If a U-joint is bad...
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Tuned
Joined: Jan 2002
Posts: 491
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From: Fort Fun
If a U-joint is bad...
...will the vibration come and go at different speeds?
I noticed the vibration starting about a week ago. I noticed it under load (accelerating-truck empty. Haven't hauled in a while) between 25-40. Then it smooths out. Then it comes back between 55-65.
At first it was subtle, but now it shakes the driver mirror. It also has gotten to where it is almost constant from 25-65. It occurs only while accelerating. When I let off the pedal, it stops vibrating immediately. Hit the gas, vibration starts again. I have put u-joints in already but that could have been 60-80 miles ago. I currently have 167k on the truck. I'd have to check to be sure tho.
I am fairly confident it is the U-joint but wanted to see what you all think. Last time I replaced them it acted the same, but only at 50-65, not at lower speeds. I suppose it could be the carrier bearing (CC LB) but I checked that for play and it didn't seem more than normal.
Your (collective) supreme wisdom?
Big
I noticed the vibration starting about a week ago. I noticed it under load (accelerating-truck empty. Haven't hauled in a while) between 25-40. Then it smooths out. Then it comes back between 55-65.
At first it was subtle, but now it shakes the driver mirror. It also has gotten to where it is almost constant from 25-65. It occurs only while accelerating. When I let off the pedal, it stops vibrating immediately. Hit the gas, vibration starts again. I have put u-joints in already but that could have been 60-80 miles ago. I currently have 167k on the truck. I'd have to check to be sure tho.
I am fairly confident it is the U-joint but wanted to see what you all think. Last time I replaced them it acted the same, but only at 50-65, not at lower speeds. I suppose it could be the carrier bearing (CC LB) but I checked that for play and it didn't seem more than normal.
Your (collective) supreme wisdom?
Big
Fleet Mechanic
Joined: Apr 2007
Posts: 1,433
Likes: 7
From: NH
Did you reinstall the shaft in the same orientation as when you removed it? It may need to be rebalanced. Try removing the shaft at the pinion end and rotate it 90 deg.. If not reindex on the spline end and try that.
Laughing Gas
Joined: May 2009
Posts: 908
Likes: 2
From: Covina, CA.
I know it's basic, but easy enough to check and/or overlook. But are all the weights on the wheels? Before disconnecting the drive shaft, I would check for any clean spot on the wheels where weights may have been a week ago or so.
It's a good possibility that it's related to your u-joint replacement since it sounds fairly recent. But you never know.
It's a good possibility that it's related to your u-joint replacement since it sounds fairly recent. But you never know.
Thread Starter
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Tuned
Joined: Jan 2002
Posts: 491
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From: Fort Fun
To be clear, last time the Ujoint was replaced was over 80,000 ago and a reputable shop did it. The drive shaft hasn't been off since then. I would think that if the shaft were out of balance, it would shake all the time, and certainly would not stop immediately when I let up on the pedal. I could be wrong tho.
As far as the wheels, all the weights are on still. I checked the drive shaft too, cuz I thought there were weights on it. There are and they still are on.
As far as the wheels, all the weights are on still. I checked the drive shaft too, cuz I thought there were weights on it. There are and they still are on.
Posting Guru
Joined: Jan 2003
Posts: 2,181
Likes: 3
From: Eastern CT.
80,000 miles on it since the change,,,,You definetly could have another bad u-joint!
check wheel bearings also!,,,a Buddy of mine told me,,,a well known shop in my area,,,,private guy,,,works on all diesel pickup's,,,says that the main rear diff carrier bearings go bad,,causing a vibration in the truck ! Not sure how true this is,,just what I heard 2nd hand !! ,,,,,I would say after enough miles on the truck it would be good to change them too.
check wheel bearings also!,,,a Buddy of mine told me,,,a well known shop in my area,,,,private guy,,,works on all diesel pickup's,,,says that the main rear diff carrier bearings go bad,,causing a vibration in the truck ! Not sure how true this is,,just what I heard 2nd hand !! ,,,,,I would say after enough miles on the truck it would be good to change them too.
Laughing Gas
Joined: May 2009
Posts: 908
Likes: 2
From: Covina, CA.
To be clear, last time the Ujoint was replaced was over 80,000 ago and a reputable shop did it. The drive shaft hasn't been off since then. I would think that if the shaft were out of balance, it would shake all the time, and certainly would not stop immediately when I let up on the pedal. I could be wrong tho.
As far as the wheels, all the weights are on still. I checked the drive shaft too, cuz I thought there were weights on it. There are and they still are on.
As far as the wheels, all the weights are on still. I checked the drive shaft too, cuz I thought there were weights on it. There are and they still are on.
It may be time to change them again. Looks like m350 has some additional suggestions that I would look at as well.
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Tuned
Joined: Jan 2002
Posts: 491
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From: Fort Fun
Got the truck back from Fort Wayne Clutch and Driveline. Great guys and reasonable too.
All 3 U-joints had slop or were dry. Drive shaft carrier bearing was going too. The rubber boot around the carrier bearing was cracking as well.
SO...they replaced all 3 u-joints, carrier bearing and balanced the shaft. Total for the job (included remove and reinstall - I didn't drop the shaft myself) $316.xx. Very fair in my opinion.
Now my truck rides like butter. No more mirror shake, no more shudder, just smooth.
As far as the greaseable u-joints, they recommended against them on the F Three Fiddy. They say the solid -joints are much more durable than the greaseable ones. Given that my truck has become a really big station wagon as of late (i.e. not much towing), I am sure the solid u-joints will provide years of enjoyable smooth driving.
Oh, and I see that in my OP I did put 60-80 miles where I should have put 60-80K miles.
Big
All 3 U-joints had slop or were dry. Drive shaft carrier bearing was going too. The rubber boot around the carrier bearing was cracking as well.
SO...they replaced all 3 u-joints, carrier bearing and balanced the shaft. Total for the job (included remove and reinstall - I didn't drop the shaft myself) $316.xx. Very fair in my opinion.
Now my truck rides like butter. No more mirror shake, no more shudder, just smooth.
As far as the greaseable u-joints, they recommended against them on the F Three Fiddy. They say the solid -joints are much more durable than the greaseable ones. Given that my truck has become a really big station wagon as of late (i.e. not much towing), I am sure the solid u-joints will provide years of enjoyable smooth driving.
Oh, and I see that in my OP I did put 60-80 miles where I should have put 60-80K miles.
Big
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