New drums to correct running gear imbalance?

[TomW]

In past posts, Inland Andy has repeatedly stressed the importance of balancing the running gear, a sentiment with which I wholly agree. Balancing the running gear entails balancing the wheel/tire mounted to the brake drum on the Airstream so as to correct for imbalances in either. The problem is that no one around here can do that; The best I can do is have the tires balanced on a machine, mount them, keep my shocks in good shape, and hope for the best.

It strikes me as odd that today's trucks & cars appear to do fine with just balancing the tires. My vintage Airstream, however, appears to need more as I routinely find signs of interior vibration damage that I would prefer to either eliminate or minimize.

The other day I had my wheels off to tend to leaky wheel well issues, and took the time to spin each of my 38 year old drums by hand & watch how visibly out-of-round they were. While out-of-round does not necessarily mean out-of-balance, it does indicate "manufactured to loose tolerances". To make matters worse, my drums are of a two-piece design - the magnet plate is riveted to the drum. Statistically, there is more chance for an out-of-balance condition with an assembly. Modern-day trailer drums are of a one-piece design.

Most authorities agree that cast drums can not be safely balanced. So, with the next brake job, I am contemplating replacing the drums (along with new bearings) in an effort to minimize running gear imbalance. My assumption is that modern-day trailer brake drums are manufactured to much higher tolerances than they were 38 years ago, and will rotate with less imbalance.

I would welcome discussion on this topic whether it be disagreement, or a recommendation for a vendor who sells high quality trailer brake drums.

Thanks,
Tom

[BigAl]

Hi Tom,
I have read previous posts and have had the same questions.
Obviously the wheel and tire are further from the axle and have a much greater influence on the balance of the total assembly but the brake drum does have some influence.
It seems rediculous that we would have to take our brake drum and wheel assembly to a shop to have it balanced and then install a new grease seal etc., just to balance the assembly.
For my own piece of mind I am going to have my wheel and tire assembly balanced just as you would on an automobile and then I am going to install Centramatic wheel balancers which rebalance your assemby every time you get out on the road. At about 20 miles per hour they have eliminated any out of balance.
Al

[markdoane]

Tom,

I agree that today's one piece drums are much better than in the past. I replaced my two piece drums with new Dexter drums a year ago.

I don't recall the exact number, but I believe one drum was out of balance by a little more than one ounce, the other by less than an ounce.

[Ken J]

It is my understanding too that todays drums are better balance than the old one's were - since I can't find anyone around here to do a on vehicle balance - thats what I plan to do too. I just put new Dexter axles this week.....


Ken

[TomW]

Originally Posted by BigAl

... and then I am going to install Centramatic wheel balancers which rebalance your assemby every time you get out on the road...

Al,

I was hoping to use Centramatics also. After ordering them, and trying to install them, I found that they are designed for zero-offset wheels which my vintage Airstream does not have.

On to plan B...

Tom

[TomW]

Originally Posted by TomW

... I would welcome discussion on this topic whether it be disagreement, or a recommendation for a vendor who sells high quality trailer brake drums.

It sounds like new drums are a good idea.

Since my family is used to buying unusual things for me in the gift-giving system, would anyone care to recommend a brand and/or vendor for new brake drums?

Thanks,
Tom

[markdoane]

I assume you are staying with electric drum brakes, which limits your choices.

I like the Dexter one piece drums. First of all, they were fairly well balanced out of the box, and the design has lots of fins and two bosses that you can CAREFULLY remove a little weight from, to get them perfectly balanced.

And you can't beat the price.

[uwe]

I did the axles on my 1971 Tradewind 2 years ago. I bought complete Henschen axles from Andy. Henschen shipped the wrong axles, so i had to do the job twice,and was exposed to the brake drums twice as well, since I had to transfer them from one set of axles to the other.
Better balanced? Not even close....
Took the trailer to Andys InlandRV shortly thereafter for a balance job, and it took an ungodly amount of weight to make things right.
There might be a slight improvement, but it's still far from perfect.

[markjoandall]

Originally Posted by TomW

the problem is that no one around here can do that; The best I can do is have the tires balanced on a machine, mount them, keep my shocks in good shape, and hope for the best.


Tom

Tom,

I went to my local auto mechanic. He has a snapon spin balancer. I offered to purchase the cones necessary to balance the entire wheel assembly. As it turned out, he had the cones necessary. He mounted the entire assembly less the bearings on the machine and spun them. Just for kicks, he spun them without the tires and rims. The out of ballance was amazing. Almost 6 oz. on one hub. He marked the wheel stud with white paint corresponding the air valve so I could remount exactly on the trailer. He even repacked my bearings for me with a high temperature grease. All four wheels for about $20. When I mounted the wheels back on the trailer, I also put the centramatic wheel balancers on.

I've put about 12,000 on the trailer since then, and nothing moves around in the trailer any more.

Someday I'm going to put the disk brake system on the trailer, but until then, I'm pleased with my current results.

Mark

[markdoane]

I guess I'm just lucky. The drums I got balanced real easy.

Roll of the dice I guess.

[Action]

Tom,

If you are seeing evidence of items shifting inside, you may have axle(s) that are tired. While getting the tire/wheel assy balanced is important, the travel in the axle assy (and shocks) should absorb some of the unbalance condition. If not you may have more issues than the drum out of balance.

>>>>>>>>>>>>>Action

[LRPorter]

I have my trailer at a local rv dealer. They do not want to change the shocks and they are putting 4 new tires on. As I read this thread it seems my rv dealer is not up to snuff on these issues. He tells me he can check the shocks with a jack. Should I get the trailer out of this place?

[Action]

LR,
What do YOU want to do? It's your trailer! You are paying for the service, so you direct the work, not them.

If it were mine and the shocks were over 5 years old I would want new ones. And the importance of tire/wheel/brake drum balance is important too. In addition I would be inspecting the torsion axle for being set or compressed to a point that replacement would be needed. And i would have my bearings repacked and inspect the brake friction material and magnets.

And that's me.

>>>>>>>>>>>>Action

[overlander63]

Shocks are (relatively) inexpensive, especially if you have a single-axle trailer. Two shocks would run around $75 from our favorite vintage RV parts dealer in California. Really, the only way to check the shocks while the wheels are off, is to remove the shocks and compress and extend them, while checking for oil leaking out of them, and if you are going to remove and replace them, you may as well install new shocks and be done with it.

[Inland RV Center, In]

LRPorter

What kind of tires is that dealer selling you?

Goodyear Marathon is best as that has been the factories choice for many years.

If he is selling something else, I would pull the trailer out like a rocket, especially since he 'obviously" does not know how to check shocks.

Rule of thumb is easy. When you put new tires in the trailer, replace the shocks as well.

Keep in mind that your trailer uses horizontal shocks, and they are only available from an Airstream dealer.

Can that dealer balance the running gear for you, as it should be done?

Andy

[axleman]

Originally Posted by uwe

I did the axles on my 1971 Tradewind 2 years ago. I bought complete Henschen axles from Andy. Henschen shipped the wrong axles, so i had to do the job twice,and was exposed to the brake drums twice as well, since I had to transfer them from one set of axles to the other.
Better balanced? Not even close....
Took the trailer to Andys InlandRV shortly thereafter for a balance job, and it took an ungodly amount of weight to make things right.
There might be a slight improvement, but it's still far from perfect.

Uwe,

It has been my experience that "Disc Brake Rotors" are fairly true, while drums vary quite a bit.

Well said,
Henry

[TomW]

I finally got around to replacing my wheel drums, and I must say that these new ones rotate much truer than the original ones did. Although the real test will not be until the first part of October when we head to Disneyworld, I sense that all my vibration issues have been resolved.

I feel much better now.

Tom
p.s. FWIW, the new drums came attached to new axles.

[scottanlily]

Andy is right about the balance of running gear ,the reason its so important on the torsion axles is because the axle tube is in direct contact with the frame ,even welded to it on early bambis sometimes. the torsion arm is short
so all vibration from imbalance ,drums ,tires etc is transmitted right to the trailer ,of course some is absorb by the rubber rods in the axles and
the shocks .something needs to control that shaking .the leaf spring axles
on the other hand do not have the axle anywhere near the frame to make contact with it ,and with good shocks and good tire balance ,no issues to
speak of .I will say that a good quality tire ,radial or otherwise will work fine.

Scott

[ROBERTSUNRUS]

Hi, You did the right thing replaceing the 38 year old brake drums. I don't remember brake drums being so bad 38 years ago, But with normal wear, loose plates, rust, and the machineing of warped, out of round, and with hot spots being removed its going to change the balance of the original casting.
In the old days cast iron parts were made in America and set aside to cure; To take final shape before final machineing was done. Now some of these parts are cast, machined, and shipped to America from God knows where?
Also in the old days we had a few ways to spin balance wheels on the vehicle. Therefore balance all spinning parts. But it was too time consuming. So here we are in modern America wanting everything yesterday.
Bottom line your drums were bad from age, wear, and tear, not poor workmanship done 38 years ago!

Bob

[LI Pets]

I have a hard time seeing the need to balance the wheels with the drum.

I never heard of this being done on cars-trucks.

It has been working on millions of cars for years without doing this.

Anybody backup this procedure with doc's from the manufacturer