Driveshaft center support bearing

[Dooley Dude]

Changed the oil in my '85 C-30 today. Also wanted to look the driveshaft over, since I've been hearing a sort of whirring sound, most noticeable at low vehicle speeds. Sound does not change when I kick the trans out of drive. It varies only with vehicle speed.

Everything looks okay under there. I shot a little grease in the slip coupling between the front and rear driveshafts. Doesn't seem to be any slop in the U-joints, or in that bearing,but it does look pretty old.

I check parts prices on rockauto, and the parts are pretty cheap. Read the Haynes manual and it seems pretty easy to do. I'm thinking I might do the bearing and both U-joints just for peace of mind. I don't run a lot of miles, but heck I've owned the truck over 10 years.

So what do you guys think? Drive it 'til it breaks, or go ahead and replace it?

[old Rusty C10]

if there is no play in the thing dont replace it... are you sure its coming from mid truck and not the rear end? alot of the time it can be rear end bearings either in the wheels or the yoke

[Dooley Dude]

Originally Posted by old Rusty C10

if there is no play in the thing dont replace it... are you sure its coming from mid truck and not the rear end? alot of the time it can be rear end bearings either in the wheels or the yoke

Yes, that sounds like good advice. I guess I'll drive it a while longer and see it it gets worse. Last time I drove it awhile at highway speeds, it seemed like I had a little vibration that I didn't have before.

I was in the differential last year to change the fluid, and everything looked great there.

[cableguy0]

Get a good spray lube and not a penetrating oil. Those bearings will make a good bit of noise when they arent properly lubed. A good synthetic spray lube will stay in place for a long while. Without taking it apart its gonna be hard to get bearing grease in there.