Bad Vibrations

Did you have the new tires spin balanced? Some people say you don't need too, but in my experience its a must. Even on the RV..

Dave

What chassis, length, and year?

Jim, "Mo' coffee!"

Lots of causes of vibrations. You need to check them one at a time:

1. Is the vibration more noticeable in the steering wheel or floor (front or rear)?

2. Even before checking tires for balance, you need to check them for RUN-0UT. If over .035" fix it-- even a perfectly balances egg-- well, it rolls like an egg.

3. Then balance the tires. On front, best to balance on the rig.

4. After tires have been eliminated as the cause, check U joints and drive shaft alignment.

Sorry, right more coffee...

It's a 2007, made by Thor. Or at least it has a Thor name plate on it. Ford E450 chassis. 28A frame.

On the way back from picking it up, we had a rear tire blow out, inside left. I stood in the bedroom on the right side it appeared to be worse. Then the wobble went away for 100 miles and then came back right before the tire blew. This was a different feeling than what we have now. Was more like a washing machine out of balance as one person suggested, now we have a higher frequency vibration. While traveling back we could not get above 65 mph, it was vibrating too bad. Wanted to get home to work it out. Now we can get up to 70 with no issues, other than the constant microwave shake. It also happens at lower speeds like 40. So I would say it is no longer speed related, but rpm related.

I pulled the microwave on this first trip because from the drivers seat I could see it moving in and out, so the metal plate that secures it was oil canning maybe a quarter to half and inch! On this last trip I could still see the movement. We pulled the microwave again to get some quiet. I did not let the wife drive and get in the rear.

We already had all four rear tires replaced and spin balanced. Not sure if they are true, but all new tires. The fronts were replaced by the dealer. I have no vibrations in the steering wheel.

I was hoping someone would chime in and say, oh yeah, I had that and this fixed it. Sorry I'm a bit lazy and was hoping not to have to do a lot of troubleshooting. One can still dream.

I pulled the hood, and secured the back of the microwave with a turnbuckle to the outside wall. Hopefully I wont pull a section of the wall off!! Turnbuckle is secured to a wood strip holding the cabinets up to the metal of the back of the microwave. This may allow us to keep the microwave in the hole while doing the troubleshooting.

Thanks for the input. All good.

If tires are ok, and none of the U-joints are bad, and the drive shaft has not lost any of the balancing wheights and has not been disasembeld and turned out of balance, check the shock absorbers some times one or both shocks on the rear or front will be bad just enough, and all it takes is a small bump on the road to set a vibration going.

To check this out, drive until the vibration starts, note the speed and then slow down, do not stomp on the brake, note when the vibration stops, if it stops fairlly soon then the shocks are bad if it stop a long way down the decel curve then you have someting else, maybe a torque converter that lost a balancing weight or a bad bearing on the rear axel.

navegator

High frequency vibration is usually the driveshaft. Most common cause for driveline vibration is a worn out center support bearing. But it could also be U-joints.

At this point, I'd suggest comparing your actual tire pressures to the door post sticker, and to what other owners are using on similar units. My C is very much smaller & on a different chassis, so I'm no help. But I know some lot jockeys see the '80 psi' on the sidewalls and pump them up to that without reading the rest of fine print. That can cause a minor vibration to become a lot bigger.

Also, some RV makers cut & lengthen the chassis between the axles. This requires lengthening the driveshaft, so it's a suspect... thrown weight, damage, etc. If it's a two-section driveshaft, check the center bearing.

Good luck with it!

Jim, "The buck doesn't even slow down here."

Like Bryan I suspect driveshaft. Is it possible that when the tire blew a tread belt wrapped around the shaft and bent it a little? Even if it later came off. Look for drag marks on the shaft. Also, at least with some vans, if a shop lifted it on a frame lift, the rear axle could drop far enough for the driveshaft to drop into contact with the head of the lift. That could dent or bend the shaft.
Has anybody removed the driveshaft? From what I'm told, the sections should NOT lie in a straight line. A slight offset cancels vibration. If perfectly aligned, the sectional shaft tries to vibrate as a long one-piece might.
Oh, a driveshaft shop found one of our shaft yokes was not welded true into the shaft's tubing. They cut it out and welded back straight. Smoother!

Had my mechanic check out the U Joints, all three drive shaft joints looked good. He suspects that the shocks might be a source of allowing vibrations. All four are original. Low miles but 8 years old with original shocks. Also taking it back to tire store to have the tires rebalanced. Not sure I know where to go from there. Hate to pull all three drive shafts and have them balanced until all else is exhausted. Nuts.

See my post above. Check tire run-out as well (actually before) balancing.

You can balance an "egg-shaped" tire 'til the cows come home and it will still vibrate.