speed_demon24

iTrader: (6)

My car has a very pronounced whine under light load while driving at a constant speed. If I give it gas or let off in gear the rear end becomes almost silent. I'm just wondering if there is anything specific to look for when I tear into it since the whine is only at a constant speed type load. Just to give an idea how loud it is, it is almost ear piercing.

Bob@BruteSpeed

iTrader: (16)

Here's a little bit of info that may help you out from my website. Bob

10 Bolt, 12 Bolt and 9 inch Information
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.