Will do , your the best

 

Just something to try.

Have you tried running without the front driveshaft installed?

 

Not yet but someone did recommend that, and was gonna try this weekend. Do u know off hand if front drive shaft should spin free by hand in 2hi?
l

 

Your truck is a 2000 Blazer Trailblazer correct. If so, then it will have the NV236 transfer case which has a preloaded clutch on the front output shaft. This will cause drag on the front output even when in 2HI.

 

Well, no luck so far, but I'm all about trial and error now. I'm already into this truck for way more than its worth street value wise, but worth more to me at this point. I get this vibration at highway speeds even in neutral, and my control arms are covered in grease from my inner cv axle seals. Uh, yea, think its time for a change? Maybe this explains why the vibrations were so different when in 4hi? Would bad axle cv's cause vibration similar to a bad tire/tire balance?

 

Mine had a similar problem. Vibration at highway speeds starting as low as 45 mph felt under front floor. Found a bad CV joint on the front driveshaft. It had excessive lateral play near the transfer case. Also I had a bad vacuum switch on the transfer case causing the front hubs to be constantly engaged, making the front driveshaft spin all the time. I believe the bad switch caused premature wear to the shaft.

 

Sorry been so long for a reply, but I am so grateful for your suggestions. Wow.... after a couple of thousand bucks dumped in, I have finally dropped my front drive shaft and took it for a spin, and wouldnt u know, smoother than a babies bottom. Dropped off the drive shaft at a drive shaft guy to check balancing. It took some weight on both sides. Now the shaft is back in , and so is my vibrations. But I will say, that they are way less, and they start later in speed and end earlier . Much better and actually tolerable. Do u think this was my problem? Maybe the cv is no good, or maybe this guy just didn't do a good balancing. He said the shaft looked strange to him, somewhat fabricated. I will try to upload a picture and any input is greatly appreciated . Thanks again .

 

The rear CV joint in these driveshafts likes to get loose. No amount of balancing will correct that. The fact that it did get better with a balance job means that you are hunting in the right spot!

 

I am so grateful again for all the advice. By the way, I am subscribed to a post about chirping serpantine belts where u recommended th gatorback belt, fixed my problem . Thanks again, really loving this truck.....