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| | | | Joined: Apr 2005 Posts: 32 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 32 | Can anybody tell me what the rear axle ratio would be in any or all of these model years for Chev half ton pickup with a 230 or 250 engine, 3 speed trans. Model years 63, 64, 65 and 66. Thanks, Bill
Bill garvey
| | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 |
Bill Burmeister
| | | | | Joined: Apr 2005 Posts: 32 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 32 | Thanks, Longbox, are the any markings or numbers on the housing or any other way to tell what exactly is inside for gears? If so, where about would they be or how else could I tell? Thanks, Bill
Bill garvey
| | | | | Joined: Jul 2008 Posts: 1,262 Shop Shark | | Shop Shark Joined: Jul 2008 Posts: 1,262 | Pulling the rear differential cover (& counting the teeth) is the most accurate method to determine gear ratio but another way to check the rear end ratio is to jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posis and lockers -or- 2 full revolutions for open diffs. Carefully count the number of full revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 ¾ turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading.
I hope this helps!
Last edited by Hot Rod John; 09/25/2010 4:38 PM.
| | | | | Joined: Feb 2004 Posts: 29,885 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,885 | If you have a non-posi differential, the spider gears double the rear wheel speed when only one wheel is off the ground. To get an accurate ratio estimate with only one wheel jacked up, it's necessary to turn the rear wheel twice and count the driveshaft turns. Another, possibly more accurate method is to make a mark on the tire sidewall, roll the vehicle straight forward one turn of the tire, and count driveshaft revolutions. I prefer to pull the cover plate, count teeth, and get out the calculator!
Jerry
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| | | | | Joined: Jul 2008 Posts: 1,262 Shop Shark | | Shop Shark Joined: Jul 2008 Posts: 1,262 | If you have a non-posi differential, the spider gears double the rear wheel speed when only one wheel is off the ground. To get an accurate ratio estimate with only one wheel jacked up, it's necessary to turn the rear wheel twice and count the driveshaft turns. Another, possibly more accurate method is to make a mark on the tire sidewall, roll the vehicle straight forward one turn of the tire, and count driveshaft revolutions. I prefer to pull the cover plate, count teeth, and get out the calculator!
Jerry Rotate the tire one full revolution for posis and lockers -or- 2 full revolutions for open diffs.  | | | | | Joined: Apr 2005 Posts: 32 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 32 | Thanks, Hot Rod John, I have done that before but I thought they might be marked like the double reduction Timken 2 speed in the the big bolts. Bill
Bill garvey
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