Highway driving

[Gintory]

We just came back from our first long trip in the Interstate. I enjoy driving on country roads, even mountain roads - but on the interstate it's different. At speeds over 65 mph the van feels like it is being buffeted by wind, even when there is none. I could really feel 18 wheelers pass by. I more comfortable at 55-60 mph. I don't think it was just "highway hop" as I felt side-to-side movement.
Anybody else notice this?
Any ideas on how to make it less of a problem?

[Dennis C]

Can you provide more information on your trailer and tow vehicle? Are you using a weight distribution hitch?

[jaybauman]

Originally Posted by Dennis C

Can you provide more information on your trailer and tow vehicle? Are you using a weight distribution hitch?

OP is referring to Interstate motorhome.

[Dennis C]

Yup, I see that now. I read it as Interstate highway. Thanks.

[majorairhead]

I don't own an Interstate. But I have driven a few miles in the past 45 years.

First place I'd check would be wheels/tires.

Proper tire pressure? Tires balanced? Wheels installed properly to hubs?

I drove a stepvan for years. It would get buffeted by winds for sure, and while being passed by large rigs.

Tractor trailers, buses, class A's, all of them move some wind when they're going 70 or 80 mph. past me, so I expect a little nudge, some times more, some times less, from that, whether towing, or running a class A, B, or C.

[OTRA15]

Originally Posted by Gintory

. . .
. . . I could really feel 18 wheelers pass by.
. . .

Have you ever driven any other "large boxy tall and long solid sails" down the road?

My guess would be that what you have described is normal IMO.

As already mentioned, fine-tuning the tire pressures, front-end alignment, etc. may help. Are after-market [or Mercedes] sway bars available? I would consult your AS dealer and Mercedes service center for feedback.

Hopefully knowledgeable Interstate owners will chime in.

Happy trails,

[Zach05855]

When I picked up our Atlas from the dealer it was all over the place while on the highway. Once I got it home I checked the air pressure in the tires and they were set at 85-90 psi.

Once I dropped them down to the required 61 psi all was fine


Had the identical problem once before with a Ford mini bus I drove tire were over inflated causing the back end to float around.

[djb75]

Never had an Interstate, but did have a Sprinter-based Navion. It used to do a lot of bouncing and rocking. Then I put on a Hellwig sway bar, Koni shocks, and Sumo springs. Of the three, the Sumo springs made the biggest difference, but the rest certainly helped. I would recommend looking into (1) Sumo or Bilstein spring helpers (they are easy to install and the cost is not too bad), then (2) a heavier sway bar, and (3) heavy shocks if you only have the Sprinter stock shocks.

[BayouBiker]

As others have mentioned, tire pressure and alignment makes a tremendous difference. Look at tread wear and online tire wear guides. Get an alignment if the tires show signs if abnormal wear.

Also look a tire pressure. Start at recommended pressure. If steering is mushy ad 5 psi to all, if the steering seems overly sensitive to correction add 5 psi to rear only. Then try again. If tire pressure adjustment does not help, camber and castor may be off a bit, even if the tires are wearing nicely get an alignment. Be sure to get a report of before and after so you know if an adjustment was made.

Also possible the loading is off. Is your gear evenly distributed? did you have any unusually heavy items near the back? If you are running a bit heavy add 5 psi to the rear tires but stay below max sidewall.

Report back once you have tried tires and alignment, and let us know if you are still having issues.

[Gintory]

I really appreciate all your input. I have driven large boxy things, like a u-haul, but I had never been in a moving B or C camper until now. This thing is new, now barely over 2000 miles after this last excursion - I wouldn't expect mal-alignment right out of the box, but I shouldn't be too surprised. With small compartments it seems hard to be off-balance with my load, or I really don't have many ways to be off. Even coming home the first day, with no gear, it seemed off; and running with extra weight such as half-full fresh/grey/black tanks, it was no better or worse. I was advised to run at 75 psi by one guy at the dealer, then 70 by another - no change.

So we were at our first AS rally (Alumilina, in NC). A nice gent there, who seemed to know what he was talking about, talked with me about the sway bar. Since the Sprinter chassis was designed for a delivery or service van, maybe the weight was off for a camper and the stock sway bar needs to be stronger? Made some sense. So like you said, djb75, I'm going to check into a stronger sway bar and maybe shocks. I'll let ya'll know if it works out.

[Zach05855]

I would not pay much attention to what " a guy" at the dealership says. Check the drivers side door tire sticker for the proper air pressure which was set by Mercedes Benz engineers who know what they are doing.