Vibration

[greg]

I have a 1977 American Clipper that belonged to the founder of the club, Bob Cornwell.  It has 63K on it with a 440 motor.  Everything is in great condition but, under load at or above 45 mph there is a vibration from around the trans area under the cowling.  The vibration is under a load only, up hills passing ect.  When cruising at or above 45 mph its smooth as silk. At lower than 45 I can feel little to no vibration.  I pull a jeep wrangler and its under a load quite a bit and the vibration is agravating, but once I am up to speed and cruising it goes away.  It is more like a strong buzz and you can feel it all through the cab and into the steering wheel.  It is similar to the vibration you get when you hit the sleep strips they put on the sides of the highway to remind you to wake up if you are drifting out of the slow lane.  I have replaced u joints and had the rear end looked at with no improvement.  Any suggestions?  The mechanics I have dealt with want to throw parts at it until they figure it out.  
P.S. A dodge expert I talked with stated that certain rear ends in Dodges have a wear point in them and are famous for such a vibration.  He states not to worry as it feels a little scary but it will not break.  I do not want to end up at on the Washington Coast and have a tranny or rear end go out.  Been there, done that.  Any help would be appreciated.

Greg

[bigray]

Greg,

Congrats on your Clipper. I'm surprise Bob parted with his Clipper. My guess is he has a couple of them.

At any rate, I heard that  a bad center bearing can cause vibration like you described. You may want to check to see if  any play is in yours.

Good luck

[handyman]

Also check your u joints this will also cause a bad vibration you didn't say do you get a klunking noise whell you let off the gas

[bigray]

Also check to see if your harmonic balancer is bad. I experienced some noise on the front of my engine and couldn't determine where it was coming from. I had to pull out the trusty water hose to determine where the noise was coming from. Once I pinpointed it and saw that the harmonic balancer had a slight wobble.

The purpose of t he harmonic balancer is to absorb vibration from the engine (the crank specifically). If it is really bad you may experience significant vibration.

I'm not a mechanic but grew up around lots of them. While the purpose of my Clipper in 10/2003, I think I will be promoted to ShadeTree mechanic real soon. And I'm not speaking ill of my Clipper. With a vehicle 25 years old, that can be expected. I have enjoyed every project and every minute was well spent.

[Horst]

Greg,
This probably has nothing to do with your problem, but......

What gear are you in when experiencing this vibration under load at or around 45mph?
Just a thought - but  anything close to 45  is a "flat spot" on the torque curve of a big block Dodge - especially in a motorhome under load. Maybe it's just stressing the beast too much? I try and stay out of that speed zone under load - and will drop to 40-42mph in second gear.
Our Clippers will cruise fine in 3rd gear at 45mph on a flat road! Under load however, at this speed, they struggle when left in 3rd.

Have you tried dropping into second gear, and pulling the hill at say, 42mph to see if your vibration issue goes away? It would be easier on your torgue converter too.

[cat]

Greg,  

 Are you certain you've got Bob's clipper?  As I recall he had a '79 rear bath that had a engine fire and he had completely rewired and the cab only was repainted and restriped.  He eventually sold it and moved to one of the New England States to be closer to his grown children.

 There was a Bob Cornell from Sacramento that members used get confused with "Bob Cornwell".

 Getting to the point of your inquiry, check for a loose torque converter too.

[Horst]

two more things
1) be sure to get a real expert to check out your rear-end to see if it's healthy - not some run-of-the-mill tranny shop

2) another thing that could cause your symptoms is an out-of-balance drive shaft

[cat]

Speaking of drive shafts.  Some years ago I took mine to a place called Driveline Specialties in Stockton, CA. and had it straightened and balanced.  If you live near a "Ag." (farming) area, there's bound to be a similar shop around.  If you remove your drive shaft make sure you mark the shaft and U joint with chalk to assure getting back to the same spot rotationally.  If it's even slightly out of balance it'll cause vibration.

[tomfridley]

just another approach to driveshaft vibration is the shaft angle.
i replaced a sagging transmission mount and it fixed my slight vibration that occured about 50 mph.
if the driveshaft angle changes even a small amount at the transmission or the rear axle, it can cause a light to moderate fast rumble feeling.
many truck repair shops have a driveshaft inclinometer for checking this.
my suggestion is to replace the trans mount before having a truck shop charge for their time.
the mount is very easy to change and is quite inexpensive.

[junebob]

GREG--Vibration.  If you truly have Bob Cornwells Clipper you might want to check whether or not you are running a fan clutch. Towards the last Bob was disenchanted.[maybe even fed up] with fan clutch problems. As I recall he had the fan clutch removed and ran the fan at engine speed.  This can cause a variety of strange loud sounds :oops: Anyway check it out. Another possibility. :? With a thermoquad carb  it is not at all unusual for it to make a vibrating noise or sound when you kick down and only partually encage the two rear barrels. As oppossed to when you kick it down firnly into passing gear. Which besides the rig taking off like a stiped ass ape, the carb  emits a definite howling roar.
                                Just a couple possibilities for what their worth.
                                       Bob Chaney #2626

[greg]

Thanks for your help everyone.  I think the issue with the vibration is tied to the trans mount.  I had a friend look at it and he stated that the rear tail shaft on the trans is somewhat messed up.  I was also told if it is not alligned correctly it will cause the vibration.  So thanks for all the suggestions.

[Plante]

On one of our trips last summer the right rear wheel bearing froze up and slid us to a stop on the highway.  We had it towed and fixed but by the time we got home there was lots of vibration - especially slowing down.  I was also towing my 3,500# boat.  The wheel bearing problem had somehow damaged both u-joints and the bearing at the back of the tranny - causing severe vibration.