Vibration on Acceleration

[Midniteoyl]

Originally Posted by Chuck & Marca

Matt,
Some of your post sounds like what we were experiencing prior to our differential problem the 29th of June. Ours started as a strange noise in the rear under the commode area (2006 40' Apex FDQS) and I (Marca) noticed it as I went to the back with (Chuck) driving. At first we thought it was tire/road noise as this was the first trip with our new tires. It was only on increased or steady acceleration and not when off the accelerator. We traveled 200 miles and stopped for the night. The next morning I drove some and Chuck tried to hear it but could not.

We traveled on and about 300 miles later, it was getting worse. It was now a strange noise clear across the back and a slight vibration. It was then noticeable up front in the driver/passenger area. We saw a Freightliner shop and at 5:00 PM on a Friday evening pulled in. Before doing anything else, Chuck crawled under and checked the temperature underneath. He could find nothing out of the ordinary at around a max of 135 degrees. The night foreman took it for a drive around the parking lot and agreed that there was indeed a strange noise coming from the rear. So we waited until morning. On Saturday morning, they pulled it into the shop and drained some gear oil from the differential. Sure enough there were metal pieces and shavings in it.

That started the week long process of finding the part, tearing it down, dealing with the warranty insurance people including an inspector making sure that yes, it did need replaced, etc. The part that failed was the pinion bearing and the holder that it is supposed to reside in. It appeared one of the ball bearings was damaged/missing and the bearing race was starting to destruct. Please keep in mind that this is a woman trying to explain this so if some of the terms are incorrect, I apologize. Also, we had to produce service records regarding the differential to the warranty company. The latest service on it had been done approx. 900 miles before this occurred and the synthetic gear oil was used. At the time of failure, the coach had 57014 miles on it. The repair shop said that it appeared that this one was in the early stages of failure but the problem is that after metal appears in the gear oil no one can determine how far or long one can travel before it fails entirely. We were lucky in that no other components were damaged. In order to repair it, they had to remove the entire rear end assembly including wheels, tires, brakes, etc. and slide the assembly out one side to get to it because of the coach wide brace underneath. It's not like changing a differential on a truck they informed us.

Thanks to IRV2, Engineer Mike, Cris Cratch, Kraig, Mike from Redlands, Sully and many others too numerous to mention, we were back on the road in one week and made it to Calgary.

I will be posting the part numbers on the original post later today. If you need any further information, please let us know. I forgot to mention that since this has been repaired and with the new Michelins, it is really quiet in the rear now. I never could rest back there going down the road but may be able to now.

Hope this helps. Good luck finding the culprit causing the noise.

Thanks Marca! And a great explaination, even for a guy

[zinom]

FIXED!! My next move was to get the rig on a dyno. I stopped by Country Coach for the dyno but CC's service manager recommeneded I have nearby Anderson Brothers check it out. Anderson's drive line pro felt it was the drive shaft not the differential; removed the differential; and I watched as he tested it and found it indeed was bent. Also the shop that had earlier subcontracted to Cummins in Coburg,OR to balance the shaft, had added weights on the wrong side of the shaft when they balanced it.
It was interesting to watch the process where the shaft was straightened and then balanced. (See me at Mirimar or Quarzsite if you are interested in the details) Reinstalled the shaft and vibration was significantly reduced.
A drive from Eugene to Newport was a dream.
THANKS ALL for your suggestions. Matt

[FW5000DRIVER]

So it was the drive shaft. Sneaky dang shaft!

[Marca]

Sure glad you found the problem! Safe travels!

[Old Trucker]

Originally Posted by zinom

I have a strong vibration coming from the area of my rear axle whenever I accelerate (even if only slightly) at about 1500rpm. As soon as I take my foot off the accelerator the vibration goes away. I have had the universals replaced,adjusted ride height,had drive shaft balanced, line timing, line angle, and yokes checked. Cummins coach care in Coburg said it has them stumped. Has anybody out there had this problem or have any suggestions.

Hi Zinom, Sounds like you have a lot of good technical advise. I have a 99 Alpine. I had it towed with the drive shaft removed. When the shop reinstalled the drive shaft, they did not get it timed right. I know, we do not think about timing on a driveshaft, but this was definatly the problem with mine. You might also drive it several miles deliberatly trying to make it vibrate, then while everything is hot, use a non contact thermoter and take temperature readings at various points. like axel ends from side to side, each side of differential etc. Vibrations and sounds can carry to other areas and be very deceiving. You might also have a shop check your engine harmonic balancer. Perry White suggested a camera mounted underneath, not a bad idea, he also mentioned pinion bearings. Another thought would be to block to wheels good and apply power while someone else was looking undernearh the coach or under the bed. Maybe the rear end pitching upward causing the drive shaft to be in a bind. You said you had already replaced the universals, that is the first place I would have looked. Hope all these suggestions can help. As an Old trucker I have been all through vibration problems. Old trucker

[Renipladlo]

Well I am gald you figured it out, one thing I did not see posted was the rear axle hanger bolts, as some 05 coaches had the smaller bolts installed and they either fail or break causing the rear axle assembly to shift in place which then causes all the other stuff to be out of line. There is a post about that problem, but you fixed it so no issue now, but if you have not checked those bolts, hunt up the thread and read it for more information.

[zinom]

Thanks Monty & all. I do have the "fat" bolts so that was one less problem.