Reply
 
Thread Tools Display Modes
Old 09-10-2013, 10:20 AM   #1
Junior Member
 
Join Date: Jun 2013
Posts: 21
Porpoising

I've got a Chevy chassis 2014 Coachmen 28QB with less than 2K miles on it.

On wavy (not bumpy) roads (and my town has a LOT of them), the front end bobs up and down to the extent that the front wheels will come off the ground.


I have minimal "stuff" in the back and no water in the tank, but I'd guess that it is a matter of balance and softness in the front suspension.

Does anybody else have a Chevy chassis 28QB that does this?

Tim
__________________

__________________
Healeyman is offline   Reply With Quote
Old 09-10-2013, 10:23 PM   #2
Junior Member
 
printman's Avatar
 
Join Date: Dec 2011
Posts: 13
I have same year and everything. How fast are you going? On the way back to my storage the road is like that and I feel it bounce but not wheel off the ground.
__________________

__________________
printman is offline   Reply With Quote
Old 09-10-2013, 11:55 PM   #3
Junior Member
 
Join Date: Jun 2013
Posts: 21
Terry,

The porpoising seems to happen when the speed is anywhere between 25-50, but it seems worse when the speed is 35-40 MPH.

All mechanical assemblies have a "resonant frequency". That is a frequency when bad things become worse. My RV's front end bouncing up and down is a frequency and 35-40 MPH seems to be its resonant point.

I called my Dealer (in Alvarado) today and the service manager had never heard of this problem and they sell a LOT of these 28QBs.

Because they do not do work related to the chassis or drive train, he referred me to a Chevy Truck dealer in Ft. Worth. The RV service specialist there had not heard of this problem either, but commented that my Chevy 4500 chassis probably was not strong enough for a 30 foot (bumper-bumper) RV.

She did suggest installing heavier shocks.

I have a good friend who had a similar problem with his 31 foot Winnebage. Last weekend, he installed Heavy Duty Bilstein shocks. Today, he told me that eliminated the problem.

Changing the shocks obviously changed the resonance frequency.

I'm going to order H D Bilsteins and install them on my 28 QB.

We've got a 2,000 mile trip planned for next week, so I want to do it quickly.

Tim

__________________
Healeyman is offline   Reply With Quote
Old 09-11-2013, 08:21 AM   #4
Junior Member
 
printman's Avatar
 
Join Date: Dec 2011
Posts: 13
Keep us posted on how the shocks do. I was curious about how an aftermarket shock would feel.
__________________
printman is offline   Reply With Quote
Old 09-11-2013, 08:36 AM   #5
Senior Member
 
Roll's Avatar
 
Join Date: Feb 2013
Posts: 476
I wonder where your fresh water tank is and if located midpoint or forward of midpoint, would filling the tank help with the problem?

Roll
__________________
Gary, Cindy, Reacher (Maine Coon), and Vivian (in spirit only now).
Retired: July 31st, 2013 and loving it.
__________________________________________
2011 Coachmen Encounter 37 TZ pulling a 2012 Wrangler Unlimited Sahara. Many upgrades, additions, mods, and changes.
Roll is offline   Reply With Quote
Old 09-11-2013, 09:16 AM   #6
Senior Member
 
Join Date: Jun 2013
Location: Dillsburg, PA
Posts: 308
Shouldnt this be something the dealer fixes? I mean if the front tires literally come off the ground often that's a pretty big issue on a new 2014 model....or do they blame the TOAD on the back?
__________________


2013 Rockwood Mini 2503S
2011 Chevrolet Silverado 1500 5.3L
Bryan2503S is offline   Reply With Quote
Old 09-11-2013, 01:06 PM   #7
Junior Member
 
Join Date: Jun 2013
Posts: 21
Quote:
Originally Posted by Roll View Post
I wonder where your fresh water tank is...located
Roll,

The water tank is immediately behind the rear axle. For the past 10 years with my old 22' Class C, I always traveled with a full fresh water tank.

Filling this tank would add weight aft of the axle taking more weight off of the front axle. I think that filling this tank would worsen the problem.

Tim
__________________
Healeyman is offline   Reply With Quote
Old 09-11-2013, 01:11 PM   #8
Junior Member
 
Join Date: Jun 2013
Posts: 21
Quote:
Originally Posted by Bryan2503S View Post
Shouldnt this be something the dealer fixes?
Perhaps, but which dealer. The RV dealer doesn't cover the Chevy chassis and my first pass with the Chevy dealer is that perhaps the chassis has been overloaded by the RV manufacturer.

I can see a months long goose chase to resolve this issue.

I wanted to see if anyone else had this problem and what they did about it.

Failing that, IF I can fix this situation in a week with $125 worth of shocks, to ME that's better than spending months chasing "Not My Fault" dealers.

Tim
__________________
Healeyman is offline   Reply With Quote
Old 09-11-2013, 01:23 PM   #9
Senior Member
 
Join Date: Jun 2013
Location: Dillsburg, PA
Posts: 308
Perhaps I should have said manufacturer rather then dealer but I see your point and forgot the part about a trip next week. Good Luck!
__________________


2013 Rockwood Mini 2503S
2011 Chevrolet Silverado 1500 5.3L
Bryan2503S is offline   Reply With Quote
Old 09-11-2013, 02:17 PM   #10
Junior Member
 
Join Date: Jun 2013
Posts: 21
Quote:
Originally Posted by Bryan2503S View Post
Perhaps I should have said manufacturer
Who has EVER gotten a positive resolution from an RV manufacturer???

Tim
__________________

__________________
Healeyman is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Virginia Campgrounds

Reviews provided by




ForestRiverForums.com is not in any way associated with Forest River, Inc. or its associated RV manufacturing divisions.


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 03:22 PM.