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jdpm · 10-24-2021, 06:23 PM

Kind of long post but trying to give as much info as possible to get good advice.
I'm the 2nd owner of a 2015 Winnebago Vista 27n on a 2014 18k chassis. I purchased it a thousand miles from home back in July with less than 7k miles. The drive home was good other than a reverberating noise that I thought was wind turbulence produced by the mirrors deflecting air against the side windows, aged out tires out of balance out of round, etc.
The coach had the original tires on it, too, so I tried not to be to critical until I got it home and had new tires installed as well as an alignment.
Well that's all done now and I still have the obnoxious reverberation.
Yes, its like someone pounding on a glass window. It comes on goes at times but overall is pretty constant above 50 mph.
Today is only our third trip with the coach. The first two were only 1 hour drives in which 30 minutes were highway. Today was a 4 hour trip mostly highway. So today I walked around inside the coach while the other half was driving. I do NOT think the issue is what I originally thought!
We don't experience vibration at our feet in the cab area or in the steering wheel. Nor do I notice the vibration in the rear even standing right over the rear axle.
I first noticed our cat shaking while riding on the sofa which prompted to get up. Right when I got about 5 feet behind the cab area is when I felt the vibration shaking the sofa and even the sink cabinet across from the sofa.
So again, I walked to the rear of the coach and stood right over the rear axle and no vibration. It's strictly in the middle.
So once parked, I looked underneath and I can see a drive shaft joint and frame mount right in the vicinity of where I felt the vibration.
Does this sound like anything anyone else has experienced? Could I have a drive shaft issue?
It's really obnoxious and makes an otherwise nice drive a bit annoying.
Thanks in advance.

Skip426 · 10-24-2021, 06:39 PM

Could you have a U joint or other drive shaft issue . YES .

Long drive shafts , multiple joints , center steady bearing , shaft angles , section phasing . There is a long list of possibilities .

Sitting and possible rust in the U joints is the most likely cause . But all things involved must be investigated .

mr.tommy · 10-25-2021, 05:43 AM

Quote:

Originally Posted by jdpm

Yes, its like someone pounding on a glass window. It comes on goes at times but overall is pretty constant above 50 mph.

Have you checked that your TV antenna on the roof is pointed in the right direction? If the pointed edge is not facing forward it makes quite a banging noise like you describe. It gets worse when you have cross winds on the highway.

jdpm · 10-25-2021, 06:42 AM

Thanks, but I don't belive it's anything like the antenna or anything loose. I make reference to "banging on the window" just as a reference to the reverbrating sound.

TeJay · 10-25-2021, 07:24 AM

I guess the original owner (OO) never tried to do anything in regards to the vibration? Could you determine if the vibration is centered or off towards one side or the other? That is important because a driveshaft (DS) issue would be in the center.

If you think it's the DS and as Skip mentioned it could be. Be very, very careful in several respects.

First of all the DS is computer balanced and if balance was needed then weights will be spot welded onto the shafts. If one is missing it should be easily spotted. Secondly I doubt there has been any work done to the DS since it only had 7K miles on it. It is possible but not very likely. Maybe contacting the (OO) or check to see if they left any repair tickets in your paperwork.

Lets assume the DS has not been worked on. Inspect the DS U-joints and look for signs of rust. Sometimes a worn U-joint will spew out rust because the bearing is dry.

I guess it's possible the DS was not installed or balanced correctly from the factory. I've done this before and it helped with a diagnosis. Take a 2 OZ wheel weight and using a hose clamp install it on one of the driveshafts to create an imbalance. Take it for a short drive and see how the vibration changes. If it's worse then yes you created an imbalance. If it's not any different maybe it's not the DS but an out-of-round tire or just not related to the DS.

If you suspect the DS then try to find a shop that has a technician that can deal with it. Also make sure you magic mark and take pictures of all joints so who ever takes it apart gets it back together correctly.

There's a thread somewhere on the forum of a guy in CA who had the DS removed and his vibration took a very long time before he finally found a shop that fixed it.

If the vibration is not centered swap the front tires to see if the vibration changes or moves. The last suggestion if that has no effect take two rear tires and move them to the front. My experiences over many, many years is a difficult vibration to find is probably close to 95% due to tires. I've mentioned this also. The main reason shops can't seem to find the vibration is once the tires have been computer balanced no shop cares to re-visit tire balance issue because we assume again COMPUTERS are never wrong!!!!!

One more point. Since your significant other can drive your RV placing your fingers against a window, door, floor or sidewall can easily dampen and therefore should help to isolate or pinpoint its location.

jdpm · 10-25-2021, 12:57 PM

Thanks much for the detailed analysis. I'd like to think it's not tires since I have new ones. I asked the installer to check the rims for trueness and the new tires for reing out of round. If a tire, wouldn't I fell it standing ir sitting in the vicinity of the axles/tires? When I walk around in the coach where I feel the vibration it at a cross member and where a drive shaft joint is located. Here is a pi if the area. Thanks

Skip426 · 10-25-2021, 01:41 PM

Ok, I'm hoping I have front to rear of the coach straight in my mind , I'm thinking the transmission would be to the right of the parts in your picture.

The yellow box I've added to your photo , under the bellows are slip splines , the red circle part of the slip joint , must line up with the solid section of the front drive shaft tube at the transmission . Google two piece drive shaft phasing , for more info .
The blue lines are the U joint angle for the joint in the picture , there would be info in a F53 service manual for the optimum angle with the chassis loaded , there is a shop tool for measuring this angle and shims would be added at the green arrow both sides of the center steady bearing support to adjust .

Of course , the first step is to mark the shaft , then remove to check all U joint are free no binding .
Wheels need to be blocked , if the park brake is mounted on the back of the transmission .

jdpm · 10-25-2021, 01:49 PM

Yes, you're correct. The photo posted up side down. Way over my head. However, could area in the photo create the oscillating vibration I'm describing? Now trying to fi d a reputable shop to diagnose it.

Skip426 · 10-25-2021, 02:21 PM

Quote:

Originally Posted by jdpm

Yes, you're correct. The photo posted up side down. Way over my head. However, could area in the photo create the oscillating vibration I'm describing? Now trying to fi d a reputable shop to diagnose it.

Yes , issues in the U joint (s )or with phasing or angles will set up a harmonic vibration.
The vibration can even change with chassis load or over bumps .

The site computer system will rotate photos as they're being posted ; if they're too large , reducing photos to 1000 pixels or less will get them to post as you want them .

jdpm · 10-25-2021, 04:23 PM

I'm certainly not qualified to say, however, it does seem to be a stong possibility of my issue. Seems coincidental that the area of vibration we experience is right in the vicinity of the mounting br⁷acket. The RV is box so it makes sense the vibration could create the horrible buffeting sound to our ears.
Now I wonder where to take it and what kind of cost I'm looking at.

donr103 · 10-25-2021, 08:58 PM

The u mount in your pictures is driveshaft bearing. They go out a lot.. not greasable.. they are around 50.00 or so.. about 1hr.. labor.. and yes.. you need to mark.. or make sure driveshaft is reconnected same or proper way.. most shops really don't care.. or Mark them..
Basic hand tools.. you can do it.. but must use all safety precautions..
I bet it's that bearing under u shaped support..
Good luck and let us know what you did and maybe better members then me will help you

tiffy2000 · 10-26-2021, 05:27 AM

download a vibration analysis app and see if you can track it down

https://static.nhtsa.gov/odi/tsbs/20...42259-9999.pdf

jdpm · 10-26-2021, 09:01 AM

I phoned a highly rated drive line service place near me and they said I have to remove the drive shaft myself and bring it to them. That's beyond my capabilities or comfort level.