Sway bar

[ScottG]

Another fellow posted about adding a HD sway bar to the back of his truck and it got me to thinking..

Has anyone added a rear (or heavier front) SB to a truck used for towing a TT and if so did it make a noticeable difference either while towing or bob-tailing?

[wmoses]

ScottG wrote:
Clarification, by "Sway Bar" I meant the SB or "anti-roll" bar that comes with the truck - not a trailer sway control system. Either term is correct and indeed "sway bar' is used in both my Ford and Dodge manuals.
At any rate, I wondered if anyone had installed a bigger front SB or added one to the back of a PU truck and what their impressions of it's performance were.
It doesn't sound like anyone has done so.

Thanks for the clarification.

We will agree to disagree on the correctness of the term, however, even if it is stated as a "sway bar" in the manual (and I have also seen is called such). The fact of the matter is sway and roll are two different motions. 🙂

I have not personally added one to a truck but have added bigger anti-roll bars to both a sporty car I had and my current Audi A4 and in both cases it made cornering flatter. It does nothing for up and down suspension rates. I see no reason why the response in the truck would be different. One thing I can offer is - when one end is stiffened against roll and the other ends is not (i.e. it is not a balanced increase) it can introduce slightly more twist in the chassis and will change the cornering dynamics making one end tend to slide more than it would before the change. That could be desired or not.

I suspect that if you pose your question in the Tow Vehicles forum you might get more responses.

[RJCorazza]

ScottG wrote:
Clarification, by "Sway Bar" I meant the SB or "anti-roll" bar that comes with the truck - not a trailer sway control system. Either term is correct and indeed "sway bar' is used in both my Ford and Dodge manuals.
At any rate, I wondered if anyone had installed a bigger front SB or added one to the back of a PU truck and what their impressions of it's performance were.
It doesn't sound like anyone has done so.

I have not installed one on the same truck and evaluated. My F150 has no rear sway bar, and leans in turns (mushy). The F250 with a rear sway bar does not lean in turns and is very stiff in a turn. Different trucks with totally different suspensions, but the stiffness in turns is directly a result of the sway bars operation. There is no difference in towing performance relating to the sway bar on the tow vehicle.
All that said, I like having the rear sway bar... Makes the ride feel much more precise.

[ScottG]

Clarification, by "Sway Bar" I meant the SB or "anti-roll" bar that comes with the truck - not a trailer sway control system. Either term is correct and indeed "sway bar' is used in both my Ford and Dodge manuals.
At any rate, I wondered if anyone had installed a bigger front SB or added one to the back of a PU truck and what their impressions of it's performance were.
It doesn't sound like anyone has done so.

[wmoses]

mericksonjr wrote:
Maybe he was referring to a sway bar on your hitch. I towed a 27' weekend warrior toy hauler for five years with a 3/4 ton pickup with out one in windy conditions here in Wyoming and there were only a hand full of times that I thought maybe I should have invested in one. Although my neighbor tows a 24' trailer with a older Ford Explorer and he swears by his sway bar. I think the secret is truck weight verses trailer weight. If your trailer ways alot more then your truck then maybe you need one more.

Trailer sway is actually not related to the robustness of the tow vehicle. In your example above, two different trailers (and loadings) were responsible for the different behaviour. No doubt, however, that a heavier truck vs trailer would handle wind "jostling" (not sway, which is a oscillating resonance condition) better.

Variables affecting sway principally include improper fore-aft weight balance, speed, external pertubation (such as wind and air pressure), and friction at the articulation joint. What anti-sway bars and WDHs with anti-sway built in do for sway is increase the friction at this joint. But the weight must be properly balanced first and the speed must be slow enough to be safe with respect to sway (i.e not close to the natural frequency(ies) of the combined rig). 🙂

[wmoses]

Anti-roll bars on cars and trucks are often incorrectly referred to as "sway bars" and so I am not surprised when I see the occasional confusion when it comes to RV towing and resisting trailer sway.

Not sure if this is the case with the OP.

As RJCorazza said these two "sway" bars resist motion in 2 different degrees of freedom, with the ant-roll bars resisting motion (of the TV only) about a longitudinal axis.

[mericksonjr]

Maybe he was referring to a sway bar on your hitch. I towed a 27' weekend warrior toy hauler for five years with a 3/4 ton pickup with out one in windy conditions here in Wyoming and there were only a hand full of times that I thought maybe I should have invested in one. Although my neighbor tows a 24' trailer with a older Ford Explorer and he swears by his sway bar. I think the secret is truck weight verses trailer weight. If your trailer ways alot more then your truck then maybe you need one more.

[RJCorazza]

Trailer sway is a lateral motion and will not be influenced by a vehicle sway bar, which works in another axis. My truck has a rear sway bar and it has zero effect on trailer towing, which was a factory option in the "camper package". It has a significant benefit in a truck bed camper application in keeping the vehicle from leaning from side to side.