Diagnosing drivetrain noise

rammertide07 · #1 Sat, September 17th, 2011, 05:53 PM

For a while now I've had a vibration that feels like its coming from right under me. Sometimes I can hear and feel it and sometimes I can only feel it. It mainly does it between 50-60mph, with enough pedal to hold 55mph and even coasting in neutral. The sound comes just as fasting as it goes. Best I can describe the sound is is you hum and bring the pitch up and down smoothly. I'm not sure where to start with this one but trans fluid level and differential fluid. The carrier bearing/center support bearing is about 6 months old. I replaced it because I thought that was the issue. My thought are flex plate, slip yoke, or worn ring and pinion...if all the fluid checks out.

ticopowell · #2 Sat, September 17th, 2011, 07:34 PM

I wouldn't just throw parts at this one, it could be number of things. I have a similar vibration and Cody said that it could be the U-joints, so I would check those out, or have a shop diagnose the problem. keep us posted on your findings

Thanks!

rammertide07 · #3 Sat, September 17th, 2011, 10:00 PM

I had the local alignment shop to install the carrier bearing and they said the ujoints looked fine. And I think if it was a wheel bearing, it would jave fell off by now. I've thou about taking it back to have them to diagnose it....just hesitant at the moment. I really do need to get something done because I plan on driving it back home for the holidays. I'll post back when I get something done. But if anyone else has any other ideas or suggestions, please share. Thanks

***907DAVE*** · #4 Sun, September 18th, 2011, 07:03 PM

My bet is a u-joint that is on its way out. A quick visual can be all it takes to diagnose your concern, look closely at the u-joint, inspect for rust coming from the cap(s). A joint that has no more grease left in it will squeak at first and eventually get loose. If there are no signs of rust or looseness you need to pull the driveline a feel the movement of each joint. They should move freely and smooth. If there is any tight spots the u-joint will need to be replaced.

If you do all this and find nothing, inspect for missing weights on the driveline.

Good luck!

ticopowell · #5 Sun, September 18th, 2011, 11:46 PM

What if the whole thing looks rusty?

rammertide07 · #6 Mon, September 19th, 2011, 07:15 AM

Thanks 907Dave...that gives me some hope that it wont be as much $$$ as I think it could be. I will check out the u-joints later today (or the near future...I'm a bad procrastanator). If I can't see rust or signs of a bad u-joint, I'll just have the shop replace them anyways and balance the shaft. I'm probably at 200k mi or more, even though the odometer says 193k. Larger tires throw my spedo off by 5mph. And I'm pretty sure those u-joints are the same one from factory. Man I'd be so happy if that's all it is.

rammertide07 · #7 Sun, September 25th, 2011, 07:55 PM

Ok, I've been under the truck a little today installing the new egt probe (didn't fix my gauge issue) and took a look at the drive shaft. The ujoints themselves look like rust. Anyways, found that the rear drive shaft boot is missing. So I will be taking the truck to the alignment shop to have them to replace all ujoints and have them grease everything up. would it be worth it to have the drive shaft balanced?