vibration in rear end

[philsblazer]

I have a 2000 Blazer LT that has a vibration in the rear end at speeds between 60 and 70 mph. I have had the tires rebalanced and had new tires put on, swapped the wheels around and still the vibration persists. Anyone ran into this ?

[goldz28]

I had a 96 silverodo and the U joint or constant volocity joint was going out and caused the truck to shake I could also hear a clanking sound to at low speeds.... Check your rear diff oil to maybe its low... Good Luck

[BlazerLT]

bad U-joint.

That or time to check your rear diff fluid.

[philsblazer]

GM representative says this is a known issue - there is no fix for it !!!--- all u joints, differentials, shocks, drive shaft etc check out OK!

[BlazerLT]

He is full of crap bro.

There is no known shaking with any of the Blazers.

They are all more or less the same from 1995-present.

Are you running Goodyear tires?

[philsblazer]

I am running Goodyears now, Goodrich before that -Gillettes before that- same vibration - can't feel any difference when I changed tires. I agree - there are only so many things under there to cause a vibration, it will be a matter of finding it.

[BlazerLT]

It will be tough.

Do you have any noise with the vibration?

[philsblazer]

Mainly the rattle of interior components being shaken loose by the vibration - but maybe a faint whoom - whoom -whoom noise. Doesn't sound like a u joint rattle or a clicking

[BlazerLT]

have you taken the rear hubs off and looked at the brakes?

Check the rear bearings?

[Bobbido]

I have a 99 Silverado that has the same problem. Are you sure it's coming from the back? I bought new tires because the original set had uneven ware on the inside of the tires like the truck has been bouncing. The tire place said it was from not having the tires rotated. Since I was not the original owner, I thought my problems were solved, but 70k miles later the Michelins have the same ware pattern and my truck still feels like my tires aren't balanced and I take it in every 15k miles for balance and rotation. I have read a thread on this forum that gives detailed instructions to repair this problem, but I can't find it again. When I do find it or if someone can shed some light on this matter, I will pass it on to you.

[Rick Norwood]

I agree with BlazerLT, I would also suspect the U-Joints. How were they inspected? If you have the type that are held in the drive shaft with the injected plastic, I am wondering how your mechinic inspected them since you really cannot take them apart without damaging them. I'd double check the U-joints.

BlazerLT, how would you suggest to inspect the U-Joints without damaging them?

However, Since you're running into brick walls with the rear end, you might just check the front wheel bearings too. When my Front wheel bearings went out on an 82 Olds, it sounded like an airplane noise and vibrated to beat the band at higher speeds, but simply spinning the wheels while jacked up didn't reveal a problem. Once I pulled the bearing out, the metal flakes were a dead give away. It may be possible that the vibration/noise is transfering.

[BlazerLT]

U-joint can't really be inspected, but only replaced.

There are two u-joints and it is best get them serviced anyways.

It is that or a rear bearing problem.

[Rick Norwood]

Exactly my point! Simply crawling under a jacked up vehicle and trying to shake or twist the drive shaft won't really tell you much about the condition of the U-Joints at high speeds unless they're about ready to fall out.

By "getting them seviced" I assume you mean replaced, as the factory U-Joints don't normally have grease fittings. I would replace them in a heart beat before spending any more money on tires, brakes etc.

[BlazerLT]

Yea, true, I would get them both replaced first before moving on.

Also, a good check is to put the truck in reverse, and then to drive and listen for a clunk coming from the rear of the vehicle.

[philsblazer]

Thanks for all the info - I jacked the Blazer up and physically checked the u-joints, they felt OK but I will replace them anyway when I replace the rear wheel bearings. There is a little movemant in bot rear wheels when you grab them and move them up/down or side to side. Still cant hear any clunks when I go into reverse.