Rear Sway after mild Lift

I installed a dobinsons twin tube lift 2nonths ago with JBA front UCAs and front and rear dobinsons springs. I got 2 inches of lift up front and 1.5 inches in the rear.

I've noticed that when I go over a rough area at a decent speed (35ish) that I can feel the Rear end sway to the side just slightly. I really only notice it when I go over a patch of pavement on my commute where dump tricks have tore it up. I don't feel like I'm going to lose control but it is noticeable. I searched and read that this may be the panhard bar not being aligned anymore. I also read that this shouldn't be an issue on less than 2 inches of lift in the rear. Do I need a panhard correction kit or adjustable panhard bar? I also was curious if it was the drivers side lean. I am .5 inches lower on the driver's side front.

 

I have the OME BP-51 components on mine. I can't remember what their advertised lift is, and I didn't measure. Anyway, I noticed the rear end jiggles in the first 10 minutes. I did the panhard bar correction, and it vastly improved it.

 

It sounds like spring rates are too high, causing the rear to hop over bumps instead of absorbing them.

 

Good thing you brought that up! I completely forgot I had gotten medium load springs for future-proofing. Guess that kind of makes my response null and void. Very sorry!

 

I have the lightest duty spring rates from dobinsons. I know they are still higher than oem though. It's not a rough ride but I rarely carry anything at all back there so maybe that is it.

 

I have a 1.5 lift and can feel that very slight/momentary sideways push on some bumps. I don’t think it’s worth correcting though.

The way I understand it, the panhard moves in an arc. Half way through the travel range of the rear suspension, the axle is furthest towards driver’s side, and it moves slightly towards the passenger side when it moves more towards the compressed or extended travel range of the axle.

At stock height, the axle is sitting slightly on the “compressed” end of the overall range. When you hit a bump, the arc of the axle means it move only towards the passenger side.

when you lift the suspension, now the axle sits at the slightly above the midpoint of the arc. When you hit a bump, the axle’s travel arc first moves it towards the drivers side, then it crosses the center of the arc, then it changes direction and the panhard moves the axle to the passenger side. It’s the quick change in direction when the arc moves over-center that causes that feeling of sideway acceleration. That makes it feel like the back end jiggles side to side on bumps.

 

^This

Take a look under the rig and see if your panhard bar/ trackbar is level. If it's not level, a simple solution is the BOTCK
https://drkdss.com/products/bopck-bolt-on-pan-hard-correction-kit

I have this kit and it corrected the track bar geometry for 3" of lift. There is a weld in solutions from Eimkeith as well if you prefer that route.

Like @McSpazatron said though, for 1.5" of lift it may not be worth correcting.

 

It's called bump steer. As recommended above, take a quick pic underneath of your rear axle, so we can see how level your lanyard/track bar is sitting. Let's start there.

 

Here's some images of my panhard bar. I didn't have time to remove my spare so it may be hard to tell but my panhard bar is definitely higher frame side according to the level.

 

BOTCK will solve that.

 

I'll look into it. Thanks!

I may also just ignore it now as it seems it's not hurting anything.

 

It won’t hurt anything at all. It will just solve that “sway” feeling you described

 

Throw a couple hundred pounds back there, and see how it handles.

 

Your panhard/track bar angle doesn't look awful, but I'd like to see how high it truly is on the other side. Can't see it with the tire in the way. That being said, the shorty BOTCK would even things out, but you're not at a crazy angle like some people.

 

Adjustable panhard bar would take care of the sway. It's probably the easiest solution. You may have to play with the adjustment to get it right, you know, a couple of trial and error times. The spots you're talking about must be pretty rough to get the panhard to move that much. We have +2" in the rear, it doesn't put up a fuss, lucky I guess.