another carrier bearing Q

[D-Rat]

what are signs of it going bad aside from obvious driveline vibes? Dang truck is too low for me to get under it easily....haha

Am getting some vibration under the truck, and I feel the truck doing the opposite of surging on the freeway...like the brakes are being tapped intermittently almost, and I'm wondering if there could be enough rotational resistance in the carrier bearing to get this feeling, or if the issue is engine related. In other words I can't tell if it's running rough or if the issue is further down the drivetrain. The truck is idling good, has no vacuum leaks that I can find, and the ignition system seems to be in good shape with nearly new wires and HEI. I don't really feel this at lower speeds.

strange thing to ask, I know, but I'm having trouble diagnosing exactly what's happening here

[trapper68gmc]

I am having the same issue. Mine is making a noise like something is lose as well. I am going to rip it apart this weekend. I described what you did to a mechanic friend of mine and he said he would check the carrier bearings out. My seals are starting to leak too so I think it is time to change it all out anyway.

[CSGAS]

Only a good look will tell you for sure but some other things that can cause those symptoms include dragging brakes or bearing/seals going bad in the rear end. when you come to a stop, feel the axle centers where your wheels rest on them. They may be warm but if they are hot you should track down that problem and eliminate it.

It could be as simple as backing up in a straight line and stopping hard so the wheel adjusters do their job properly.

Is there a growling noise coming from the vicinity of the center bearing when this happens? I know my bearing doesn't growl but the surrounding rubber is slowly trying to escape, so I will be replacing at least that soon. The only way I know that--is because I can see it.

I also had some shuddering from separating tires a ways back, but that doesn't cause the resistance you describe...until the tire comes apart and wraps around your axle (I headed off that part of the process at least)

[Old Yeller 1970]

I'd say that if the rubber around the carrier bearing is all torn up then you have to replace it. You may need to have your drive shaft balanced. I had that done to mine and it took care of all my problems. You may also have a tire out of balance too.

[D-Rat]

My DS was rebalanced recently by the PO. I have the receipts, so I think that's good. I'll get under it and check the bearing itself as soon as I have some time in the daylight to do so.

I coasted down an onramp today in neutral but there was no percieved resistance, so I'm thinking this isn't the problem. I think it's in the fuel delivery or spark. I'll be pulling the plugs too when I get the time to see if they're black and sooty, or wet due to a cylinder not firing.

Sometimes diagnosing a problem really sucks. Might be time to ditch the old Holley for a new shiny Edelbrock.

[Old Yeller 1970]

Don't ditch the Holley without at least an attempt at a rebuild. They're pretty simple to take apart and you can blow out all the holes with carb cleaner and/or compressed air.

You may also have a bad spark plug wire. Watch it run in the dark and look for sparks arcing to ground or if you're brave enough run your hands over the wires while it's running.

[D-Rat]

Yeah, I figured pulling the plugs would tell that story without risking shocking the heck out of myself . The wires are fairly new though...under 12k miles and about 2-3 years old. I checked them pretty closely and they're all in good condition, visibly anyways.

[splehigh]

A couple years ago the my carrier bearing broke where it bolts to the cross member. I guess it broke from flexing right below the mount. I wish I would have taken pics. I was able to limp home with the drive shaft tied up with a piece of rope. Every couple miles the rope would wear through and I would have to stop and tie it up again. Was quite an experience. LOL

[D-Rat]

Welp, that wasn't my problem at the time, but on saturday, my carrier bearing broke. The rubber part is fine...the metal itself broke where it bolts to the crossmember. %#%$! The truck is so low it's a serious PITA to get it lifted far enough to get under it. May just bite the bullet and pay a shop to fix it. Any links to good how to's would be appreciated though before I spend the cash. The thing is almost new too...still nice and shiny.