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Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Michelle on February 17, 2016, 05:38:36 pm

Title: Vibration in a 2004 U270 36' coach, changes with retarder use
Post by: Michelle on February 17, 2016, 05:38:36 pm
Quote from: djonmoss –
Since driving across country I have one mechanical question (for now) about the retarder. As the Coach reaches normal cruising speed (60 to 70) from a stop I can feel and hear a slight vibration. Since the whole diesel pusher thing was new to me it took awhile for me to decide what was normal and what was not. What I eventually found was that when I pulled back one position on the retarder and let it retard speed for an instant I could move the lever forward again to the 6th position and the noise as well as the vibration went away. The vibration would then return every time I attained cruising speed from a stop or after a major slow down. Since joining this list I have read up on the possibility of the U joints in need of lube and will investigate that possibility in the future.

Splitting David's technical question out and putting it in Tech Talk for better visibility.  Coach is a 2004 U270 that is 36' in length.

David, one thought is the P3 carrier bearing in the transmission. I don't know what years were affected, but I believe there were reports as late as 2003  Scratch that - just checked and looked like it was 96/97 only.  Will try to dig up some posts in addition to the threads I PM'd you via iRV2.

Michelle
Title: Re: Vibration in a 2004 U270 36' coach, changes with retarder use
Post by: Pamela & Mike on February 17, 2016, 06:11:17 pm
David,

How many miles does this coach have on it?  With enough miles or neglected service it could be a bad/dry "U" joint.

On some years the drive shaft has a harmonic balancer on the transmission end.  Check to see if yours has one (harmonic balancer) and if it does make sure it is tight and the match marks line up.

Pamela & Mike
Title: Re: Vibration in a 2004 U270 36' coach, changes with retarder use
Post by: djonmoss on August 19, 2016, 07:55:28 am
Vibration update: After thoroughly greasing all driveshaft components the source of the vibration was finally located. The Transmission output shaft / bearing retainer was loose. The tabs that get folded over had worn through and broken off allowing the load on the bearing to loosen.
The good news is that the tabs were located when we changes the oil and filters. So from now on when I am under the coach greasing the driveline I will grab on the yoke and see if I can detect any movement. At 78K miles I did not expect an Allison problem however at 7K miles the output shaft seal was changed and it appears the locking retainer with the tabs was not changed, tabs re-bent and eventually failed. That's my best guess. The Allison parts man said "We sell a lot of those, its a common problem"   
Title: Re: Vibration in a 2004 U270 36' coach, changes with retarder use
Post by: Chuck & Jeannie on August 19, 2016, 08:25:19 am
David,

Excellent investigative analysis!  Having a problem is irritating, but persevering until you positively pin down the cause is very rewarding.  ^.^d
Title: Re: Vibration in a 2004 U270 36' coach, changes with retarder use
Post by: John44 on August 19, 2016, 09:03:47 am
Trying to figure out the above posts.If the retaining tabs are a tab you fold up and down to hold a bolt in place then they
should never be re-used and the parts dept. should be selling alot of them.

If the shop selling the part is the same shop doing the work then they did not do a good job.

Probably the best solution would be to use some blue loctite along with the retainers.
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