Help diagnosing vibration from the front end which seems to increase over time

[VILeninDM]

hey everyone,

About a month ago my trailblazer developed this new features. When you get into the car and start driving, everything feels completely fine. Then after about 5 minutes you start noticing slight vibration (very slight, just feels like something isn't quite right). After about a 20 minute drive, the vibration is very noticeable. By that time, it almost sounds like low engine rumble, but its pitch and volume vary directly with car's speed, not engine speed. When it gets to that level, it is also easily felt in the steering wheel.

Three weeks ago, I jacked the car up and noticed that there was a ton of grease spewed around passenger side CV boot. So I went through the motion, which took a while for various reasons, of replacing passenger CV shaft and while in there, also rebuilt 4WD disconnect with fresh bearings and seals. Yesterday I put the car back on the road and the vibration is still in there unchanged.

I tugged on both wheels to check wheel hubs and at first glace the wheel bearings appear fine. I've had bad wheel bearings on this car before, left one is 5 years old. right one is 1 year old. Whenever wheel bearings were bad a) vibration would be constant through out the drive (i.e. you can feel it the second you start driving) and b) they would change in sound when turning left or right.

This current vibration is...
1) unaffected by turning left/right or going straight
2) does not change in sound if 4wd is engaged or disengaged
3) unaffected by putting the car in neutral and revving the engine

I also checked the front differential fluid level (obviously destroying the fill plug in the process) and topped off the oil level. It was a little low, but no where near empty.

Any ideas what would be causing it?

 

[The_Roadie]

Were the bearings a name brand or Ebay cheapies? Sometimes a bearing can fail and not change noise while turning one way or another. And they can fool you if you spin the tire while it's in the air because a different part of the race is in use when the wheel is hanging compared to when the weight of the vehicle is on it.

Or it could be something like tire tread separation that's worse when warmed up.

 

[VILeninDM]

Driver side (5 yo) was done at the dealer. Passenger side (1 yo), I did last year and I'm 95% positive I bought replacement hub in advance auto, don't remember exact brand but I just checked their site, the only one they carry is Moog and it's very likely that's what I bought last year. I do usually try to stay with brands I've heard about before.

It kinda felt that vibration was coming more from driver's side, but yesterday when my wife was in the passenger seat, she said she felt it more from her side. Then again, it took her almost the whole 20 minutes to admit that she feels the vibration in the first place. Taking the car to work tomorrow, will drive some friends around to see what they hear.

The tires are all new which I had to buy at the dealer this last november when the car didn't pass inspection. I bought Bridgestone Dueler Alenza's. How likely is it for these tires to fail after one month? Would tire tread separation be visible? I had both front tires off the car this weekend and overall they looked nice and new.

I guess I should have swapped front/rear tires to see if that would make any difference.

 

[fadyasha]

At first I was going to suggest wheel bearings but i'm not sure that starts upon launch. My experience was vibration starts as you pick up speed. I did face a similar issue where getting vibration in my previous car and grease was everywhere. The CV joints were fine but grease got out because wasn't tight, so I jacked her up put in some grease, put it back together and tightened it up. No more vibration after that.

Not really sure if that's related or if I just got lucky!

 

[VILeninDM]

So turned out to be driver-side wheel bearing. I replaced the hub earlier today and the car now drives smooth as butter.

I've had 4 bad bearings before this one and all them sounded almost same and different from this one, but I guess it all depends on what exactly fails. One thing that gave it away was few days ago after 30 min drive from work, I came home and felt the rims. Driver side was significantly warmer than passenger side. My guess it was due to extra friction in the failing bearing.

 

[fadyasha]

So turned out to be driver-side wheel bearing. I replaced the hub earlier today and the car now drives smooth as butter.

I've had 4 bad bearings before this one and all them sounded almost same and different from this one, but I guess it all depends on what exactly fails. One thing that gave it away was few days ago after 30 min drive from work, I came home and felt the rims. Driver side was significantly warmer than passenger side. My guess it was due to extra friction in the failing bearing.

Glad you got it fixed! but 4 bad bearings wow ! what replacement parts are you using?

 

[woody79]

Glad you got it fixed. Hope this last set of bearings works better than the last few.

 

[The_Roadie]

...Driver side was significantly warmer than passenger side. My guess it was due to extra friction in the failing bearing.

A good point. When I'm towing my pop-up trailer, I carry one of those infrared temperature sensing guns, and point it at the wheel bearings at every fuel stop. It alerted me once to a problem starting to happen, so it's part of my process forever more now.

 

[VILeninDM]

... 4 bad bearings wow ! what replacement parts are you using?

Not all on the same car

1. TB driver side - 5 years ago, replace at Chevy dealer under warranty. That's the one that failed this time. Hopefully new moog will last a bit longer.
2. TB passenger side - Last year, bought moog replacement
3. Wife's BMW 330i
4. My old acura integra that I gave up when it had almost 200k miles.