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JDOnTheGo

Coach Vibration Sanity Check

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Hello all,

I'm mostly looking for a sanity check to see if my thinking makes any sense.  While I certainly enjoy tossing large sums of money at my coach, I generally like to see some improvement as a result. To date, the results have not been good. Thanks in advance!! 🙂

I've been fighting a fairly significant vibration on an MCI coach (102-EL3) for a couple years now. In general, it starts at 55mph is bad up thru 63 mph and is tolerable at 66-68mph. It may be better when cold - definitely bad after being in operation a while. Up/down hill doesn't matter. Coasting downhill doesn't make any difference. I won't bore you with all the details but will say that I've had every king pin, bushing, rod end, etc... replaced that mechanics have even given a second glance, all eight tires, four wheels, Road Force balanced all eight wheels/tires at least four times each (different shops), replaced tires, used Tru-Balance to mount wheels, etc...  I have never tried balance beads and nobody has spent much time looking at the drive shaft.

It makes complete sense to me that my problem is not the wheels/tires (given two different sets of tires and the number of times the wheels/tires have been balanced - perhaps the brake disk or ???). I was looking for a shop that would perform an on-vehicle balance and ran into the threads here about the Centramatic balancers. I haven't yet found such a shop in the NM area so was thinking of tossing another thousand $$ at it with these Centramatic balancers.

Sound like a logical next step?  Or, do you know of a really good shop that will do on vehicle balance in the SW (NM but I would go to PHX if there was optimism).

Thank you!!

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You've balanced the tires/wheels. Have you had them checked to see if they are running true? A bent wheel can be balanced but still cause vibration.

Have the hubs been serviced? Worn or loose bearings can be problematic, as can pitted bearing races.

Have you checked the drive shaft and u-joints. Any slop there can cause vibration, as can an out of balance drive shaft. What about engine mounts and transmission mounts?

Just a few ideas to ponder.

Perhaps posting a question on one of the bus conversion sites would be helpful. Two big ones are busconversionmagazine.com and busgreasemonkey.com

 

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1 hour ago, JDOnTheGo said:

Hello all,

I'm mostly looking for a sanity check to see if my thinking makes any sense.  While I certainly enjoy tossing large sums of money at my coach, I generally like to see some improvement as a result. To date, the results have not been good. Thanks in advance!! 🙂

I've been fighting a fairly significant vibration on an MCI coach (102-EL3) for a couple years now. In general, it starts at 55mph is bad up thru 63 mph and is tolerable at 66-68mph. It may be better when cold - definitely bad after being in operation a while. Up/down hill doesn't matter. Coasting downhill doesn't make any difference. I won't bore you with all the details but will say that I've had every king pin, bushing, rod end, etc... replaced that mechanics have even given a second glance, all eight tires, four wheels, Road Force balanced all eight wheels/tires at least four times each (different shops), replaced tires, used Tru-Balance to mount wheels, etc...  I have never tried balance beads and nobody has spent much time looking at the drive shaft.

It makes complete sense to me that my problem is not the wheels/tires (given two different sets of tires and the number of times the wheels/tires have been balanced - perhaps the brake disk or ???). I was looking for a shop that would perform an on-vehicle balance and ran into the threads here about the Centramatic balancers. I haven't yet found such a shop in the NM area so was thinking of tossing another thousand $$ at it with these Centramatic balancers.

Sound like a logical next step?  Or, do you know of a really good shop that will do on vehicle balance in the SW (NM but I would go to PHX if there was optimism).

Thank you!!

Wondering if it might be the drive shaft. What year is the MCI Coach?  Did it start after some rear end work? or was it tower to a shop for repair before the problem started?

The later question could be in play if the drive shaft required work or was reinstalled out of phase. The second part that could be  the ride height being off causing some miss alignment. If one starts moving and the air ride is not up, the shaking will get ones attention very quickly.

Good luck !

Rich. 

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1 hour ago, desertdeals69 said:

Is the vibration at wheel speed or 3-4 times faster which might be driveshaft speed?

My thoughts exactly. A high frequency vibration would be a driveline issue where a wobble would be on the wheel end. 

As mentioned, was the ride height checked? Too much of an angle on the drive shaft can cause a vibration as well as a drive shaft being perfectly level is also not a good thing. U-joints are designed to be at an angle so the needle bearings rotate.

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Let me add to the drive shaft. Have the universal joints been checked. As speed increases so does the angle of the drive shaft which could affect loose or bad "U Joints".

Herman

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How many actual miles on the coach? Have you called MCI technical support (800-241-2947)?  I have called them on several occasions and always got good service and answers. I am in the same camp with others about the drive shaft being a possibility, it is very short and not very forgiving. One other suggestion that cost no more than fuel, try dropping the air in the trail axel and see if the vibration changes to a different speed. One other person to call for advice is John Cherry at Evolution coach, located in White Haven Pa. Nearest MCI service center to you is Dallas Tx.

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Thank you all - excellent input.

The wheel/tire balancing was done with the 'Road Force' machine that measures run-out/out of round so that has been checked.

As far as I am aware (and can see from the chassis) there hasn't been any major damage/repair.

No, the ride height has not been checked.

As I noted, I asked for the drive shaft to be checked but no idea if it really was (or they even knew what to check). Lacking any confidence in the people working on the coach is very frustrating. I suppose taking it to an MCI service center is about the only remedy for that (at least I hope).

I have not tried different ride heights at speed but that is easy to do - thank you for that suggestion!

Ya'll have given me some ideas - thank you!

 

 

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1 hour ago, JDOnTheGo said:

As I noted, I asked for the drive shaft to be checked

The best way to check it is to remove it and manually rotate each bearing cap. I have seen on many instances where a shop reported ("its all tight, nothing wrong") and they were right, one cap was seized causing the vibration. Most will check for looseness, not seized caps. 

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