Rear end sway/shift

[BGarsteel]

I have a 2011 3500 mega 6. 7 with a tuff country 6'' lift (blocks in the rear) I bought the truck lifted. When i first drove the truck i noticed a sway (shift from side to side)from the rear whenever i turned or was on a long sweeping turn on the hwy. Coming from a 1/2 ton truck i just thought that i had to get use to this new lifted truck. Now that im towing i notice its becoming a problem as its almost tough to stay in a lane. Especially in any wind. I have added an air bag helper spring kit thinking this may help, but it still needs help. Any suggestions? besides taking the lift off.

 

[Okie-Go]

By your last statement I think you know what you will have to do. The truck is top heavy.

 

[crispyboy]

Lifted, big tired trucks make for poor tow vehicles.
I would check to see if other suspension components such as sway bars have been removed.
Tire pressure?

 

[BGarsteel]

There is no rear sway bar, do they all come with one? If so its been removed. Ive allways had lifted 1/2 tons (although 35s not 37s)and towed with them, never had side to side shifting. Ive checked ubolts ,tire pressure... . it does it without towing also. Is there a track bar kit available out there?

 

[cerberusiam]

Hellwig makes a sway bar for these trucks. Dodge eliminated the factory sway bar when they went to the longer springs, likely there was not one there to begin with.



The big question is whether the roll is supsension or tires. Taller tires not rated for the weight are going to have issues under a load and there is no fix for that except training wheels or heavier tires rated for the weight.



Since it is doing it empty again the question becomes suspension or tires. Since you added air bags that should eliminate suspension and now its back to tires, or misaligned axle, or suspension bind.



What are the tires rated at and how much air pressure are you running in them?

 

[BGarsteel]

Im running 37/13. 5/20 Toyo OC MT's load range E at 65 PSI. Its hard to describe what it feels like... . in a sweeping turn on the hwy , once i get into the turn, i feel like the rear end shifts horizontally 1-1/2" away from the turn, then its maxed out.

I imagine those blocks and ubolts leaning that much? They would have to be pretty loose... leaf pack on a 3500 flexing that much? How could they when my 1/2 ton springs were 1/2 the size with the same size block.

It doesnt lean, it shifts(or at least it feels like it). The only way i know how to stop that is a track bar.

 

[cerberusiam]

So its not body roll then, more of the rear end just seems to move to the outside a little?



The only time I have seen something like that is a set of bad tires, mismatched tires front to rear, or the pivot point on the springs seized and binding.



Maybe the problem is not the rear but the front wanting to dive into the corner harder? What parts have been upgrade din the front suspension and what caster are you running on it?

 

[BGarsteel]

First off, thanks for all the input!

I just got off the phone with my buddy who races Rolex GT class.

He said to check the track of the rear end (measure off the same point on each side of the frame to the housing). This dim not being the same will cause a shifting feeling ,especially one way as the truck will actually turn one way easier than the other. This would be enhanced by bigger tires and towing.

I measured and its a 1/4" off. He said the race cars are measured within 100th of a inch! So i'll correct this and see what happens.

 

[BGarsteel]

Cerb... . just saw your reply, thanks again

... tires are all the same and have even wear of 8000mi...

the front has Fabtech springs with TuffCountry tube link bars and stock(appears) sway bar.

 

[Schumacher]

If the spring center pin is broken or not in the center hole of the lift block the axle will shift under load. I broke a spring center pin on my off-roader and had the same feeling.

 

[BGarsteel]

If the spring center pin is broken or not in the center hole of the lift block the axle will shift under load. I broke a spring center pin on my off-roader and had the same feeling.

Tomorrow im going to loosen the u bolts and see how much movement there is. I can see the blocks sit different on each of the spring pads. Hoping for an easy fix!!

 

[mwilson]

It is starting to sound like tread squirm to me. That is the same behavior that semi's exhibit when new tires are installed. Feels like the rear almost slides a little.
Will pucker you up in every corner until they wear down and harden the rubber.

Can you post a picture of the tread?

It would be a shame for you to frig with this truck only to discover that it fixed itself once the tires wear down a bit more.

Thought I should at the least toss the idea out.

Mike.

 

[mwilson]

I just found a picture of that tire, that is a high, blocky tread.



Could be some if not all of your issue.



Mike.

 

[Beast2B]

I towed with those same tires on my 2nd gen and, while rated correctly, they did have some of that squirmy feel. One other thing to look at is wheel width. I had a TON more squirm with a 12. 50 width tire on an 8" wheel than I got with the Toyo 37s on a 10" wheel. Minimum 10" wheel would be my suggestion and a larger diameter 20" wheel would allow for less sidewall to roll in the turns.

 

[BGarsteel]

Yeah Mike thats what it feels like, kinda sketchy.

Beast... running 20x10 BMF Novakanes and 37/13. 5/20. I hope its not the tires!! There $500 each... only 8kmi on 3 of them.

Last week i tore the sidewall out on the front right tire. Now that you guys bring it up, i remember thinking how flimsy the sidewall was as i forked out $500.

Im going to get the back end straightened out tomorrow morn, hope that settles it. .

 

[cerberusiam]

37's on a 20 inch rim should not have that tall a sidewall. That tire is rated at 3800 lbs load so its got good stability. I have a few sets of those tires and never had any tire squirm out of them. Hard to believe it is that but naything is possible when you go that big and lift the truck. Messes the suspension all up.



If it actually has a stock track bar you will never get the fornt and rear diffs aligned without a dog trail. Adjustable track bar or a relocated drop bracket and drop blocks for the sway bar are mandatory or ther eis no telling what manner of screwy things can happen.