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Old 12-05-2010, 06:10 PM   #1
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Fleetwood Owners Club
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Location: Austin Tx
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RV vibrates when I press on gas pedal

I have a '05 Fleetwood Revolution 40C. Above 25 mph, when I press the gas peddle, the pedal and steering wheel begin to vibrate. As the RV increases speed, more of the RV vibrates - it seams like it comes from the rear forward. Regardless of speed, when I let off the gas peddle, the shaking and vibrating immediately stop. If it was a pickup, I'd say the U-joint may be going bad.

Any suggestions?

Austin Heath
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Old 12-05-2010, 06:12 PM   #2
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have you checked rear ride height?

'02 Ultimate Advantage 40J Spartan MM - Cummins ISC
2013 Jeep Rubicon JK Unlimited
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Old 12-05-2010, 06:26 PM   #3
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I would check u joints too,.. Can you have someone drive it while you have the engine cover off and you watch
2008 Monaco Cayman XL 38PBD
Twenty years from now you'll be more disappointed by the things you didn't do than by things you did. Explore, Dream, Discover. Mark Twain
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Old 12-05-2010, 06:27 PM   #4
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Still sounds like it may be a U joint
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Old 12-05-2010, 10:58 PM   #5
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A few thoughts, and then I will share my incredible experience with our 03 Fleetwood Revolution (Cummins/Freightliner) this past July. There are important questions that should be answered. Is this something that just started or has it been getting progresively more noticeable? Does it do it at a particular RPM both driving AND parked? This is REALLY important since a vibration with the unit parked rules out most driveline issues, certainly U joints (although obviously many internal engine and even some transmission components are rotating). Has someone recently serviced or worked on your coach, or has something been added or changed in or near the engine bay? If it started rather suddenly, then something causing it just occurred....broken/cracked fan blade on the cooling fan; broken accessory bracket or mount; badly damaged belt; bad a/c pulley or idler pulleys...to name just a few. There may be a sudden internal engine issue as well, but that is not likely. I would look first for an accessory vibration which would usually occur at low speed, low rpms and build from there, diminishing or disappearing quickly as rpms go down. Most driveline vibrations, including U joints, usually occur at higher speeds and diminish gradually rather than suddenly as vehicle speed decreases. Also, it's been my experience that most U joint or driveline vibrations come up through the floor and seats, not so much through the steering wheel or accelerator. Engine vibrations usually are transmitted through various types of linkages, such as accelerators, transmission linkage and steering components. I am not an expert on anything, so these are just my thoughts based on my experiences over the years.

Now, about July. Had the coach at our friendly Freightliner dealership to have a leaking hydraulic cooling fan motor repaired. It's a big job ($$$'s), but it had to be done. When I picked up the coach 2 days later, I went about 4 blocks when I knew there was big Trouble in River City! Any speed over 10 miles per hour on acceleration set off a vibration the likes of which I have NEVER experienced. It actually scared me! The whole back of the motorhome vibrated violently....but it went away when I let up on the throttle. I also remember vibrations coming through the steering wheel and the accelerator. I limped back to the dealership.

After a quick discussion with a tech, he stood at the rear of the coach and I brought the RPM up....while parked. Same situation. He told me to turn off the engine immediately...and the coach was moved into a stall. I went back home.

The next day, the S/Manager called to tell me they found the problem. When the original tech reassembled the cooling fan back on to the cooling pump, he mistakenly put one washer between the fan and the flat mounting surface of the pump flange....and it was NOT supposed to be there! Washers here are only supposed to be on the other side of the fan underneath the locking nuts, with the surface between the fan and the pump flange flat and smooth. This "extra" washer put the fan at a very slight angle and put the whole unit badly out balance. When I picked up the coach, I could not believe that a small stainless steel washer, misplaced, could reak such havoc. Unbelievable! I drove the coach home...still shaking my head. Fortuanately, the coach was no longer shaking and the problem went away.

Also, keep in mind that diesels vibrate naturally. That is one reason most accessory components and mounts are super-industrial strength. But if one of these mounts or components cracks, breaks or is slightly out of balance, things go South in a hurry. Not sure if you have an extra washer installed incorrectly, but, bottom line, look for something fairly simple or obvious. I would suggest you take look at that cooling fan area. See if the vibration is there at a particular RPM...parked. If so, raise the rear panel at the back of the coach and have someome rev the engine to that RPM....maybe you'll see or hear something. Raising the bed, etc., and having someone rev the engine to look for the problem is possible....but can be VERY dicey. The air turbulence, dust and dirt blowing around can be VERY, VERY intense, not to mention the noise. Eye protection is a must! Ask me how I know this....

Sorry for the long-winded post, but I thought all of this might be of use. I would really appreciate your letting us know what you find out. Thanks!!!
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Old 12-06-2010, 02:44 PM   #6
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Austin, you need to be real careful about driving this MH to the place you are going to get it fixed. If it is a U-Joint then it is in pretty bad shape and the driveshaft can come loose or something else come loose. Have you been greasing your U-Joints every 5000-10000 miles?????

If you are parked and the tranny is in neutral and you slowly bring up the RPM of the motor does it shake then? If so it is not the U-Joints but something in the motor. If it was smooth then it is either the U-Joints or something else.

Have you parked and blocked the tires and just got under the motor home and shook both ends of the driveshaft with both hands while looking for movement in the joints?

If the motor is running and you are parked and you turn the steering wheel back and forth slowly and quickly can you hear any thumping or feel any slack?

For safety check that all your lug nuts are tight on all your wheels

Mike Canter
"Gunner" USN Retired, Airdale
2004 Monaco Signature 44' Conquest. Detroit 60
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accelerate, joint, ujoint, vibrate

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