Electric brake drums - how to correct out of balance

[em1942]

Having trouble with tires on my tandem and noticed the drums are way out of balance as they rotate rather quickly with the heavy side down when the tire is removed. There isn't any area on the drum to drill for balancing. The center hub is steel and about 6" dia x 1/2" thick that the drum is pressed onto. I could turn a steel balancing weight in a lathe and then cut/weld to the center hub but it would take a lot of weight since it would only be 3" off center. There should be an easier way to do this. Any suggestions?

[em1942]

I thank everyone for their input. Since the drums are no longer available I found a machine shop that could turn the outside diameter. Took off about .100 on one side - now round and in balance.
Ed

[em1942]

The drums and axles are no longer made so replacement is not an option. Talked to a guy that has balanced many drums by welding on weights. He said about 10% crack when welding so that is not an option since they're not replaceable. Finally went to a machine shop and had them turn the outside. Removed about .100 at the worst spot (still 1/2" thick) at a cost of $50. Fixed now and the drum only weighs 64 lbs instead of 65 lbs! FYI: One post asked about what kind of tire problem - always separation at about 1/2 amount of tread (this will be the 4th tire on this axle). Axles are parallel and square on trailer and I keep it up on stands when not in use. I found a piece of steel 6" x 2" x 1/4" thick (about 16 oz or 1 lb)and strapped it to the drum and it needed a little more to get close to balance. Here's some things I heard about increasing tire longevity (comments welcome) 1) From the guy I bought tire pressure monitors from - "Never run LESS than the PSI noted on the tire to keep the running temperature down - a little more OK" 2) If a 80 psi tire, store at 40 PSI when not in use (on stands). 3) Always keep tires covered when not in use to reduce expansion/contraction of plies (as well as ozone deterioration). Thanks guys for the input - I'm keeping my fingers crossed.

[C_Schomer]

The Alemite balancers from the 60s spun the wheel on the vehicle, along with the drum, hubcap and any rocks, nails, dirt and grease on the tire and wheel. I've even seen them used on class 8 duals. Maybe you can find a shop that still uses one. Craig

[Harvey51]

Maybe not useful but interesting. While swapping summer wheels for winter ones, a balancing weight fell off the drum of our 2004 Toyota minivan. Someone suggested JB weld so I put the weight back on with that. The van had a nasty vibration, especially affecting the little table between the front seats. Sure enough, the weight had fallen off and was gone. I lived with the vibration all winter. Next summer I mig welded a piece of steel on that drum where the weight was. The vibration was much reduced but still there. I ended up buying a new drum. It had no balancing weights. And there was no vibration. I don't know what this says about Toyota vs the aftermarket maker. I guess the Toyota drum was badly made.

[MEXICOWANDERER]

Holee Molee.

Something so simple. Remove drum, pop the bearings out, clean bearings, races and EVERYTHING shiny clean. No seals! Reassemble. Loosely. LOOSELY! If the drum turns out of balance, use MAG WHEEL WEIGHTS, but epoxy them or JB Weld them to the drum until the drum is reasonably balanced.

Pop the drums off again. Pack the bearings, pound in the seals, and reassemble.

Yeah, you can go further and mount the tire to the lubeless drum bearings, and balance the tire that way too. It isn't spin balancing, but I can tell you it works just fine for low speed trailers.

[Lynnmor]

RCMAN46 wrote:
Balance beads in tires that have been balanced will offset drum out of balance.
I have done this on all of my trailers and it works very well.

My drums were out of balance 5.5 ounces, the tires out 4 ounces. So how much of this sand do I put in there?

[j-d]

What kind of Trouble With Tires? Tires themselves have been known to be out of round or have misplaced radial plies. Your hub/drum assemblies clearly spin freely. What do the tires (and Rims!) look like when you spin them and look carefully. Stand something by the tire, then under the tread, so you can see if lumps roll around. I've heard of breaking tires down then re-mounting to smooth them out. Every tire and every rim has a high side. Car manufacturers mount the tires so they offset. If they happen to match then the high spots become additive.
I can imagine where it's easy to end up with a bent rim on a trailer, especially tandem, too...

[AH64ID]

Balance beads or centramatics, easiest solution.

[RCMAN46]

Balance beads in tires that have been balanced will offset drum out of balance.
I have done this on all of my trailers and it works very well.

[Lynnmor]

RJsfishin wrote:
Quote:
The drums are NOT balanced from the factory and there is little point in balancing wheels under this condition.
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I have seen many drums w/ balance weights spot welded (fused) to the drums, and others that have been drilled.
And if the wheels are spun balanced on the vehicle (like they used to be) or the drum and wheel are balanced as an assembly off the vehicle, the entire assembly gets balanced. So there is a way around out of balance drums.

Please post photos of recently produced trailer drums that are balanced. I gave a very brief description of how the assemblies can be balanced. Another way is to make a spindle that fits the bearing ID's and place that spindle in low friction bearings to balance an assembly. This won't require dis-assembly of the hub. I see that the OP has a lathe and this might be a good idea for him.

[RJsfishin]

Quote:
The drums are NOT balanced from the factory and there is little point in balancing wheels under this condition.
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I have seen many drums w/ balance weights spot welded (fused) to the drums, and others that have been drilled.
And if the wheels are spun balanced on the vehicle (like they used to be) or the drum and wheel are balanced as an assembly off the vehicle, the entire assembly gets balanced. So there is a way around out of balance drums.

[RCMAN46]

Most likely the drum was not machined correct during manufacture. I would bet you will find it is not concentric. Having the drum returned so it is concentric may help.

But it is most likely junk.

Balance beads in tires that have been balanced may offset minor drum balance.

Trailer drums are not balanced like automotive were. If you look you will not find balance weights or machine cuts like you will find on an automotive drum.

[wa8yxm]

Balancing a drum is not for the faint of heart. it is a professional job.

IF in fact the drum is out of balance some shops may have the ability to do it, it is done by welding metal to the drum in an area where it won't be bothered.

Another posibility is the drum may need to be turned or it may be out of round.

Again a professional who has the tools (And sadly those are rare these days) is needed to figure it out... I can not, and do not know off hand anyone who can, but your Tire Professional MIGHT. I stress MIGHT. I know one weld shop that might too but less you are in metro Detroit,, Not much joy there. (Marty's On Telegraph between 5 and 6 mile I as I recall)

[donn0128]

I am sure there is a mathimatical equasion to determine the effect of a rotating mass 6 inches from the center versus 15 inches from the center. If the drum was manufactured by a reputable company the ammount of out of balance should be so small as to be barely noitcable. Now a tire out of balance that can be felt, or rather seen as most people do not ride in a trailer to feel the out of balance. Balancing trailer tires should be sufficient for most folks.