98 Chevy front drive train vibration

[LikemyChevys]

Hello,

 

I have a 1998 Chevy 1/2 T 4WD ext cab with 134k miles that's slowly developed a front drive train vibration. It starts at about 65 mph and the vibration increases with speed. Right now it's a minor vibration but enough to cause some concern. It's not the steering, alignment, tire balance or suspension and I can't feel any play in the front wheel bearings.

 

The CV joints have some rotational slop (particularly the passenger side), none that I can detect up and down and they don't make any noise, the boots are intact and haven't leaked any grease. One thing I've have found is the passenger side stub axle bearing has a little bit (1/16 or less) of up and down or side to side play.

 

I know the things I've mentioned are probable causes but I'm hoping someone has ran into this before and solved it. So, here's my question.

 

Would a minor amount of slop in the bearing be enough to cause a vibration or could it be a CV joint/axle?

 

Thanks in advance.

[00Silverado4x4]

Can you guessitmate where you "feel" the vibration coming from?

 

Any slop in the bearing is too much. Also yes I would check CV joints and also may even a driveshaft balancing problem. Also a quick check, is your hood adjusters adjusted. I remember I worked on a car that was having vibration issues. Low and behold one of the little rubber bumpers on the hood corners was broken/missing allowing the hood to "vibrate", replaced/adjusted and all was good.

[LikemyChevys]

Thanks for the reply

 

There's no way to exactly tell where the vibration is coming from. I can feel a little bit through the steering column (it's not shaking the steering wheel like a tire out of balance) and I can feel a little bit through the gas pedal. It runs perfect and it's not an engine rpm related vibration.

 

The hood doesn't vibrate either.

 

I think I've found the problem (the bearing) but I hate tearing into it without knowing for sure.

[kstruckcountry]

Bearing is actually a pretty simple fix. If they haven't been replaced yet they'll need it soon anyhow.

[LikemyChevys]

Here's some more info.

 

My first thought was a driveline vibration so I replaced the rear driveshaft u-joints. The rear u-joint was rusted out and in need or replacement so I did both while I was at and It helped a tiny bit but didn't cure the problem. I've owned the since new so while it's possible the rear drive line is out of balance I just don't think it's likely.

 

The front drive shaft was replaced years ago, it was damaged from crow hopping in 4WD on dry pavement, and the vibration problem occurs in 2WD so that's not a likely suspect.

 

I found a youtube video on rebuilding the right front axle and it clearly shows the roller bearing at the end of the long axle housing. Usually a roller bearing of this type does not fail and if it wears to the point of getting sloppy it will grind itself to pieces in a very short time. FWIW, the left side is tight as can be

 

The seal is not leaking, it's not making any noises that I can hear so I'm wondering if the very slight up and down play is normal? I can only assume that it is considering all of the above.

 

I need some experienced wisdom.