Hello everyone:
This might have already been addressed but I kept thinking about it...
Upon re-reading Jim Lane's (I think) thorough explanation about the Firestone air bags and his concern over potential axle wrap, I recall he suggested taking out different leaf springs. How about just installing ladder or traction bars: would they interfere with the air bags?
Your thoughts!

 

I don't see how taking out springs would help.

 

I think Jim Lane was suggesting to remove some leaves in the rear to improve the ride quality and using the bags when hauling. IIRC his truck is a 2wd dually so it has no lift block in the rear.

 

Bigredbrick, that's what I meant.

Taking a couple of leaves may increase the risk of axle wrap under strenuous conditions, such as towing heavy. The air bags do nothing to this condition: all they do is cushion the ride. So, I was wondering if, in the interest of preventing torsion of the rear axle, adding ladder bars would be a solution.

What does the lift block contribute to in this scenario?

 

To answer your first question, yes ladder bars would prevent "axle wrap".

4x4 trucks have 6" lift blocks factory, which give the axle even more leverage on the spring so they would be more prone to axle wrap. Without some sort of ladder/traction bar...

Aaron

 

Depending on how many leafs you take out and the power level of your truck, I would reccomend putting some ladder bars on if you were to ditch half the pack.. I took the two bottom leafs out and didn't make much difference.... It is all in the shocks... unbolt your shocks and go for a ride and see if you like it other than the bounce...

 

What would removing the 6" lift block and adding some leaf springs that are arched for the differnce do?? In other words adding a spring pack desgned for 6 inches of lift. I'm also am looking for a way to solve axle wrap when I get back from my deployment.

 

"What would removing the 6" lift block and adding some leaf springs that are arched for the differnce do?? In other words adding a spring pack desgned for 6 inches of lift."

I did this on my truck, and it did reduce the amount of wrap, but didn't eliminate it entirely. Be aware though, that the additional arch in the springs really messes with the geometry of the path the axle moves through when the truck is loaded vs. unloaded. I've been chasing a pinion angle/vibration issue since I put the new springs on and haven't got it completely sorted yet. Problem for me is that I'm normally empty or loaded heavy and I haven't found a setup that works for both conditions...yet. If you don't load the truck it might not be an issue.

 

Brain, did you install shims to correct the pinion angle with those lift springs?

http://stuff.is-a-geek.net/PhotoAlbu...ics/CTD_68.jpg

Mine rides about 2 degrees nose up relative to the driveshaft in the "brokeback" u-joint arrangement, and runs fine loaded or unloaded. But (very BIG but) axle wrap becomes an even more critical issue in this configuration because the pinion's torque leverage is disadvantaged in the "up" angle. Some sort of tractions bars is almost a necessity with any power increases if you don't want to beat the pinion and u-joints to an early death.

 

Ace,

When I swapped springs I set up the pinion with 2.5 degrees down angle from the transfer case output, static. I think that spec came from the FSM. It worked OK empty but when loaded the arc change in the springs moved the pinion to about 3 degrees up. Add in the axle twist from moving a lot of frontal area at 60 mph and it was undrivable. I added shims to bring the pinion down around seven degrees static unloaded and now it's fairly smooth loaded but has a pretty good rumble from 50 to 55 mph unloaded. It's annoying, but I can live with it for now, just don't push it hard in that speed band. I haven't made up my mind if I should try Timbrens to limit the spring travel or ladder bars to control the pinion angle yet. Any insight there is welcome.

It may just be crappy springs. I had to send the rears back once, and the fronts were assembled backwards, but I don't have the old parts anymore so I'm stuck fixing this mess.

Your pinion looks really high just going by the old calibrated eyeball. How does the pinion angle compare to the output shaft angle?

 

They are equal at rest. I'd be willing to bet pinion angle is your problem and you have the shims in exactly backwards. Try going to a brokeback angularity. I can't find the picture I posted last time somebody had this problem, but your driveline basically points "up" into the driveshaft at both u-joints, if that makes sense.

 

I think that traction bars are what I will be doing. Everything else just seems like a hassel!!! thanks for the input guys

 

Ace,
The "Broke-back" configuration goes opposite of everything I've read or seen done, but it obviously works for your setup. Might be worth an afternoon of wrenching to try it out. Do you have a one or two piece drive shaft? And I see you have the Gear-vendors, how does that affect things? Do you have a pic of the torque link referenced in your sig?

Thanks for the input.

 

Single-piece DS. It's about 20" shorter than the original. I was worried how the u-joint angles would come out with the shorter shaft, but did not have to change anything in terms of the shims for setting pinion angle. Brokeback is a common lifted 4x4 DS arrangement, in fact the only way to do it in most cases. I was researching it back when I did the GV over two years ago and nobody here could explain my pinion angle and I thought the same as you, might be a problem, even though I had no driveline issues at the time. Then the guy at my driveline shop explained it to me. Here's the torque link writeup:

http://www.1stgen.org/viewtopic.php?t=2322

The only issue I had was with the stock cover I had to jack up the rear or face it downhill to get enough gear lube in it. No problem now with the Hag-hytec cover, top fill and dipstick. Some have said the front pinion bearing will starve for oil, but I believe the braking involved in normal driving and because the gears are submerged in oil slinging it everywhere inside, keeps it wet. I have had no problems yet in the 3+ years I've owned the truck.

 

has anyone installed airbags and ladder bars, and got rid of the leaf springs completely? would this make a smooth ride while unloaded, then pump the bags up when loaded?