Rear End Problems need suggestions

90 SC AOD, with 56k. I am chasing what I thought was a chewed up rear end. last week on the highway at about 70 it sounded like I lost a gear in the rear end after an aweful grinding, bucking noise I threw the car in neutral and coasted off the next exit. The grinding \ popping only lasted but a few seconds 5-10 but seemed like an eternity. I had the rear end checked, signs of wear but overall nothing needed replacing. mechanic tells me my tires are "chopped". wearing unevenly. After reading many posts tell me if this makes sense.

Are my upper inner bushings worn out causing a sag in suspension? in turn causing undo wear on the wheel bearings, maybe causing one to grind and get burned up. Mechanic checked for play as he thought the bearings would be the problem too, no play at all solid as a rock, however he says the tires seem to be binding up when trying to spin them on the lift.

After I got the car home tonight I jacked up the car (frame) and while in neutral I tried rotating teh tires forward\backward, either way it seemed as if the breaks were hanging up something definately tight. Shoudl the tires spin freely like the front end (given of course you have half shafts causing some natural resistance) If its not my calipers hanging up causing the drag what else could it be. Both rear tires have identical problem(s)? I rotated tires after approx 12k since new. Expensive but poorly made tiresm I have Bridgestone Potenze RE730's.

I appreciate any help or suggestions you can give me before I have my mechanic tear into the bearings only to find out they are fine and have to put back new ones anyway. Please help as I just won the battle with the wife to keep my beloved SC. (even with twins on the way

Check it yourself

Jack it up, grab the top and bottom of the wheel and push the top/ pull the bottom; back and forth. This should give you an indication of bearing play and or knuckle bushing wear.
Now take the wheel off. Try to spin the hub by hand, this should shed a bit of light. If still unsure, disconnect the parking brake cable and see if that helps. Still unsure, remove the two rear brake caliper bracket bolts (15 mm) that hold the caliper assembly to the knuckle. hang the caliper out of the way and slide the brake rotor off. Now spin the hub, there shouldn't be an mysteries at this point.
Grab the hub with both hands muscle it up and down; look at the knuckle while you do this and see if there is play at the bushings.
It's really not that much work, just dirty.

Check out todays post on rear bearing replacement.
It's easy to do a poor job replacing the rear bearing/hub (even for a shop), so you don't want replace them unless neccessary. If you do get them replaced, it can't hurt to print Georges instructions up and give them to the guy doing the work.

Is it possible you ran something over on the highway, spun it up, then spun it off?

good luck
Bob

Check your rear half-shafts!

Thanks guys. Per the Half Shafts, what will I be looking for per signs that they are worn out, would it be an obvious grinding off of the teeth on the end inside the hub? or near the diff? I can remove boots etc to look for damage but if you can provide specifics that would help. I am probably going to buy a jaw puller to get the half shafts out of the hub end and then check the bearings. I take it the bearings should spin cleanly inside the hub right?

Thanks again for your help!

Jack the car up and support it with jack stands. Then crawl underneat and grab the axles and try to move them up and down. There should be very little movement from the half shafts. If you get a lot of movement then the half shaft is toast!