Steering Stabilizer vs. Anti-sway bars

[fourleos]

Our 1991 26'BF has some play in the steering and also sway. It has king pins which we have had replaced, and that made an improvement in the play in the steering, but we still have sway. I posted awhile back asking about anti sway bars and made follow-up calls around here. It didn't occur to me, but the one shop pointed out that the anti sway bars add weight, and that ideally you do front and back, but if doing one, do the back because otherwise you would be front end heavy. Our BF is on the 350 chassis, so we really have to watch our weight. It looks like the steering stabilizers go on the front and have less mass, so maybe less weight added? I am not sure what would work best for us, maybe doing nothing, since too much weight is a concern. I actually don't quite understand the relationship between play in the steering and sway. Could someone explain it or direct me to a post where it has already been discussed? Thank you, Reni

[Tahoe]

Our 1991 26'BF has some play in the steering and also sway. It has king pins which we have had replaced, and that made an improvement in the play in the steering, but we still have sway. I posted awhile back asking about anti sway bars and made follow-up calls around here. It didn't occur to me, but the one shop pointed out that the anti sway bars add weight, and that ideally you do front and back, but if doing one, do the back because otherwise you would be front end heavy. Our BF is on the 350 chassis, so we really have to watch our weight. It looks like the steering stabilizers go on the front and have less mass, so maybe less weight added? I am not sure what would work best for us, maybe doing nothing, since too much weight is a concern. I actually don't quite understand the relationship between play in the steering and sway. Could someone explain it or direct me to a post where it has already been discussed? Thank you, Reni

I apologize ahead of time since I've only owned an RV 2 days (I can hear the moans), but the principles are the same for all vehicles. First weight is not an issue. What your mechanic said incorrectly when referring to heavy is the feeling of a heavy front end when trying to turn. It's correctly called understeer or the tendency for the vehicle to resist turning, which is a good thing in most street vehicles in moderation. That doesn't answer your question though. There are many factors which affect handling so before replacing things follow the following general steps.

First start with the tires, which I assume are in great shape and most importantly inflated to the correct pressure. Tire pressure can affect the handling and can amplify other issues.
Second, make sure your coach has had a quality front suspension allignment.
Third, would be the condition of your shock absorbers which dampen the sway and can make sway less likely. Quality shocks like Bilstein can make huge difference in the stability of a vehicle.
Fourth, would be to check sway bar bushings. If worn they create slop and replacing them will firm up the handling. You can also replace them with firmer bushings.
Fifth would be sway bars. Always replace them in pairs to maintain the correct balance. Unless your sway problem is severe, I wouldn't replacement them, but being an older model it might be a nice upgrade.
As far as steering stabilizers go, well I've tried them on a few off road vehicles and don't like them. The are, in my opinion, masking other problems. If your vehicle has good tires, alignment, shocks, and bushings it should drive fine.

I'm sure I've forgotten something so those with more RV experience pleas chime in. My experience comes from years of sports car ownership.

[Roger H]

First... welcome, Russ. Good, informative post.

fourleos, you asked some good questions here. I'll try to help if I can. The physics of a motorhome going down the road are complex in calculation, but simple in theory. You have a high center of gravity compared to a sedan, and the chassis has a much more difficult time keeping the load (the living space) centered over the axles and suspension when it begins to rock side to side after it hits a bump. Add to that forward momentum with steering around corners, for example, and you can imagine that the side loading can get pretty high energy sometimes.

The suspension is supposed to be beefy enough to keep it from leaning too far under all conditions. That's where the shocks, radius rods, and sway bars come into play. The shocks and sway bars (actually anti-sway bars) limit the lateral roll of the body over the chassis. Those components need to be of an adequate size to do the job with all of the bushings in good condition. Radius rods (on the rear axle) help to keep the chassis and body centered over the axle. If the springs aren't strong enough to keep the chassis centered over the axle during driving, the coach will wander and feel vague (also known as rear-axle steering.) I just bought a 32 RQ on the Kodiak chassis, and some owners of other rv brands on the Kodiak have complained of that problem. It can be really scary during windy situations when passed by semi trucks.

Last, is the steering stabilizer. Most vehicles in the US tend to have significant under-steer. Large tires, brakes and other wheel components are heavy and when moved by bumps and pot-holes, can make steering heavy and difficult because of the sheer mass that you're trying to return to center. A steering stabilizer is basically a large suspension shock absorber that is valved for the same amount of effort in both directions. It prevents the front end components from moving too much when they encounter road irregularities. It fights the fast input movements of the steering from rough roads so the driver doesn't have to. If the steering isn't moving from road irregularity input, then the mass of the coach isn't thrown from side to side by the steering either.

So, each of those components handles a different piece of the handling puzzle.

When you have weak shocks, no radius rods, no anti-sway bars, and no steering stabilizer, and you're driving on rough roads in heavy wind, the coach can be pushed around over the rear axle (rear axle steering,) the body can move over the chassis without dampening (sway,) and rough roads can play havoc with your steering. When all of those happen simultaneously AND you're passed by a semi truck, keeping control of the coach can be problematic.

Not all chassis need all of those components to be safe. Most are quite well-behaved as they come from the factory, but others (like the Y2K Ford Excursion I had towing a 34' Airstream tri-axle) needed to have ALL of them installed to be a competent handling vehicle. With an older coach, the first thing I'd do would be to consider having the shocks and all of the bushings in the suspension and steering replaced, and then see what else you'll need to do. Likely some or all of your issues are from worn bushings.

Good luck!

Roger

[fourleos]

Thank you for your detailed replies, I am learning a lot about trucks! I checked our repair records and we have new tires, shocks, stabilizer bushings and king pins. We didn't do anything with the rear radius rods. My husband said we basically had the whole front end redone, so perhaps the rear radius rods are causing the worst of the sway. I looked on line and in the manual, but found no reference to them on our 1991 F350 model. Are they a standard part, or an optional one like anti sway bars and steering stabilizers? I would like to check into the radius rods before we proceed with other options. We don't have any long trips planned for this year, so at least I have time on my side. Thanks again for the helpful responses! Reni

[Steve W]

fourleos

Perhaps I can add some further confusion. We have a 2007 24RB which we purchased new and had it delivered to us in CA. When I first drove it I was amazed that someone was even able to drive it out from Iowa to CA. To say the front steering wandered would be a massive understatement. I subsequently went the route, bearing in mind that the vehicle was new. First to a Ford dealership and then on to a large front end shop and was told that everything was within Ford tolerances, though it was admitted that said tolerances were "loose". I then ended up at a shop that specialized in truck & RV suspensions. A rear sway bar did little so that was removed and a Safe T Steer rod was installed in the front steering. That did cure approx. 85% of the problem. Lately, I have had a specialist at a shop in Oregon fine tune the steering mechanism and had a Track Bar installed in the rear. It is better. It will never drive like a Porsche but considering it's size and weight, it now works for us. As indicated in prior posts, a wandering RV can be the result of any number of things, sometimes a combination of factors. The problem lies in finding just which problems are yours without completely rebuilding your suspension. Based on our own experience, I can only suggest finding the right shop, have them prioritize any faults they find and then take it from there.

[Roger H]

Thank you for your detailed replies, I am learning a lot about trucks! I checked our repair records and we have new tires, shocks, stabilizer bushings and king pins. We didn't do anything with the rear radius rods. My husband said we basically had the whole front end redone, so perhaps the rear radius rods are causing the worst of the sway. I looked on line and in the manual, but found no reference to them on our 1991 F350 model. Are they a standard part, or an optional one like anti sway bars and steering stabilizers? I would like to check into the radius rods before we proceed with other options. We don't have any long trips planned for this year, so at least I have time on my side. Thanks again for the helpful responses! Reni

Reni, radius rods are almost never standard equipment and would seldom appear on any kind of truck chassis unless they were installed after-market for a specific problem. They're even hard to find for most chassis as they just aren't needed. Radius rods wouldn't cause sway, all they do is to keep the axle in place and keep it from wiggling around under the chassis.

Steve's counsel is sound. Find a competent suspension shop and let them systematically figure out what the problem(s) are. A 1991 chassis could have age-related deterioration in the spring shackle bushings, and/or the rear springs could be getting weak.

[fourleos]

Thanks again for the information and advice. It will be easier to understand the suspension shop's description of needed work, now to find one. It has been challenging to find a place to work on our BF. We were not thrilled with the place that did the earlier repairs, so I hope to find someone we like better. Reni

[stevek]

I wonder how the liquid springs option, would factor into the handling of the Born Free?
Thanks

[randallrae]

I had 1998 BFT E350 and it came without a rear stabilizer , also Radius rod sometimes called track bar .

[Tahoe]

Great comments. I just wanted to add that my experience is completely void of RV experience, but look forward to all the experience here for BF's. When I test drove my 24RB it was on 395 in Nevada with very strong side gusts, and it felt very stable. The previous owner replaced the tires, shocks, and had it aligned, and it performed wonderfully. It was that drive that sold me. I guess that what I want to say is that I saw no need to make improvement at this time. The Bilstein shocks were working great, the tires were responsive, and I never felt like I was out of control. I'd realy like to here feedback on steering stabilizers and thereaffect. Like I said in the past I found them useless, but that was offroad vehicles.

[Roger H]

Great comments. I just wanted to add that my experience is completely void of RV experience, but look forward to all the experience here for BF's. When I test drove my 24RB it was on 395 in Nevada with very strong side gusts, and it felt very stable. The previous owner replaced the tires, shocks, and had it aligned, and it performed wonderfully. It was that drive that sold me. I guess that what I want to say is that I saw no need to make improvement at this time. The Bilstein shocks were working great, the tires were responsive, and I never felt like I was out of control. I'd realy like to here feedback on steering stabilizers and thereaffect. Like I said in the past I found them useless, but that was offroad vehicles.

Tahoe, it's been my experience that the larger the mass of the tires on the front end, the more likely a steering stabilizer will be of value. Steering stabilizers limit road irregularities from affecting the steering wheel so significantly, and the larger the mass that the road is acting on, the more you have to fight it at the steering wheel. So a pickup, for example, with stock tires won't benefit much from them. A pickup with 33" mudders would benefit more from a steering stabilizer because of the increased mass of the tires. A class "A" moho with 22.5" wheels has several times the mass of a stock pickup's front end, so it would likely benefit more; the issue there, of course, is that it also takes a much larger road irregularity to deflect the mass of those tires. Usually folks put them on to try to correct (or mask) some other problem in the front end (worn bushings or tie rod ends) rather than correcting what is actually causing the problems.