newbie vibration question

[hootymo]

hi everybody! i am new here, i just got a 2000 blazer lt 4x4. i am noticing some very subtle but annoying vibration that sounds like it is coming from the rear end, however i can feel it a little bit in the steering wheel too. it only starts when i hit 40mph and go from there. the weird part is, its worse at 40mph then gets less noticeable as i go faster. there is no moaning or howling like a wheel bearing usually does, just a steady vibration whose sound kinda resonates through the whole truck, like a very low-pitched humm. could this still be front wheel bearings? i replaced the driveshaft rear u-joint but not the front one, could this be a cause as well? any and all help would be greatly appreciated, this is annoying me because i thought these trucks were supposed to have really smooth rides. thanks!

[BlazerLT]

hmmmm...

First thing I would have said was rear u-joint.

Odd that that wasn't the problem.

Could be the front one. or the driveshaft is out of balance.

[hootymo]

how hard is it for the home mechanic to change a front u joint? do i need any special tools or anything?

[BlazerLT]

The front one is a pain and you will need a torch to melt the nylon asembly to get it out.

I would spend the 100 bucks and have a shop do it. They have all the tools.

[hootymo]

hmm ok, but you are definitely thinking front u joint? anything else that can cause vibration? cuz i know the driveshaft is balanced correctly. thanks for the quick replies

[BlazerLT]

Before anything I would have the tires checked out for balance and for proper pressure.

32psi cold.

[hootymo]

oh yea i forgot to mention that, i just had new tires put on and balanced and a front end alignment done. it definitely feels different than tires out of balance too, its a different kind of vibration. i just wish i could describe it better or you could take a ride in my truck

[BlazerLT]

I would have the front u-joint checked before you replace it.

If it moves freely, it is fine.

[ricksza]

If the vibration just started after having the tires put on, suspect the tires first. Move the rear tires to the front and see if the vibration changes. Possible bad tire, the balance is off, or a rim is bent.

[hootymo]

well we changed the u joints and still doing it, any more suggestions? what kind of rear wheel bearings does the 2000 blazer have, hub and bearings or can the bearing itself be replaced?

[Officer Redneck]

Sounds like a weight may have fallen off a rim. My uncle owns a tire shop and it's a common problem.

[hootymo]

tires have been balanced twice already, problem hasnt gone away. definitely not tires... any other ideas? how easy is it to change rear wheel bearings?

[chcknugget]

I have the same problem. My moaning noise starts at 50mph now. I'm thinking it's either wheel weights or bad bearing. I' doin some research on the rear bearing now.

[hootymo]

awesome let me know what you find out about the rear bearing, i cant possibly find anything else wrong with this truck... could it be the front u-joint on the rear driveshaft too though? because i do get a clunk when i put the truck from reverse to drive, and i have seen people talking about that on here when they have bad u joints that it makes that sound... help!!

[chcknugget]

You might want to look into a bent axle if you've been in any sort of accident. I think I get slight road noise from the front passenger side of my jimmy from that.

I've seen documents where people say park to reverse clunking is normal on 4wd vehicles, I've also read that it is not normal. Go figure.

I'm planning on going to a shop and have them look at it. I just don't want them to poke, play, and charge me if nothing gets fixed.