Have a unusual vibration

[Wbruiser2]

I have a weird vibration that starts after about 30mph and seems like it goes away at about 70. I hear it more than I feel it and I can barely feel it in the steering wheel. It started after I replaced everything in the front end except the I-Beams. So everything between the pitman arm and the rims were replaced to include kingpins and tires. I noticed the vibration before the new tires and after the new ones there was no change. I had a front end alignment: no change. The vibration sounds/feels kind of like running over rumble strips on the side of the interstate. I replaced the u-joints just to rule them out. I have new rear brakes (shoes, wheel cylinders, and hardware). I haven't messed with the engine internals, transmission, or rear-end so it would be a heck of coincidence if one of those were the culprit.
Anyone have any ideas?
76, 2wd, 302, C6...

 

[DNFXDLI]

Are the shocks good or did you change them?...wheel balance maybe?

 

[BuzzGun79]

How does the vehicle track while driving? does it pull to one side or the other with or without braking...if so ide start there and go back through checking things out like bearings,brakes,calipers to see if something has come amiss...

 

[dustybumpers]

Do you hear any noise on hard cornering?

Check your rear gear oil, it could be low.

Jack up the front, and check for wheel bearing pre-load, you may have gotten a false reading when you set them, and now they are loose

 

[Wbruiser2]

Shocks are good, tracks good, and no noises when cornering but this is what I did find that might be the culprit. While checking for wheel bearing tightness, I felt slop in the driver's side tire but not from the wheel bearing. I jacked it up an inch off the ground, put the handle under the tire, and see the up and down slop between the spindle and I-beam. I need shims there I reckon. They wouldn't fit when I was putting it back together. The passenger side is good. I don't know if that would cause that weird vibration/ noise like the running over rumble strip noise but I can't find anything else amiss... Thanks for the replies.

 

[Beach66Bum]

Do you hear any noise on hard cornering?

Check your rear gear oil, it could be low.

Jack up the front, and check for wheel bearing pre-load, you may have gotten a false reading when you set them, and now they are loose

very interesting on the rear gear oil, I am going to check mine, I have a small vibration that starts at about 50mph. And I know I have a bit of a gasket leak on the dana 60.

 

[Wbruiser2]

Does anyone have any experience with this issue being related to the Torque Converter or Transmission and how did you narrow it down?

 

[Fellro]

What did you put on for tires? Never had speed determined troubles with converters, they tend to be more RPM related, as the rpm varies through the time that you go from 30 to 70 as each gear shifts.

 

[Wbruiser2]

The tires I put on were coopers, 275-60/15 (on 15x8 wheels) but the vibration was there with the old worn out cupped tires. The C6 is usually in 3rd gear by 25mph just normal driving but when the vibration starts I'm pretty sure it's over 2200rpm. I was told by the previous owner that it had a 2000 stall converter (I can hold the break, in gear, and rev to over 2000rpm before it wants to spin). I guess I need to pay more attention to the RPMs the next time I drive it. I noticed that when I'm doing 60 or so and the vibration is present, I can let off the gas and it's still there for a few seconds (until it drops below 2200 or so rpm?) then it goes away... I checked the Harmonic balancer and all seemed well with it... I appreciate the response.

 

[Fellro]

If it has a kind of buzzing like sound, and gets louder the faster you drive, sounds like a wheel bearing failure. That kind of issue often is speed related.

 

[Wbruiser2]

The wheel bearings, races, rotors, well everything is new except the spindle and I-beams. Less than 300 Miles on them. And the sound is like running over rumble strips as well as the feel..

 

[Fellro]

How about the rear wheel bearings?

 

[Wbruiser2]

I thought I'd update my problem here. I changed the transmission fluid(drained the TC and replaced the filter) and substituted a quart with a can of seafoam transtune. I didn't notice anything odd about the fluid and there wasn't any debris but the bottom of the pan was coated in a black film. I topped it off and went for a ride and that rumble strip vibration is gone. I still have a slight vibration but I can feel it in the left front wheel area so I have to assume that is due to the slop and the need for the shims I mentioned earlier.

 

[Mil1ion]

Did you replace the U-joints anywhere in there?
These are usually the culprit ..so many different applications for U-Joints

 

[Fellro]

I replaced the u-joints just to rule them out.

1st post. they have been done.

 

[Mil1ion]

But were they done right ?

There is a precise way and different applications for U-joints

Read the procedure in the manual located in the other 73-79 forum

 

[DNFXDLI]

Are you referring to out of phase Dennis?.

 

[Mil1ion]

Yes because someone installed the wrong U-joint or the right U-joint the wrong way

That's why one should mark the drive shaft and use the correct Ujoint

http://www.fordtruckfanatics.com/forum/showthread.php?t=29290