First off I am 19 years old and live at home with mom and dad. I got my tahoe back around christmas time and absolutely love it. Now when I bought this truck it ran fine with nothing wrong. My parents want me to sell the truck and I don't want to. So heres what has gone on so far. I was driving home from school one night on the highway and all of a sudden if felt like something let go and the truck started shaking real bad. so ihav replaced all the uv joints, both front axles hubs bearings. Now the virbation is only really noticible at around 15-35 mph other that not bad. but I dont want to drive because I don't want to do anymore damage. Today I took out the front driveshaft and still not real change. Also at 40 mph or higher when you slow down it makes a loud whinning noise like either a bad bearing or gears grinding but it will only do this in 2wd this was with the front driveshaft out still. any help would be great.
Thanks
Ryan

I would be jacking up the back end and turning the driveshaft by hand to feel for any roughness. Then remove the diff cover and inspect the rear diff, if ok, drain out the transfer case fluid and look for chunks of metal coming out.

Safe to say something in your driveline has had the bisquit. Since you've almost completely replace the front end parts It must be somewhere from the transfercase back. That leaves the t-case, rear-driveshaft, and rear-end. Try turbovanmans advice and the problem will probably present itself.

My 93 sounded like that and the fix was rebuilding the rear end.

The front drive shaft only turns when in 4 wd. Have you ran the truck with the rear wheels off the ground , still have the noise ,only a lesser amount? Have you removed the the rear differential cover for a look in the bottom for visible metal particles ? Do you have a mechanics stethascope ? If not borrow one. Run the truck & listen at the housing , check from underneath with engine turning the rear wheels from 50 mph down. It may not make the loud noise without load on the diff. But the diff will most likely emit some abnormal sound if it has an internal problem. Here in the west the AAMCO shops are checking & diagnosing these types of noise at no charge. While I'm certainly not at this point recommending you do buisness with any one there is a value to that diagnostic service . Check it out & let us know your findings & Good Luck

Sorry I forgot to metion that I have already had the rear end apart and all is fine back there. I have had the truck jacked up and drove it in 2wd with no virbation but when 4wd I get a little vibration but nothing like when under load. also where is the plug to drain the transfer case. also what are the chances of the front diff being bad. when the 4wd is engaged it goes into gear but when you drive it you get a loud clanking noise and the truck jumps.
thanks again
Ryan

Sounds like the transfer case is done or the front axle isn't engaging properly. The drain plug for the TC is at the left rear, aprox 1 1/4 socket or adjustable wrench works.

Safe to say something in your driveline has had the bisquit. Since you've almost completely replace the front end parts It must be somewhere from the transfercase back. That leaves the t-case, rear-driveshaft, and rear-end. Try turbovanmans advice and the problem will probably present itself.

if i remember there is also a drive shaft carrier bearing. that would cause shaking. had it once in a f250. also what about a harmonic balancer. would that do it. just throwing ideas out there. Ed

if i remember there is also a drive shaft carrier bearing. that would cause shaking. had it once in a f250. also what about a harmonic balancer. would that do it. just throwing ideas out there. Ed

Think you might be right on the carrier bearing. just one more thing for him to check. BTW I wouldn't be selling my truck over a drivetrain vibration either. A diesel 2-door tahoe is a pretty cool ride for a lot of reasons.

what transfer case is in it?....mine has a BW 44-01 and there is a gear that shifts it from high ranger to low ranger and the fork that shifts the gear has little plastic keepers on it and they wore out and it would act like it was jumpin' out of gear and make a god alful bangin' noise...replace gear and plastic keepers and it fixed it right up.........

Hey guys just a couple more questions.

if i remember there is also a drive shaft carrier bearing. that would cause shaking. had it once in a f250. also what about a harmonic balancer. would that do it. just throwing ideas out there. Ed

this carrier bearing is that in the transfer case? Also I did not think that the harmonic balancer would cause vibration at certain mph as that was at certain engine speeds or rpm correct me if I am wrong. I also do not want to sell this truck but if I put to much more money in they are going to want me to. Also I can get a deal on a new or reman. transcase if this what you guys think this might solve my problem.

if i remember there is also a drive shaft carrier bearing. that would cause shaking. had it once in a f250. also what about a harmonic balancer. would that do it. just throwing ideas out there. Ed

There isn't one on a 2 door Tahoe.

I would double check the universal joints on the rear driveshaft and also the engine/transmission mounts. If the driveline is shifting under load and one of the u-joints is bad the flexing could exagerate the problem.

Yeah, what JeffMD said. Are you sure the U-joints are perfectly centered in the seat they sit down into. It doesn't take being off much to cause a bad vibration. Even dirt in the pockets where the caps sit can cause the joint to be out of alignment. Double check these before spending lots of money on something else.

SnowDrift

sorry to go off topic, but how to you evaluate the transmission mount as being good or bad? At what height are you getting metal on metal contact?

I think i would take all the load off rear tires & check for any play at the rear diff yoke. I have seen the yoke nut loosen & allow the pinion gear to change its engagement with the ring gear depending whether accelerating or decelerating. If that looks ok there is a snap ring on the output shaft of the transfer case. It limits the thrust movement of the shaft. When the ring breaks, it allows the shaft to move fore & aft, essentially shifting itself between 2 & 4 wheel drive. will make some nasty noises.

Does it do it in neautral at any engine speed or not?

so thanks on all your help. I had just replaced all the uv joints as that was the cheapest place to start and one was already broke. I have been reading some of the website for rebuild kits on the transfer case and the say that there is a snap ring on the out put shaft that is know to break allowing the shaft to move. I will check all the motor and tranny mounts and if all checks out I think it is time to just pull the transfer case and have a look. I thats the problem does any one know if these are hard to rebuild or pretty straight forward.
Thanks
Ryan
sorry missed tag's post so this sounds like the problem to me.

did you run it in 4wd w/out drive shaft? if not take drive shaft out and run fourwheel. if bad vibration still then you know its transfer case if not then its most likely front end somewhere

You dont have to pull the case if its the snapring. Just pull the rear driveshaft, then output shaft extension housing. If its the snapring it will be laying in the bottom of the extension housing when you pull it off. I have only found the snapring locally at the dealer, its around 5 bucks iirc.

Have you tried having the driveshafts balanced.

Mike

Alright today was the first day that I got a chance to get ooutside and take a look at the truck and it wasn't raining. Some of you guys said check the snapring on the output shaft. I think some said to take off the extension housing and I need help figuring out what that is. Is it on the front output or the rear output shaft. Also here is a picture of a part on the front of the transfer case. what does this do and what can go wrong with it.
http://www.partsamerica.com/product_images/img/a1c/48106.jpg (http://www.partsamerica.com/product_images/img/a1c/48106.jpg)
thanks
Ryan

That is called the "encoder motor" it can fail and then you wont' get 4 wheel drive or it can do the opposite and fail on 4 wd. Its basically an electric motor that shifts the TC for you.

Just to add something you may have already thought of, but didn't say...

When the truck is in 4WD and you are on dry pavement, there may not be enough "slop" in the drivetrain to allow for:
1. Tires of different sizes to turn.
2. Sharp turns with same size tires.
3. Even gradual turns can put a bind on the drive train, especially if there is a locking/limited slip differential.

If you force the vehicle to endure the above conditions, you can even twist a drive shaft.
Also, some imbalances don't show (can't SEE them with naked eye) unless their under load.
I had tires with bad belts (perfectly balanced) that drove me crazy trying to find. (vibration)
Whatever it is, I hope you can still keep it.

Ok guys I don't have an extension housing on my transfer case. I also tried to look for a model number and I find a round metal plate that has nothing on it. Did GM use a different transfer case on the 1500 series or what.
TIA
Ryan