Bad vibes

[chillman88]

Hey all,

I'm not really sure where to start on this.

I thought it was my junk tires, but I've since replaced them with no change. New ones balanced out fine.

Bad vibration starts about 30, is really bad around 35-40 and almost gone at 60.

Gear doesn't affect it, clutch in or out doesn't affect it, I can't tell if load makes a difference or not. Don't notice it too bad getting up to 60, but in town its pretty bad.

91 F350 Twin I beam, Sterling rear, dually.

I also have a clunk, I notice it most when backing in my driveway and the rear axle (drivers side first) drops from the pavement to my gravel driveway. No clue if its related.

Plan is to start by checking rear wheels for play while off the ground.

Any pointers or advice is greatly appreciated!

 

[Macrobb]

Check the u-joints and carrier bearing(if you have it)

 

[Thewespaul]

Carrier bearing causes my 30 mph and 80+ mph vibration. I have the part just not the time to fix it

Clunk may be the rear sway bar bushings. That’s an easy fix

 

[Sidewinded_idi]

Sounds like a bad ujoint

 

[icanfixall]

I'm with everyone's comment.Best check things before you drop a drive shaft.

 

[Cubey]

My bad luck is usually on the side of good. My carrier bearing “exploded” but didn’t damage the shaft. I’m sitting in a shop having it done right now.

Try pushing and pulling the driveshaft side to side at the carrier with your foot and see if it has any play.

 

[chillman88]

The carrier bearing seemed fine a few months ago when I replaced the rubber. U-joints appeared fine at the time as well but I will check.

Thanks!

 

[Macrobb]

I had a U-joint that 'seemed fine' when I pulled the clutch like a month ago. 2 weeks later, vibration... and shot u-joint. One side was OK, other was rusty and totally gone.

 

[chillman88]

I had a U-joint that 'seemed fine' when I pulled the clutch like a month ago. 2 weeks later, vibration... and shot u-joint. One side was OK, other was rusty and totally gone.

Yeah that's definitely worth looking into. I replaced the rear most one but there are two old ones left...


Well, it's just a tiny bit better since I took the NEW TIRES OFF!

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Yeah, BOTH of them. About 70 miles on them. A little over an hour driving.

 

[icanfixall]

When you say... "New tires". Is this new to you or actually a new set of tires.How many miles on them? 70... Sounds like a defect and you probably can get free replacements... Hopefully.

 

[chillman88]

When you say... "New tires". Is this new to you or actually a new set of tires.How many miles on them? 70... Sounds like a defect and you probably can get free replacements... Hopefully.

They are actually remoulds. They should be covered under warranty but this is still rediculous. I didn't have any problem with the last 4 and figured I'd have a matching set so I ordered 2 more. (The other 4 are a year and a half old and are now on the rear of my dually.)

 

[rhkcommander]

I had a U-joint that 'seemed fine' when I pulled the clutch like a month ago. 2 weeks later, vibration... and shot u-joint. One side was OK, other was rusty and totally gone.

this x100. cant always tell from inspection

 

[chillman88]

this x100. cant always tell from inspection

Yeah maybe. I looked under there, there's a tiny amount of play in the slip joint but nothing "noticeable" in the universals. I'm still not convinced it's not the tires though...

 

[nostrokes]

Yeah maybe. I looked under there, there's a tiny amount of play in the slip joint but nothing "noticeable" in the universals. I'm still not convinced it's not the tires though...

I would still be suspicious on the u joints. A little play on by hand can still be a huge vibration while driving.. Never been a fan of recap tire either.. Had 3 of them fly apart on me..

 

[chillman88]

I would still be suspicious on the u joints. A little play on by hand can still be a huge vibration while driving.. Never been a fan of recap tire either.. Had 3 of them fly apart on me..

I am considering just having the driveshaft rebalanced with new joints. It just makes me wonder because load doesn't seem to affect it. Except the other day with the trailer on, but that also put more weight on the back so....

I might just change the joints myself. Wouldn't be surprised if they're original, just can't stand working in the cold.