GravZ28

I have an 01 Z28 and lately I have been hearing a whine or a groan coming from my rear end when in reverse. It could be doing this while in drive but I can't really hear it because my exhaust is too loud. Along with the whine I have been noticing a low toned clicking noise when making turns. I put in a 3.73 gear a couple of years ago. I had one guy tell me recently that it could be an axle bearing. After reading a few posts here, some people with similar situations have said their problem was a pinion bearing and carrier bearing. Any thoughts and how much am I looking at if I had to replace a pinion bearing or carrier bearing? Any advice is very much appreciated.

Bob@BruteSpeed

iTrader: (16)

The factory 10 bolt that came in these cars has a very small 7.5" gear. A variation of this rear was used back in the '70's in the Chevy Monza, then in the Chevy S-10. GM had to of known they would have warranty claims when they decided to use this rear in the 3rd and 4th gen f body's, apparently the cost of creating a stronger rear was higher than what they thought the warranty cost would be. This has been a real plus for the aftermarket, as a bone stock LS1 F Body with a manual transmission can break one of these 10 bolt rears! Many people have tried to beef these 10 bolt rears, spending a lot of money in the process. What they normally end up with is a rear that still breaks, as everything on these rears is too small.
The 12 bolt rears that are available for these cars is a step in the right direction. The 12 bolts are well known for being a stout rear that was a factory option back in the day in many performance cars. You can have a 12 bolt in an early Chevelle, Nova, Camaro, etc, and beat the snot out of it and not hurt anything. Put a 12 bolt into a late model f body that uses a torque arm, make a couple 4000 to 5000 rpm launches at the dragstrip, and I can just about guarantee you'll have a lot more gear noise on the way home. The torque arm seems to distort the housing on the 12 bolts, and it seems to happen to all the brands of 12 bolt rears. This does not happen to the 9 inch rears, and there is no price difference between the 12 bolt and nine inch rears. As the horsepower in our engines keep escalating, most people these days go straight to the nine inch rear. The 9-inch has an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads. This seems to be the major reason why the 9 inch doesn't start whining after high rpm clutch dumps, when the 12 bolt will pick up noise. The 9-inch locates its pinion gear lower on the ring gear to improve tooth contact, better the 12 bolt does. The 9-inch also has a 0.125-inch larger ring-gear diameter and internal pinion support than the 12 bolt.

You won't know what is wrong until you pull the rear apart. Wheel bearings usually put out a roaring sound, I'll bet you'll find it in the center section. Bob

GravZ28

Alright thanks a lot Bob. I appreciate it.

Bob@BruteSpeed

iTrader: (16)

You're welcome! Bob