Causes of Vibration and Solutions

[Mike Groves]

All,

While driving from Ashland, Oregon along 5 North, to Rt 138, to 38 to 101 up to Newport, OR the ol' '99 had way too much vibration for my tastes.  I've always had a bit, mostly from the passenger side of the coach, but yesterday it was especially bad.  I felt nothing in the steering, rather just a rhythmic vibration where I could see, for instance, the passenger seat vibrating and hear, for example, the window treatments knocking against the surrounds.

What could be the major causes of this vibration, how would one trouble shoot it, why nothing in the steering wheel, and where are the best service centers that might be able to actually rectify the problem?

Thanks,
Mike

[Steve Huber Co-Admin]

Mike,
Rear tire balance problem or maybe an out of balance drive shaft, although I've never heard of this on a pusher, it can cause similar problems on a front engine unit that has a longer drive shaft. Probably a number of other causes but none come to mind now.
Steve

[Gerald Farris]

Mike,
The highest probability by far for the cause of your vibration complaint is a tire problem. It could be out of balance, out of round, or even a tire construction problem causing a hard spot in the tire. However, from what I have seen in regards to truck tires the hard spot issue is rare. You can also have an out of balance problem with the brake rotor and hub assembly, but that is uncommon on a coach.

Something that may help you in troubleshooting the vibration is to answer the question, "when did the vibration start". If it started after installing new tires or having tire work like tire a flat repair, the problem is almost definitely located there. However, if it started after a curb impact, you may have a bent wheel or a damaged tire. A lot of tire failures are first noticed as a vibration that gets worse before the tire fails, so when the vibration starts and is it getting worse can be a safety issue as well as a comfort issue.

Another clue in troubleshooting a vibration is the frequency or speed of the vibration. The engine is rotating much faster than the wheels at low speeds, but it slows down as the speed of the coach increases in relation to the tires. However, the driveshaft is always rotating at about 4 tines the speed of the wheels, so a driveshaft vibration is at a much higher frequency than a wheel speed vibration and an engine vibration will vary in relation to wheel speed.

Gerald

   

[Joel Ashley]

I'd plan a trip to Grants Pass and have Henderson's check the tire balances and driveshaft.  They'll likely want to do their full road test which will cost a bit, but it helps them ferret out issues, and brings you as the owner a better understanding of your coach;  that's worth it.  I spent a pretty penny there last fall changing a lot of things underneath the rig, but it's now a better handling coach.  I do have a slight vibration they deemed normal, but I may still run back through Grants Pass and have Bob's crew reassess it;  Les Schwab (Bob Dickman's) in Junction City balanced the front on the new Toyo install but not the rears, and it may be a rear tire out of whack (or just my unreasonable expectation of a Cadillac ride).  Henderson's has excellent balancing equipment and techs.

Joel

[Mike Groves]

I'd been operating under the assumption that I needed 120lbs for a full load but my table up front gives 110 max.  So, all my tires are overinflated.  When I first got it, had the new tires put on I ran 105lbs all around.  I guess I'll set them all to 110 at 65 degrees and see what happens next trip.

Mike

[Jim Houghton]

Since you said you had new tire installed when you got the coach. Not knowing how much it has been driven. You might want to insure the wheel lugs nuts are tight to a proper torque.

[Edward Buker]

Mike,

I do not know exactly what table you are referring to, I think the plaque behind the driver seat maybe. More often then not these are wrong given they do not reflect the brand/model tires that are currently on the coach and it does not reflect your individual running weights on the axle and the corners.

This is not something to "try out" given it is a safety issue. The only inflation table that is correct for your coach is the one from the tire manufacturer for your model tire. From there, without getting the actual coach weight, you should always error on the side of higher pressure, then you think you might need, until you can learn the actual loaded weights. 110psi in the front sounds low to me for your Marquis. Perhaps someone with a similar Marquis can share their weights for a rough estimate.

Later Ed

[Mike Groves]

I think you're right Ed.  The rear can be at 110 but according to the doublecoin guide, the fronts need 120. 

Mike

[Edward Buker]

Mike,

That sounds about right until you can have the opportunity to get the corner weights measured. Good job hunting the tire info down. Our job as the driver is to keep them all safe...

Later Ed

[Mike Groves]

Since we're at Pacific Shores in Newport, Oregon and the Les Schwab here is not Coach Friendly (especially with a tow vehicle) I will see what they want to come out to us to inspect the tires and for tightening the lugs.  I think they charge a road fee to come out but other than that they should look over the tires and AT LEAST tighten down the lugs to eliminate that concern.  I don't know of much else I can check now that my Viair has the fronts at 120 and all 4 rears at 110.

Mike

[Mike Groves]

We drove back to Portland yesterday with no change in the vibration which occurs at about 45mph and higher.

Since we purchased the Double Coin tires at Les Schwab I stopped by a store and their "expert" thinks I should balance the tires as a first step with something called "Counteract" for $20/tire but the only ones that could be causing the problem he stated would be the front tires as the rears are under such a weight load and locked in so that they can not move much.

I do admit that $40 total doesn't sound like a bad idea but he didn't have any on hand so I have time to ask here for advice.

Anyone?

Mike

[Joel Ashley]

Mike-
Your symptoms are much akin to what I've experienced in a few vehicles over my half century of ownership.  My 70 Shelby GT500, for one, came off the dealer lot with a vibration at freeway speeds;  it was a faulty driveshaft. 

As I've suggested previously, the cause in your case is most likely either wheel balance or driveshaft.  I've used Les Schwab numerous times for purchase and service.  They are reputable but on rare ocassion let me down.  I can vouch that the Goodyear service center in North Portland has state-of-the-art balancing equipment and may be worth a call, but it will be more than $20/tire, if they even deal with other branded tires. 
http://www.yellowpages.com/portland-or/mip/goodyear-auto-service-center-297518

Our current Toyos in fact are Les Schwab installed, but the Bob Dickman facility in Junction City that sold them is more atuned to motorhomes than most.  I'm not familiar with the "Counteract" term, nor was it mentioned at Dickman's.  But they did offer both a front and rear balance option at the time, saying they didn't really think doing the rears was necessary, probably for similar reasons to what you were told - the fronts are more susceptible to balance problems.

Our coach still exhibits some vibration, although pretty much at all speeds.  I would repeat that Henderson's in Grants Pass is the place to go if you want the ultimate analysis.  Though they said our coach rode as expected when they were done with their final test last fall, I still want to have them do a recheck;  having the rears balanced and knowing the driveshaft is true and knuckles are optimal are about the only things left that could be done to ours.

However I refer you back to Gerald's input here also, regarding a damaged wheel or brake issues if the problem appeared sometime after the tire installation.  You could spend the $40, but you may end up heading to Grants Pass in the end anyway - that's up to you.  It would seem that if Les installed the Double Coins and balanced them at the get-go, they should stand behind them being balanced originally, especially if the vibration was there ever since.  Like your "expert" indicated, assuring the fronts are okay is a sensible first step, and is likely what Henderson's would first check also.

-Joel

[Steve Huber Co-Admin]

Mike,
Get your tires balanced before chasing down any other possible causes. Counteract is the installation of balancing beads. From my experience they are very effective but you need to use the  long valve stems as the normal length ones can stick open if a bead gets lodged in them. I'm sure that they will install them. Also they should put Red capped valve caps on which signifies beads in the tire. I had beads on my Marquis but switched back to Centramatic on the 07 Contessa as I already had them from my 01 Contessa. There was a discussion of beads here a few months ago. http://beaveramb.org/forum/index.php/topic,5628.msg42197.html#msg42197
Steve

[Mike Groves]

Thanks Joel and Steve.  We're stopping by Les Schwab's in Wilsonville, OR today since the one in Woodburn was fresh out.  As a first step not a bad idea.  I wouldn't necessarily expect them to stand behind a 2 year old balance job when they put the tires on.  But should I?  Dickman put these on for me along with the extension valve kit.  I have noticed that on one side the rubber grommet has to be pushed back true to the tire sometimes while the other side stays in place.  Does that tell me anything?

Mike

[Joel Ashley]

I'd certainly mention that to them.  Les Schwab has often been good about servicing their installs, regardless of age.  If the vibration has been going on since the install, it probably should've been brought to their attention back then, as now they could say it's due to a curb bump or road hazard if it's no longer balanced.  The bead method would've been at additional cost at install no doubt, regardless.  They may consider some recompense against the original balance cost if it wasn't inclusive back then, but it usually is.  It may not be worth arguing with them about.  You should know as soon as you hit I-5 if the rebalance does the trick.

Joel