hey everybody,
I am new to this forum but i have been following it closely and gotten a lot of help from it so far. I trust someone will be able to help me out.. I recently bought a 2000 trailblazer, from a mechanic( 1st mistake buying from a mechanic), since ive gotten it i've had nothing but trouble, but the thing thats the worst is vibration in what appears to be my front end. It is simiar to a cell phone vibration, not a shimmy. It only happens at highway speeds, say 55 mph plus. Since ive gotten it I have

replaced tires and had rebalanced twice
replaced front drive shaft with used drive shaft, bad cv
replaced both front hub assemblys
replaced front pads/rotors
replaced left motor mount
replaced Idler arm
replaced upper/lower ball joints both sides
and of course alligned

there is more, but not really relevant to viibration. My steering box has some play, and minimal play in pitman arm.
not really sure if they give this type of vibration anyway. I see there is a tbs about highway speed vibrations.
2000 Chevrolet Blazer Trailblazer 6Cyl4.3L - Steering & Suspension
any info on the TSB #01273B NHTSA ID #10004146.

im going broke, but learning a lot. everything ive done so far has helped, but vibration is still there.
Ive seen a lot of really knowlegable people on this forum, so if anyone can help, I really appreciate it.
thanks in advance..........Paul

 

This may not be what you want to hear, but when the wheels are removed and replaced, have you noticed that air guns are used? Some of these guns will torque your lug nuts to 200+ foot pounds, eventually warping your rims. This warp will not be resolved by balancing the wheels. Having learned the hard way, I now insist that the lugs on my vehicles be tightened with a torque wrench @ 100 foot pounds and I check them when I get home. No more warped rims. This may be what has happened to your vehicle.

 

Agreed, my first thought when reading was that maybe a rim was slightly bent or something? Does the vibration follow the wheel after a tire rotation? Or does it stay at the same corner of the truck? It will immediately rule out either suspension or wheel.

 

How can u determine if you have a warped rim? Can you see n e thing by lookimg at the rim itself

 

I took my vehicle back to the tire shop after noticing a vibration in the rear after a rotation that had never been there before. We checked the torque and found the nuts way too tight. ~220 foot pounds. We put each wheel on their balancing machine, secured a screwdriver on the machine where the tip of the screwdriver just contacted the outer edge of the rim and slowly hand turned the wheel. One of the rims "wobbled" slightly and the screwdriver scraped the rim in an area and then it had a larger gap as we turned it further. We checked the lug hole adjacent to the gap and found the metal had been deformed from the lug nut being too tight. There are probably other ways to do it.

 

you might not like this either but go back to a tire shop and have the tires removed and have just the wheel itself spun... ask to watch as they spin it and you will see if the wheel is warped... ask them to lossen and tighten the wheel on the machine a couple of times to make sure it is on the balancer properly.... if it requires more than a 1/2oz of the wieght then the wheel is bent/warped and is no good.... and aluminum wheels will usually break before it bends.... i have been workin with commercial, passenger, and otr tires for about 5 years now...

 

Ill definitely check this out more thoroughly, as i think I mentioned, I am new, I have been tightening the heck out of every lug, and not torqueing to specs, just thought ,"make it tight, cant go wrong" . I did however have them rotate front to back and back to.front , and didn't seem like the vibration moved at all. It all seems to be in the front end I can feel it in me floor boards, I'm suspicious of u joints.

 

You seem to be on top of this. The U-joints may very well be bad. As you know, vibrations are notorious to track down. Could be from engine or transmission components. Worst case, the vehicle frame, front suspension or rear axle has been damaged from a crash. Regarding the TSB you mentioned, a helpful service tech could research this or you could subscribe to a service like AllData. Good luck.

 

My worst fear is a bent frame, rear axle may be possible however. The truck has a clean carfax and no salvage title, but I did notice some over spray under the rear wheels wells but to me that is not indicative of a complete or serious paint job

 

Ok everybody, I think I've made some serious headway on this, my mechanic says my u joints check out ok, as I thought they did. And my drive.shaft still has its weight. He did however replace the other motor mount and tranny mount, but to no avail. However , on my way to work this morning I started messing around with my 4wd. I noticed that the more I switched from 2hi to 4auto to 4hi and back to 2hi, the smoother it got! This is funny too, because once I noticed that my hubs where staying engaged, found that the vacuum hoses on my actuator switch were reversed, switched them, played with the plunger for a while and magically the vibrations where gone. Well they were gone only for minutes until I got my truck washed . I think that the guy wiping down my dash hit the 4wd button, and stared my vicious cycle all over again. In any case, could a bad actuator cable, or even a bad 4wd solenoid cause these vibrations . I thinly they may be centralized from my front transfer case