Traction Bar Necessary?

[JWARNE]

Getting ready to install a D44 rear axle and was comptemplating going spring over axle although lots of other issues arise the more i look into this option. Beyond having to build up the front suspension and steering components I keep reading and being told that a traction bar is an absolute necessity if you run spring over axle. I don't per say take my truck wheeling but i do travel off road in the mountains on old skid trails for work and out on the prairie through some hairy drainages/slough bottoms and river bluff areas . I need the clearance and floatation that 33'' tires offer and some but not extreme articulation.

 

If truck is spring over axle is traction bar necessary? If it is then why when the truck is spring under it doesnt? the same forces are being applied on the springs via drive shaft and diff pinion moving forward and in reverse. Only thing changing is the angle on the drive shaft ends from the transfer case and differential which both can be accounted for i.e.(SYE, altering the angle of the rear axle to accomidate the driveshaft) so I must be not understanding some of the physics and geometry here.

 

Help!! I need to get my new axles and tires under the truck before snow fly and that happened last week.

 

I'm really only trying to gain clearance under the axles with 2'' more of tire over the 31'' tires I'm running now and by moving the leaf springs above the axle. I want to keep the truck as low as possible achieving both the spring over axle and clearing the 33'' tires. I am willing to trim fenders thats not an issue its the spring under that bothers me.

[Blue88Comanche]

i don't know if it does or not but my thoughts would be the higher center of gravity with spring over vs spring under the sway bar would help with body roll

[mvusse]

My trail rig's rear axle is spring over, locked, on 35" tires. Only time I had an issue was bouncing during a rear wheel stand trying to climb a near vertical ledge. Pinion rotated up to where the u joint couldn't turn anymore and I twisted the rear driveshaft in half. Only issue over more than 50 trips off road in the past 4 years.

 

Traction bars are overrated.

 

If you do think you need it, look into a "BAM bar".

[Garvin]

I never had an issue with the first axle swap (8.25) but now have the issue with the Sterling 10.25 due to the weight and the nose of axle being much farther out. That 8.25 was SOA with IronMan4x4 adjustable shackles on 33's (equaling about 6.5" lift in the rear). Now I'm running straight SOA in the rear and sitting about 4" in the rear. If you aren't afraid of trimming then you won't have any issues fitting larger tires. I'm running 4" lift and running 38.5's with space for the 42's that are on my wish list (this is with 4-5" of uptravel with the current setup), I trimmed up to the body line front and rear though.

 

Traction bars really aren't as overrated as most people thing, they have their place. If you're running a soft spring then traction bars help keep them alive.

 

Guess that was a little bit of a tangent...With a 4.0, you really don't need one. I didn't need one with the carb'd 350 I had in my '86 but sure as hell need one now with the fuel injected 350 and one tons...

[Eagle]

Blue88, he asked about a traction bar, not a sway bar.

 

As previously commented, traction bars have their place. For a stock vehicle running on stock (or near stock) tires, things are all pretty much as the manufacturer designed it so we can probably safely assume that it pretty much works.

 

Go to a SOA and a lift and much bigger tires, and everything changes. And ALL the changes are bad for the springs. All the changes allow the tires to apply more twisting torque to the springs. Just think about the effect of tires. Stock MJ tires are approximately 29 inch diameter. A jump to 33-inch tires changes the diameter by 4 inches and the radius (which is the lever arm) by 2 inches. With NO other changes, a jump to 33-inch tires increases the torque transmitted back into the springs from the axle by 13.8 percent. Then consider that with a SOA, the centerline of the axle is farther away from the main leaf than when running SUA -- I haven't run the numbers, but there's another torque increase.

 

There's no question that a lot of people don't run traction bars, but they ARE a good idea. If you can't run one, be sure your springs have the long, thick overload leaf on the bottom, because that will help considerably to resist spring wrap.

[JWARNE]

These Hell Creek MT leafs on my jeep have two overload leafs under the main leaf. I was actually thinking about removing one of them if I did go to SOA just to reduce the lift as much as i can. Also thought about making a oversized spring perch (longer perch) to help with the spring wrap issue not sure that would work all that great though since the u-bolts only anchor the leaf down in an area the width of the axle tube.

 

Thanks for the responses and information on this traction bar issue. I honestly didnt feel its necessary for my application but a few people who have been building 4x4's for way longer than I preached about the traction bar.

[Blue88Comanche]

woops, sorry about that. but learn something new every day.