Vibration at 55-60 mph

[Rob S]

I get this vibration I can feel in the drivers seat that occurs most of the time right around that speed - maybe more so when starting out for the day - less noticeable after driving for a while. It has survived unchanged a recent install of new tires all around, so the idea it was an unbalanced tire seems unlikely.

Any ideas?

 

[ECU]

I had a vibration like that at 40.
Made sure trans fluid was at proper level and it went away.

 

[Winterbagoal]

Steering wheel vibrates, front tires may be out of balance/alignment. Seat vibration usually means rears. If it's the problem.
I'd try the transmission fluid level check first.

 

[sprintlock]

Speed dependent vibrations and noises are mostly due to tires, suspension and driveline in that order. At a given speed the vibration becomes resonant and hence more noticeable. If you it became more noticeable with the installation of new tires, have them rebalanced. Check to see how much weight it took to balance the tires, if one of them has significantly more weight on it that the others, that one may be the culprit. Many tires shops will not take the time to balance the tire properly by spinning the tire on the rim to find the best balance point.

Check the shocks and all suspension joints. Also, if the vibration is very sensitive to throttle changes when it occurs, it is most likely the drivetrain.

 

[TJLee089]

My guess is rig never had a COMPLETE front end alighment. My original front tires had very uneven wear after only 15k and had to be replaced. Info buried in the manual indicated new owner should get a FEA. Winnebago rep told me they only do "toe in" on new vehoicles.

"FRONT AXLE TIRE ALIGNMENT We recommend that you have the front suspension and steering alignment checked and adjusted after you have fully loaded the vehicle according to your needs. Thereafter, have alignment inspected periodically to maintain vehicle steering performance and prevent uneven tire wear."

 

[Rob S]

Thanks, all

Front end alignment done 6 mo ago, just prior to my purchase, I have a full report that looks detailed enough.

Tire changeover did not affect the amount of the vibration much at all.

Transmission service just completed by MB of Nanaimo does not appear to have affected it.

I am beginning to suspect out-of-balance driveshaft - is that likely, and if so how does one check for that???

 

[Winterbagoal]

I've seen that mentioned before elsewhere. Can you get underneath the vehicle and verify the presence of all the nuts/bolts connecting the driveshaft (propeller shaft in the OM) to the transmission and rear end? When these things get flat towed, the tow truck guys are supposed to disconnect/remove the propeller shaft so as to not damage the transmission. Maybe they missed one?

 

[lenore]

Have read somewhere that the propeller shaft support being worn can cause this.

 

[sprintlock]

Thanks, all

Front end alignment done 6 mo ago, just prior to my purchase, I have a full report that looks detailed enough.

Tire changeover did not affect the amount of the vibration much at all.

Transmission service just completed by MB of Nanaimo does not appear to have affected it.

I am beginning to suspect out-of-balance driveshaft - is that likely, and if so how does one check for that???

One way to check driveshaft balance is to drive and determine if the vibration occurs at the same vehicle speed and/or engine rpm. If it happens consistently at one of these variables it is usually resonance of the entire drivetrain and it may/may not be the driveshaft.

If it is occurs over an rpm range but gets worse with speed then it may be a balance issue. Then you can tick mark the driveshaft every 45 degrees near the yoke lift the vehicle and let the engine spin the drive train and observe the vibration. Stop the engine, add a small weight at one of the tick marks and move it to different locations after you see the effect in vibration. Use a small weight and don't rev it too fast. The effect of the weight is noticeable even at low rpm.

The process is akin to balancing a tire and is best done in a shop.

 

[Rob S]

Finally crawled under there, and looked over the whole driveshaft area. Did not detect anything unsymmetrical in the way of parts, and the steady bearings were totally tight.

For now the vibration is infrequent, and appears to go away after driving for a while, ie only vibrates when cold?? and between 55-60 mph, so I'm going to wait and see for a while.

Thanks, all for your input