Shackle flip and towing

[98dango]

I am in the planning stage of my Superduty build. I plan for a flat bed and 39" irocks.

Now on every lifted full size truck I have ever built. There has been a shackle flip. This inverts the rear shackle to the pointing down like a jeep. Now I have towed small trailers with this setup but never any thing big. I live in a 32' 5th wheel and we have a 27' pull behind we use for long trips hunting and such. I can install air bags and I know with that much sidewall I will have a squishy ride. There are plenty of guys running 35+ tires towing bigger loads way more often then I will be.

My issue is with the rear suspension in this new configuration what side affects have I missed.

 

[pappawheely]

Flipping the shackle raises your center of gravity in the rear. That is why they run them inverted, to keep the COG down.

 

[98dango]

Any lift raises your COG but will a flip raise it more and 6" lift springs. I have towed with my brother in laws 97 6" lift and 235-85-16 yes I know it dosent need the lift. This set up is not ideal but it tows fine.

So how much more is my COG going to change. I know Larry has a flip with a camper.

 

[LovinPSDs]

Will 5th wheel fit with that big of a lift/tires?

My 4.5" and 37's is pretty tall for a 5th wheel..

 

[rxinhed]

I think the positioning of the spring shackle does not apply to the OEM situation of COG. Most of the light duty trucks...Toyota, Mitsubishi, etc. have shackles below the frame. Folks flip the shackles to save the expense of buying proper springs, or to gain articulation.

 

[98dango]

Yes the 5th wheel should fit just fine

In my case articulation is what I'm after.

 

[mccustomize]

It's not the orientation of the shackle that determines the rate, it's the shackle angle, I flipped mine at the stock angle and tow capacity was the same. Barely any squat, once I moved the hangers forward it made a decent increase in articulation fooling the springs into flattening out faster and giving it a softer spring rate. But I also notice quite a bit more squat when towing now.

 

[Buliwyf]

I think there's rear spring setups out there that'll get you where you need to be without the shackle flip.

 

[98dango]

Not the travel I want. I con is the best but still not there in my opinion. I use my truck in big rocks as much as the hwy.

 

[Wh1t3nukle]

Here's some good info on shackle angle mechanics: http://www.quadratec.com/jeep_knowledgebase/article-93.htm

Note that early trucks had the shackle above the bracket and now later trucks are reversed. It is not impacting tow ratings for those OEM configurations. However, in a modified configuration the angle (as mentioned) will impact overall handling and response. YMMV b/c the using the stock leaf springs might mean you need to keep lift blocks for height. With that you increase axle wrap tendency and shudder. Have the caster checked after doing a shackle flip. I did a shackle flip but was able to ditch the blocks and built longer rear shackles. The ride is "different" as it's so much more boat like, which is the function of the shackle angle I ended up with.

I will be improving this later when changing this axle. Improvement meaning to have the angle less than 90° to the leaf, slightly. Lastly, I don't tow so I can't communicate that experience.

 

[98dango]

Well in the past 15 years I have been doing this its worked out well. Now I never really towed any thing. I contacted Larry with his welth of knowledge and resources he has run a flip on his blue 78 k10 for a while with camper installed. To his feelings there has been no ill effrcts. So that is enough with my years of liking how the set up performs off and on road to build one for.my superduty.

Prose I have found from previous truck

Helped my chevys with drive line angle
Rides much better on wash board roads
Less axle wrap / wheel hopp
Better articulation

 

[madmax718]

I had the worst experience towing with a shackle flip. Im not saying their all the same, but I will never do a flip again for towing.

If you want the flex, I'd just consider doing air bags and softer springs. But your situation is different, I bumper pull, you have a 5th wheel, so you shouldnt have any sway issues. But shackle flips do make stock springs softer due to the factors listed above.