flexiride 2,000lb or 3,500lb half axles

[Brankulo]

trying to decide which half axles to get for the build. 2k one comes with 7" brakes, 3.5k one with 10".
if i get 3.5k one and the build weight is nowhere near that would that cause any issues? im thinking from future proof standpoint i should go with larger capacity axles and bigger breaks.
my trailer size will be 8'x5'. based on the calculation method i saw in other thread, using length x width x 25 formula, the weight comes to 1000lbs. but i assume this is just weight of the trailer and wood structure?
i am planning on having battery, water supply, roof top tent plus some misc stuff. but even with all that seems like 2k would be sufficient. but 3.5k being just a bit more it makes more sense.
also, any idea on how 7" brakes perform vs 10" brakes on this type of trailers?

[tony.latham]

if i get 3.5k one and the build weight is nowhere near that, would that cause any issues?

Your camper will bounce like an empty dump truck ––as if it has no suspension.

My last three teardrops are fitted with 2200-pound Dexter torsion axles down rated to 1600 pounds, and they ride great. They weigh about 1330 pounds unloaded and probably 1450 loaded and ready to camp.

Tony

[Brankulo]

i assume the spring curve for axles is not adjustable on half torsion axles. sort of like mtb shock. prob works with air suspension only. i guess 2k axles i better fit then.

thanks

[tony.latham]

i guess 2k axles i better fit then.

For sure.

Tony

[Brankulo]

also, this just occurred to me, so before i pull the trigger i thought i would pick people brains on this.
so say your square drop is 1,600 lbs. on 2k axles, that is 1000 lbs per axle. no problem on nice paved roads or dirt roads.
on rugged backcountry roads though, there might come situations when the trailer is leaned to the point that majority of weight is
on one side. for example you could have 1200lbs on single 1k axle. that plus going bumpy road will result in impacts that would result in even more force imposed to single axle.
not sure if that is even possible real time scenario, but how much more can you load the axle past its listed limit before you get into trouble?
i am also wandering, if these torsion axles have same ride characteristics as leaf spring axles. from my research, it seems that torsion axles
seem to absorb more of the bump and resist the bounce afterwards, as compared to same rated leaf spring axles.

[Onajourney]

on rugged backcountry roads though, there might come situations when the trailer is leaned to the point that majority of weight is
on one side.

You bring up an interesting scenario although I think it is extremely unlikely for most. I also think if the manufacturer states they are rated to say 1K lbs, they probably have a sizable safety buffer calculated in that figure..like 25-50%. I have 2K lb rated torsions on my off-road trailer that weighs about 1700lbs.I have a had it on the road and rough trails and they have worked great for almost a year. Very smooth. I feel they are a good match for my setup. As Tony mentioned, any stiffer I'd guess my plates, bowls, and glasses would be busted, and they're all plastic. LOL.

[working on it]

...

• 1) so say your square drop is 1,600 lbs. on 2k axles, that is 1000 lbs per axle. no problem on nice paved roads or dirt roads.
  on rugged backcountry roads though, there might come situations when the trailer is leaned to the point that majority of weight is on one side. for example you could have 1200lbs on single 1k axle. that plus going bumpy road will result in impacts that would result in even more force imposed to single axle.
  
  not sure if that is even possible real time scenario, but how much more can you load the axle past its listed limit before you get into trouble?
  
  
• 2) i am also wandering, if these torsion axles have same ride characteristics as leaf spring axles. from my research, it seems that torsion axles seem to absorb more of the bump and resist the bounce afterwards, as compared to same rated leaf spring axles.

• 1) Since the 2k axles come with 7" brakes, and the 3.5k axle has 10" brakes, does that mean the bearing size is also smaller on the 2k axle than on the 3.5k unit(s)? If so, then the larger axle bearing would be able to support more weiht/side-loads than the smaller ones.
  
  
• 2) Torsion axles have a rubber "torsion" core that acts as its' own shock absorber (Timbren axles use a rubber puck that does the same), while the leaf spring axles may need a shock absorbing device attached to the suspension, to absorb shocks. Usually the shock absorbers are telescopic hydraulic units, but Timbren an Sumo Springs offer (expensive) hollow rubber units that do the same function.
  
  I made my own (for much less $$$) substitute (before I learned about the ones from Timbren or Sumo) from a tall "progressive" bump stop, that I inserted between axle and frame, always in contact; it performs well, and makes my overweight, over-springed trailer ride as smooth as a torsion spring axle is purported to perform.
  

  

  Active suspension Daystar bumpstops.jpg (349.8 KiB) Viewed 2235 times

[tony.latham]

but how much more can you load the axle past its listed limit before you get into trouble?

Overloaded torsion axles simply stop flexing. When you're towing off-road, it's time to slow down and in the scenario you are referring, to a crawl.

t seems that torsion axles
seem to absorb more of the bump and resist the bounce afterwards, as compared to same rated leaf spring axles.

I can't speak about the axles you are considering since I use Dexter Torflex axles that are downrated to the weight of my loaded trailer. Tuned so to speak. But, in my experience, they ride a heck of a lot better than a trailer with old-time spring axles.

Tony

[Brankulo]

on rugged backcountry roads though, there might come situations when the trailer is leaned to the point that majority of weight is
on one side.

You bring up an interesting scenario although I think it is extremely unlikely for most. I also think if the manufacturer states they are rated to say 1K lbs, they probably have a sizable safety buffer calculated in that figure..like 25-50%. I have 2K lb rated torsions on my off-road trailer that weighs about 1700lbs.I have a had it on the road and rough trails and they have worked great for almost a year. Very smooth. I feel they are a good match for my setup. As Tony mentioned, any stiffer I'd guess my plates, bowls, and glasses would be busted, and they're all plastic. LOL.

ok, great, i guess i just needed more assurance to go with 2k axles. my trailer weight calculations come to about 1,600lbs loaded.
thanks

[tony.latham]

ok, great, i guess i just needed more assurance to go with 2k axles. my trailer weight calculations come to about 1,600lbs loaded.
thanks

Let me put it this way: If you put a 3500-pound suspension under a 1600-pound trailer, it'll beat itself to death.



Tony

[twisted lines]

torsion axles
seem to absorb more of the bump and resist the bounce afterwards, as compared to same rated leaf spring axles.

Our Work Engineer my minion and myself delivered a new boat, trailer and two large outboards in the truck,
stopped for dinner. Minion Driving out of parking lot hit a curb; Trailer and boat bounced hard and high
Very happy with my 2000 Lb Leaf Springs @ 1250 empty! and 2000 lbs Loaded. Its soft maxed.
Long way's till testing #2 with 1 thousand pounder's

[working on it]

torsion axles
seem to absorb more of the bump and resist the bounce afterwards, as compared to same rated leaf spring axles.

Our Work Engineer my minion and myself delivered a new boat, trailer and two large outboards in the truck,
stopped for dinner. Minion Driving out of parking lot hit a curb; Trailer and boat bounced hard and high
Very happy with my 2000 Lb Leaf Springs @ 1250 empty! and 2000 lbs Loaded. Its soft maxed.
Long way's till testing #2 with 1 thousand pounder's

This thread reminded me of another, back in 2016 https://www.tnttt.com/viewtopic.php?f=39&t=66773 titled "Offroad Trailer Suspension", where everyone (as usual) gave their considered opinion concerning the merits of each axle (or axle-less) suspension type. Also, as usual, everyone has their position and sticks with it. I'm no different. I believe in leaf spring trailer suspensions, and have my reasons to stick with it. twisted lines related a story that pinpoints a fundamental reason for my choice: resilience (synonyms include "suppleness" and "strength").

Brankulo stated that rubber-cored torsion axles absorb force and resist rebound better than steel leaf springs, whereas twisted lines countered with an example of steel leaves bouncing hard and high (which, in itself) seems to affirm Brankulo's assertion. I agree with Brankulo, but I (like twisted lines) I am very happy with my (insert weight rating here)lb leaf springs.

I favor leaf springs because of their strength, durability, and their ease of replaceability (which also entails replacing damaged springs quickly, or getting a new set with higher or lower weight ratings, later on). I outlined my prior experience on replacing a broken spring within hours (broken due to age and drastic overloading/overflexing, without using shock absorbers or bumpstops), something not possible on a torsion spring (must be replaced outright), and possible but more delayed repairs on Timbren-type (rubber hollow airspring) or trailing arm-type (with airbag) suspensions, in the other thread listed above.

Lightweight trailers probably will benefit from torsion axles, but unless rubber compounds have gotten better over the years, owners might see a degradation of their axle over a period of years. Years before I built or used any trailers, I learned from the experience of two others that had 10+ year-old pop-up trailers with sagged torsion axles underneath; back then, they scrapped their trailers since no ready-fix was available for either (in the early-mid 60's, in N.Texas, pre-internet, no average Joe knew where to source replacements). 50-60 years later, it may be easier, but not as easy or as cheap, to replace worn or damaged torsion axles as it is to replace leaf springs and associated hardware.

Heavier-weight trailers (we're talking about smaller trailers: teardrops, squarebacks, other TnTTT types, and consumer-not-commercially used utility trailers, only, nor military trailers with torsion-type suspensions...apples not oranges) might require higher rated torsion or leaf springs, which both should ideally get some assistance resisting excess travel & rebound cycles, which will wear either type down over years of usage. I know of no external aid for torsion axles, but leaf spring axles can benefit from using shock absorbers and/or bumpstops that limit or absorb excess travel & flex, which stress the suspension components more, the heavier the trailer gets. My 4x8 squareback has always been a comparative heavyweight, and needed assistance in the form of "progressive bumpstops" that I made for it.

adapted text, from the thread I listed above:

Both times that I've experienced broken leaf springs (and the one-unmentioned shackle tear-off) there was no bumpstop to cushion/limit the flexing of the spring past its' working arc limits... The leaf spring had nothing limiting it from flattening out, or even reversing its' normal arced shape... (thus) bottoming out, resulting in a severe jolt, and breakage...

Now (after 2014), even Timbren recognizes the problems of over-travel in their suspension, and sees the need to "progressively" absorb the energy before the absolute "stop". I chose not to use shock absorbers with my new leaf spring suspension (with relatively little travel), reasoning that the shock absorbers couldn't absorb enough energy in their limited motion to do much good before their absolute stop was reached.And, I was going to add a bumpstop to prevent the possible overtravel of the leaves past the flattened arc stage. So, I combined the functions of shock absorber and bumpstop into one, using a Daystar progressive bumpstop, made of resilient polyurethane, as an active part of the system (always in contact with, and following the motion of the axle); sorta like Timbren does with their component. I described my "active bumpstop suspension" in my thread: http://www.tnttt.com/viewtopic.php?f=35&t=59570#p1075076.

I modified the Daystar bumpstop to be softer-acting (by cutting away the hard "bump" of the top of the piece, and curved the remaining body to slip-fit between my axle and frame (at full droop of the springs). With the top part of bumpstop so modified, the remainder relies on the two lower "ligaments" to progressively flatten out, before compression into the bottom layer, when the overtravel is finally prevented.

I wondered how well it would work, as did may doubters on the forum, but I think it proved itself when I encountered a large chughole in the road at 75 mph. My truck and trailer both got bounced into the air, with my truck tires being the only damaged parts afterwards. In normal driving situations, I really haven't noticed any of the trailer bounce that I should be seeing, as a result of using too stiff of springs. In any case, the bumpstop at least kept the leaves from overflexing, preventing breakage. If I ever soften the suspension, and/or add conventional shock absorbers (if suspension travel becomes greatly increased), I will still use some form of progressive bumpstop to limit overtravel. I try different things, sometimes re-purposed from originally designed function, to do what I need them to. Sometimes it works....

[working on it]

Just two items to add to my post above:
1)

now this all-steel device is a torsion axle (of sorts) that I'd buy!

ad from Sept.1950 Popular Mechanics.JPG (36.39 KiB) Viewed 1793 times

2)

wedged between axle and frame, rubber (or polyurethane) "spring" action supplants rubber torsion axles

homemade Daystars vs factory-made Sumos or Timbrens, active bump stops.jpg (89.28 KiB) Viewed 1793 times