I have a couple questions regarding traction bars i currently have a set of hommade ladder bars on my 01 superduty they have a shackle setup on them so that they have some give in them my question is im going to make a set of traction bars just one single bar on each side and i was wondering if they should be mounted solidly to the frame or should i run them on a shackle also and were should they be mounted at on the axle the top or bottom.

 

Mounting it solid to the frame will kill any flex that the truck has. The SD axles tend to move in an arch and without a pivot, the bars will bind you up a little when the suspension flexes. You'll at least want so kind of Heim joint at the frame to allow the bar to twist.

Mount the bars at the bottom of the axles, this is where they are try to rotate at. You'll need a good solid mount that cradles the bottom of the axle, but also doesn't kill you ground clearance.

Also, try to get the bars along the same plane as the drive shaft. This will help keep you driveline angle in check and not make the axle move in a strange arch.

Take a look at the Fabtech bars. They are a pretty clean install and may give you an idea of what will work as far as length, mounting, brakes, joints, etc. The only thing I don't like is the shackle up front, seems like it would sorta defeat the purpose.

 

Agreed
Again, agreed.

Not exactly. Since the axle housing tries to rotate backwards under acceleration, the amount of force created anywhere around the circumference of the tube will be the same...just the direction of movement will be different.
If you mount the bars under the axle tube, the twisting force of the axle will PUSH FORWARD on the ladder/traction bar. In this setup, it may be required (depending on amount of axlewrap you're trying to control) to run a triangulated (ladder bar) setup due to the flex/buckle of a single bar.
However, if you mount the traction bar above the axle tube, you're now creating a TENSION force on the bar and can get away with one simple piece of SCH40 per side.

I have made both setups and can honestly say that if you have the room to mount the bars on top of the axle, do it. You have the ability to make the mounting location farther from the centerline of the axle tubes which will give the bars more leverage to control axle wrap. You can't get too far from the centerline of the tubes on the bottom due to the ground clearance issues BFR told you about.

Agreed

They do look good. The shackle does work to a point as it does allow for the small arch that leaf springs cause in wheel travel, but it also controls axle wrap in that you still have a fixed point at the axle shaft and the shackle does not COMPRESS toward the frame. By compress I mean the center to center distance beween the two shackle holes does not change. The bar will TRY to push up on the frame at the mounting location.

The only real drawback to BUYING pre-fabbed parts is just that...you have to pay a boatload for them. Making things (if of course you have the skills) is the way to do it. Not only do you learn a ton about geometry and how suspensions actually work, but you get the pride in knowing that you made something that worked.
Cody

 

one more question i have heard that mounting traction bar solid to the frame will eventually lead to stress cracks in the frame from the bar pulling on it is there any truth to this or is it just a myth, about the only thing the truck does is haul a couple loads of wood every now and then and i could take them off for this when the time comes witch is no problem just to be sure not to put any extra stress on the frame, is this something i should worry about or not

 

Well, with any solid mounting and moveable parts, something has to give eventually.

The problem is the movement of the SD's axle, it's not straight up and down, it's arched. This will put stress in a few places; 1 - The point it mounts to the frame, 2 - The bar itself, 3 - The point it's mounted to the axle, 4 - The springs and where they are mounted to the frame.

More than likely, a point on the traction bars will fail before the frame on the SD. Could it cause cracks, yes. Likely, not as much as the bar getting damaged.

2 Things. Either put a slip shaft / Heim joint setup or do the shackle type setup on the Fabtech's. Either of these takes the stress off the frame, bars, axles, and suspension components. Hard mounting it will likely bind the suspension and make your ride worse.

 

Traction bars...........that reminds me, years ago a guy I worked with bought a set of chrome tracion bars for his Duster. Since he could not see much of the chrome bars when they were installed facing the front of the car, he mounted them facing the rear of the car, everyone laughed so hard when they saw them.