no traction bar is the u-joint is able to point up when the pinon is under enourmous torque and bind.

if your friends were breaking more than on a peice while running traction bars that proves my point, but changing the location will not make the load any different.

No it transmits the shock load to the wrap bar and mounting points that the wrap bar has.

 

[Jetboy]

You two are talking about two different forces. The reason for the trac bar here is to keep from the pinion tilting up and the ujoint binding. These pinions hold up fine with 4links, so a track bar shouldn't hurt.

XXX have you ever driven an SOA cruiser? the reason I ask is that the springs of these older 40's become very soft. Often 30+ year old leafs. they allow lots of axle wrap. The bars are to reduce or eliminate axle wrap. We aren't twisting pinions from shock load. The carriers are very strong and don't deflect much.

 

[projektdotnet]

My friends had their axle wrap forward, the ujoint bound and snapped their pinion, end of story.
The trac bars mounted below axle centerline doesn't allow the axle to wrap forwards as most cruiser axles want to with old springs and therefore the pinion stopped breaking.
We know it was spring wrap because they were out hot rodding and watched the springs from cruiser to cruiser. After using the lower than center bar the guys noticed that their axles no longer twisted the 3rd upwards and pinions on these just stopped breaking.