NJFBOA - Home of New Jersey's Camaros and Firebirds - View Single Post

alamantia · 10-03-2007, 08:28 PM

Correct on any 7.5 / 7.625 application 2 series = 3.23 and lower and 3 series = 3.42 and higher. Of course you can buy aftermarket gears for either series, like you can buy 3.73's for either a 2 series or 3 series... but you already know that.

I have used GM 2.73's for a 2 series
I have used GM 3.42's for a 3 series
I have used Motive 4.10's for a 3 series

Any set for $20 picked up, I only listed the motives cause i just took them out when I did my rebuild because of a whine at around 60mph. I was told that if i buy genuine GM (AAM) gears the whine will subside, so i did, same whine at 60mph just not as loud. I hear its a trait with 4.10's and 4.56's for GM 7.5 corperate 10 bolts, the higher the ratio the smaller the pinion diameter, the 2.73's have like a 2-3/4" diameter pinion whereas the 3.42's have about 2-1/8" diameter pinion, the 4.10s have only about 1-3/4" diameter, I hear this is what causes gear noise in hypoid gear sets in conjunction with improper set up of course. So to answer your question no, they are not damaged, I just replaced them to eliminate whine, and truthfully, they really werent bad to begin with.

10-03-2007, 08:28 PM	#5
alamantia Join Date: May 2006 Location: Midland Park, NJ Posts: 1,389 iTrader: (7)	Correct on any 7.5 / 7.625 application 2 series = 3.23 and lower and 3 series = 3.42 and higher. Of course you can buy aftermarket gears for either series, like you can buy 3.73's for either a 2 series or 3 series... but you already know that. I have used GM 2.73's for a 2 series I have used GM 3.42's for a 3 series I have used Motive 4.10's for a 3 series Any set for $20 picked up, I only listed the motives cause i just took them out when I did my rebuild because of a whine at around 60mph. I was told that if i buy genuine GM (AAM) gears the whine will subside, so i did, same whine at 60mph just not as loud. I hear its a trait with 4.10's and 4.56's for GM 7.5 corperate 10 bolts, the higher the ratio the smaller the pinion diameter, the 2.73's have like a 2-3/4" diameter pinion whereas the 3.42's have about 2-1/8" diameter pinion, the 4.10s have only about 1-3/4" diameter, I hear this is what causes gear noise in hypoid gear sets in conjunction with improper set up of course. So to answer your question no, they are not damaged, I just replaced them to eliminate whine, and truthfully, they really werent bad to begin with.