Sucking and Turbulence

[Delco Bobby]

While reading about be sucked in to other vehicles while driving on the highway I decided to start a specific thread on the subject.

My REV24 RB is much less affected by other vehicles than my previous Sunseeker of about the same length.

1. The sucking in seems to happen more often with busses than trucks. But it occasionally happens with smaller vehicles including SUV’s.

2. It may be that the closer I am in my lane to the offending vehicle the more likely I will be sucked in. If a bus and I are both close to the lane stripes I can be taken in by surprise.

3. Not all busses and tractor trailers suck me in.

4. I usually don’t feel turbulence from tractor trailers but when I do it is significant. I haven’t determined what causes the few to give me a hard time. Some will bother me only while I am behind them in the same lane while in most cases there is no problem. Some will bother me if I am behind them in an adjacent lane but most don’t .

5. I find it interesting that the larger, heavier rigs have the sucking in problem.

6. Dynamax should have installed some sort of anti attraction, anti sucking device on our motorhomes along with a turbulence mitigator .

7. #6 was not serious.

8. Comments are welcome.

[ETF]

We all know what causes it but I have no idea how to mitigate it. I will say that the DX3 37TS seems to be a lot, lot better than the Forester we had previously. When a big rig would pass you in it, you got pushed over towards the shoulder. When you compensated to get back in your lane and straightened out, the tail end of the semi would pass you and you got sucked over towards it. It made for some stressful driving.

I think that the additional weight and better suspension on the DX3 helps. I know that some of the other members will have a much better technical explanation and more than a few remedies.

[caswelld]

There can be control issues with passing 18-wheelers depending on speed and wind direction. It seems that with a crosswind a passing truck or bus is even more likely to give our MH a push. Here are some fixes that I have found to help considerably: Sumos, Safe-T-Plus steering damper, upgraded shocks, an upgraded sway bar. We have all but the Safe-T-Plus on our Isata 3 and we normally don't experience any affect from large passing vehicles. Although, with the right wind and highway speed we occasionally get a little push.

You can look around on the forums to see what others think of these. IRV2.COM should have a chassis specific area that may also help.

https://www.supersprings.com/products/sumosprings
Products | Safe T Plus
https://www.bilstein.com/us/en/
Hellwig - Load and Sway Control Products

Happy camping



Dave

[hook47]

In NASCAR they call it "side drafting". Whatever you do don't try "bump drafting"!

[wahoonc]

Look up Bernoulli's Principle.

Aerodynamics most definitely come into play. Your current rig is not as much of a flat box as your previous one was. I have noticed a marked difference even in cars, my 2011 Subaru Legacy would get pushed around a fair bit, my 2018 Honda Accord or 2015 Ford Fusion not nearly as much.

Aaron

[HappyCamper1962]

When I am passing one of those "suckers" or when I see one coming to pass me, I move to the farthest side of my lane away from them to maximize the side distance between us. Nearly all 18-wheelers do this, too. When they see us coming, or as they approach, watch them - they move to their outermost point in the lane. Very considerate.

[old40ford]

My 5th wheel is not effected by trucks, buses or anything that I have noticed, but, my 30ft car hauler is just as you described. I thought I was going crazy when I notice how bad a bus made me move. Like you and others, I try to keep an eye out for them and move as far over as I can from them. Seems to help some.

[Delco Bobby]

Seems like I need to remember to move further away in my lane.

Passing is not a big deal because I am anticipating some lateral movement.

My main problem is when I don't notice a fast mover come up on me and they take me by surprise. On turnpikes and similar roads I am usually doing 65 to 75.

Still wondering why some 18 wheelers cause unpleasant turbulence but most don't.

[The Renegade]

The one piece of advice that kept going through my head during my purchase process was a friend of mine bought a Class A and cant remember what kind or how big. He told me he left for Florida his first trip and was white knuckled but thought it would go away as he drove. He said not only was he white knuckled all the way there but all the way back home. That was his first and only trip in the Coach. He traded it immediately on a Jayco Seneca and swears by the Super C. He would offer no advice on brand or size but offered a lot about not buying the Class A...

Bought a Dynamax 37TSHD.. I took his advice.

[RobertDS]

Originally Posted by Delco Bobby

Seems like I need to remember to move further away in my lane.

Passing is not a big deal because I am anticipating some lateral movement.

My main problem is when I don't notice a fast mover come up on me and they take me by surprise. On turnpikes and similar roads I am usually doing 65 to 75.

Still wondering why some 18 wheelers cause unpleasant turbulence but most don't.

I am new to all of this but in reading this thread, two things occur to me.

1. Busses are boxes on wheels. _Some_ big rigs are boxes pulling boxes. The point is that as the boxes shove aside (displace) air they cause turbulence. Some truckers spend considerable time and money making their rigs slice the air efficiently thus increasing their economy and reducing the wind effect. Perhaps a partial answer?

2. There have been times when I have been startled by a trucker going in the opposite direction. I always seem to check for strong cross winds AFTER one of these incidents. I have not looked to see if the truck who rocked my world had those devices under their trailer to cut down on the turbulence or not. I am betting it did. Maybe the same thing you have noticed.

[Delco Bobby]

Originally Posted by RobertDS

I am new to all of this but in reading this thread, two things occur to me.

1. Busses are boxes on wheels. _Some_ big rigs are boxes pulling boxes. The point is that as the boxes shove aside (displace) air they cause turbulence. Some truckers spend considerable time and money making their rigs slice the air efficiently thus increasing their economy and reducing the wind effect. Perhaps a partial answer?

2. There have been times when I have been startled by a trucker going in the opposite direction. I always seem to check for strong cross winds AFTER one of these incidents. I have not looked to see if the truck who rocked my world had those devices under their trailer to cut down on the turbulence or not. I am betting it did. Maybe the same thing you have noticed.

I see the “shields” under the trailers and I tried to correlate them with the turbulence when they are in front of me but it is not consistent.

To be clear, I can follow many trailers with no noticeable turbulence but then there are those that I have to stay way behind or pass.

I have also been sucked and pushed by some SUV’s (Nissan) and an occasional pickup truck.

[Delco Bobby]

Originally Posted by Mountieman

The one piece of advice that kept going through my head during my purchase process was a friend of mine bought a Class A and cant remember what kind or how big. He told me he left for Florida his first trip and was white knuckled but thought it would go away as he drove. He said not only was he white knuckled all the way there but all the way back home. That was his first and only trip in the Coach. He traded it immediately on a Jayco Seneca and swears by the Super C. He would offer no advice on brand or size but offered a lot about not buying the Class A...

Bought a Dynamax 37TSHD.. I took his advice.

I have read many posts of white knuckle trips after taking delivery. Quite often the cause is the tire pressure is too high.

[Reverse_snowbird]

You can usually tell when a professional truck driver is paying attention because they move left while you move right.

Any big box passing me affects handling slightly.

What I hate is 'cross winds' in the mountains when you're coming over a hill or crossing a bridge. At least with a big box passing me, I can anticipate where the vacuum is coming from.

Slowing down by taking my foot off the accelerator helps more than anything.

The REV handles much better than my Tundra towing a 21' trailer.

[FOURWHL]

Talk about a click bait thread title...

[porsche84]

Delco Bobby

Have you replaced your rear sway bar? I replaced mine with the Hellwig 1.125 dia bar. It has adjustable stiffness settings and I have it in the middle setting. It made my REV 24 much less affected by passing big vehicles. https://www.suspensionconnection.com...gory=sway-bars

[Delco Bobby]

Originally Posted by FOURWHL

Talk about a click bait thread title...

Should I plead guilty now or later?

[Delco Bobby]

Originally Posted by porsche84

Delco Bobby

Have you replaced your rear sway bar? I replaced mine with the Hellwig 1.125 dia bar. It has adjustable stiffness settings and I have it in the middle setting. It made my REV 24 much less affected by passing big vehicles. https://www.suspensionconnection.com...gory=sway-bars

No I have not felt the need to make any suspension modifications. I am very satisfied with the way the REV drives and handles.

The reason for the thread was more curiosity and education rather than a complaint. Most trucks and busses have minimal affect. But occasionally I am taken by surprise.

[caswelld]

If you do decide to upgrade your suspension the Hellwig sway bar will likely be the most bang for the buck. At under $400 you’ll notice at difference.