weird vibration
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Freshman User
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weird vibration
about 4 days ago my truck developed a weird vibration. 45mph+, any gear, only when applying gas. take your foot off the gas and it goes away. its not like a bad tire (whole truck shacks) its just a subtle (sp?) little shake that really woudlnt even be noticable except it rattles the windows like crazy and it make an audible buzz. i looked the truck over the other dayand found it had a bad u-joint (middle joint, rear shaft) so i replaced it, but no change. it also feels like it has lost some power when this occurs. any ideas?
Postmaster
Joined: Aug 2000
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From: Eldorado Ca. USA
Did you double and redouble check ALL of the Ujoints? How about the center bearing? Pinion on the rear end? A vibration under power makes me think either rear end, or transmission, providing your Ujoints are all good, and are not overtorqued,or installed incorrectly.
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Freshman User
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no slack in any of the other joints. center bearing? the little ball inbetween the 2 front joints? if i re packed it while i had it out. i havent checked the fluid levels in anything, but i dont have any leaks so im doubting those. iv had the truck for 2 months and put several miles on it with no problems, so im also doubting the overtorqued/incorrectly installed idea aswell, since the problem just occured. also no slack in the rear end either
Senior User
Joined: Nov 2008
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From: southwest WA
Could you have put the driveline back in 180 degrees from its original position? I have heard they wear a certain way and after 30+ years of wearing, it could cause vibration if installed 180 from where it was.
Postmaster
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From: Eldorado Ca. USA
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Freshman User
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a wheel bearing wouldnt be effected by throttle level owuld it? and its a 77 f150 4x4. engine miss could be a possibility, it does run rich. but it idles fine, and like i said it only happens at 45ish +. and on a side not how do you adjust an edelbrock carb?
Senior User
Joined: Aug 2008
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From: Downs,IL
Could possibly be the accelerator pump in the carb.. When you try to press down on the pedal it could not be getting a full squirt and starving out on gas. Then when you let up it returns to normal.
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My truck is doing the SAME thing..This week the vibration is at 45-50..last week 35-40 week before 55-60...My just starting doing this and dad said check the U joint. I recently replaced the back one a few months back but the other not.
Now wierd enough my truck stutters or really hesitates when easing in on the throttle from idle. This is new and same time as the vibration. Accel Pump? I lookd down the carb throat and hit the gas, it does pump but how to know it it pumps enough?
just jacked your thread..but i might help us both.lol
Now wierd enough my truck stutters or really hesitates when easing in on the throttle from idle. This is new and same time as the vibration. Accel Pump? I lookd down the carb throat and hit the gas, it does pump but how to know it it pumps enough?
just jacked your thread..but i might help us both.lol
Senior User
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From: Downs,IL
I relly don't know how to tell you how much is enough. I only know that many times if you press down on the accelerator and it dies out and picks back up when you ease off the pedal it's usually the acc. pump. This could cause a stutter that feels like a vibration.
Lead Driver
Joined: Jun 2006
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From: Near Yosemite CA
I am going to be pulling my rear driveshaft/CV joint apart soon, my 77 F-150 4x4 shortbed has a vibration about 55-60 when coasting, no load on it. Also, thanks for the accel pump, I need to check mine, it has a "flat spot" if you ease into the gas,,, you can let up and find it , weird, maybe see if you have a CV joint driveshaft 99sbm, I have heard the magic inside of it wears out and needs rebuilt after awhile.
Elder User
Joined: Jan 2003
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From: Baltimore
You checked each of the u-joints for play. Did you check each for roughness. U-joints typically go bad in one of 2 ways:
1) They simply wear out and get lots of play in them.
2) The inner bearing surface gets grooves in it and the joint, although still tight, has roughness to it because of the grooves. If you pivot the drive shaft pieces to work the u-joint, it should move easily and smoothly in all directions. If it feels tight or rough, take it apart and find out what is wrong with it.
I have had many u-joints fail because of the "grooving" problem.
- Ron
1) They simply wear out and get lots of play in them.
2) The inner bearing surface gets grooves in it and the joint, although still tight, has roughness to it because of the grooves. If you pivot the drive shaft pieces to work the u-joint, it should move easily and smoothly in all directions. If it feels tight or rough, take it apart and find out what is wrong with it.
I have had many u-joints fail because of the "grooving" problem.
- Ron