Chasing a Vibration... Really need some insight

[1997XLTRollover]

Hey all, I have been chasing a vibration on my 96 AWD 5.0 for a while now and am at wits end and hoping someone has an idea. Long story short she was in dire need of some repairs and quite a bit of the truck is new now, but I have what seems to be a high pitched vibration (thinking drivetrain) at around 70-75 mph. I can start to feel it around 35 mph.

I think part of the vibration is in the front driveshaft because with the drive shaft removed the vibration gets slightly better, however that also unloads the front drivetrain, so I'm not totally sold on this theory. The obvious thing to me is my passenger CV shaft. It's loose on the axle side. Sounds easy right? Well I replaced the CV with new and the vibration actually got worse thanks to Chinese parts, so I put the factory CV back in. Rockauto also wouldn't take any of the garbage parts back, but that's another story, probably won't buy from those guys again.

Now being that this is my daily it's a huge pain, but I then ripped everything back apart thinking ok has to be a bad axle bearing. Well replaced that, no change, CV is still loose. Ok intermediate shaft splines must be worn, replaced the intermediate shaft with another used shaft, same issue. Now all this being said, the splines aren't perfectly tight on the CV and I'm thinking not perfectly tight inside the carrier either where the intermediate shaft goes in. I'm thinking this is causing it since the bearing was replaced, as well as the CV itself. I would honestly like the bearing to fit tighter on the axle shaft, but it seems like that's just how things are, because the new bearing fits the same (slightly loose IMO).

Any thoughts on this?

 

[donalds]

Wheel bearings
Cv axle...you already looked at...
Front diff ...bearings...oil
Brakes....rotors
Suspension bushings...wearing out

When I had a drive train vibration I put my truck on 4 Jack stands in drive with a trusted person in the driver's seat then I found it quickly
This is very dangerous be careful ...don't get under the truck obviously lol
If you aren't comfortable put it on a lift and look that way

Be a little more patient ..not that you aren't ...
You will get lots of suggestions probably better than mine lol
Hope this helps

 

[Turdle]

Go have tires balanced and while doing so check closely for a bent rim. The balanace machine has a cover that usually prevent visual inspection of the spinning wheel and this is often overlooked as they hang pounds of lead on the wheel. On this note, do any of your wheels have a large amount of balance weights? How clean are the inner rims?

EDIT
70-75 MPH vibration is usually something large out of balance IMO.

I had a bent rear axle shaft causing this same symptom. Used the above suggestion of running the drivetrain with the truck levitated to find it. I saw a rear caliper walking side to side.

 

[Gary Crist]

Try rotating the tires and see if there is a change.
But, I think balance too.

Does it also vibrate at 55 too?
If so, balance..

 

[1997XLTRollover]

Wheel bearings
Cv axle...you already looked at...
Front diff ...bearings...oil
Brakes....rotors
Suspension bushings...wearing out

When I had a drive train vibration I put my truck on 4 Jack stands in drive with a trusted person in the driver's seat then I found it quickly
This is very dangerous be careful ...don't get under the truck obviously lol
If you aren't comfortable put it on a lift and look that way

Be a little more patient ..not that you aren't ...
You will get lots of suggestions probably better than mine lol
Hope this helps

Drivers wheel bearing is brand new, passenger only has 40k miles on it. But would a wheel bearing actually cause a vibration? They feel tight.

Front diff oil is brand new and it looked ok inside when I had it apart recently, but I did not pull the carrier or pinion out, so I suppose bearings could be worn, but the diff only has 90k miles on it and it was from a v6 truck that was not AWD, so probably had very little load on it over its life. Fluid also looked good and it was pretty clean inside.

Brake rotors up front are brand new (front is where it seems the vibration is coming from, but hard to tell). That being said I was thinking maybe they are out of round... a long shot but I suppose they could be bad out of the box.

Suspension is totally replaced. New upper and lower control arms with ball joints, all new bushings, new sway bar endlinks and new outer tie rods (inners feel tight). Also just had it aligned and it aligned well.

 

[1997XLTRollover]

Go have tires balanced and while doing so check closely for a bent rim. The balanace machine has a cover that usually prevent visual inspection of the spinning wheel and this is often overlooked as they hang pounds of lead on the wheel. On this note, do any of your wheels have a large amount of balance weights? How clean are the inner rims?

EDIT
70-75 MPH vibration is usually something large out of balance IMO.

I had a bent rear axle shaft causing this same symptom. Used the above suggestion of running the drivetrain with the truck levitated to find it. I saw a rear caliper walking side to side.

I did you one better, took a known good set of tires and wheels and swapped them on. Same vibration. I'll have to get the truck up in the air and check how things spin, but I did that not all that long ago and it wasn't too horrible. Suppose something could have changed though, god knows NJ is pot hole heaven.

 

[1997XLTRollover]

Try rotating the tires and see if there is a change.
But, I think balance too.

Does it also vibrate at 55 too?
If so, balance..

Not really, I seem to feel it 35-45 mph and it doesn't come back bad until 70-75. I can feel it 60-65 but it's the worst around 75mph.

 

[1997XLTRollover]

No thoughts on the front CV? It's literally loose. I can move it up and down probably a good 1/8" maybe even 1/4". But I changed everything up there other than finding all new parts with perfectly tight splines. I also lowered the torsion bars to level out the CV's and that seemed to help ever so slightly so I'm kind of hung up on this CV joint being loose.

 

[Gary Crist]

It used to be 35-45 was U-joints, drive shaft.
55 ish the 75 ish wheel balance.
Low speed out of round, separation etc.

 

[donalds]

As suggested above I'd start with the wheels
Yes a wheel bearing can fail at that mileage
What brand wheel bearings did you buy

The forum members are usually correct take a good look at your wheels if you feel it in the front put the front wheels on the back ...rotate the tires .. see if it makes a difference that will give some direction

 

[1997XLTRollover]

As suggested above I'd start with the wheels
Yes a wheel bearing can fail at that mileage
What brand wheel bearings did you buy

The forum members are usually correct take a good look at your wheels if you feel it in the front put the front wheels on the back ...rotate the tires .. see if it makes a difference that will give some direction

Timkin wheel bearings, and as said above it's not tires, I replaced them with known good ones and still have the vibration. I take back what i said before though. I feel it slightly starting at 35mph and it only gets worse as speed increases. The pitch changes as I let off the gas too it seems. It's more of a vibration than a shake.

 

[donalds]

Timkin wheel bearings, and as said above it's not tires, I replaced them with known good ones and still have the vibration. I take back what i said before though. I feel it slightly starting at 35mph and it only gets worse as speed increases. The pitch changes as I let off the gas too it seems. It's more of a vibration than a shake.

Did you look at your rear diff / bearings
Letting of the gas and it changes pitch sounds like a bearing in my case it was the pinion bearings so I rebuilt the whole differential
This can happen in the front diff to as the diff is spinning even though the front driveshaft is removed
Is the front shaft still off ?

 

[1997XLTRollover]

Did you look at your rear diff / bearings
Letting of the gas and it changes pitch sounds like a bearing in my case it was the pinion bearings so I rebuilt the whole differential
This can happen in the front diff to as the diff is spinning even though the front driveshaft is removed
Is the front shaft still off ?

Rear axle was totally rebuilt just recently. Front shaft is back in as I didn't want to burn up my transfer case. It could be the front axle bearings as the front diff was a junk yard special, but did only have 90k miles. I probably should have pulled the whole diff apart and rebuilt it looking back. Too late now.

 

[Gary Crist]

Another cheap trick is to rotate the driveshafts 180 degrees.
Sometimes after replacing u-joints, if the shaft was not
marked relative to the yoke, an imbalance can occur.

 

[Turdle]

Both of my cv axles seem loose fit but after asking around before a long trip, according to others it is normal to have the sloppy feel in the cv joints.

 

[1997XLTRollover]

Another cheap trick is to rotate the driveshafts 180 degrees.
Sometimes after replacing u-joints, if the shaft was not
marked relative to the yoke, an imbalance can occur.

Rear driveshaft was swapped out with another used one I had with no change. Front one was professionally balanced with slight change but i still have a vibration. Both driveshafts were rebuilt with new joints and im wondering if a flange bent in the process. The front shaft is the double cardon design fwiw.

 

[1997XLTRollover]

Both of my cv axles seem loose fit but after asking around before a long trip, according to others it is normal to have the sloppy feel in the cv joints.

Really? Interesting. I would think that would vibrate like crazy. But good info. Its odd because my drivers side is tight passenger not even close.

 

[Eric Tang]

Is it AWD? Every V8 I've seen was. If so are all 4 tires "same make, same model, same size" ? If not, T-case pulsing on and off could feel like a vibration.

 

[Mbrooks420]

Is it AWD? Every V8 I've seen was. If so are all 4 tires "same make, same model, same size" ? If not, T-case pulsing on and off could feel like a vibration.

The T case in the V8 wouldn't pulse on and off, it’s always on.

All V8s aren’t AWD.

How tight are the output shaft bearings on the t case?

 

[masospaghetti]

My passenger side CV has some play in it too and I don't have any vibrations. That said, I've had various vibration issues on vehicles in the past. A bad wheel bearing has caused it before. Cheap CV axles have too. Might be worth getting a new high quality axle from Raxles (or some place similar) that uses OE-quality CV joints.

You said the rear axle was rebuilt recently - does that mean new carrier bearings, wheel bearings, and axle shafts? Any of these can cause highway speed vibrations. Bad front axle or carrier bearings would probably cause the same symptoms.

At this point you don't know for sure if that new Chinese axle was actually bad. The tighter joint might be transmitting the vibration from another bad part. I don't blame Rockauto for not taking it back, they would take huge losses if they allowed returns on parts that people had used for diagnosis.

Granted, there's a fine line here when you "know" a part is bad. If you really think it's bad, then get a high quality axle from Raxles and confirm it. I suspect Rockauto would honor their return policy in this case. Just be warned that Raxles aren't cheap.