Dynamic balancing media used on unsprung or very stiff suspensions.

[MarkT]

Have you used Ride-On or Dynabeads or any similar products to balance tires on a very stiff suspension?
Seems like it has the effect of unbalancing the wheels.

Ride-On explains how it works. (I think it was them; however I can't find the explanation I remember - had a frisbee in the example.) In a nutshell, the suspension lets the wheel revolve around it's CG. As a result, the lighter side is further from the axis so that throws the media there and the result is the wheel balances.  They don't mention the suspension travels only up-down rather than unhindered in the plane perpendicular to the axis, but that doesn't seem to matter.  My own experience is the balancing absolutely happens, having used Ride-On exclusively for years now.  When I first installed it on Deerslayer, a buzz smoothed out that I hadn't even noticed was there.  Miraculously, the ride was suddenly much smoother.  

Conversely, if the suspension doesn't move sufficiently from the imbalanced wheel to let it rotate around it's CG, then the wheel would revolve around it's axle instead and the balancing media should fling to the heavy side making the imbalance worse.

A couple years ago I bought this cargo trailer from Harbor Freight.



Seemed like it had a really stiff suspension.  Wanting to be thorough, I put Ride-On in the tires to balance them.  I noticed a buzzing in the handlebars that could only be coming from the trailer.  I found things I put in the trailer, some were being damaged by vibration.  A plastic bottle of antihistamines, the child-safe cap unscrewed and the contents emptied in the trailer and all the pills vibrated into powder. Camping chairs and a tent, the fabric was chafed in spots putting holes in it. The wife riding near the trailer on her bike could hear buzzing.  This was with around 300# in the trailer.

Pushing down on the side of the trailer, even with it loaded well, the suspension doesn't move at all. I'm glad I had the sense not to put something really sensitive in there, like electronics.  The trailer is rated at 600# GVW, and the 2-leaf springs appear to be much higher capacity than that.  I removed the helper leaf before a 700 mile ride this fall, but still too stiff.

So I found online the lightest springs I could, rated at 230# and a couple inches longer and replaced the OEM's.  These are clearly much lower capacity with thinner and narrower and longer leafs.

Still too stiff - don't get much suspension movement.

I am concluding that one cannot balance wheels with Ride-On if the wheel is unsprung or sprung too stiff.

I understand that dynamic balancing media is used to balance even semi-truck wheels.  That would seem to be a very stiff suspension and to me, results may be doubtful.

Any experience with this?  Comments?

[Toovalks]

Mark... perhaps the angular velocity of the inside of the outside surface is too high for the beads to react . OR  .Perhaps the tires are not of sufficient mass for the beads to really "sense " the very subtle differences. Perhaps the bouncing of the trailer is applying more force on the beads than their own centripetal acceleration ...hence they are flying around in there very haphazardly . OR  I could be FOS.
 Take them out and you'll know.

[Ramie]

I always wondered how hard it would be to convert one of those trailers to a torsion axle.  I know their not cheap but I would think they would work a lot smoother.

[Houdini]

My .02¢ is that a semi, when loaded, is heavy enough to not bounce much and would allow Dyna Beads to fulfill their destiny.  In a small stiff trailer they are just bouncing around in the tire every time the trailer bounces.  OTOH, the Ride-On is a gooey gel and would have a better chance staying on the inner-surface of the tire.

I've used both and prefer Ride-On, I have the same trailer you do and it is quite bouncy back there so if you come up with a solution please post it for the rest of us.

[MarkT]

I thought about the different type suspension as well.  Probably too much trouble/cost to go to either coil springs or torsion however.  Unless I could cannabilize the parts off an existing system and install them.  Or change this system so the support is from only one end of the leafs.  That would likely be easiest.  

Again, I'm using Ride-On.  It doesn't fly around like beads.  And works very well on the bikes.  It's not as easy to take it out, like beads.  On the latter, pretty sure I could break the tire beads and suck them out with vacuum.  With Ride-On I'll have to remove the tires and wash it out then remount.  Sometimes mounting these small tires can be a bear.  Yep I have the HF machine and lots of different size spoons/irons. Might be it would just be best to either use lead weights or just forget it.  Most folks don't bother balancing trailer tires.  But if they are out of balance they can sure destroy some stuff you haul in there.  

I'd like to use a device that can measure the vibration, before and after removing the Ride-On.  A seismic recorder type device.  Haven't decided what could do that.  Googling for Android aps for that. Might get lucky.  Hmmm.  Just found some.  This one looks promising: http://appcrawlr.com/android/vibration-meter#authors-description

Recall I have already reduced the spring strength twice.  And added dampers on the spring's free end made of old tires to stop the rattling.

[WoodyFL]

Mark,
I have the exact same trailer. I run it stock and have taken it from Central Florida to Murphy TN once and from here to North Myrtle Beach twice. Both routes were on Interstate hwys for most of the trip and was 2 up. I had no problems with noise or anything else. Hardly even knew the trailer was there. Load was about 350-400 lbs.

Bob

[MarkT]

Mark,
I have the exact same trailer. I run it stock and have taken it from Central Florida to Murphy TN once and from here to North Myrtle Beach twice. Both routes were on Interstate hwys for most of the trip and was 2 up. I had no problems with noise or anything else. Hardly even knew the trailer was there. Load was about 350-400 lbs.

Bob

I have run the trailer cross-country on long road trips several times now. On interstates and state and county highways with varied road qualities, and sustained speeds up to 90. Have replaced the tires twice. The wife riding behind the trailer says it bounces a lot.  Suspect that's a function of how much weight is in it, as well as the spring stiffness and tire pressure.  I increase the tongue load as needed with the large cooler I added. It does trail well with that.  No swerving with a too-light hitch weight. But there has always been a LOT of vibration in the trailer.  I suspect you might not be aware of it.  Don't haul a computer in there. Or haul something inexpensive that will show the vibration damage. I suspect you will be surprised.  As I said - I get a strong buzz noticed mostly in the Brake-away shutoff button that is coming from the trailer at speeds 60+.  That's when I started working on the problem.

[Avanti]

Do these trailers use shocks?

[MarkT]

Do these trailers use shocks?

No.  Shocks on trailers are unusual, particularly on small ones.  Also, these aren't sprung soft enough with leaf springs to need them.


Looks like this is a more suitable android ap for capturing vehicle vibrations.  Read the reviews.

https://play.google.com/store/apps/details?id=com.nowinstruments.vibsensor

[mrtlc]

Those little tire/wheel combos can be why out of balance. I had a set act like your talking about, bouncing quit bad. It took several ounces on lead weight on a bubble balancer to get them to smooth out. 100 + was real smooth after they where balanced.

[Avanti]

If you have an extra set of adjustable motorcycle rear shocks, you could replace the leaf springs with shocks and trailing arms.

[MarkT]

If you have an extra set of adjustable motorcycle rear shocks, you could replace the leaf springs with shocks and trailing arms.

Yeah I do have extra shocks. 2 pairs in fact.  Actually that wouldn't be hard. Half of it is the mount points and the pivot bearings. Might use large Heim joints there.  Plus I'll get variable preload I don't have now. And the better suspension movement will enable the Ride-On to work for balance. I'm pretty sure there's enough length of the side frame rails to mount the trailing arms.  I already have all the steel box tube.  I'll have to add sway bars which adds some complexity.  Good idea. Thx. Think I'll look into that in between other projects / pipe orders.  Oh yeah, I have to make up the door prize donations for Inzane too.  That'll only take a cpl days.

[MarkT]

Looking at using the leaf springs with the back ends cut off, as trailing arms.  Then just make mounts for the shocks, attached at the axle (below it some), slanted fwd to the frame.  Likely add a single sway bar between one end of the axle and the opposite frame, close to level, using Heim joints. This is simple enough to make it a Saturday project.  Need to do some calculations to set the angle of the shocks to provide the correct range of support for various trailer loads.  Have to freshen up on some trig math.

[mark81]

I wonder if maybe your vibration isn't coming from the tires but wind buffeting. have you tried putting something on top of the trailer to change the aerodynamics of it?

Here is a video of the basics of beads. I would imagine ride on works in a similar manner with the exception of all of the mass of it settling at stops.

https://www.youtube.com/watch?v=w8b6eqde_5A

[WintrSol]

I wonder if maybe your vibration isn't coming from the tires but wind buffeting. have you tried putting something on top of the trailer to change the aerodynamics of it?

If it is[/u ]buffeting, turning the body of the trailer around so it slopes to the rear makes it more aerodynamic. I assembled mine that way, on the assumption it would have less drag that way; didn't think about turbulence, but that would be reduced, too.

[MarkT]

It's a high-speed and very vigorous buzz.  Not attributable to something like buffeting.  I know it's coming from the wheels. I will prove it soon; have downloaded the vibration ap VibSensor (and 2 others) for my phone, will run tests at various speeds with & w/o the Ride-On. (Don't have time right now; customer pipes have priority) Or instead, run the vibe test before and after the suspension change - if it smooths out a lot, call it a day. The vibes don't vary with wind direction.  Gets much higher frequency and more vigorous with more speed.  Also, with the understanding how Ride-On works, it's clear that with the wheels unsprung or sprung very stiffly it won't balance and in fact should be worse with the media installed.

That youtube explanation is really lame.  He doesn't explain it at all; basically just says it works w/o explaining WHY the beads migrate opposite the heavy side of the tire; "take my word for it, DAYna beads work" (paraphrasing).

Here's a demo demonstrating the theory in practice using a drill and water bottle.  Still not explained: https://www.youtube.com/watch?v=eq263AYgyYg

Here's a diagram illustrating the phenomenen:
http://innovativebalancing.com/HowItWorks.htm

Here's one of the best explanations I've found.  From  https://engineering.stackexchange.com/questions/6015/how-do-tire-balancing-beads-work

Note the "Note" in yellow - saying the same I did - the suspension must move for it to work.  My trailer suspension is so stiff it's not moving.  I will be correcting that with the change to bike-shock supported axle with forward links and sway bar.


Short of a mathematical proof, the concept provided in the manufacture's description is valid- the beads dynamically distribute mass to align the center of mass with the geometric center of rotation.

The following time steps are listed in the above link. I have tried to clarify the physics of each time step.

    Tire at Rest: The beads rest on the tire floor due to gravity.
    Tire in Motion: The beads distribute uniformly by friction as the tire begins to rotate, where they are held in place by centrifugal force (F=mv2r), acting perpendicular to the tire wall. Note that beads would remain in this state for a perfectly balanced tire. For completeness, gravity still acts on the beads but is small relative to centrifugal forces.
    Heavy Spots in Tire: In this time step it is important to remember that the vehicle's suspension allows the wheel assembly to move vertically- Upward motion is resisted by the car's suspension (spring) while downward motion is assisted by the suspension (spring) and resisted by tire pressure against the roadbed. As the 'heavy spots' in the tire are rotated at higher velocities, their centrifugal (inertial) forces physically move the tire up and down- poorly balanced tires can literally cause 'wheel hop'! As the tire moves (up and down), the beads, with their own masses resisting motion, do not move rigidly with the tire's translation; they move relative to the tire. Note that without vertical movements, only centrifugal forces act on the beads and they maintain their new position on the tire wall.

    Imagine a bead when the tire moves up (ie. the 'heavy spot' on top)- Reversed when the tire moves down (ie. 'heavy spot' on bottom):

        At the top: As the tire moves up, the bead does not. No longer guided by the tire wall it maintains its tangential velocity until it reestablishes contact at a new tire wall location, further from the imbalance.
        At the bottom: As the tire moves up, the bead is lifted with the tire and does not change its location in the tire wall.
        On a side between top and bottom: As the tire moves up, the bead rolls down the tire, changing its relative location in the tire wall further from the imbalance.

    Reduced Tire Oscillations: Each oscillation (tire movement, up and down) moves the beads progressively further from the imbalance ('heavy spot'), reducing the imbalance. Therefore, the tire becomes more balanced each oscillation until the tire is balanced.
    No Tire Vibration: The beads are held by centrifugal force in their balanced state. Because no imbalance exists, there are no vertical movements of the tire to disrupt their positions.

However, there are practical considerations worth mentioning.

    Because the beads are free-floating (unlike mounted weights), accelerations create transient imbalance. For example, until the beads are distributed, their mass actively contributes to wheel imbalance. Similarly, road bumps, braking or driving accelerations will disrupt the equilibrium state.
    Because the mass is distributed furthest from the center of rotation, more force is required to accelerate the wheel assembly, resulting in decreased fuel efficiency. This effect is magnified by larger diameter tires. Additionally, more mass is required to balance the larger tire mass.

Note: Tire balancing machines do not validate this method because they have a fixed axis, unlike the axis on a vehicle that moves. Without movement, the beads gather at the 'heavy spot'. To accurately measure the effect, the machine must allow movement.

While tire balancing beads are a valid method to correct imbalance, their effectiveness depends on speed, tire size, and driving accelerations.

Also note that steel BBs, sand, water, or similar may also be used to dynamically distribute mass, but beware of abrasive or chemical effects (that may damage the tire). There is also a liquid that solidifies in its balanced state, liquid tire balance.

[WintrSol]

Gets much higher frequency and more vigorous with more speed.  Also, with the understanding how Ride-On works, it's clear that with the wheels unsprung or sprung very stiffly it won't balance and in fact should be worse with the media installed.

Clearly, one or both wheel/axle assemblies are out of balance, perhaps out of round. I also accept the argument that the tire beads won't work in this situation, because of your rotating mass vs. suspension arguments.

Balancing the wheels on the axles may be the only solution, unless the tires are out of round; in the latter case, grinding rubber may be the only solution. You must have gotten a bad one, as mine runs smooth on smooth pavement. I did, however, service the axle bearings before pulling it the first time. One was over tightened, the other way too loose, and neither had adequate grease.

[MarkT]

Fortunately, HF sells these tires with wheels cheaply - $30 IIRC.  They don't last even as long as bike tires as they spin fast and are pretty heavily loaded per sg in. Try to keep the pressure appropriate - 45#. Tires rated to 60; run them high and they wear faster.  I got under 5,000 out of them last couple times.  If the hubs are out of balance, then the dynamic balancing Ride-On should take care of that, too. If they are out of round - well they are cheap, just replacing will fix that.  I rigged up a spare wheel under the frame for roadside flat fixes.  There's Harbor Freights all over the country. Don't carry a jack - likely if needed I can improvise with a 2X4 in the ditch or the like.  Have the right socket in my road tools - though breaking a lug nut will take some muscle.  Maybe should include a piece of pipe and a small jack.