Thinking of large Momentum (37' or longer) and just found out about frame flex/failure - is this a bad idea for my usage?

[daveola]

I just learned about frame flex and it sounds like a nightmare.

I'm looking at a toy hauler and want to get one of the longer toy haulers (like 40' or more).

I won't be full-timing in it, but won't just be leaving it in a park. My plan is to take it on 3 or 4 trips a year. And I'm not planning on carrying a vehicle in the garage, just using it for storage (that will weight much less than a vehicle), which evidently is a balance issue? Also I plan on driving (very slowly - 5 to 10mph) on bumpy (but at least not inclined) roads for about 15 miles total (I go to Burning Man every year).

And seeing all this info makes me think I'm setting myself up for frame issues in anywhere from 1-10 years, which doesn't sound great to me.

Is this something that can be prepared for in advance? I know about adding better independent suspension to the wheels, but is it also possible to pre-strengthen the frame up by the riser? Or should I just be looking at other or shorter options?

 

[Calbar]

Grand Design now has a 5 year warranty on the frame. They also put all of the lag bolts in now, or are supposed to. We have also heard from one of the forum members that works for a dealer and this is not just a Grand Design issue, just Grand Design seems to be getter the focus laterly. I am concerned as well so I had the TSB done to all the larger lag bolts and all of the bolts. Don't know if it will fix it permanently or not. Too soon to tell.

Get all of the information and then only you can decide but be aware of all the information you can be to make an informed decision.

Rob

 

[jjbbrewer]

I just learned about frame flex and it sounds like a nightmare.

It might be just a tad bit overblown on the net (shocker). People who have problems are *really* having problems, but for me and my 349M, we had the TSB done (upper deck lag bolts) and seem to be fine. I have a little more than 20,000 miles on my 2021 and barely noticed the upper deck moving just recently.

.. just using it for storage (that will weight much less than a vehicle), which evidently is a balance issue?

It's not, don't worry about it. Besides, if you're going to Burning Man (cool!), you'll probably want to carry water and generator fuel, which will definitely add weight.

Also I plan on driving (very slowly - 5 to 10mph) on bumpy (but at least not inclined) roads for about 15 miles total

I drive on bumpy dirt roads (including water bars) pretty much everytime I go camping - and quite a bit faster than 5-10mph.

I know about adding better independent suspension to the wheels, but is it also possible to pre-strengthen the frame up by the riser? Or should I just be looking at other or shorter options?

For what you're describing doing, I don't think you'll have any problems. Just make sure to have everything inspected before you buy something.

 

[daveola]

I hear you - but ... "I have a little more than 20,000 miles on my 2021 and barely noticed the upper deck moving just recently."

So how many more miles do you think you have? Because only 5 years or so of a lifespan doesn't quite cut it for this kind of investment.

I see the warranty from Grand Design, and that's comforting.

But how they have handled their customers is not comforting, and the fact that I sent an email to their "frames questions" email address about exactly what I am thinking about and they have not answered me is concerning. They don't have time to even answer questions of prospective customers of 6 figure purchases?

 

[daveola]

Looking at the warranty, they have the exclusion:

l. Damage caused by road surface conditions, including, but not limited to
applications of salt or de-icing chemicals, gravel/sand, ruts, or pot holes;

so.. considering how quickly Grand Design seems ready to blame the driver, that kind of excludes one of my planned uses - so I have to figure out if I want to completely give up on that or not.

 

[jjbbrewer]

I hear you - but ... "I have a little more than 20,000 miles on my 2021 and barely noticed the upper deck moving just recently."

So how many more miles do you think you have? Because only 5 years or so of a lifespan doesn't quite cut it for this kind of investment.

To be clear, I have 20k miles occasionally going into some rougher areas. And it was just now (nearly 4 years later) that I started noticing upper deck motion. That's before the TSB fix. I don't expect to see this issue again.

I'll emphasize this - nothing was broken. The unit was still 100% functional - I just didn't want this to get worse and perhaps run out of the warrantee.

As of now, I would expect to have 10-15 years more available on my RV, which is pretty much what I had on my previous RV that was built much worse then my 349M.

Honestly, though, RVs aren't for everyone. If you go into the experience with trepidation and are not comfortable doing frequent maintenance, troubleshooting, and moderate repairs, you probably should consider doing something else. I've found that those who rely on dealers and repair technicians to do most everything needed on their RV typically end up angry and broke.

 

[daveola]

I appreciate that. I'm not new to the idea of RVing. I spent 20 years with a bus conversion that I converted myself and fulltimed in it for 10 years. I can handle doing frequent maintenance and moderate repairs, but I'm not interested in on-the-spot large vehicle repairs (one of the reasons I'm looking at a trailer instead of an RV) and I'm not interested in fixing frame problems. That's why this frame issue is particularly troubling to me. I want something that will easily survive 20 years - and I'm not talking about without any water pumps breaking or trim coming loose or fridges needing replacement, I can handle that.

 

[daveola]

And the fact they weren't using all of the bolts and that they may have been the wrong size (3/8 instead of 1/2?) is terrifying to me. Just because they are using them 'now' doesn't instill a mass of confidence in their build ability.

 

[Conner58]

I can't believe the the lag bolts have much to do with the flex.
They are in a piece of wood 1 inch at best and a thin piece of metal from one side .

 

[daveola]

I thought the TSB for helping deal with frame flex involved putting in all the missing bolts - are they not structural? I.e., they are for mounting things to the frame as opposed to holding the frame together?

 

[jjbbrewer]

Not to be insulting, but if you guys are really interested in this issue, there are tons of articles and videos out about it.
"Frame flex" is kind of a misnomer on the smaller units since the frame isn't really flexing. For "upper deck flex" (which my unit had) the aluminum frame walls were moving around relative to the upper frame steel deck because of small/few lag screws.
My understanding is the triple axle units have actual flex in the stee frames themselves which can lead to cracking. That might happen in the smaller dual axle units, but it hasn't happened to mine.

 

[Conner58]

They hold the wall to the frame.
I suppose they may help a bit but personally don't see them holding 3,000 lbs bouncing up and down .