How much vibration is normal?

[jeffwink]

I am trying to diagnose a potential vibration problem. On our last trip (in 2010) we had a blowout and some wheel well damage. On the return leg we had a second tire blowout as well, but without any collateral damage. Once we arrived home we found that the rear dinette bench had vibrated loose, shearing off the mounting bolts and the charger/converter had vibrated loose from its mounting on the bench as well. I have also discovered a couple popped rivets in the dinette area (CS).

Fast forward, the tires have all been replaced, the wheel well fixed, the bench remounted, etc. On the short drive to return the trailer to storage the bench has vibrated loose again (however this could just be settling and I just need to tighten things up). Trying to figure out what's going on, today I did a road test with me in the trailer to gauge any road vibration that might be causing the problem.

Of course, the problem is that I don't have any context for what I experienced. There is definitely road vibration. It begins at 30-35 mph and is fairly stable through 55 mph. It is definitely more noticeable over the wheels than towards the front of the trailer or in rear part.

So, my question is how do I tell whether I've got normal vibration or I have some more serious issues like: 1) wheel or running gear imbalance, or 2) need to replace axles, etc.

Any help would be greatly appreciated.

[Jammer]

There shouldn't be any noticeable vibration. I would start by having wheel balance checked and go from there.

[JimGolden]

Absolutely, get your wheels/tires dynamically balanced! You will often hear "Uh we don't balance trailer tires." And I ask "Why not?" They reply "Uh we don't know, we just don't." I say "Well, you are going to dynamically balance all six of mine." I can drive 500 miles and not shake a soap dispenser off the sink.

You definitely have vibration issues. If your wheels and tires are not dynamically balanced on a spin balance machine (like they do for the tires on your car) then there's your answer. If they are balanced, then maybe your hubs are super out of balance. A machine shop can fix that.

You might put a friend in the back with a walkie talkie and drive down the road at highway speed and talk to them and see if they can ID what's going on. It may be "extra legal" where you live, but you can sure as heck find out what's going on that way. Or, your friend could wind up like Lucille Ball in the movie and have salad and flour all over them

[Silver Goose]

Vibration is not good. As suggested, have your tires properly balanced. Check for out of round, you can do this yourself. Jack one side up enough to allow tire rotation and while rotating the tire place something like a board lightly against the tread. You don't want any high or low spots. Look at the rim and note if the rim looks bent as you rotate it. Look how the tire seats in the rim. There is usually a rib on the tire just outside of the rim. The distance of that rib to the rim should be equal all around. Check each wheel. Pull back and forth on the wheel while it is unloaded from the ground. Is there more bearing play in one than the others? Do you hear any odd noise from the bearing when rotating the wheel. Are the bearings overdue for service?

Most of us have never had the (likely illegal) opportunity to ride down the highway in our trailer so we don't know how much shaking is going on back there unless we find screws, rivets and other things where they shouldn't be. Your case sounds like something is seriously in need of attention.

Do you know the cause of your tire failure? Under pressure? Overloaded? Pothole damage? Over 5 years old per date code stamped in tire? Besides the vibration induced by an unbalanced wheel, this causes undue sidewall flexing that generates additional heat in the tire which can lead to premature tire failure.

[eubank]

You know, I might want to have the whole of the running gear checked out -- in addition to a good balance job (or centramatics, if they'll fit). There really should be little or no vibration.

Lynn

[Silver Goose]

I use Centramatics. They fit, they make a model specific for the Airstream and Andy has them. They are effective at what they do, but you still need to start with round wheels and tires and I would still have them computer balanced to start.

[jeffwink]

New tires were supposedly balanced. Need to find a shop that can look at the running gear.

As for the cause of the previous blowouts, my initial thought was that it was simply a tire issue. They were 5 years old and had gotten intermittent use.

[dmcinfo]

I just bought two new tires for my 1968 GT. Both of the tires I replaced looked nearly new but sat in one spot for a long time.

Before installing my new tires the installer put the old tires on the computer balancer and let me watch the movement of the tires and the balancing readings. One tire was way off balance (4oz) and appeared to have a flat spot even after weights were added to balance. The other tire had a less noticeable flat spot, was off balance (by 1.5 oz) but, also moved laterally as well. Then he mounted and balanced the new tires and let me watch again. The tires seemed to rotate as if they are perfectly round and balanced but the lateral movement in one of tires could not be eliminated.

I'm guessing that the lateral movement in the one tire (cuased by the rim not being true) may have been a contributing factor to the shaking inside the coach. How much, I dont know.

I haven't been on a trip yet to compare the before and after. But, I suspect that I may be looking for a new rim. I could be wrong, but you might want to determine if your rims are true and eliminate that possibility. Maybe someone on this board is more experienced than I and could verify my suspicion.

[Davern1]

I have the same model and year trailer. My dinnette came loose after every intial trip until we reinforced the mounting brackets. I've since done away with the dinette completely and added centramatics from Andy on all four wheels. They seem to have made a difference. Last, I had a blow out with damage at the five year mark on the original tires. Anyway, centramatics, new tires, and enhanced brackets should hold the dinette down. If you search our model you will see that the sub floor material is less desirable for the model year than other models and may also contribute to the screws working lose on the dinette.