Please help
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Senior User
Joined: Jun 2009
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Please help
I have a 460 c6 np208
I have a horrible vibration while accelerating and decelerating.
I run the truck with rear shaft and it is vibrating while accelerating and decelerating not while maintaining speed.
I remove the rear shaft and drive with front only and it does the same thing.
I have replaced 2 driveshafts 1 with a cv joint and the other strait. I have replaced 2 sets of gears and 2 transfer cases.
1 thing I can't get over is that the np208 is touching the underbody, could this be transmitting the vibration from the motor to the shafts???
I have a horrible vibration while accelerating and decelerating.
I run the truck with rear shaft and it is vibrating while accelerating and decelerating not while maintaining speed.
I remove the rear shaft and drive with front only and it does the same thing.
I have replaced 2 driveshafts 1 with a cv joint and the other strait. I have replaced 2 sets of gears and 2 transfer cases.
1 thing I can't get over is that the np208 is touching the underbody, could this be transmitting the vibration from the motor to the shafts???
Elder User
Joined: Jan 2009
Posts: 741
Likes: 8
From: Western N.C.
No, that transfers vibration from the engine to your kidneys. Try this thread:
https://www.ford-trucks.com/forums/8...vibration.html
Is it a divorced transfer case? If it is, make sure you check the driveshaft between it and the trans. You could have a u-joint locking up.
Otherwise, it sounds to me like either the bearings in the transfer case are gone or possibly the rear output bearing in the trans is bad. From what you've said, it probably isn't in the driveshafts themselves or the axles.
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Senior User
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well I have had the vibration for a while, 2 months and that is roughly the time i have had the truck on the street. before the paint it was basically a mud truck so never noticed it in 4LO never had taken it on the street till recently
Senior User
Joined: Nov 2008
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check your mounts, especially the transmission to engine bolts and motor mounts. This is going to make me look really stupid however I had a bad vibration, couldnt figure out where the hell it was coming from. Well due to sitting in a field for 12 years and only god knows what, I was missing two of the four bolts holding the tranny to the motor AND the other two were loose! I almost kicked my own a$$ for that one
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You're still leaving a lot of information out:
Is the truck lifted? Were lift blocks used? Were the driveline angles corrected after the lift?
Is the transfer case and transmission lined up and bolted to the frame? If you have a divorced t-case what condition is the prop shaft?
Do you have big tires that need to be balanced?
Do you have the correct flywheel and clutch?
Does you engine have the harmonic balancer?
All the lug nuts tight?
If the truck has been sitting for a long time on bias ply tires you'll have flat spots until the tires heat up.
Josh
Is the truck lifted? Were lift blocks used? Were the driveline angles corrected after the lift?
Is the transfer case and transmission lined up and bolted to the frame? If you have a divorced t-case what condition is the prop shaft?
Do you have big tires that need to be balanced?
Do you have the correct flywheel and clutch?
Does you engine have the harmonic balancer?
All the lug nuts tight?
If the truck has been sitting for a long time on bias ply tires you'll have flat spots until the tires heat up.
Josh
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Senior User
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damn bullit, check out his pictures lol, i believe answers to your questions are yes big a$$ lift, big a$$ tires, looks like his driveline angle is wack fo sho!
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Brett Foote
Certified Thread Hijacker
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No doubt the driveline angles and the Boggers are the vibration. 
Dude the truck isn't going to ride like an Escalade!
Josh
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Senior User
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I know it won't ride like an escalade but this noise is not from tires
I am running the truck on jack stands and it goes crazy. its not a slight vibration that a bogger causes its a vibrating sound that when something like a bolt is hitting on a rotating object.
romac balancer designed for 8000rpms
bb's in tires ride perfect on other truck
mounts are all new
example have you ever put a can in the front tire of a bicycle..... like that
I have lowerd the transfer case mount and it is almost perfect, its not my first lifted truck actually my smallest the others had 44's and 49's. I have never had an issue like this before.
at first it sounded like a bad chain in transfer case so I replaced it and no fix same sound
I am running the truck on jack stands and it goes crazy. its not a slight vibration that a bogger causes its a vibrating sound that when something like a bolt is hitting on a rotating object.
romac balancer designed for 8000rpms
bb's in tires ride perfect on other truck
mounts are all new
example have you ever put a can in the front tire of a bicycle..... like that
I have lowerd the transfer case mount and it is almost perfect, its not my first lifted truck actually my smallest the others had 44's and 49's. I have never had an issue like this before.
at first it sounded like a bad chain in transfer case so I replaced it and no fix same sound
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the first time I started to look for it I lifted the rear with a jack and had it put in gear and gave it some gas.
I went crawling around to see where the sound was coming from. it sounded like the rear gears so I was about to upgrade from 4.56 to 5.43 so I said I'll do them now. New gears in and same noise. so again lift the rear and listen for noise and it started to sound from the driveshaft top joint so I thought lower the transfer case and put cv joint instead.. nope same noise. So a buddy said lets take off the transfer case maybe thats it so swapped out and nope same noise. So now lets take off the rear shaft and run on the front to eliminate rear shaft and gears...... same noise
I went crawling around to see where the sound was coming from. it sounded like the rear gears so I was about to upgrade from 4.56 to 5.43 so I said I'll do them now. New gears in and same noise. so again lift the rear and listen for noise and it started to sound from the driveshaft top joint so I thought lower the transfer case and put cv joint instead.. nope same noise. So a buddy said lets take off the transfer case maybe thats it so swapped out and nope same noise. So now lets take off the rear shaft and run on the front to eliminate rear shaft and gears...... same noise
Elder User
Joined: Jan 2009
Posts: 741
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From: Western N.C.
Is it a vibration or a noise? You've changed symptoms since your third post.
HAVE YOU TRIED...
1. RUNNING IT IN GEAR WITH BOTH SHAFTS REMOVED AT THE SAME TIME? This would permanently remove all of your lower drivetrain from the equation.
2. PUTTING IT IN NEUTRAL AND GIVING IT GAS? If it still makes the sound, then it is not your transfer case or internal transmission components.
If you try #2 and it still makes the noise, I would double check the flywheel-to-converter bolts first. It is sounding more and more like something has loosened up in the bellhousing. You may actually have a bolt hitting the back of the block. If that's OK, then check the torque on your engine-to-trans bolts.
Post your results. I'm as curious about to the source as you are!
HAVE YOU TRIED...
1. RUNNING IT IN GEAR WITH BOTH SHAFTS REMOVED AT THE SAME TIME? This would permanently remove all of your lower drivetrain from the equation.
2. PUTTING IT IN NEUTRAL AND GIVING IT GAS? If it still makes the sound, then it is not your transfer case or internal transmission components.
If you try #2 and it still makes the noise, I would double check the flywheel-to-converter bolts first. It is sounding more and more like something has loosened up in the bellhousing. You may actually have a bolt hitting the back of the block. If that's OK, then check the torque on your engine-to-trans bolts.
Post your results. I'm as curious about to the source as you are!
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
How about the transfer case's rubber insulators? Are they old, cracked and causing the problemo?
How about the rear springs? Are all intact or has one of leafs broken?
With just one broken leaf, the rear axle will shift over to one side causing dog-tracking and a vibration.
Have you inspected the slip yokes to see if they're scored? Another vibration cause.
Driveshaft out of balance? Did you have it standing on end at some point, and accidently knock it over?
How about the rear springs? Are all intact or has one of leafs broken?
With just one broken leaf, the rear axle will shift over to one side causing dog-tracking and a vibration.
Have you inspected the slip yokes to see if they're scored? Another vibration cause.
Driveshaft out of balance? Did you have it standing on end at some point, and accidently knock it over?