Rear leaf spring issue

[bonedoc]

Hello everyone,

Need a little help here. Have a 1993 Ford Ranger supercab 4x4. 4.0L with 5spd. The truck just underwent a complete rebuild of axles and suspension. Completely rebuilt the front and rear axles and re-geared them with 4.88 gears and lifted the truck with a James Duff 5.5" stage 3 lift kit. The truck is rolling on 33" tires and runs and drives beautifully. Will likely move up to 35" tires this summer or fall.
The problem is that shortly after installing the lift I noticed a slight sag in the rear of the truck on the passenger side. I didn't think much of it at first figuring it was just the springs settling. Now about 3 months after install and about 1000 miles of driving and my passenger side rear sits about 1.5-2.0" lower than the left.
I contacted James Duff and they are trying to resolve the issue. Shackles are intact, truck has not been offroad yet, nor used to haul or tow and items since rebuild. The last contact I had with Duff they are now asking me to swap the springs from one side to side and see what that does. They claim that the truck is putting all its torque through the right side upon acceleration and that is causing the sag. I have never heard of that, especially with an open diff. Plus the truck accelerates nice and straight with no pulling to either side. To me it is a simple issue...bad spring, not holding its arch/spring rate.
Any suggestions or is what my gut is telling me about feeling like I'm getting a run around correct.

Thanks

 

[ianyboy]

From my experience with my 2011 Ranger, with open 4.10 diff, the truck does deliver power to the right wheel first.

 

[4x4junkie]

Power (or more correctly: torque) is delivered to both rear wheels equally by an open diff. The right side tire is often observed to slip first because the rotational torque of the driveshaft against the axle housing transfers a small amount of weight off that tire, putting it over to the left tire (makes for less traction under the right tire).
It also does load the right side spring a very slight bit more too, though generally it's not significant.

I would swap the springs over like they suggest and see if the lean follows the spring over to the driverside. If it does, then obviously it's a bad spring. If it doesn't, then it should be clear something is amiss elsewhere (maybe a front coil isn't seated properly in it's mount?)

 

[bonedoc]

They told me not to worry about swapping the springs. The front end is nice and level. Actually...the entire truck sat perfect right after the suspension install. They agree it appears to be a bad spring and are working out a solution which will likely be a new set of springs. I understand the torque issue but we aren't talking a big high power v-8 but a 4.0L with 140K+ on it. Not exactly a monster....lol

 

[bonedoc]

Okay, well after some further inspection we found a significant crack in the frame of my ranger right at and in front of where the rear leaf spring mount is. So I have frame repair to do. Anyone know anyone with a frame laying around. Thinking it may be best to just remove the damaged section of frame and replace with a solid piece.