MH Sway

[cerd]

The last few trips we have taken, were during some pretty heavy winds. On one of them, my wife was driving separately and called to see if I was falling asleep because I was struggling to stay within the lines. After some research, I found a few things that could improve side sway, namely steering stabilizing shocks and sway bars.

I will check tonight if mine has sway bars, but I was wondering how much it actually helps. I am looking at about $600-800 doing the work myself and 4-8 hours of labor depending on how much rusty the parts are.

 

[Gary RV_Wizard]

You didn't say how much wind, but th suspension on a 1990 vintage G30 probably isn't all that great and I'll bet the rig is loaded to the max (near GVWR). There isn't much that is going to fix that.  It probably has a modest anti-roll bar built in, but back then they were not really enough for a heavily loaded chassis (and all van-based motorhomes are heavily loaded right from the factory). A stiffer roll bar would help a little.

Air bag assist on the suspension might help some, but my real advice is to get off the road when conditions get like that. You have a huge sail mounted on a marginal chassis and it's really not safe when the going gets tough.

 

[cerd]

I don't have a record of how much wind there was. It felt like I was being passed by semi's pretty consistently. I'm not sure if that helps. I am going to start keeping track though.

I found a document that explains the van specs, but I am also not sure how that compares to a MH.
https://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/G-Van/1991-Chevrolet-G-Van.pdf

Maybe I will call the local grain bin and see if they will let me weigh it when they aren't so busy.

The sway bar kits that I have seen are a fair bit heavier (1.25") than most auto parts stores (1.0-1.125"), so I'm sure its a lot more rigid. I don't know if I have one on the back, front, both, or none. Would it be worth upgrading for an extra 1/8 inch OD on the sway bar? I may upgrade shocks anyways. I bet these ones are still factory.

 

[SpencerPJ]

Coming from someone who often drives too fast, when the wind gets rockin, slow down.  Simply amazing how much better they drive  :

 

[cerd]

Coming from someone who often drives too fast, when the wind gets rockin, slow down.  Simply amazing how much better they drive  :

Yup, I never drive more than 60mph and when the wind picks up, I usually end up driving about 45. I even put a "vehicle does not exceed 60mph" sticker on the back. It actually helps with tailgaters.

 

[Gary RV_Wizard]

"C" Motorhomes are usually built on a van cutaway (cab-only) chassis with the maximum suspension options. Sometimes it s the same option set as used for an ambulance, and the spec or parts books may have en entry for an ambulance version. A chassis service manual may help you identify just what components you actually have. Chilton or similar.

 

[blw2]

I'll bet you could look up the historical weather data online, for where and when you were when this happened to get at least a rough idea of the wind speeds.
I just did for the time I remember my highest winds, it looks like it was 23MPH winds in the nearest city.... but I don't know if that was the highest gust or just the average.  It was probably higher anyway, because I was at a higher elevation coming down a big hill well above the town. (eastbound on 64 coming out of the Grand Canyon area towards Cameron, AZ).  I had to slow way down...significantly so... and it was still white knuckle.... and then some folks in the Super C I was oogling over earlier in the parking lot, flew by me like I was standing still without a care in the world about the wind
See attached photo.... I'm the mini-cooper on the right.....

"C" Motorhomes are usually built on a van cutaway (cab-only) chassis with the maximum suspension options. Sometimes it s the same option set as used for an ambulance, and the spec or parts books may have en entry for an ambulance version. A chassis service manual may help you identify just what components you actually have. Chilton or similar.

...and then for the bigger ones like I have, the manufacturer cuts and extends the frame significantly, making it a longer wheel base and with a longer overhang out the rear than the way Ford built it.... so it's got a significantly bigger box on the same tires and suspension of an ambulance (or whatever)

 

[cerd]

I'll bet you could look up the historical weather data online, for where and when you were when this happened to get at least a rough idea of the wind speeds.
I just did for the time I remember my highest winds, it looks like it was 23MPH winds in the nearest city.... but I don't know if that was the highest gust or just the average.  It was probably higher anyway, because I was at a higher elevation coming down a big hill well above the town. (eastbound on 64 coming out of the Grand Canyon area towards Cameron, AZ).  I had to slow way down...significantly so... and it was still white knuckle.... and then some folks in the Super C I was oogling over earlier in the parking lot, flew by me like I was standing still without a care in the world about the wind
See attached photo.... I'm the mini-cooper on the right.....

...and then for the bigger ones like I have, the manufacturer cuts and extends the frame significantly, making it a longer wheel base and with a longer overhang out the rear than the way Ford built it.... so it's got a significantly bigger box on the same tires and suspension of an ambulance (or whatever)

Do you think theres a huge difference in weight distribution on super Cs? Maybe they have extra beefy frames and more metal down low, so they are more stable where regular Cs are top heavy since they aren't so rugged?

 

[cerd]

I finally got around to checking underneath the MH last night. It doesn't look like there is any sway bar under there. I am thinking it'll help quite a bit having anything vs nothing.

 

[blw2]

Do you think theres a huge difference in weight distribution on super Cs? Maybe they have extra beefy frames and more metal down low, so they are more stable where regular Cs are top heavy since they aren't so rugged?

I honestly have no idea.
Regardless, I recon it's like two F150 pickups...one with two bags of mulch in the bed, the other with a huge pallet of bricks taking it to or maybe even above it's capacity limit.
While that super C chassis has been stretched and is loaded differently from it's intended design as a semi-truck, I guess it's well below it's capacity
+ it's designed for long haul travel.  The E series vans are probably designed more for local delivery.

 

[Lou Schneider]

The biggest factor is what JD Gallant described over 20 years ago as the wheelbase to length ratio of the motorhome.

If the rear axle is well forward so you have a long rear overhang (wheelbase to length ratio of approximately 50% or less) side wind forces will center at or behind the rear axle, pushing the rear more to the side than the front.  This creates the need to constantly correct the steering as you go down the road, first steering one way and then the other as side winds come and go.

A long wheelbase to length ratio (60% or higher) causes the wind forces to center between the axles.  The motorhome may lean but isn't pushed off course as much as one with a shorter wheelbase to length ratio.

Most motorhomes fall somewhere in between these examples, but there are exceptions in both directions.

For example, the Class C in this picture with it's very short wheelbase to length ratio has a lot of sail area behind the rear axle and will be a handful in side winds no matter what you do to beef up the suspension.

I had a 1994 Damon Intruder gas powered motorhome similar to this picture with a long wheelbase to length ratio and even with just the stock suspension it was very stable on the highway.

It's a tradeoff between stability and maneuverability.  School buses that need to maneuver around narrow roads and sharp corners have short wheelbases and long rear overhangs.

Greyhound and other highway buses have the opposite ... longer wheelbases and shorter rear overhangs for higher stability at highway speeds, at the expense of low speed maneuverability.

 

[RTsRV]

The wheelbase length to overall length ratio does mean a lot to the effects side winds will have on your ability to stay in your lane.  That 50% aspect is a good rule of thumb.
Sway bars are meant to reduce the lean of the body by using their spring force to try to keep both sides of the body from moving too far vertically from the level of the tires to the road.
A track bar is different from a sway bar.  A track bar attaches to the rear axle and the chassis frame.  What it does is keep the chassis from moving sideways as the wind force makes the leaf springs flex sideways.  It keeps the body tracking inline with the wheels on the pavement.
I have the dreaded less than 50% ratio and I had a handful with side wind issues until I installed a track bar.  That really made a difference.  The worst handling occurred when class As or regular buses passed me.  The large flat fronts pushed a huge wave of air directly at the side of my class A and I had to struggle to keep in my lane.  Now, with the track bar, I notice them but don't have nearly as much trouble dealing with the small effect.
The combination of sway bar and track bar should resolve most of the side wind issue.

RTsRV

 

[cerd]

RTsRV, thanks for the info. That may not be a bad idea. Unfortunately, a quick search didn't come up with any bolt on kits for this chassis, so I may have to go with a universal kit. For under $200, it can't hurt to at least try it.

 

[jaydude]

I was traveling through Alabama at night in my Super C trying to pass slower trucks and had a semi blow by me at over 85mph.  The force of the wind pushed me over on the shoulder about a foot.  There happened to be an Alabama State Trooper/Highway Patrol parked off the shoulder on the grass.  Of course, I got pulled over, nevermind the semi who was clearly speeding.  The officer wanted to make sure that I had not been drinking.  I chuckled and asked him if he saw the semi that passed by me, he didn't answer.  He saw that I wasn't impaired and let me go. Wow, must have been my California plate.  I put a heavy duty set of bars on the front, haven't had that severe of reaction to the wind since.

 

[NewmanRacing]

What tire pressures are you running?

I have a 1993 1 ton Chevy chassis. At 25 years the suspension is just worn out. I added Roadmaster heavy sway bars front and back, new front coil and rear leaf springs, Bilstien shocks for all corners, and a pile of bushings.  Handles like a dream now!