Vibration @ 59 - 61 mph

[john brunson]

I realize that I am peeling an onion....

beginning was BAD vibration 50 mph plus... noise and vibration worst in vicinity of rear axle.

proper tire inflation = big improvment

centramatic balancers = another huge improvement

new shocks = no improvement in ride but much better driving manners

balance driveshaft at local Volvo truck shop (guy said it was bad out) = almost all gone except mild vibration 59 to 61

63 to 70 = silky smooth ride....0 to 59 is like glass...

Calling all experts.... what should i check next???  ideas?

thanks

[Steve Huber Co-Admin]

John,
Is vibration in steering wheel or throughout the coach? If latter, can co-pilot check to see if it is more pronounced in front or rear of coach?
Steve

[john brunson]

Nothin in steering wheel... co pilot reports starboard rear axle is loudest

[Lee Welbanks]

I assume that your coach has alum outter wheels and steel inners. Could be a bent wheel, a bad bearing usually will not cause a vibration. Would be great if you  could find a dyno to run it on and really zero in on the cause.

[Jerry Carr]

John you show a location, if your on I-5 near Grants Pass go to Henderson's Line Up they can tell you the problem

[john brunson]

I am on the opposite side of the Continent! (Troy, Alabama)

[Steve Huber Co-Admin]

Might find a shop close to home here. http://www.rvservicereviews.com/StateList.asp?state=AL
Steve

[Gerald Farris]

John,
There is not much that I can tell you without more information and/or driving the coach myself. However, before you spend more time or money on the vibration, you need to determine where it is coming from, and one way to do that is to change engine RPMs to check if the vibration changes. So drive in two different gears at the same speed to see if the vibration changes like if you are in 6th gear when you notice the vibration shift to 5th or 5th to 4th. If the vibration changes noticeable or goes away, you may be looking for an engine problem but if there is no change you have ruled out the engine as a source.

Also, since you installed centramatic balancers, I assume that was to correct a wheel imbalance condition, but they will not correct a high degree of imbalance, so you may still need to balance your tires if the above test makes no changes. Also you should have already checked the tires and wheels to see how straight and round they are because this is the number one cause of vibrations after wheel balance.

Gerald         

[john brunson]

Gerald,

vibration is solely dependent on what the speedometer says, not the tachometer. It is definitely in the back of the coach... I am currently looking for a shop that can true 22.5" truck tires.... will have the rear axle tires checked.

[Dave Atherton]

John, passing along repair that happen to Monaco knight motorhome ( winter snow bird).
What had happen, the 4 inch square tube that Monaco built to hold rear differential to frame of
Motorhome cracked open in between the u-bolts on bottom and up the side of square tube about
3/4 inch allowing a change in measurement from parallel to motorhome and put up vibration
like you posted on passenger side tube. The crack just opened up tube but still holding on top
but 3/4 inch on one side did change the tracking. Dave Atherton Retired Cat Mechanic

[Keith Moffett]

John, just a thought but the Tiffen folks do very good work by all accounts so you might do a road trip.