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-   -   New drums to correct running gear imbalance? (http://www.airforums.com/forums/f439/new-drums-to-correct-running-gear-imbalance-19327.html)

TomW 11-23-2005 03:17 PM

New drums to correct running gear imbalance?
 
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 11-23-2005 03:42 PM

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 11-23-2005 03:44 PM

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 11-23-2005 03:49 PM

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 11-23-2005 04:10 PM

It's a great idea...
 
Quote:

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 11-29-2005 04:07 PM

Making a Christmas list
 
Quote:

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? :flowers:

Thanks,
Tom

markdoane 11-29-2005 04:43 PM

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 11-29-2005 05:10 PM

Not Really...
 
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 11-29-2005 05:48 PM

Quote:

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 11-29-2005 06:13 PM

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

Roll of the dice I guess.

Action 12-01-2005 12:43 PM

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 12-25-2005 10:52 PM

1976 Argosy
 
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?:sad:

Action 12-26-2005 07:02 AM

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 12-26-2005 07:35 AM

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.


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