Running Overweight with MORryde IS

[TMitt70]

Why not have Morryde install 9k axles if you are worried about weight? When we had our IS installed, another customer with a DRV Mobil Suites unit was there because he kept breaking the rubber bushings on the suspensions. His unit was 23k, 9k on each axle and 5k on the pin by scale. They upgraded the rubber bushings to 9k to fix the problem. Morryde IS is stock on DRV units.

I inquired about that before ours was installed. The 9K axles are a LOT heavier, stiffer and not suited for 12K to 22K GVWR trailers… According to Morryde. They told me that they would NOT install the 9K’s on our application.

[KamFlyer]

Off the wall suggestion... Have you thought about adding a 3rd axle? I don't know if it would be practical with your rig but I have seen it done on Solitudes.
Joshua at Rooted Off Grid has added a 3rd to his Solitude. And no, that isn't a 374TH.

He has a YouTube channel and is also on FB.
-Rob-

[BrokeDown]

We have almost exactly the same scenario. We have a ‘21 380 FL-R. It’s also a tandem axle trailer with a GVWR of 16,800. Our ‘as built’ weight is 15,570. Which only leaves a paltry 1,230 lbs of payload (not at all reasonable for someone who wants to spend months at a time living in their unit). We added 1,400 watts of solar, a big 48V LFP bank and a washer/dryer… so that burned up a sizable portion of our payload right away. Here’s where we are now:

Loaded (with about 40 gal of fresh water) our weights were recently as follows:

Front axle of truck: 5,080 lb
Drive axle of truck: 7,800 lb
Pin Weight: 3,550 lb (calculated from weighs with/without trailer)
Trailer Axle(s): 16,380 lb
GCWR: 29,260 lb

This makes the trailer GW a little under 20K. Like you, we have the Res fridge and a combo Washer/Dryer in the back. We can shed a few pounds (who can’t) and we can travel with less water (we will/do). But we’ll still be over the GVWR limit of 16,800 published by Grand Design. So here’s my reasoning why I don’t worry about it:

We’ve done the following upgrades:

- 8K Morryde IS and disc brakes
- Morryde rubber pin box
- Upgraded to Boar 19.5 wheels/tires (LRH Michelin commercial tires)
- Hensley Trailer-Saver BD5 suspended hitch

1). The Morryde IS is legit. It’s significantly overbuilt (I spoke with one of their tech’s specifically about the design and testing and weight ratings of the IS). It does an amazing job isolating road shock and significantly reduces impact impulses to the frame and build structure of the trailer.

2). The wheels/tires we selected are about 125 lbs each (500 lbs total). They’re a massive commercial couple with a long proven track record. This is NOT ‘sprung’ weight and does NOT load the axles (or the frame).

3). Our coach uses the same Lippert frame construction (12’ I-beam and 10’ drop frame) as the big Momentum 20K GVWR trailers. The difference is the number of axles (3 vs. 2) on these big TH’s.

4). The suspended BD5 hitch significantly (and I mean it’s a stark improvement) reduces road shock and impulse loads from crappy roads. We also have air bags on the truck which further dampens impulse load.

5). We load our trailer to keep the pin weight under 4K lbs (which is well within the recommended pin weight ranges for a 20K GVWR trailer (even within the range for a 16,800 trailer)

When you back out the weight (500 lbs) of wheels/tire, our effective axle(s) run weight is at/below 8K and we’ve done many things to mitigate impulse loading which contributes to long-term structure fatigue.

That said, I’m sure there will be plenty of people eager to tell me that I’m a menace to society (and that’s fine… Maybe I am.

I’m a pretty conservative person and (after a 30 year career in Aerospace/Mechanical design/testing/manufacturing) know a bit about Statics/Dynamics. I’m confident that I’ve engaged the appropriate diligence to operate our equipment safely without adverse longer term effects.

That’s my story and I’m sticking to it (unless someone convinces me otherwise

Love this post and my thinking too.

I heard a comment made by BTBRV in one of his videos. He said that weight distribution is more important with IS. He did not explain his reasoning???

I plan on putting our 900 lb golf card in the garage which I hope will lower the pin weight.

-B

[BrokeDown]

Why not have Morryde install 9k axles if you are worried about weight? When we had our IS installed, another customer with a DRV Mobil Suites unit was there because he kept breaking the rubber bushings on the suspensions. His unit was 23k, 9k on each axle and 5k on the pin by scale. They upgraded the rubber bushings to 9k to fix the problem. Morryde IS is stock on DRV units.

I asked MORryde about doing this. They will take 7,000-pound axles to 8,000 pounds, but they will not take 8,000 to 9,000. Also, the price of the 9,000 pound IS is triple the cost of the 8,000 pound IS.

[A.Texas.Yankee]

Love this post and my thinking too.

I heard a comment made by BTBRV in one of his videos. He said that weight distribution is more important with IS. He did not explain his reasoning???

I plan on putting our 900 lb golf card in the garage which I hope will lower the pin weight.

-B

It has to do with weight NOT being distributed between the wheels/suspension and over a tighter span of the frame. With a linked/leaf suspension, there is some physical weight/inertia deferred to adjacent axles as well as attachment points spread across a larger section of the frame.

The benefit of IS is the lack of connection and distribution (as well as just being constructed better) to other wheels/axles, offering a softer ride because that jolt is not distributed to the rest. But neither is the weight, so an unbalanced distribution will be felt by individual wheels more on the IS.

[BrokeDown]

Off the wall suggestion... Have you thought about adding a 3rd axle? I don't know if it would be practical with your rig but I have seen it done on Solitudes.
Joshua at Rooted Off Grid has added a 3rd to his Solitude. And no, that isn't a 374TH.

He has a YouTube channel and is also on FB.
-Rob-

That would give me piece-of-mind, but that will not change the GVWR. Just like adding the 8K IS to an RV that was built with 7K axles.... the GVWR does not change.

A friend just told me that her friend was recently stopped in CA and weighed. I am not sure what they would have done if the RV would have been overweight???

[CWSWine]

When I attended the Hershey RV show I talk to the product manager for Solitude and he said the GVWR is NOT based off the axles but on the frame. He said they order chassis based on GVWR and each GVWR has different frames designs and axles are selected to support the GVWR with a margin to cover different loading of the user within the GVWR of the frame.

[BrokeDown]

When I attended the Hershey RV show I talk to the product manager for Solitude and he said the GVWR is NOT based off the axles but on the frame. He said they order chassis based on GVWR and each GVWR has different frames designs and axles are selected to support the GVWR with a margin to cover different loading of the user within the GVWR of the frame.

He is not 100% correct. My GVWR changed when I upgraded to the 8K axles. The frame did not change. You can see this yourself on the GDRV website.

[BadDogPSD]

When I attended the Hershey RV show I talk to the product manager for Solitude and he said the GVWR is NOT based off the axles but on the frame. He said they order chassis based on GVWR and each GVWR has different frames designs and axles are selected to support the GVWR with a margin to cover different loading of the user within the GVWR of the frame.

Does this mean that units ordered with the upgraded axles option also get an upgraded frame?

[Second Chance]

I'm sure the consensus is not to go over weight, but as you stated, you're probably unable to accomplish more weight loss. My initial thought would be the Morryde IS would be better, but maybe you should call Morryde. Does Morryde weigh the RV before putting on the IS? If they do a pre-weigh, maybe it's not an issue if they can put on a suspension designed for your weight.

Yes - MORryde weighs before installation to determine which sheer springs, etc., to install. We were up there for the installation on our previous Reflection 337 and they didn't have to weight because I had wheel-by-wheel weights to hand them from the Escapees SmartWeigh folks - otherwise they would have weighed.

@BrokeDown - how are you determining your weights (what method/formula)?

Rob