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Rear Vibration Problem

Rear Vibration Problem
About a week ago, will traveling from Houston to Cleveland area, we suddenly picked a strong vibration in the rear of our 2000 U-295 36 foot FT.  The vibration appears after we start out at around ~35 mph and calms down above ~62 mph.  Since it is around the 5th/6th gear change speed, we tried forcing the trans back to 5th using touch pad and vibration did not return.  We then tried slowing down in steps down to 50 mph and the vibs did not return in either gear.  This has repeated for several days now especially when we start up from a rest area, etc.  Called Foretravel and they thought it may be related to the drive shaft or transmission.  I now have an appointment in a few days at Williams to look at trans but I think its may be relate to tires.  Rear tires about 4/5 yrs old and have no outward signs of distress. Appreciate any thoughts on how to proceed.
Bill & Deanne Brown
'03 U-320 Previous Owner in Houston

Re: Rear Vibration Problem

Reply #1 –
Have you checked you tire pressure?
John Duld
1995 U320C SE 40'

Re: Rear Vibration Problem

Reply #2 –
Check U joints and tires.
Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Rear Vibration Problem

Reply #3 –
Bill,

Do you guys have 2 coaches?  Your signature says you have a U320...

There are quite a few past Forum threads pertaining to driveline vibration.  I could post links to them, but it would be more efficient if you just do a search for the term "drive shaft vibration" or "drive line vibration".  Then you can look at the ones that seem closest to your symptoms.

Here is one example thread, which discusses vibration in early U295 models.  May or may not apply to later U295 models.

U295 Driveline vibration issues

Here is another one discussing the "transmission dampener" and the "P3 bearing carrier" on some Allison HD3060R units.

Transmission Dampener
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Rear Vibration Problem

Reply #4 –
One way to tell if it's tire related is to fill the tires in question with maximum air pressure and drive and then at minimum air
pressure and drive,if there is a difference while driving it's the tires.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Rear Vibration Problem

Reply #5 –
I have 79,000 miles on my U270. Had vibrations since I bought it 3 years ago. I thought that it was a tire problem loose cookware etc.  not knowing better. In May while visiting M.O.T. tech diagnosed a real bad vibration when they test drove a month ago. They thought it was the harmonic balancer or a bearing. Went to Cummings in Little Rock when Harmonic Balancer arrived.  Old balancer was diagnosed as still good at Cummings so they referred me to the Allison shop. Allison shop was looking for filings from cone/cup bearing. They suggested removal to check this output bearing  transmission about 1/2 days work. Due to time constraints a temp repair resulted in tightening nut slightly,  replacing seal,  new trans fluid. I don't know if U joints were greased though,...
 (American Shifty Corporation a Allison shop in North Little Rock.) They replaced a seal $50.00 (29546233-3),  2 hours labor @ $95.00hr.  Fluid-4 @$15.50,  MSC 115.00,  Total $416.00. Mechanic said it might be fixed if I didn't feel any vibration on way home. Wow what a difference on I-30 going back home 47 miles! No vibrations noticed from drivers seat. ( Kitchen wasn't shaking). Still concerned and monitoring situation.
99 40' U270 #5574
2010 Honda Element
Hot Springs Village, AR.
K5IIK

Re: Rear Vibration Problem

Reply #6 –
If your old trans fluid was good and the level good,all they did to fix the vibration was tighten this nut.Exactly which nut did they
slightly tighten?
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Rear Vibration Problem

Reply #7 –
Sounds like the trans  output flange retainer nut . 
  Another idea to change the wear pattern is to change the ride height and let all of the rotating parts find new places to run. Just a lite change may help.

Re: Rear Vibration Problem

Reply #8 –
Quote from: bbox –
I have 79,000 miles on my U270. Had vibrations since I bought it 3 years ago. I thought that it was a tire problem loose cookware etc.  not knowing better. In May while visiting M.O.T. tech diagnosed a real bad vibration when they test drove a month ago. They thought it was the harmonic balancer or a bearing. Went to Cummings in Little Rock when Harmonic Balancer arrived.  Old balancer was diagnosed as still good at Cummings so they referred me to the Allison shop. Allison shop was looking for filings from cone/cup bearing. They suggested removal to check this output bearing  transmission about 1/2 days work. Due to time constraints a temp repair resulted in tightening nut slightly,  replacing seal,  new trans fluid. I don't know if U joints were greased though,...
 (American Shifty Corporation a Allison shop in North Little Rock.) They replaced a seal $50.00 (29546233-3),  2 hours labor @ $95.00hr.  Fluid-4 @$15.50,  MSC 115.00,  Total $416.00. Mechanic said it might be fixed if I didn't feel any vibration on way home. Wow what a difference on I-30 going back home 47 miles! No vibrations noticed from drivers seat. ( Kitchen wasn't shaking). Still concerned and monitoring situation.
They don't come any better than American Shifty in Little Rock.. We use them for all gear work in our diesel rigs and if I ever have an Allison problem Little Rock is where I will head.. Glad your issue was fixed, a vibration can be a nightmare to stop and more often than not, unnecessary parts are "thrown" at the issue before replacing the one causing the issue.
Dub McBride 1996 270

Re: Rear Vibration Problem

Reply #9 –
Bbox's issue is fixed,still need some feedback from the original poster,still looks like he has 2 coaches.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Rear Vibration Problem

Reply #10 –
I had just purchased a 4107 bus in Fall River, MA when about 100 miles later, I got a pretty good vibration that seemed to come from the rear. Looked and looked but didn't have a tire gauge although they all looked OK. Turned out to be an flat inside dual. I spent a day looking for a new tire but several months later, found a brand new Michelin behind the fold down front bumper.

Tires are always the first thing to check when a new vibration crops up.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)