BAC Forum

General Boards => Technical Support => Topic started by: Michael Bartkoski on April 26, 2015, 04:07:58 PM

Title: Vibration at 55mph
Post by: Michael Bartkoski on April 26, 2015, 04:07:58 PM
We have a vibration on our 2005 Monterey 38 but only at 55mph +/-  it seems to be coming from the rear of the coach.  Any troubleshooting suggestions are appreciated.  What has been done...rear tires are 15 months old with ~5K miles, using sand balance inside, checked the drive shaft and u-joint no obvious signs of damage or out of balance, tire pressures at 105 psi.
Thanks
Title: Re: Vibration at 55mph
Post by: Keith Moffett on April 26, 2015, 11:34:13 PM
Vibration can be hard to nail down for the source.  If it were indeed a wheel balance problem, in my experience anything above 50 mph is usually a front tire unlike lower speeds.
Are the front tires sand balanced as well?
Title: Re: Vibration at 55mph
Post by: Michael Bartkoski on April 27, 2015, 04:28:50 PM
Thanks for the reply. Yes the fronts are sand balanced as well.  I get no vibration through the steering at all.  Am thinking of trying the Centramatic big rig wheel balancers.  Anyone have experience with those?
Thanks in advance for your help, suggestions
Title: Re: Vibration at 55mph
Post by: David T. Richelderfer on April 27, 2015, 05:07:16 PM
Just a thought...   You could have a tire with a break in the belting under the tread.  In my pickup I had a tremor ongoing for a couple years.  Finally it got bad enough I stopped by a Firestone shop in Billings.  They found nothing.  A few weeks later I went into a Les Schwab's North of Sandpoint, ID.  The experienced fellow on duty found a worn-down-flat spot, a "bald" spot, on the tread about 4" to 5" in diameter.  There was a break under the tread that allowed the tire to bulge un-noticeably, but the bulge in the tread caused a tremor and caused excessive road wear over the bulge to make a bald spot.  Since I purchased these 6-ply tires new at Schwab's, the tire was replaced with a used, traded-in tire at no cost.  Within a month the tremor returned and Schwab's in Reedsport, OR replaced another tire at no charge - same problem, a break under the tread causing a bald spot.  After returning home to Hermiston, OR I had yet another tire replaced with a break under the tread and a bald spot.  The Hermiston Schwab's, where I originally purchased the new set of four tires, wanted to charge me for the replacement tire.  When I pointed out this was the third of the set of four tires that developed a break under the tread and the other two tires were replaced by other Schwab stores, then the employee immediately capitulated to no charge.

One thing I learned is if the wheel is removed from the vehicle and placed onto a spin-balance machine at a slow speed you can plainly see that a tire with a break is out-of-round.  The tire kind of wobbles while spinning.  Thus the vibration we feel.  I would submit even if your tires are new, one tire can still be defective.  I now have a new set of 10-ply Cooper tires from Big O in Yuma, AZ.
Title: Re: Vibration at 55mph
Post by: Gerald Farris on April 27, 2015, 07:07:39 PM
Mike,
Before spending money on Centramatic balancers, I would have the tires put on a spin balancer to see just how bad out of balance they are and to make sure that they are not out of round. I have seen many brand new tires that you could spend a fortune on balancing, but never cure a vibration because they were out of round.

Money spent on a proper diagnosis is a much better investment than throwing parts at a problem and hoping to fix it.

Gerald     
Title: Re: Vibration at 55mph
Post by: Steve Huber Co-Admin on April 28, 2015, 03:42:26 AM
Mike,
I put Centramatics on my Contessa as the Goodyear tires were constantly losing balance. They worked well. I have beads in the tires on my Marquis and they've performed as well as the Centramatics.
But, I fully agree with Gerald. Find out what is causing the problem first.
Steve
Title: Re: Vibration at 55mph
Post by: Michael Bartkoski on April 30, 2015, 12:42:24 AM
Thanks for the advice guys...I'm off to find a tire store that has the capabilty to spin these.