Rear Sway Bar for Tow Vehicle, not Hitch

[RivetED]

My TV is a Chevy 2500 HD (Duramax/Allison) off-road 4x4 (Z71). It does not have a factory rear sway bar. I do have a 40 gal aux. fuel tank plus all my camping gear in the ARE covered bed. MY weights are all within spec but at times I can feel the body 'roll' somewhat.

My question is about adding an after-market (Hellwig?) rear sway bar and what you think I'll gain (or lose-besides the cost) by doing so.

Have you added one after-market for a little more TV stability or did one come with your TV? What do you think?

I'm looking for some input to help me decide if this something I want to do.

[Mr. Merk]

I've added rear swaybars to multiple pickups and always loved the way they handle. I have not yet added one to my 2500 Duramax...yet. I also plan to off-road this truck some and swaybars do not aid with suspension flex. On-the-road manners are much improved though.

[CBWELL]

I pull with a 2012 GMC Duramax Z71,and have never felt the need for a rear sway bar. A good, correctly set up hitch system, is much more importand in my opinion. If you feel like spending cash, Bilstein shocks are a very good investment.

[Collyn]

Originally Posted by RivetED

My TV is a Chevy 2500 HD (Duramax/Allison) off-road 4x4 (Z71). It does not have a factory rear sway bar. I do have a 40 gal aux. fuel tank plus all my camping gear in the ARE covered bed. MY weights are all within spec but at times I can feel the body 'roll' somewhat.

My question is about adding an after-market (Hellwig?) rear sway bar and what you think I'll gain (or lose-besides the cost) by doing so.

Have you added one after-market for a little more TV stability or did one come with your TV? What do you think?

I'm looking for some input to help me decide if this something I want to do.

The problem with a sway bar at the rear end alone is that doing so results in the roll couple (i.e. resistance to roll) being increased at the rear. This will result in the rear tyres taking more load. It is thus necessary to increase their tyre pressure by about 10-15%.

Collyn

[Dustybird]

You will be really thrilled with the Hellwig and super easy install

[mtbmitch]

Timbren bottom out bumpers might be an option

[BayouBiker]

As Collyn indicates, adding a sway bar to a tow vehicle may be a mixed blessing. Consider this, the vehicle manufacturers are not leaving off a rear sway bar on heavy haulers to save money, they do it to increase safe and stable towing capacity. So if your trailer weight is well below towing capacity, a sway bar will improve feel and comfort and is worth considering. If you are near capacity, Collyn's warning is worth heeding as the sway bar could cause your vehicle to cross over into oversteer.

Food for thought.

[RobH41]

My Duramax did much better with new very good aftermarket adjustable shocks...either towing or not. Might be all you need.

[guskmg]

Full air ride such as Kelderman will eliminate the rolling tendency and the dipping tendency when braking. I have had mine for 12 seasons and would not leave home without it.
guskmg

[Spaggs]

I have front and rear sway bars from Hellwig. My Excursion came with a front bar, but Hellwig offers a slightly larger one than OEM. After installing both sway bars, Bilstein 4600 shocks, I've got the 4x4 rear shocks for my 2 1/2" rear lift, and a nifty device called the Roadmaster Active Suspension (RAS) the big SUV handles much better. I help instruct a course called Street Survival (StreetSurvival.org) which helps teenagers practice emergency maneuvers in a safe environment. One time, recently, one of the instructors who set up the autocross course section told me that he might have set it up too tight. So, I thought, why not. I blasted around the course with the Ex and didn't touch a cone.
Sway bars are the best thing you can do to your suspension and not have any effect on ride comfort.

[BayouBiker]

Remember though this is a trailer towing site and your experience does not provide any information about how addition of a sway bar affects towing stability.

[Collyn]

Originally Posted by RobH41

My Duramax did much better with new very good aftermarket adjustable shocks...either towing or not. Might be all you need.

This a far better solution as it will only marginally affect the fore/aft roll resistance ratio that is major factor in oversteer/understeer.

Brian

Tow vehicle roll causes the tow hitch to move laterally - thus introducing trailer sway.

Collyn

[Spaggs]

Originally Posted by BayouBiker

Remember though this is a trailer towing site and your experience does not provide any information about how addition of a sway bar affects towing stability.

I'm sorry. I thought I was on the IMSA racing forum.
Let me try to better explain what I was trying to convey.
Stability is stability. Whether you are towing an Airstream or carving corners on your favorite winding road. It is the same principle. Side to side movement in excess, in any case, is not a good thing. I also changed all of the rubber frame-to-body, suspension and steering bushings to polyurethane, which are other modifications I implemented to help stiffen up the chassis. An exchange of any worn out rubber bushing for a new polyurethane one will help in reducing sway. With the increased roll stiffness, your tow vehicle (TV) will also give you more input as to its connection with the asphalt, meaning your balance receptors in your brain will give you more data about your tire/asphalt connection.
Trailer towing analogy: a semi passes by you at a high rate of speed and nearly sideswipes you. At this moment, I will be driving a vehicle that has every tool in the bag to make this a non-event. On the other hand, if I had a TV with worn shocks, rubber bushings and no sway bars, I might have cause for worry, with good reason.
I hope this better explains what I was trying to say.

[BayouBiker]

The dynamics of towing is complicated. Some adjustments that improve tow vehicle cornering when not towing can degrade safe and stable towing depending on the vehicle and trailer. Addition of a rear sway bar is one example. The effects are generally greater when towing near the vehicle's capacity, so if your trailer is light, adding a rear sway bar won't affect towing stability much.

I completely agree that worn shocks and bushings are cause to worry. A front sway bar is also a good idea. A rear sway bar when towing can be a mixed blessing for the reasons previously mentioned in this thread.

[Collyn]

Originally Posted by BayouBiker

The dynamics of towing is complicated. Some adjustments that improve tow vehicle cornering when not towing can degrade safe and stable towing depending on the vehicle and trailer. Addition of a rear sway bar is one example. The effects are generally greater when towing near the vehicle's capacity, so if your trailer is light, adding a rear sway bar won't affect towing stability much.

I completely agree that worn shocks and bushings are cause to worry. A front sway bar is also a good idea. A rear sway bar when towing can be a mixed blessing for the reasons previously mentioned in this thread.

"Complicated"

Now there's an understatement!

I have in my many decades of workinng and publishing in this area identified 27 mostly inter-depending variables. I've probably missed a few.

Mathematically it (for me at least) it is close to impossible. It involves Lagrangian-Hamiltonian double differential equations.

I tend to think conceptually and find this is the best to go. I did however, when working at Vauxhall/Bedford Research develop a 48-channel analogue computer that really did help.

So to does Newton's Laws of Motion (yet some clown on another posted that Newton's stuff is just an opinion - the poster was a plumber).

I do however feel I have a reasonable overview (as I suspect has Brian). For (academic) authorities its hard to go past Richard Klein and Henry Szostak and Prof Jos Darling.

Collyn