Balance Question

[Lynnmor]

Here is a perfectly balanced tire/wheel that I had to add two ounces of weight to bring it into balance when mounted.



Here is the video before adding weights:
Video

Any guesses to the cause?

[Grit_dog]

And all that tender loving care for a China bomb Maypop tire?

[Grit_dog]

Great write up and thanks for sharing, but OMG, who has the time for this? I suppose if this is what you to do list is down to...”balance trailer tires by hand” what could possibly be left to do? Polish rain gutters with Meguiars, or remove all traces of lint from the lint trap in the dryer?

[mosseater]

I've been using Dynabeads for years and have very even tire wear ever since. I can't say definitively that "they work", but I have no evidence to the contrary. I had a small tire wear problem at first and it hasn't resurfaced yet. On my second set using them.

Hi J Barca! Long time no see.

[Lynnmor]

I've been balancing trailer tires this way for forty years, the worst case was a tire that was 5 oz. out and a drum that was 5.5 oz. out. I used my method and only needed a tiny weight to bring it into balance. Had I not known the heavy spots, it would have taken a considerable amount of weights or balance beads to make it work. Using my example, even 10.5 oz. would not be enough as the beads will spread out over a large area. The thing about using the beads is that there is no way of knowing the correct amount. I prefer to physically balance the assemblies and not depend on beads re-balancing after every stop.

One thing I am sure of is that nearly all trailer wheel assemblies are out of balance despite so called balancing done at tire shops.

I pulled snowmobile trailers for many years that had the small 10" diameter wheels, for those I made an arbor to fit that had low friction bearings. This way I was able to balance without all the de-greasing. Good tires in this small size are impossible to find, so I did a lot of replacements.

My single axle utility trailer has no brakes, but the hubs still were considerably out of balance so I removed material where I could but had to quit before compromising the strength. The quality of the axle assemblies in nearly all trailers is extremely poor, so we must recognize the problems and do what we can to live with them.

I also have an on the vehicle electronic balancer but of course it can't tell where the heavy spots of each component is located, so I only use it to verify balance.

[JBarca]

Lynnmor,

Getting back to you. Thanks for explaining your static balance setup. I have had to do a similar method at work, just on a 10,000# rotary drum. We leveled steel plates on the floor, then rolled by hand the large drum with machined race rings that were friction drive wheels. The drum is 6ft dia x 25 ft long, and as we rotated it, we stopped every few degrees. We added weight to the correct location to balance out the system so no matter where it stopped, the weight would not start the drum from moving. When all 360 degrees worked, then we declared it was statically balanced good enough, It only rotated 30 rpm. But that big, 30 rpm gets your attention.

As I was reading through your write up, I thought, the grease is going to add friction, you took care of that and the grease seal and bearing preload if any and you took care of that too.

Then it came to be, that you balanced a wheel and brake drum to a specific axle location and lug pattern. And yup, you took that into account too.

Yes, I see what you are doing and it is a sound mechanical basic process that should yield good results.

I have the ability to reproduce what you did, never thought of doing it, even through I know the method. I do not trust the tire shops setup and then with the poor machining of the brake drums, even if tire shop balanced the wheel right, it, still won't work.

I use Dyanbeads in the my trailer tires to overcome the problem. http://www.innovativebalancing.com/ I have my own tire machine (think, 1970 vintage) but it still works well on trailer wheels or other zero offset wheels. As such, I use the larger truck beads and put them in the tire as I am mounting it.

I see Robertsunrus is using centramatics on the camper, https://www.centramatic.com/balancers.rhtml That is the more Cadillac approach. I bumped into them before and was planning on using them on the F350. Not a cheap way to go, but from everyone who has used them all they say is, smooth riding. I will see how they work out on the truck first, then figure out if they will gain me more then the dynabeads on the camper to help justify the added cost.

I will say this, anyone who plans on keeping a camper a good long time and tows long distances, trailer suspension and tire balance go a long way in keeping the trailer frame and entire camper from fatiguing. Shocks and a rubber equalizer if you are on double eye leaf springs along with a more true working tire balance helps the whole camper live longer. The double slipper spring setup with shocks also helps or rubber ride (torsion spring) axles if you have them in your size camper.

John

[Lynnmor]

I wanted to demonstrate that balancing tires on a machine is of little value. You did some measuring and verified the inaccuracies of trailer parts and why there is a need to find an alternative method to bring things into balance. While some suggest using a lug plate on a balancing machine, that doesn't take into account the run out of the lug pattern on the trailer drums. I had one brake drum that needed 5.5 ounces of weight at the usual wheel location to counter the inaccuracies. Had I paid for a fancy high tech spin balancing, it would have still been 5.5 ounces out of balance, possibly more.

While few will go to the trouble of doing it, I'll explain what I do. I have an on-the-vehicle spin balancer, but even that is best only after the following process. I have a spare axle to use for the process, but an axle already on a trailer can be used if the brakes are backed off, or removed, till there is absolutely no drag. This is best done when replacing tires or doing a complete wheel bearing service so that not too much unnecessary work is done.

1. Remove the grease seals and completely clean the bearings, then put a few drops of very thin oil on them. Gun oil or sewing machine oil is fine. Any trace of grease or debris will be a problem. Keep all bearings in their original positions.

2. Mount a brake drum on the axle used for this work and adjust the spindle nut loosely so that the drum rotates freely. The heavy spot on the drum will rotate to the bottom, so there mark the heavy spot, I use a paint marker and use the letter H. You will do this with each drum as its turn comes up.

3. Balance the first drum using small c-clamps or whatever you have. Now you can mount a tire/wheel and find its heavy spot. Again mark the spot with an H, I use chalk. Do this with each tire on the balanced drum.

4. Remove the added weights on the drum.

5. Mount the tire with the H markings opposite each other as best you can, but first mark an S on the drum where the valve stem will be. This will minimize the required amount of weights. Also, it would be a good idea to mark on the drum and wheel where the wheel will be mounted.

6. Add wheel weights to bring the whole assembly into balance, most of the weight should be on the inside of the wheel to better counter the unbalanced drum. If you have the assembly turning freely, you can balance to within 1/2 ounce.

7. Repeat for each assembly. The spare tire can be balanced after step 3 but of course there is no way of knowing where it will be needed, so it will only help a bit.

8. Clean the light oil from the bearings, grease and assemble as usual.

9. Always mount the wheel on the matched drum with the valve stem in the S position.

10. Each person doing all this should add their name to a list below, I expect a very long list. 🙂

[JBarca]

Lynnmor wrote:
Here is a perfectly balanced tire/wheel that I had to add two ounces of weight to bring it into balance when mounted.



Here is the video before adding weights:
Video

Any guesses to the cause?

A question, when you say the tire and wheel was perfectly balanced, can you describe:

1. The tire and wheel assembly balancing process?
2. What part of the wheel was used to hold the assembly?
3. What was used declare the center of rotation of the wheel?

I have found several out of balance conditions that can exist on the standard trailer setup, maybe you found a new one. I have found on brake drums, the brake shoe surface diameter and grease seal diameter show they run true to each other as turned in the same setup. And on the same drum, the inner and outer bearing bores are machined true to each other as they where bored in the same setup, but the brake shoe and seal diameter are on different centerlines the the bearing bores. Some are off center greater then 0.015" TIR and some over 0.020" TIR.

I have not yet measured the lug stud centerline to sort out what centerline that spin true to, but would really surprise me if it ran true with the bearings. The drum wheel face can be out of square with the bearings bores also creating wheel wobble.

Trailer wheels many times have stamped center bores that are not very accurate to the center of the wheel rotation, as the center bore is not machined in relation to the tire bead area. "Standard" trailer wheels are called "lug centric" on most travel trailers/fifth wheels and small utility trailer as they spin by the lugs studs/lug nuts. There is no machined brake drum center pilot to mate with the wheel center bore. If a wheel balancer used the center bore to balance a tire to, that could affect wheel balance as the wheel assembly could not run true with the lug nut holes that mount on the brake drum.

Sadly, all that above could be made very accurately like the auto industry has done for years, but yet, standard trailers fall into cheaper made versions. If you happen to look close at what U Haul uses on their rental cargo trailers, they spent the extra money to have piloted wheels on brake drums (hub centric), and they do not use cheap nylon spring pin or shackle plates in the suspension. U haul does not want to have to deal with the suspension failures while the miles add up.

John

[ROBERTSUNRUS]

🙂 Hi, unlike cars and trucks, trailer brake drums are not balanced. This is why I have Centramatics on my trailer.

[Lwiddis]

IMO the rim’s “contribution” to balance issues is minimal.

[cougar28]

I would guess the tire. All tires will have a slightly heavy side some more than others.