Fact or Fiction: Oversized suspension is bad?

[Chaostactics]

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?

 

[jkwilson]

Hard to know where the line is. Eventually you will get to a suspension that is so stiff the trailer is absorbing the impacts.

 

[nprario]

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.

 

[traveldawg]

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?

 

[Scott'n'Wendy]

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.

 

[huntindog]

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

 

[Hoopy Frood]

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.

 

[huntindog]

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.

 

[Hoopy Frood]

Can't argue with that assumption since I have no alternative theory.

 

[SSROSS]

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.

 

[huntindog]

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?

I am not a fan of alignment for trailer axles.
For one, there is no alignment adjustments that can be made like there is for an automobile.
These shops BEND the axles to align them.
From the factory, a trailers alignment is set when the spring hangers are welded to the frame. If that is done properly then the axles will be aligned. Occasionally the hangers are misinstalled.
In this case the proper fix is to cut them off and install new hangers properly. Trying to fix misinstalled hangers by bending the axles into alignment can be done,..But the downside is that if such an axle becomes damaged later, a new replacement would need to be custom bent to match the original. It will also make it weaker. If this had been fixed by installing the hangers properly, one could just bolt up a new axle and be done. No need to find an alignment shop.
The other way for an axle to become unaligned is due to an accident or road hazard. Simply bending it back into spec leaves it weaker, and more prone to needing another alignment. Installing a heavier axle makes a more durable fix.
Alignments are not cheap either. Especially if it needs to be done agan and again.

As for the axle ratings,,,Many including myself think that they are to say the least, optimistic. GD seems to agree as some models have an option for heavier axles.
Best to upgrade to heavier axles installed with properly installed hangers, and be done with it.

 

[jkwilson]

I am not a fan of alignment for trailer axles.
For one, there is no alignment adjustments that can be made like there is for an automobile.
These shops BEND the axles to align them.
From the factory, a trailers alignment is set when the spring hangers are welded to the frame. If that is done properly then the axles will be aligned. Occasionally the hangers are misinstalled.
In this case the proper fix is to cut them off and install new hangers properly. Trying to fix misinstalled hangers by bending the axles into alignment can be done,..But the downside is that if such an axle becomes damaged later, a new replacement would need to be custom bent to match the original. It will also make it weaker. If this had been fixed by installing the hangers properly, one could just bolt up a new axle and be done. No need to find an alignment shop.
The other way for an axle to become unaligned is due to an accident or road hazard. Simply bending it back into spec leaves it weaker, and more prone to needing another alignment. Installing a heavier axle makes a more durable fix.
Alignments are not cheap either. Especially if it needs to be done agan and again.

As for the axle ratings,,,Many including myself think that they are to say the least, optimistic. GD seems to agree as some models have an option for heavier axles.
Best to upgrade to heavier axles installed with properly installed hangers, and be done with it.

My boat trailer had a bent spindle several years ago, and I called around and found a place that said they could align it. I put new tires on after they worked on it and measured tread depth at every groove when I brought the new tires home and after every trip. Several months later,it was obvious the tires were still wearing unevenly. They tried again and it still wasn’t right. Replaced the axle and the tires now age out before they wear out.

Measuring and bending an axle to correct problems is certainly possible, but it requires an obsessive level of measurement accuracy that you won’t find in the average trailer shop worker.

 

[traveldawg]

I am not a fan of alignment for trailer axles.
For one, there is no alignment adjustments that can be made like there is for an automobile.
These shops BEND the axles to align them.
From the factory, a trailers alignment is set when the spring hangers are welded to the frame. If that is done properly then the axles will be aligned. Occasionally the hangers are misinstalled.
In this case the proper fix is to cut them off and install new hangers properly. Trying to fix misinstalled hangers by bending the axles into alignment can be done,..But the downside is that if such an axle becomes damaged later, a new replacement would need to be custom bent to match the original. It will also make it weaker. If this had been fixed by installing the hangers properly, one could just bolt up a new axle and be done. No need to find an alignment shop.
The other way for an axle to become unaligned is due to an accident or road hazard. Simply bending it back into spec leaves it weaker, and more prone to needing another alignment. Installing a heavier axle makes a more durable fix.
Alignments are not cheap either. Especially if it needs to be done agan and again.

As for the axle ratings,,,Many including myself think that they are to say the least, optimistic. GD seems to agree as some models have an option for heavier axles.
Best to upgrade to heavier axles installed with properly installed hangers, and be done with it.

Lots of ifs ands or buts here….

We all make our choices. I’m still in the take it to a professional alignment shop and get an expert opinion.

 

[traveldawg]

My boat trailer had a bent spindle several years ago, and I called around and found a place that said they could align it. I put new tires on after they worked on it and measured tread depth at every groove when I brought the new tires home and after every trip. Several months later,it was obvious the tires were still wearing unevenly. They tried again and it still wasn’t right. Replaced the axle and the tires now age out before they wear out.

Measuring and bending an axle to correct problems is certainly possible, but it requires an obsessive level of measurement accuracy that you won’t find in the average trailer shop worker.

My one experience, and that of countless people who pointed in the direction of a profession trailer axel alignment shop, worked out great to resolve my odd tire wear pattern. They use to bend the axel manually but now prefer heating for the dead-on accuracy. They had alignment equipment that matched the best auto tire alignment shops.

 

[huntindog]

Lots of ifs ands or buts here….

We all make our choices. I’m still in the take it to a professional alignment shop and get an expert opinion.

It's your RV and your money.
Twice I have had catasthropic axle failures on the road far from home. If I previously had my axles bent to fix an alignment problem, I would have needed to find a shop that could bend the replacements into alignment, after the new axles were installed. It is unlikely that such a shop would have been close by. In my two cases I was able to simply replace the failed axles and continue my trip.

The mechanic in me believes that the root cause of any problem should be found and fixed.
Simply going to an alignment shop to have them bend the axles skips this important step.
However, I am sure there are shops out that are glad to take your money so they can "fix it" for you.
Often an "expert" has a different motivation. As in expertly getting paid, regardless of whether or not the service they sell is the best option.

 

[goducks14]

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?

What's your HF? Etrailer sells 86-1/2" HF
https://www.etrailer.com/Trailer-Axles/Dexter/8327816.html

You just cut off the spring perch and weld a new one on in the spot you need. BTDT with my TT. The issue you may run into is your rims are 5-5.5 vs 6-5.5 for 5200 lb axles. I'm not aware of 5 lug hubs with bearings that fit the 5200 lb axles. if there is then that will save you some big $$$$. If not then you'll need new rims and tires but you'll get bigger brakes with the 5200 lbs drums as they're 12"x2". Not sure if you have 14" rims or not but if you do then you'll need to add something to increase the ride height of the TT since you need 15" rims and tires to go on the new 6-5.5 15" rims.

 

[Ski Pro 3]

From personal experience, it's not weight that bends the axles, it's impact. In other words hitting something. Usually that something is a pot hole, but it could be a curb or cutting a corner and dropping into a rut along the road. Also, rather than bent axle tubes, I've found the spring shackles (hangers) are more prone to becoming bent and even busted off. They are simple U shaped thin bands of metal with a hole in them for the leaf spring bolt to attach through. But boxing in the U shape with a flat stock of steel welded, and some triangle flanges, they are much better at staying true. I've also had and seen done, a length of angle iron welded from left side to right side shackle for better strength and to keep flex, that leads to bend and break of the hanger.

 

[Hoopy Frood]

From personal experience, it's not weight that bends the axles, it's impact. In other words hitting something. Usually that something is a pot hole, but it could be a curb or cutting a corner and dropping into a rut along the road. Also, rather than bent axle tubes, I've found the spring shackles (hangers) are more prone to becoming bent and even busted off. They are simple U shaped thin bands of metal with a hole in them for the leaf spring bolt to attach through. But boxing in the U shape with a flat stock of steel welded, and some triangle flanges, they are much better at staying true. I've also had and seen done, a length of angle iron welded from left side to right side shackle for better strength and to keep flex, that leads to bend and break of the hanger.

Pretty good thoughts, but sometimes reinforcing the hangers incorrectly can lead to flexing of the entire hanger, with the result the complete hanger breaks off the frame.

 

[Ski Pro 3]

Pretty good thoughts, but sometimes reinforcing the hangers incorrectly can lead to flexing of the entire hanger, with the result the complete hanger breaks off the frame.

In my case, my brother's actually, the hangers did break, which lead to the realization they are pretty light metal and longer than necessary to gain height clearance. Two broke, which led to severe wear on the tires before they were replaced with heavier duty ones and the side-to-side angle iron brace was installed.

But you are right: it takes some mechanical understanding on how to properly reinforce the shackles without weakening them further. It's not a hard task to accomplish though. Harbor Freight sells a flux core welder for around $150, and cheaper with sales. Lots of YouTube videos on how to use the welder, even if you've never welded in your life. For around $300 in welder, accessories and angle iron, it wasn't hard to greatly improve the stiffness of the axle mounts.

EDIT
The welder is small enough to take along and can easily run off my AC inverter, letting me weld just about anywhere, any time.

 

[dbphillips]

I'll admit you didn't give us enough details to really know ?, but look here: https://legacy.granddesignrv.com/iframe/parts-detail/40477
https://www.granddesignrv.com/owners/resources/parts-lookup
2600RB axles were upgraded literally the year your trailer was built.