Strange vibration at 60 mph

[JLaud]

I've tried to research this issue quite a bit but can't really seem to find much info online. My 03 Z71 has a wierd cyclic vibration/noise only at 60-70mph, can feel it in the seat and in the steering wheel. I can hear it as well as feel it. Its there at those speeds regardless of if im on the throttle or not, tranny in neutral or D or any other gear/rpm. This all happens in 2wd, pop it in Auto 4wd and it goes away and is very smooth with no noise or vibration at any speed.

My front diff was bad so replaced it with one from a salvage yard a few weeks ago and this noise has only started recently. Filled the new axle with castrol 80w-90 Dino oil and the old stuff in there was still fairly golden and had really no shavings on the plug.

The front driveshaft and u joints are good, drained and filled the transfer case and it was clean and full. Put in the blue GM auto track 2 fluid.

Appreciate the help, we are expecting our first baby in about a month and I bought the Tahoe for the safety and reliability, don't want to have any issues with it as it will be the primary family hauler.

 

[ktmhans]

Just stating the obvous probly, but did you check wheel bearings. And tire presures are all the same. Its also not to hard to just drain the oil into bottle and dump it back if all us good. But at least youll know.

 

[JLaud]

Thanks for the response, I did replace both front wheel bearings with timkens a couple of months ago as I thought the front diff noise was bearings. Tires are brand new and are set at 40psi. I'll try the diff oil and maybe change the front to mobil 1 75w-90 same as the rear that I did a month ago.

 

[ktmhans]

I cant imagine the oil itself could do it but it wont hurt. I was more saying it so you could see a change.

Dont give up its there somewhere.

 

[JLaud]

Its the front diff.... again, had it diagnosed at a shop, carrier bearings worn due to the lame spanner tabs. Jeez bought a full size suv thinking they're supposed to be strong, tough and reliable. My old 99 Camry was more reliable than this thing, and it had over 298k.

Well, appreciate the pointers and help.

 

[ktmhans]

Yep and just from experience. If you have it rebuilt make sure they put in new retainer clips on the axles. Thats what just broke on mine. The new tab number at gm has been supraceeded by the 2006 and newer tabs which are stronger. One the good side most salvage yards will give you a 6 month warrenty on the used $&*@!