Bad Vibrations

[Mfreyder]

Bought a Four Winds Chateau Sport a month ago. Coming home we had a bad vibration that turned out to be a bad tire. RV had new tires on the front, 2011 tires on the back. Replaced all four tires on the back so we knew we had good tires to start.

So the bumping went away, but now we have a vibration that is shaking the microwave to death. Microwave floats, held in place by a face plate that has braces going around the back, and the face is held by four screws to the cabinet. On a recent trip we had to remove the microwave to be able to hear ourselves think.

Question is what is causing this vibration? Drive train vibrations? Drive shaft? Anyone have experience with this problem? I'm heading out to check U joints today. Suggestions?

Thx

[carz57r]

Did you get the problem fixed? What was the cause?

[j-d]

I think Ford used that pin in the rear hubs till about 1984. At least our 1983 chassis used them and it didn't seem later years did. The wheels weren't hub-centered (aka hub-piloted) but rather they were "Coined". Every other lug hole was recessed or raised. Inner wheel's recess had to match outer wheel's raised and the pin lining up in a hole assured that.

OP is saying it's 2007, so I'm pretty sure there's no pins. Our 2002 doesn't have them. There's still an extra hole but I haven't figured out what Ford meant it for.

[rongtamw]

On some Fords they use a compression pin as a guide for the rims. Is it possible that the pin was not aligned when the tires were changed?

[j-d]

This is gonna sound stupid-simple, but...
Make sure no foreign object got trapped between wheels and hubs or between the faces of the dual rear wheels.
I had a tire installer pinch a braided valve extender between the duals. He caught it right away and replaced it but I imagine such a thing could cause a wobble.

[wolfe10]

the_armadillo wrote:
While you have the tires off for checking balance and run out...

Actually, you want to check run-out with the tires mounted on the vehicle.

[tpi]

Chat up some of your friends or mechanic who know the difference in the feel of a wheel balance issue vs. a driveline vibration. Go for a drive-they generally are distinct from each other. Driveline vibration is generally higher frequency than wheel balance, but both are relatively low frequency. It is hard to describe but driveline vibration is frequently audible as a low frequency constant booming noise, possibly a rumbling. In a bad case it could cause stuff inside to rattle with the vibration/sound. Wheel balance is lower frequency (wheels turn slower than driveshaft).. more of a shake which can also set off rattles.

[the_armadillo]

While you have the tires off for checking balance and run out, also watch the wheels on the spin balancer to ensure the wheels are straight and watch the tread while it is spinning. I seen both improperly mounted tires and defective tires that showed excessive tread wobble. The tire shop should have caught any of these when they mounted/balanced the tires. If no joy after checking tires/wheels and drivelines, you may have to check run out on axle hubs (rarely a problem unless something bent an axle).

[wolfe10]

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.

[Mfreyder]

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.

[j-d]

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!

[Handbasket]

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."

[carringb]

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.

[navegator]

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

[Mfreyder]

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.