1999 V70XC Humming noise after installing salvage Prop Shaft

warcraftjunkie · Post by **warcraftjunkie** » 18 Mar 2014, 10:36

So I picked up a prop shaft from a salvage yard last fall. The label on it indicated it was made in 2009 so I thought I had a good find for my 1999 V70XC that had been running as a FWD since I bought it a couple years back. This past weekend I drained the bevel gear oil and rear differential oil. The rear looked to be in relatively good shape at least as far as the color of the oil. The bevel gear oil was significantly darker. Anyway after getting it all squared away and taking it for an initial spin I could definitely hear a very low humming noise when approaching 30 mph and increasing in volume the faster I went. I tried to break the tires loose a couple times, but never could so I know the AWD is working.

Prior to installation I inspected the shaft pretty good I thought. The end pieces had good flex and smooth rotation (at least by hand). The only part I was concerned with was the center carrier bearing. The rubber was in good shape visually, but I personally would have thought there would have been more free spinning of the bearing. It turned freely, but honestly it felt a bit constrained for something that will be rotating at 3500 -4500 rpm.

I guess my question is how freely should that center carrier bearing rotate? I know that Colorado Drive Shaft sells the rebuild pieces for the ends, but I suppose I have to send it to them if I need to have the center carrier bearing replaced?

Post by **JRL** » 18 Mar 2014, 17:31

They rarely "hum", they shudder.
I would look elsewhere.
A bad bevel gear bearing hums/whines when going bad but if the propshaft is out there's no load on it so it usually doesn't make noise at this point

warcraftjunkie · Post by **warcraftjunkie** » 19 Mar 2014, 07:34

Thanks JRL

When driving home yesterday I listened to the noise with your thoughts in mind and I guess I have to agree that the noise is coming from the font of the car. Did some research and it looks relatively easy to drop the bevel gear from the transmission. Any Gotcha's in that process? Looks to be along the lines of remove passenger side axle, disconnect the prop shaft, remove 5 bolts that hold the bevel gear onto the transmission and wiggle and finagle it off the transmission. Sound about right?

warcraftjunkie · Post by **warcraftjunkie** » 20 Mar 2014, 07:27

Is there a gasket between the Bevel Gear Box and the transmission that would need to be replaced, or are each units self contained with their own seals that are simply mated to together with those 5 bolts?