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Old 11-03-2013, 04:41 PM   #1
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A vs C and wind movement

DW and I have a 31SS JAYCO class C. Are looking for a similar size A. We experience considerable wind movement when 18 wheelers pass us. Do the A's experience the same turbulence?? Thanks!!

Larry, Alice, and Halle (part-time watch dog)
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Old 11-03-2013, 04:57 PM   #2
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My guess is it has everything to do with mass. Our coach doesn't move much, but I think that is because of weight not length or shape. I would presume if an A or C were of comparable weight they would react similarly to big rigs (talking smaller class A's, I assume air ride/tag axle all help on bigger DP's).

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Old 11-03-2013, 05:02 PM   #3
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The first Class A we had was a 2007 34' Hurricane built on a Ford V10 chassis. We did experience a shift when 18 wheelers passed us. I installed a Safe-T-Plus and that helped a LOT! The second coach we had was a 2006 Coachman 350 diesel pusher on a XC chassis and the coach was much more stable. In our current coach we do not have any movement when an 18 wheeler passes us!!!
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Old 11-03-2013, 05:36 PM   #4
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Class A's with tag-axles are more stable than those without. Our 40' MH without tag, moves when overtaken by semis or other MH's. The movement is not unsettling, I've learned how to prepare to be overtaken by another large vehicle, how to react to the bow-wave push, and the draft-effect when almost passed. The movement is totally different, and more than what I experienced in the dually and 40' 5er we used to own.
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Old 11-03-2013, 05:46 PM   #5
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I am about 20K lbs. Very little wind issues. No steering stabilizer. I'm not going to try and figure out why. ;-)
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Old 11-03-2013, 05:56 PM   #6
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It has a lot to do with rear end overhang. The more body mass there is BEHIND the rear axle, the less stable the driving experience. 36-foot coaches are especially susceptible to unstable driving conditions because most of them are built on a chassis with a short wheelbase and have a lot of overhang behind the rear axle.

That's why the 40-foot and longer coaches are so much more stable. They are built on a long wheelbase chassis and have a relatively short overhang behind the rear axle, especially if they have a tag axle.
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Old 11-03-2013, 06:51 PM   #7
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The class C Ford chassis are woefully short on suspension for the load they have to carry. It can be fixed. You will need to add:
-heavier anti roll bars with urethane bushings on the front and rear
-HD Bilstein shocks on all four corners
-and last possibly add air springs to the front and rear.

This will stop the bump or roll steer tendency of the Ford chassis and make if a pleasure to drive.

But start by weighing the RV with it fully loaded and adjust your tire pressures to match the loads per axle. Then get the alignment set properly at a good independent truck alignment shop...not a Ford shop.

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Old 11-03-2013, 08:20 PM   #8
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Rich mentioned on of the biggest factor on wind push and that is the wheel base compared to over all length. The greater the overhang the more you will feel that push. On gas coaches one thing that help mitigate wind push is to have track bars on both front and rear. Some people also report improvement from steering stabilizers.
Also mentioned is that DP will handle that issue better because of seer weight. My previous Allegro had a 22K chassis, my Phaeton has a 44K chassis. In the Allegro I could feel the push but I didn't think it was bad. In the Phaeton I don't feel it at all.
So, the answer to you question is... It depends!
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Old 11-03-2013, 08:53 PM   #9
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We rented a Class C to get us started on RV ownership. We bought a Class A. One of the big differences I noticed right away is the lack of movement when passed by an 18 wheeler in the Class A. This is all relative, of course, an 18 wheeler takes quite a swath through the air but you ask for a comparison and I have driven both and my Class A is much less effected.
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Old 11-03-2013, 08:58 PM   #10
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I have a W20D chassis with a GVW of 20,500. So it is a bit of a light weight.

The wheelbase is under 51% of OAL, a ratio that is supposed to make it vulnerable to wind and handle poorly. It also has over 12 ft of overhang from rear axel to rear bumper.

It handles wonderful in all aspects. Was I just lucky? Perhaps aerodynamics of the sloped sidewalls and nose? I have no clue.
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Old 11-04-2013, 01:00 AM   #11
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This is what some people with the Ford F53 chassis have done to reduce wind push.

Cheap Handling Fix

And for more info:

"Cheap Handling Fix" Poll
2004 32' National Sea Breeze 1311 Class A on a F-53 Chassis, CHF, TST TPMS, 5Star Tune.
If Dunner (RVM23) can't fix it, it ain't broke!
Cheap Handling Fix Poll. Click Here to vote?
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Old 11-07-2013, 09:15 AM   #12
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I appreciate all of y'all's info!!
Larry, Alice, and Halle (part-time watch dog)
Grayhawk 31 SS
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Old 11-07-2013, 09:28 AM   #13
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Originally Posted by larrydp View Post
I appreciate all of y'all's info!!
If ya run faster than the semi's you feel none of their wind turbulance.
"96" HR Navigator, 38' no slides, Cummins, Allison
next stop
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Old 11-07-2013, 09:42 AM   #14
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In a word Yes. I assume you are going to keep it a gasser class A and not move all the way up to a diesel pusher. There are some inexpensive things you can do to greatly reduce that effect on a Ford Chassis. First replace the rear sway bar bushings with polyurathane ones you can buy on ebay for $50. Then you must do the Cheap Handling Fix which is nothing more than relocating bolts on the sway bars. You can see actual pictures of this on the thread Dunner mentioned. That was the one most effective thing I did to reduce that side winds and cross winds problems inherent with the Ford Chassis.

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