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  1. #1
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    Fact or Fiction: Oversized suspension is bad?

    For the second time in 2 years I have a bent axle on my 2019 Imagine Grand Design 26' bumper pull. I've not ever had it overloaded not even close as I'd been camping in places with facilities and bottled water so the tanks haven't been used. Last I weighed it it was a few hundred lbs below rated GVWR of 6695#.



    It's got Dexter 3500# axles x 2.



    I'm considering adding some more lithium and doing some boondocking on BLM roads with the terrain that comes with it (albeit only a couple of times a year) where I'd have more provisions and loaded tanks.



    No one seems to make 4-4.5k axles in my HF/SC. I've been considering paying the expense of going to 5k axles one dealer and one shop says go for it another shop and some other campers say over sizing the axles that much can cause damage to the trailer and instability when towing especially if towing closer to empty weight than full GVWR.



    So is it fact or fiction up sizing the axles will cause more harm than good? Is there solid evidence beyond anecdotal reports that support/refute this?

  2. #2
    Site Sponsor
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    Hard to know where the line is. Eventually you will get to a suspension that is so stiff the trailer is absorbing the impacts.
    John & Kathy
    2014 F250 Lariat FX4 6.2L SBCC
    2014 Reflection 303RLS
    SW Indiana

  3. #3
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    I don't think the axles themselves would cause anything to create damage. To stiff of springs on the other hand could create a rougher ride and possibly some instability on BLM roads. I had the same problem with my 5th wheel bending axles and went to 7,000 thick wall axles instead of the 5,200 paper thin ones I had but kept the springs the same. I don't load any heavier and am within my GVW rating on the trailer. The one dealer may just be playing it safe because some people would thing now I can load heavier with the bigger axles and of course that is not the case. GVW does not change because it the the factory that sets that by unit. In my simple mind stronger is better as the factory operates from a 'barely adequate' mindset and that does not cut it especially on the crappy roads we all have to deal with and I'm not talking about the BLM roads.
    2022 Silverado 3500 SRW 4x4 Crew Cab Duramax with BW OEM non slide hitch
    2022 Reflection 31MB w custom 7000# axles, dual panhard rods and G rate tires.

  4. #4
    Site Team Member traveldawg's Avatar
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    I'm hardly the expert on any of this but a few things come to mind....

    Axels should not bend if not overloaded.

    Axels should be rated to carry the weight expected; maybe a bit more, but not a lot more or I would think the frame starts taking a beating (along with things inside).

    Is the weight on the axels near their rating (requires a weighing of the axes when hooked and weight distribution adjusted - not total trailer weight). I think weight distribution can actually load the axels more or less depending on the WD adjustment.

    Have you asked your local axel shop for advice (or for a reason your axels continue to bend). And, while there, have you had your axels aligned?
    Larry KE4DMG
    2022 F-350 KRU SRW LB - Airlift 5000+, ForScan, 37 RDS Aux Tank,
    2019 310GK-R - Sailuns; MorRyde IS; Disc Brakes; 20K Reese Goosebox
    Search kalakamods for my mods


  5. #5
    Long Hauler
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    You can easily go to 5200 pound axles but size the leaf springs to still match the weight of 'the box'. The only suspension stat you will be affecting is unsprung weight. I don't know the weight difference between 3500 and 5200 pound axles, but I'd be surprised if it was more than 200 pounds for the pair... not much difference to the overall trailer. I'd still go find the actual weight difference to be sure.
    2018 Dodge 3500 6.7 Cummins SRW w/Aisin
    2021 Reflection 303RLS
    New to RV'ing since 1997

  6. #6
    Long Hauler huntindog's Avatar
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    Quote Originally Posted by Chaostactics View Post
    For the second time in 2 years I have a bent axle on my 2019 Imagine Grand Design 26' bumper pull. I've not ever had it overloaded not even close as I'd been camping in places with facilities and bottled water so the tanks haven't been used. Last I weighed it it was a few hundred lbs below rated GVWR of 6695#.



    It's got Dexter 3500# axles x 2.



    I'm considering adding some more lithium and doing some boondocking on BLM roads with the terrain that comes with it (albeit only a couple of times a year) where I'd have more provisions and loaded tanks.



    No one seems to make 4-4.5k axles in my HF/SC. I've been considering paying the expense of going to 5k axles one dealer and one shop says go for it another shop and some other campers say over sizing the axles that much can cause damage to the trailer and instability when towing especially if towing closer to empty weight than full GVWR.



    So is it fact or fiction up sizing the axles will cause more harm than good? Is there solid evidence beyond anecdotal reports that support/refute this?
    IME, there is no problem in increasing axles/springs size. I have beefed up the running gear on my first 3 TTs with good results. There are just too many reports of broken springs and bent axles to ignore. My last TT a 2010 Palomino Sabre came with 5200# axles. When they failed, I installed 7000# axles/springs. That unit had a 11,500# GVWR.
    No more failures or any other issues as long as I owned it.
    My present Momentum was to have three 7000# axles. GD made 8K axles available as an option, and I was able to get them added onto my order. So GD seems to think that over rated running gear is OK. Hopefully I will not need to upgrade this unit to get reliable running gear. So far, so good
    2021 398M Full Body Paint 8k axles. LRH tires. Disc brakes.
    Two bathrooms, no waiting 155 fresh, 104 black, 104 grey 1860 watts solar.
    800AH BattleBorn Batteries No campgrounds 100% boondocking
    2020 Silverado High Country 3500 dually crewcab Duramax Allison

  7. #7
    King Pin
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    The only thing I can see that would happen concerns the camber of the axles: I believe axles have a camber, and I would wonder if heavier rated axles would not flatten out with regards to their camber. But I'm no expert, not by a long shot, and don't really know. But it seems to me that axles have a camber for a reason. Just not sure if it would be an issue.
    Howard and Peggy
    2019 Momentum 351M, and 2018 RAM Cummins dually 6-speed.
    His: 1999 Honda Interceptor
    Hers: 2013 Spyder ST-S

  8. #8
    Long Hauler huntindog's Avatar
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    Quote Originally Posted by Hoopy Frood View Post
    The only thing I can see that would happen concerns the camber of the axles: I believe axles have a camber, and I would wonder if heavier rated axles would not flatten out with regards to their camber. But I'm no expert, not by a long shot, and don't really know. But it seems to me that axles have a camber for a reason. Just not sure if it would be an issue.
    I think that the camber is there mainly because the wheels move up and down independantly, but when say the left side hits a bump, the right sides alignment is affected.
    It's not a very precise system but seems to work OK as long as the axle is not bent out of spec...
    At any rate, my experience upsizing my running gear over 30+ years and 4 trailers has not proven to be a problem at all....Just the opposite.
    2021 398M Full Body Paint 8k axles. LRH tires. Disc brakes.
    Two bathrooms, no waiting 155 fresh, 104 black, 104 grey 1860 watts solar.
    800AH BattleBorn Batteries No campgrounds 100% boondocking
    2020 Silverado High Country 3500 dually crewcab Duramax Allison

  9. #9
    King Pin
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    Can't argue with that assumption since I have no alternative theory.
    Howard and Peggy
    2019 Momentum 351M, and 2018 RAM Cummins dually 6-speed.
    His: 1999 Honda Interceptor
    Hers: 2013 Spyder ST-S

  10. #10
    Site Sponsor
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    I went through four axels in a year and a half, and after talking to a trailer shop I upgraded to 7k axles and the Road Master kit. I have put 6,000 miles on it since and have no problems. I was told the other thing that bends axels are sharp turns that we sometimes have to make to get our rigs into a camp or parking spot. I was told the slipper spring setup on the Road Master kit helps alleviate that stress on the axels. I am no expert on this and that is why I went to a couple of shops for advice. So far I have found my trailer tracks down the road a lot better and we find less stuff laying on the floor or knocked over in the fridge since the install of the new suspension. I do know the wall thickness on my old axels which were 5.2k are a lot thinner than my 7k axles and there was a definite weight difference when you picked them up. Everything on my 5.2k axels swapped over to my 7k axels which was nice.
    2020 303RLS
    2018 Dodge 2500 Cummins
    BW Companion
    Retired and loving it.

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