Need information on frames, suspensions

[askwines]

Starting to research 5th wheels. I'm following the advice of many to focus on the build first, not the bells and whistles.

I'm trying to find information on comparisons of frames and suspensions available. Tried searching but no luck.

Thanks

Alan

[TXiceman]

Oh what a can of worms.  First off...what is your budget?  And generally you will be much better off buying a 3 to 5 year old used high end RV over a new entry level.  They will be 1/2 the cost of what they were new.

Look beyond the bling and glitz and look for quality build and finish.  For suspension, you cannot do better than the Mor/Ryde IS suspension.  We like all wood cabinets that are screwed together and drawers with dovetail construction.  Better grade furniture and not the Pleather (plastic leather) that falls apart in a year or two.

Look for better grades of carpet and adequate tires.  Do not accept chinese manufacture tires and make sure the tires are fresh by date code and are of adequate rating to carry the load.

We prefer the residential refrigerators with an battery bank and inverter over the troublesome RV gas electric refrigerators.  Look for a unit with a central water manifold with shut offs for each run.  Also look for a central coaxial TV and satellite distribution panel.  Dual pane windows are a must for us as well.  Automatic hydraulic leveling system is also a must.

Have fun looking.

Ken

 

[askwines]

9 minutes ago, TXiceman said:

Oh what a can of worms.  First off...what is your budget?  And generally you will be much better off buying a 3 to 5 year old used high end RV over a new entry level.  They will be 1/2 the cost of what they were new.

Look beyond the bling and glitz and look for quality build and finish.  For suspension, you cannot do better than the Mor/Ryde IS suspension.  We like all wood cabinets that are screwed together and drawers with dovetail construction.  Better grade furniture and not the Pleather (plastic leather) that falls apart in a year or two.

Look for better grades of carpet and adequate tires.  Do not accept chinese manufacture tires and make sure the tires are fresh by date code and are of adequate rating to carry the load.

We prefer the residential refrigerators with an battery bank and inverter over the troublesome RV gas electric refrigerators.  Look for a unit with a central water manifold with shut offs for each run.  Also look for a central coaxial TV and satellite distribution panel.  Dual pane windows are a must for us as well.  Automatic hydraulic leveling system is also a must.

Have fun looking.

Ken

 

Thx 

In no particular order, I'm looking at GD solitude, DRV mobile suite, Redwood, New Horizon, Luxe, Montana. All have floor plans we can live with. Now it's more about the quality of components used.

[rynosback]

40 minutes ago, askwines said:

Thx 

In no particular order, I'm looking at GD solitude, DRV mobile suite, Redwood, New Horizon, Luxe, Montana. All have floor plans we can live with. Now it's more about the quality of components used.

Not sure what information you are looking at about frames.  I believe only 3 of the above you listed have boxed frames and the remaining have I beam frames.  I went with a boxed frame as it is stronger.  Because of that it will be a heavier unit.  I also opted for the Moryde IS suspension. I believe that your money is best spent on the most upgraded foundation possiable. Best of luck on your search.

the previous poster has some good points.  

[askwines]

1 hour ago, TXiceman said:

Oh what a can of worms.  First off...what is your budget?  And generally you will be much better off buying a 3 to 5 year old used high end RV over a new entry level.  They will be 1/2 the cost of what they were new.

Look beyond the bling and glitz and look for quality build and finish.  For suspension, you cannot do better than the Mor/Ryde IS suspension.  We like all wood cabinets that are screwed together and drawers with dovetail construction.  Better grade furniture and not the Pleather (plastic leather) that falls apart in a year or two.

Look for better grades of carpet and adequate tires.  Do not accept chinese manufacture tires and make sure the tires are fresh by date code and are of adequate rating to carry the load.

We prefer the residential refrigerators with an battery bank and inverter over the troublesome RV gas electric refrigerators.  Look for a unit with a central water manifold with shut offs for each run.  Also look for a central coaxial TV and satellite distribution panel.  Dual pane windows are a must for us as well.  Automatic hydraulic leveling system is also a must.

Have fun looking.

Ken

 

Thx, aware of all the above. Figured I'd try building from bottom up and see where it leads me. Been looking at Solitudes, Redwood, Drv mobile suites, Luxe, Montana and New Horizons. In no particular order.

[ALLOY]

Tube or HSS (hollow structural section) is no stronger than I beam. Commercial trailers use I beam.  Both NH and Spacecraft use a combination of both. 

The easiest way to identify the strength of the chassis is by the depth....after that... the welding, connection between the upper deck and main frame, number of cross members, and length/spacing of outriggers.

The easiest way to test the strength of a frame is to lift (no weight in the trailer) the pin box until the front landing gear comes off the ground. If the pin box moves up more than 1" before the landing great comes off the ground its not a high mileage trailer with limited use off the pavement.    

 

 

[Jack Mayer]

Of the trailers you list New Horizons probably has the best infrastructure. It also costs the most.  You generally get what you pay for in RVs - bear that in mind. There are always budget tradeoffs of course.....you don't always need the "best".

The best frame structure will vary somewhat depending on the loads, but the combination of I beam (technically, H beam) and tubing is generally considered to be the best performing combination when dealing with heavier trailers. But even with that, if they are not well put together you will have issues. Good welds, and proper gusseting are required with any frame type. 

[spindrift]

1 hour ago, J-T said:

Tube or HSS (hollow structural section) is no stronger than I beam. Commercial trailers use I beam.  Both NH and Spacecraft use a combination of both. 

The easiest way to identify the strength of the chassis is by the depth....after that... the welding, connection between the upper deck and main frame, number of cross members, and length/spacing of outriggers.

The easiest way to test the strength of a frame is to lift (no weight in the trailer) the pin box until the front landing gear comes off the ground. If the pin box moves up more than 1" before the landing great comes off the ground its not a high mileage trailer with limited use off the pavement.    

 

 

Not trying to be a wise guy but can you provide supporting evidence for the 1" reference?

[GeorgiaHybrid]

2 hours ago, Jack Mayer said:

Of the trailers you list New Horizons probably has the best infrastructure. It also costs the most.  You generally get what you pay for in RVs - bear that in mind. There are always budget tradeoffs of course.....you don't always need the "best".

The best frame structure will vary somewhat depending on the loads, but the combination of I beam (technically, H beam) and tubing is generally considered to be the best performing combination when dealing with heavier trailers. But even with that, if they are not well put together you will have issues. Good welds, and proper gusseting are required with any frame type. 

 

3 hours ago, J-T said:

Tube or HSS (hollow structural section) is no stronger than I beam. Commercial trailers use I beam.  Both NH and Spacecraft use a combination of both. 

The easiest way to identify the strength of the chassis is by the depth....after that... the welding, connection between the upper deck and main frame, number of cross members, and length/spacing of outriggers.

The easiest way to test the strength of a frame is to lift (no weight in the trailer) the pin box until the front landing gear comes off the ground. If the pin box moves up more than 1" before the landing great comes off the ground its not a high mileage trailer with limited use off the pavement.    

 

 

Guys, I have to disagree a bit with both of you. A tube steel (HSS section) is magnitudes stronger than a wide flange beam in torsion. The old "I" beam (actually an American Standard "S" shape with tapered flanges) or an "H" shape (actually a Wide Flange Beam or "W" shape) will resist torsion a LOT less than a tube (actually a Hollow Structural Shape or HSS). You can box in a wide flange beam and create a shape somewhat better than a HSS due to the three vertical webs but that would be cost prohibitive due to the welding required.

As a general rule, the as the depth increases, the strength of the beam will increase but that will depend on the flange thickness and width to resist weak axis deformation and the depth and thickness of the web to resist vertical (strong axis) deflection. A good structural engineer will design a chassis to resist the forces required without becoming overly heavy even though a lot of them use the old adage "when in doubt, make it stout" when design a structural component.  

[ALLOY]

4 hours ago, spindrift said:

Not trying to be a wise guy but can you provide supporting evidence for the 1" reference?

The screws around/under/along front cap/bunk area were breaking/stripping on our trailer. This is when the pin box deflection was 1 3/4".  I asked a friend of mine who is a structural P.eng about it.  Deflections of L/240, L/360 L/480 are used most often. Our trailer was L/55. After adding some steel it is now L/140.

 

2 hours ago, GeorgiaHybrid said:

 

Guys, I have to disagree a bit with both of you. A tube steel (HSS section) is magnitudes stronger than a wide flange beam in torsion. The old "I" beam (actually an American Standard "S" shape with tapered flanges) or an "H" shape (actually a Wide Flange Beam or "W" shape) will resist torsion a LOT less than a tube (actually a Hollow Structural Shape or HSS). You can box in a wide flange beam and create a shape somewhat better than a HSS due to the three vertical webs but that would be cost prohibitive due to the welding required.

As a general rule, the as the depth increases, the strength of the beam will increase but that will depend on the flange thickness and width to resist weak axis deformation and the depth and thickness of the web to resist vertical (strong axis) deflection. A good structural engineer will design a chassis to resist the forces required without becoming overly heavy even though a lot of them use the old adage "when in doubt, make it stout" when design a structural component.  

HSS stronger in torsion but a chassis is an assembly of beams, sheet and plate each being chosen by engineering/availability/ cost/fabrication/welding.....a circle I've gone around more times than I can remember. 

 

 

 

 

 

 

 

 

 

[noteven]

A stiff chassis

[Second Chance]

23 hours ago, askwines said:

Thx 

In no particular order, I'm looking at GD solitude, DRV mobile suite, Redwood, New Horizon, Luxe, Montana. All have floor plans we can live with. Now it's more about the quality of components used.

Although the RV manufacturers writes the specs for the frames, Lippert makes the frames for both Grand Design and Montana. I believe a couple of the other makes you list build frames in-house (or "next door"). Lippert does not have a good reputation in the industry and, most recently, had serious problems with their solid axle suspension systems, bad grease seals, and poor assembly procedures resulting in greased brakes. I'm personally aware of only one frame failure with a Lippert chassis - on a 2006 Keystone Cambridge which was loaded a bit over GVWR.

We have a GD Reflection ("little sister" to the Solitude series). We had all the issues with the grease seals and brakes listed above plus a bent spindle that made the suspension impossible to align (causing severe tire wear and tracking issues). I agree with Ken and believe that you cannot do better than the MOR/ryde independent suspension with disc brakes... so that was our solution to the problem. I couldn't be happier with how the rig tows, handles and stops, now. GD has recently started sourcing some axle assemblies from Dexter, but I'm still not a fan of suspension technology that dates back to when my grandfathers were kids (and they were both born in the late 1800s...). 

All that being said, Grand Design and Montana are not in the same league as New Horizon, Luxe and others. We got what we paid for and are happy with it - but it's still a mid-level unit with a vastly upgraded foundation.

Rob

[TXiceman]

On 11/12/2017 at 4:00 PM, J-T said:

Tube or HSS (hollow structural section) is no stronger than I beam. Commercial trailers use I beam.  Both NH and Spacecraft use a combination of both. 

The easiest way to identify the strength of the chassis is by the depth....after that... the welding, connection between the upper deck and main frame, number of cross members, and length/spacing of outriggers.

The easiest way to test the strength of a frame is to lift (no weight in the trailer) the pin box until the front landing gear comes off the ground. If the pin box moves up more than 1" before the landing great comes off the ground its not a high mileage trailer with limited use off the pavement.    

 

 

You have to look at the structural cross section and the moment of inertia of the section.  A double stacked frame with two 2 x 6 boxes welded together is stronger than a single 12'" high I beam section for deflection in bending.  Look at your basic mechanical engineering.

Ken

[rynosback]

Which is better?  I guess it depends on who you ask....

https://m.youtube.com/watch?v=_f3CAnH7WIM

[ALLOY]

23 hours ago, TXiceman said:

You have to look at the structural cross section and the moment of inertia of the section.  A double stacked frame with two 2 x 6 boxes welded together is stronger than a single 12'" high I beam section for deflection in bending.  Look at your basic mechanical engineering.

Ken

Which ever fails last is stronger......but we don't know which failed first.

 

 

 

[Retired fire]

I owned a 2014 Montana 3402RL and experienced frame failure in several places.  First failure was in rear cross member, had this repaired and added additional support.  Second failure was becoming apparent with cracking of fiberglass and bowing of the interior moldings at entry door.  The unit was not overloaded and was taken care of with no off road use or out of the normal rough roads.

The Montana had an I beam frame that was apparently not designed to hold as well with real life use as I had hoped.  I purchased a newer fifthwheel with double stack tube frame.  Granted this unit is significantly heavier but after a year of use I have found no evidence of frame flex,. I hate to say it but it appears that in this case heavier built frame is better in practical use.  Even though some engineers will argue that their designs are lighter and "adequate" for designed use..

I totally agree that the bling and shine is what manufacturers try to sell but the most important part of the RV is the frame and under carriage along with its ability to perform in real world conditions.