RE: [Chevelle-list] rear gears

Mon, 29 Dec 2003 13:59:35 -0800

Title: Message
Bill,
 
The "CR" code is for a 3.70 posi, 1109 is Nov 9, and B is Buffalo assembly.  I'd suggest you look at http://www.chevellestuff.com/generic/rpm_calculator.htm and play with gear ratios to find what'll work in your highway speed ranges.  If you know your tire size, you can play with ratios available and see what RPM's you'd be running at a given speed.  Transmission type selection is moot since you're looking at a 1-to-1 ratio in high gear unless you want to toss in the variable of an O/D transmission.  Being an automatic, you might want to allow 200-300 RPM for converter slippage as well.
 
For example with all things being equal (assuming a regular 205x70x14 tire), 3.70's at 75 give you about 3700 RPMs while a 3.31 drops that to 3300.  Swapping to an O/D (such as a 700-R4) and keeping your 3.70s drops your RPMs to 2600 in O/D at 75.  I used this page quite a bit when I was deciding what rear tire sizes would work for me.

Dale McIntosh
TC Gold #92/ACES #1709/NECOA #41
67SS/67 Elky
Dale’s Place – My 67 SS and 67 El Camino
ChevelleStuff – Decoding info on 64-72 Chevelles
Team 67 – 1967 Chevelle/El Camino Specific
Midwest Chevelles – Midwest Chevelle Show Information

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bill Bradley
Sent: Monday, December 29, 2003 3:13 PM
To: The Chevelle Mailing List
Subject: [Chevelle-list] rear gears

hi gang
I've got a question or two regarding the gearing of my differential.I've got a 67 Malibu that had a 283 and a powerglide, I've pulled them and installed a 305 and a TH350. My question is this "what would you recommend for the gears in my rear end"? I'm looking to decrease my rpms on the long haul and increase my mileage.to the best of my knowledge my gears are stock.
any help would be greatly appreciated
it looks like the casting on the rear end is "3894938N" ? its a non posi 10 bolt
stamped on the tube it looks like "CR1109B" or could be "cr11098" ?
hope this helps
 

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