Towing with 2" Shackle

[Billet Bowtie]

Has anyone done any towing that has a 2" shackle installed? I towed for the first time and the back squated between a half inch to a inch and I have a slight vibration at 70 mph. It goes away if you go faster. I am assuming I might need to mess with the pinion angle. Just curious if anyone else has experienced this.

[mafd2]

You will need to spin the factory pinion shim putting the thick part of the shim facing the rear.

[RAYS B4U]

What are you towing...maybe you need a weight distribution hitch?

[Billet Bowtie]

Yea I have done that which works great if the truck is unloaded but now I feel a vibration when towing.

[jps4jeep]

Get some airbags to level it out,  also as mentioned, a weight distribution hitch will help with a trailer that has a heavy tongue weight. 

My experience is a slight vibration when towing heavy loads at speed is from the change in caster when the rear squats, I doubt it is from the rear pinion angle.

[mafd2]

13 minutes ago, jps4jeep said:

Get some airbags to level it out,  also as mentioned, a weight distribution hitch will help with a trailer that has a heavy tongue weight. 

My experience is a slight vibration when towing heavy loads at speed is from the change in caster when the rear squats, I doubt it is from the rear pinion angle.

When you put drop shackles the pinion angle changes.  I and others I know that put shackles on the '19 developed a slight vibration at certain speeds.  The thick part of the factory pinion shim is facing forward and reversing the shim (putting thick part facing rear) cleared up the vibration issue.

 

Edited May 15, 2019 by mafd2

[jps4jeep]

Yes, you are correct, but the poster stated he already addressed the pinion angle and there is no mention of the front being addressed. So based on the provided information, with the added 1” squat in the rear, on top of the mentioned 2” of additional drop, when towing, the front caster is now more negative than what it was engineered and designed for. I am assuming the corrected pinion angle is adequate to return the pinion angle close to stock, 1” squat should not cause vibration as it should still be within the engineered specification of the joint. My money is on the poster leveling the vehicle when towing, at speeds, this will address the vibrations by returning the caster closer to the angle is was engineered to operate at.

[mafd2]

OK I missed where he already spun the shim around. I agree, a 1" squat shouldn't cause vibration.  Besides caster, front camber becomes positive when towing.

[Billet Bowtie]

9 hours ago, jps4jeep said:

Yes, you are correct, but the poster stated he already addressed the pinion angle and there is no mention of the front being addressed. So based on the provided information, with the added 1” squat in the rear, on top of the mentioned 2” of additional drop, when towing, the front caster is now more negative than what it was engineered and designed for. I am assuming the corrected pinion angle is adequate to return the pinion angle close to stock, 1” squat should not cause vibration as it should still be within the engineered specification of the joint. My money is on the poster leveling the vehicle when towing, at speeds, this will address the vibrations by returning the caster closer to the angle is was engineered to operate at.

This is interesting. I am not towing a lot of weight. I would estimate about 3500 pounds or so. Of course it was enough weight to make the back drop less than a inch or so. I never thought about the inch from the weight plus the 1.5" the shackle dropped it. I have towed with several trucks before that were loaded down way more than this truck but the 19s might be more sensitive to angle changes.

[mafd2]

11 minutes ago, Billet Bowtie said:

This is interesting. I am not towing a lot of weight. I would estimate about 3500 pounds or so. Of course it was enough weight to make the back drop less than a inch or so. I never thought about the inch from the weight plus the 1.5" the shackle dropped it. I have towed with several trucks before that were loaded down way more than this truck but the 19s might be more sensitive to angle changes.

Towing doesn't change the pinion angle because the springs compress evenly where as with drop shackles, the pinion angle changes as the rear of the springs is raised throwing the angle off as shown in above illustration.