Brought home my new Momentum 336M. Added Reese Goose Box.

[Doogie]

Picked up my new rig on Saturday. Had them put on the Reese Goose Box before I drove away.

Going to post for my experience and hoping to get some feedback as well.

1) The 2 1/2" shank is too high on the B&W ball setup. I'm already sending it back and getting the Reese with the 1/2" shank. The ground clearance is 20" at level. With the B&W the ground clearance was 24" in the front and 14" at the rear and the bed side rail clearance was 9". I'll see how much the change raises the backend.

2) The Reese Goose Box attach point is 6" further forward (longer) than the Rhino Pin Box. Normally, my tailgate would have 2-3" of clearance with my old rig (29RS) if I was straight. If I was slightly turned when disconnecting I would have to disengage the king pin and then lower my tailgate. With the Goose Box I have an additional 6" of clearance from truck to camper.

3) I took the rig straight to the scale from the dealer. I know my F350 dually is about 8,900 lbs. I came in at 25,120 lbs. WTH? That makes the camper unloaded 16,200! I went back to the scale and confirmed the truck is 8,920. The UVW is supposed to be 14,200 with a GVWR of 17,000. And the sticker on the side says 10,606 lbs. UVW. Truck front end went from 5,080 to 5,040 and rear went from 3,840 to 7,540. leaving 12,540 on the trailer axles. How do you go from a sticker of 10,606 to 16,200? Full propane bottles. 1/3 of a gray tank, 2/3 of fresh water tank (why so much dealer). 15 gallons gray and 72 gallons of fresh @ 8 lbs. a gallon is 700 lbs. of water. Propane tanks @ 55 lbs. each is 110. 7 gallons of gas in the aux tank, 56 lbs. A mattress? at 40 lbs. 2 A/Cs, 150 lbs. Onan genny 288 lbs. That's maybe 1,400 lbs possible. It's gonna be overweight before I even load my 700 lb. motorcycle. The goose box weighs about 170 lbs. more than the rhino box so I don't think that shouldn't go against the GVWR of the camper (the box supports the frame, not the other way around).

4) It porpoised all the way home, about 50 miles. Not just off bumps, but going down the highway at 58 mph. Not sure if the 2 1/2" high ball contributed, the truck tire pressure (60 in the rear), the 6" additional offset of the goose box, weight distribution, other? The goose box was aired up to the right level with the line in the window. I'm going to take it back to the scale when I get the new lower ball this week and see if that changes the ride as well as double check that the scale was accurate (I'll go to another scale).

5) I'm also trying to connect the compass app to the system but it's not giving me the pin number on the display when I select the camper. The app says another way to connect is to find the gateway which is in a cabinet in the kitchen and looks like a modem. I've looked everywhere and can't find it.

I'll add to this thread as I work through the issues and keep you posted. Any additional insight is appreciated.

 

[triplethreat]

What sticker and where is the number 10,606? Something is obviously wrong with that number. UVW on the website shows the 14,200 that you mention.

 

[Doogie]

What sticker and where is the number 10,606? Something is obviously wrong with that number. UVW on the website shows the 14,200 that you mention.

under the tire and loading sticker on the drivers side.

 

[BadDogPSD]

Is there room to raise the Goosebox ? Was the pressure correctly set in the airbag? I had to mount mine all the way up. My 351M is slightly nose up when hitched to the F450 and tows great.

 

[Doogie]

I could get another inch out of it if I cut the plastic trim around the top of the frame mount (underside of the camper). There is one more set of bolt holes but can't use them with the plastic trim around the frame mount. I'm gonna try a few different things, like the lower ball and air pressure in the tires, before I do that.

The air pressure in the goose box is set right in the middle. I might adjust that up and down where I can still see the line but not have it dead center in the window.

 

[triplethreat]

under the tire and loading sticker on the drivers side.View attachment 49821

I'd suggest getting in contact with Grand Design about the discrepancy with the numbers. Both the GVWR and the UVW are different from their website numbers. It looks like yours is a 2023 model by the partial VIN number, but something is not right with an almost 3600 lb discrepancy in the UVW numbers. Even the GVWR is off by 200 lbs, unless that maybe changed from a 2023 to 2024 model year.....if there is a 2024 model year.

Make sure when you call them that you have the model and VIN number available to give to them.

 

[huntr70]

under the tire and loading sticker on the drivers side.View attachment 49821

Yeah, the sticker is wrong. There hasn't been a Momentum made that has 6000 lbs of capacity......especially a front living room model.

 

[triplethreat]

Yeah, the sticker is wrong. There hasn't been a Momentum made that has 6000 lbs of capacity......especially a front living room model.

True that ^^^ My 2018 Momentum 394M had about 4500 lbs of payload or Cargo Capacity and I was elated to get something with that much cargo capacity. Triple axles (7000 lb/each) and 6 tires with a 4080 lb load capacity when inflated to the 110 psi number, and hopefully a frame that was strong enough to make that happen. It's 5 years old now and knock on wood.......no issues so far.

 

[jeririgged223]

I'm just guessing here, but it seems your UVW has got to be wrong.

I have essentially the same Momentum, with the "single veh garage" as we call it, in the 376TH model. At only 4 ft longer than yours my UVW is 16,474 with a generator, 3 ACS, etc No way that 4 ft weighs 6,000 lbs. When I loaded it and took it to the scales, with our Harley Ultra in it, the trailer only came in 120 shy of our 20,000 lbs GVWR

Did you disconnect the trailer and weigh it by itself. We always do. We weigh the truck alone, the trailer alone and the truck / trailer for pin wt.

 

[lorend]

I could get another inch out of it if I cut the plastic trim around the top of the frame mount (underside of the camper). There is one more set of bolt holes but can't use them with the plastic trim around the frame mount. I'm gonna try a few different things, like the lower ball and air pressure in the tires, before I do that.

The air pressure in the goose box is set right in the middle. I might adjust that up and down where I can still see the line but not have it dead center in the window.

Have you also checked what the ratings are on your rear truck tires? 60 psi sounds kind of light on pressure. I know my truck tires have a max 80psi and I usually run them around 73 when towing my rv, which is a lot lighter than yours. When just around town the 60 pressure gives a smoother ride but maybe that pressure is light for towing that heavy of a rv.

 

[jeririgged223]

Everyone thinking about this kind of modification should watch these two Lippert videos about frame flex.
By extending the length of the front you add to the frame stress and they are finding it is causing problems because it causes the "house" to come apart.
If you replace it with the same length pin box connections as it comes from the factory, there see little problem
But extending the length, changes the stress points.

Part 1
https://www.youtube.com/watch?v=GF-lsJ7c8vg

Part 2
https://www.youtube.com/watch?v=UiumIq0OBpE

 

[Doogie]

So here is my follow up:

1) I switched to the low profile Reese hitch but it only made a slight change to the clearance in the back. maybe a little more than 15".

2) I spoke with a Supervising Frame/Chassis tech at Lippert. He basically said the model I have connects at the front of the main framing giving additional space between the kingpin/ball hitch and the trailer. The reason for the shorter Rhino box is because they can use a shorter pin box, not because they have to use a shorter pin box. So there is no concern with the Reese Goose Box. My clearance with the tailgate down is now 14" and with the tailgate up is 31". Should help with disconnecting where I can't get completely straight and still be able to drop the tail gate most of the time.

3) Figured out most of the problem. There was 1,000 lbs of water in the camper when I left the dealer. I emptied the fresh water and the other holding tanks and went back to the scale. Weighed in at 23,980 total. The gas in truck was the same and without DW the net for the camper came out to 15,180. Figuring in the Goose Box, propane tanks w/gas, and the 5500 generator, that leaves about 400 lbs. in mystery weight over the advertised 14,200 dry weight. I can live with that.

4) I aired up the rear truck tires to about 75 psi. This helped with most of the porpoising, but the new camper is a beast compared to my old camper and I think the heavier load is something I'm going to need to get used to. I might add extended overload spring bump stops to the truck to see if that helps but not planning to do rear air bags as I don't want to raise up the back of the truck (and thus lowering the back of the camper). I guess if it was setup with in cab controller then I could air down when I was concerned about ground clearance and keep it up for freeway driving. Maybe after a few more miles I'll decide. I've had them on other trucks so I know the benefits.

5) Found the paperwork and got the compass app to work. It's cool.

I setup a Bolt It On tie down system for my bike in the back. It's awesome. I'll attach some pictures. Finally gave the go ahead to the wife to start loading up the camper now that I know the true dry weight.

 

[Doogie]

Bolt It On system

 

[Doogie]

Everyone thinking about this kind of modification should watch these two Lippert videos about frame flex.
By extending the length of the front you add to the frame stress and they are finding it is causing problems because it causes the "house" to come apart.
If you replace it with the same length pin box connections as it comes from the factory, there see little problem
But extending the length, changes the stress points.

Part 1
https://www.youtube.com/watch?v=GF-lsJ7c8vg

Part 2
https://www.youtube.com/watch?v=UiumIq0OBpE

I spoke with a Supervising Frame/Chassis tech at Lippert. He basically said the model I have connects at the front of the main framing giving additional space between the kingpin/ball hitch and the trailer. The reason for the shorter Rhino box is because they can use a shorter pin box, not because they have to use a shorter pin box. So there is no concern with the Reese Goose Box. My clearance with the tailgate down is now 14" and with the tailgate up is 31". Should help with disconnecting where I can't get completely straight and still be able to drop the tail gate most of the time.

 

[Wileykid]

3) Figured out most of the problem. There was 1,000 lbs of water in the camper when I left the dealer. I emptied the fresh water and the other holding tanks and went back to the scale. Weighed in at 23,980 total. The gas in truck was the same and without DW the net for the camper came out to 15,180. Figuring in the Goose Box, propane tanks w/gas, and the 5500 generator, that leaves about 400 lbs. in mystery weight over the advertised 14,200 dry weight. I can live with that.

As I understand it, the factory does not include the battery/propane bottles, and whatever else is not bolted down in the empty weight, so although not 400 lbs, there is some of it.

Like your bike, owned one for a number of years and loved it. One of the bikes I regret selling.

 

[Doogie]

Thanks. I did take the propane bottles into consideration but not the batteries.

I do love my ST1300...