Undersized axles on Momentum 320G or just poor design?

[howson]

GDRV-Megan -- pls see question in post 30.

[OffToHavasu]

Can't say for certain, but structural changes may have happened to the frame when they added the option. Lippert, who makes and warranties the frame, may have said, "No go" for larger rating on older frames.

[Guest]

This reminds me of the Imagine upgrade from 3500lb axles to 4400lb axles due to flat springs.

Jim

[GDRV-Megan]

So someone commented on my thread from another forum today. Apparently GD has now added the option to upgrade for 8K lb axles with disk brakes to the 320G for a reasonable $5K.

This has me scratching my head since customer service told me they don't recommend doing this. How is it different now that GD has the factory option to do this? Is this something that I can hire GD to do to my trailer now that it's an option?

I'm sorry, but I'm not sure who you spoke with in customer service who told you that you aren't able to upgrade your axles and brakes. There are no changes to the frame, the axle hanger brackets are still in the same location. The only change was that we added the actuator and the brake lines to each of the wheels for the disc brakes.

[RoyB]

I'm sorry, but I'm not sure who you spoke with in customer service who told you that you aren't able to upgrade your axles and brakes. There are no changes to the frame, the axle hanger brackets are still in the same location. The only change was that we added the actuator and the brake lines to each of the wheels for the disc brakes.

Megan, that is good news. This was the actual email I received (from generic customer service email) , regarding relocating the fresh water and the axle upgrades:

Hello Roy, hope all is well otherwise,

Our apologies for the delay in response. I do appreciate your concern about your weight concerns on your Momentum 320. The 351 M has a Longer D/S slide so the rams on the frame are further apart. There is no room to relocate the water tank on the 320G,so that is why it is located there.


In your request about adding larger axles, we do not recommend doing that. If you add larger axles and then put more weight in the RV, over time it is likely it will affect the main frame and cause frame camber issues.

Customer Service
Grand Design RV
11356 County RD 2 Middlebury IN 46540
Phone: 574-825-9679
Fax: 574-825-9249


Is this something that you recommend a dealer doing, or is it even possible to bring it to the factory to do?

[GDRV-Megan]

RoyB I'm not sure who would have sent that email, but will send a copy over to our customer service manager, so they are aware of these types of statements that are being sent to customers. I personally have seen customers upgrade their axles and suspension many times throughout my RV career. This is a very common upgrade. The issue that I can think of is that if you go too large of an upgrade, say going from 3500 lb axles to a 5000 lb axle, you will have some major structural issues as the frame is not rated for these types of upgrades. But if you're going from a 3200 lb axle to a 4000 lb axle, there is no harm done here. You just want to be sure you upgrade all of the suspension hardware to accommodate that axle upgrade. Another thing that I would note is that if you were to upgrade your axles, your GVWR rating will remain the same. We do not have the ability to adjust the GVWR after a unit is built.

I used to work for Lippert Components in the service center. They would do these types of upgrades all day long. You could contact them directly to have this done there. You could also contact a dealer. I know Performance Trailer Braking does these upgrades as well. There are many options to go to. I would recommend seeking other RVers' advice though to get some reviews.

[Villager]

Thanks to all that have posted on this topic! Based on the discussion, we decided to upgrade to the 8,000 lb axles and disc brakes on our existing order for a 2021 320G.

[Jlawles2]

RoyB, you might be surprised to learn that a lot of the axle components fall into a "range" of use. Unless you change ranges of axles, it may be more simple to upgrade the axle than you think. Within a "range" the axles are the same, the leaf springs and hubs are different. If you change "ranges" then everything changes.

After experiencing problems with an axle, I did a lot of research as I was considering changing from grease to oil bath bearings.

[espayne]

I found this post by searching. I have a 2021 320G I got in October 2020. Had it built with most options available in May 2020. Cat scaled the fifth wheel and truck to see my weight with it full of water, propane, gas, generator and a CanAm Maverick xrc just like in the brochure. Gross Weight 25280 pounds. Trailer axle weight 14780 lb. Weighed truck separately and weighed 8500lb even. Hitch weight is 2000 lb. Total weight for trailer is 16780 lb. Gross weight is rated at 16800 lb. Under by 20lb. Axles are definitely overloaded. Do you think Grand Design or Lippert would help pay the expense to get the correct axles put in as they are now a option on the same 2021 320G?

[howson]

I found this post by searching. I have a 2021 320G I got in October 2020. Had it built with most options available in May 2020. Cat scaled the fifth wheel and truck to see my weight with it full of water, propane, gas, generator and a CanAm Maverick xrc just like in the brochure. Gross Weight 25280 pounds. Trailer axle weight 14780 lb. Weighed truck separately and weighed 8500lb even. Hitch weight is 2000 lb. Total weight for trailer is 16780 lb. Gross weight is rated at 16800 lb. Under by 20lb. Axles are definitely overloaded. Do you think Grand Design or Lippert would help pay the expense to get the correct axles put in as they are now a option on the same 2021 320G?

It won't hurt to call GD Customer Service. No idea what answer you'll get...

[Wileykid]

I was the one that informed RoyB of the (new) option of the 8K lb axles, as I ordered mine with them in early February due to his writing on another forum.

As to his comment on a better balanced trailer, I just did my first trip with my new 320G. Here are some numbers that I got.

Factory: UVW: 13,078
Pin: 2510 (19%)

My numbers (CAT scale) with little less than a 1/4 tank of gas, misc junk/clothing/pots pans..etc. Originally started out with about 20 gallons of water, but most siphoned off somewhere in the trip. A 460 lb motorcycle, and I put on a Reese Sidewinder, which weighs about 150 lbs more than the stock pin box:

Trailer weight: 14,460
Pin: 2520 (17%)

To the balance, I would like more pin weight, but not excited about filling the forward black or grey tank on the trip home. Almost think I should replace the mattress with a water bed...

[howson]

Villager -- I moved your post to its own thread. You'll find it here: https://gdrvowners.com/towing-and-hi...have-questions Towing Newbie - I Have Questions

[Guest]

RoyB I'm not sure who would have sent that email, but will send a copy over to our customer service manager, so they are aware of these types of statements that are being sent to customers. I personally have seen customers upgrade their axles and suspension many times throughout my RV career. This is a very common upgrade. The issue that I can think of is that if you go too large of an upgrade, say going from 3500 lb axles to a 5000 lb axle, you will have some major structural issues as the frame is not rated for these types of upgrades. But if you're going from a 3200 lb axle to a 4000 lb axle, there is no harm done here. You just want to be sure you upgrade all of the suspension hardware to accommodate that axle upgrade. Another thing that I would note is that if you were to upgrade your axles, your GVWR rating will remain the same. We do not have the ability to adjust the GVWR after a unit is built.

I used to work for Lippert Components in the service center. They would do these types of upgrades all day long. You could contact them directly to have this done there. You could also contact a dealer. I know Performance Trailer Braking does these upgrades as well. There are many options to go to. I would recommend seeking other RVers' advice though to get some reviews.

In the email he mentioned adding additional weight. If higher capacity axles are used and a customer adds more weight based on axle rating, the frame could indeed be compromised. So to use a higher capacity axle and stay within the limits of the tag that lists GVWR, the higher capacity axle would be fine. Just want to point our his language in adding weight. I was once told not to upgrade to 2200lb springs on my Imagine that the frame would be compromised. Then I began to see folks getting approval for doing so. Then GDRV upgrades all units with 2200lb springs and 4400lb axles, and E rated tires. I can honestly state, I felt a little burned after that.

Jim

[RoyB]

I found this post by searching. I have a 2021 320G I got in October 2020. Had it built with most options available in May 2020. Cat scaled the fifth wheel and truck to see my weight with it full of water, propane, gas, generator and a CanAm Maverick xrc just like in the brochure. Gross Weight 25280 pounds. Trailer axle weight 14780 lb. Weighed truck separately and weighed 8500lb even. Hitch weight is 2000 lb. Total weight for trailer is 16780 lb. Gross weight is rated at 16800 lb. Under by 20lb. Axles are definitely overloaded. Do you think Grand Design or Lippert would help pay the expense to get the correct axles put in as they are now a option on the same 2021 320G?

Not likely since it's still a pay upgrade from the factory. RV dealers are slammed with all the new sales and everyone is non responsive. I looked at ordering new and upgrading and selling mine, but I couldn't justify the 2 year loss in value.

[chikenstiker]

RoyB Can I ask what you ended up doing with your trailer/truck situation? I am having the same issue as you with A LOT of sway on the highway and downhills. I've had the 320G to the dealer and GD had the measure a bunch of frame and axle dimensions which all came out correct, so they told me to tow without Water in the tank. I bought this expensive rid to camp in the middle of nowhere and bring dirt bikes. We don't wet camp, we're always in the sticks and it would be a great hassle to not carry water and then find a place at 10 PM at night on the way before we turn off the main roads and god forbid we need water a long the way for an emergency or bathroom break.

I feel like this is just a bad design and needs to come with 8000 lbs axles from the factory and debating if that upgrade would help?

Went camping last weekend with 3 dirt bikes in the back (usually I have 4 but ACL surgery so I'm down a few more months) and I moved as much weight as I could forward (Gear Bags in Front Bedroom, wheel chalks in Propane tank cubby) AND I brought some heavy steel targets so gimpy could shoot while family was out riding.

CAT Scales

Axles 14,340 (340 lbs over and that's a bike short of all other trips)
Pin 2,480
Pin Ration 14.7%

Trip was horrible on sway and white knuckled on 5,000' decent!

Dumped all water and Grey for ride and sway controllable, but still not what I'd expect from a 5th wheel and again that was with extra weight in the front and one bike missing.

So do I upgrade to an F450 and hope the extra Payload and Stability are enough? Do I sell this camper and go another route or back to a tow behind??? Decisions......

Side Note, I realize the truck is not enough now. I really thought an F-350 XLT was enough truck, but I was 800 lbs over Gross at the same time as not having enough pin weight....