Vibration FTL :(
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Vibration FTL :(
79 f150 4x4(front drive shaft no connected ATM) 460, NP205 and 435 combo non divorced, the truck runs FINE under 40 MPH its when i hit 4th and go above 45 mph ther is a HORRIBLE vibration that shakes the whole truck, cd's wont play alot of sqweeks ect..... i added fluid to the rear end 80w90 for limited slip (what i always use because i never know what ratio/ect it is, no tags or too much grease/dirt) BTW its a 9" rear. could all this disruptive vibration be from the rear end? input would be appreciated
Post Fiend
Joined: Jul 2006
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How high is this lifted? Is the driveshaft angle working at a crazy angle? Is the driveshaft "in phase"?
Is this only speed related, or is this also related to engine RPM? The wrong flywheel will cause a severe vibration.
Is this only speed related, or is this also related to engine RPM? The wrong flywheel will cause a severe vibration.
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stock, no lift. i dont belive it is rpm related will have to check more on that in the daylight when i can see the cops, not sure on the flywheel i bought it with a bad ring gear for $200 and replaced the gear and its been puzzeling me since then
Post Fiend
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Ah ha! we might have something here. What year is your engine, and what year did your flywheel come from?
Not all 385 series engines were externally balanced, and some were internally balanced. In 79 the 460's became externally balanced, and require a different flywheel / flexplate for autos.
You must make sure that you have the correct flywheel for the crank.
An externally balanced flywheel on a crank that is internally balanced will drive you nutz, and try to shake the crank clean out of the block.
Is it possible that you have the wrong flywheel in there?
Might inspect the driveshaft again, just to make sure that it is indeed phased correctly. Then see if you have the correct flywheel.
Not all 385 series engines were externally balanced, and some were internally balanced. In 79 the 460's became externally balanced, and require a different flywheel / flexplate for autos.
You must make sure that you have the correct flywheel for the crank.
An externally balanced flywheel on a crank that is internally balanced will drive you nutz, and try to shake the crank clean out of the block.
Is it possible that you have the wrong flywheel in there?
Might inspect the driveshaft again, just to make sure that it is indeed phased correctly. Then see if you have the correct flywheel.
Thread Starter
|
Senior User
Joined: May 2004
Posts: 262
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Ah ha! we might have something here. What year is your engine, and what year did your flywheel come from?
Not all 385 series engines were externally balanced, and some were internally balanced. In 79 the 460's became externally balanced, and require a different flywheel / flexplate for autos.
You must make sure that you have the correct flywheel for the crank.
An externally balanced flywheel on a crank that is internally balanced will drive you nutz, and try to shake the crank clean out of the block.
Is it possible that you have the wrong flywheel in there?
Might inspect the driveshaft again, just to make sure that it is indeed phased correctly. Then see if you have the correct flywheel.
Not all 385 series engines were externally balanced, and some were internally balanced. In 79 the 460's became externally balanced, and require a different flywheel / flexplate for autos.
You must make sure that you have the correct flywheel for the crank.
An externally balanced flywheel on a crank that is internally balanced will drive you nutz, and try to shake the crank clean out of the block.
Is it possible that you have the wrong flywheel in there?
Might inspect the driveshaft again, just to make sure that it is indeed phased correctly. Then see if you have the correct flywheel.
Post Fiend
Joined: Jul 2006
Posts: 6,948
Likes: 44
U-joints have to be aligned, or indexed properly. If the slip joint was ever taken apart
it will have to go back together exactly where it cane out of, or 180 degrees apart.
Any other orientation will also cause a vibration since the shaft is no longer balanced.
Try this:
Pirate4x4.Com - Extreme Four Wheel Drive
it will have to go back together exactly where it cane out of, or 180 degrees apart.
Any other orientation will also cause a vibration since the shaft is no longer balanced.
Try this:
Pirate4x4.Com - Extreme Four Wheel Drive
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jjoel
1987 - 1996 F150 & Larger F-Series Trucks
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Jun 11, 2010 06:24 PM
