[SPXTrader]

I've owned my 96 Tahoe since late 97. 4X4, 4 door, 90,000 miles, 4" SuperLift, BFG 33X10.5 AT tires. On a trip last weekend, the thing started vibrating like mad. Here's a quick list:

up to 59 MPH OK
60 to 69 MPH BAD vibration. Things are blurry in the rear view mirror. A sound and feel like you're driving on the rumble strips on the side of the interstate.
70 and above Slight vibration.

Since it was a long drive, I had time to mess with speed/RPM. In the 60 to 69 MPH range, slight pressure on the gas seemed to lower it a bit, but it was still bad. Going downhill, at the same speeds, off the gas 100% and once the tach dropped below about 1700, it stopped. Smooth as silk.

This happened all of a sudden. Three weeks ago and another long drive, no problems. I've checked the u-joints and they are tight. No drive shaft play. This happens in OD or when it down shifts for a uphill pull.

Has anyone experienced this? Suggestions as to what to check?

Any and all replies will be appreciated!

 

[TahoeFever]

check the fluid in ur transfer case i would hate to say but it sounds like a chevy transmission
problem maybe other people here will chime in for other ideas ..hope i'm wrong

 

[kickercompkid_99]

Don't know if this is even an close guess but, a while back I was riding in my brother's 96 burban, and driving it it shook like mad!! There was what we started to call a "butter zone" where if you kept it within a certain speed range it didn't shake at all. The first chance we had we stopped and I got out and checked out the tires, shook the wheels and whatnot to make sure that it wasn't a wheel bearing heading south and everything looked fine. So off we went to our destination, I told him to take it in a have it aligned, so he did. Turns out we had lost a wheel weight and the thing was now so unbalanced that by the time we had driven 250 miles on the just about brand new tire, that he had to replace it! Just an idea, but I'm sure a new tire would sure be a lot cheaper than a tranny or transfer case!!

 

[84fiero123]

Tires out of ballance,all it takes is one good pothole to loose a weight.

 

[phoebeisis]

check motor mounts

It is probably an out of balance wheel, but check the motor mounts just in case.The no vibration with no gas makes me think this is worth a check.
Luck,
Charlie

 

[PepboysASETech]

I see this all the time. If you can put the truck into park and run from idle to red line at a smooth pace with no vibration than you dont have an engine problem. Engine problems that would cause an at speed vibration would be a harmonic balance "going" bad but not noticeable yet, or even internal cam/balancer shaft problems. Not that often is it engine. Like the guys said before tyres are the biggest contributer to vibrations. Also have the idler arm, and pitman arm checked out. Those two are the first to go out on chevys of all years and models. There is an allowed 1/2" of play says chevy on the idler arm but im calling bull shi* on that. Ive replaced at least 100 idler arms on chevy vans and trucks rangeing from s10's to 2500 vans and by those being bad cause not only mph specific vibrations but inner or outer tyre wear, slight pulling, and excessive wear on other parts like ball joints and gear boxes. So check the tyres for tread separation, and balance. Get the front suspension checked out for wheel bearings, inner and outer tie rod play (shouldnt have ANY), ball joints, and especially idler arm and pitman arm. Also something else thats not real common is front axles being bad and only vibrates during acceleration and only in 4wheel drive. That doesnt sound like your problem but it does happen.

Oh and :sign0016:

 

[big red]

check the pinion play too. my buddy just lost his rearend (and $2000) because of a bad vibration he had for a long time and he went through everything to get it corrected. turned out it was the pinion bearing. be sure to check it with no load so you won't get a false sense of a tight pinion bearing.

 

[SlimyAvocado]

I'm going to second the thought of checking your rear-end.
I had a Jeep that did the same thing. I pulled the diff cover off and a tooth from the pinion fell out. Well, a good chunk of one.
It vibrated at speed really bad, but no clunking or anything like that.
If I were you, I'd start by just checking all your wheels for any wheel weight marks..fresh marks from where one could have gotten thrown. Tire pressures. then drop the driveshaft and check the play on the pinion shaft. it should be next to nothing. Then drop the fluid. Even if nothing is in there, fresh oil won't hurt and you'll know where you stand after 90k...
good luck. I'll keep my fingers crossed for you that its something simple like a tossed weight.

 

[Cableguy]

I will throw my hat in the ring with drive shaft out of balance or u-joint, but I agree with the tire and rim out of balance or lost a weight off rim.
Chevy Truck Parts

 

[SPXTrader]

Thanks for all the suggestions. I'm gonna start at the rear end (I'm suspicious of that too) and work forward.

Thanks again, and if I ever find the problem, I'll post it up for future reference!
Tahoe Parts

SPX