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04-17-2003, 07:04 PM
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#1 |
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Registered User
Join Date: Aug 2002
Posts: 15
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Gear ratio
Can someone tell me the procedure for figuring out rear end gear ratio? There are no stampings on this axel.
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04-17-2003, 08:32 PM
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#2 |
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Registered User
Join Date: Mar 2002
Location: Bondurant, IA but in Worcester, MA for school
Posts: 767
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Heres what u do to go figure it out.
1. go for a drive and write down your RPMs at a few mph. 2. Measure your tire diameter. 3. go to http://www.smokemup.com/auto_math/rear_end.php and plug in the numbers you have from the drive and it will tell you. Hope this helps. HotRod
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1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/ |
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04-17-2003, 09:59 PM
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#3 |
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Registered User
Join Date: Aug 2002
Posts: 15
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Thanks for the imformation
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04-17-2003, 11:21 PM
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#4 |
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Registered User
Join Date: Jun 2002
Location: Lafayette, LA
Posts: 500
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You can also just mark the tire and driveshaft, rotate the tire one full turn and count the turns the driveshaft makes....3.7 turns = 3.73. A little less than 3 and a half turns = 3.42
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69 SWB LT1/4L60E www.classicplace.com |
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04-18-2003, 12:42 AM
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#5 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Or pop the cover off and look for the stampings, or even count the teeth.
Fresh oil in the rear diff ain't a bad idea anyways. |
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04-18-2003, 12:45 AM
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#6 |
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67-72 Addict!
Join Date: Feb 2002
Location: The TAX State!
Posts: 7,857
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I think I checked mine by rotating 2 full turns. It's been awhile though.
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Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads |
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04-18-2003, 01:26 AM
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#7 |
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Recovering Truck Driver
Join Date: Mar 2002
Location: Orleans, NE USA
Posts: 1,883
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I'm with andy on this. The best way to tell is to change the gear oil and count teeth while you're at it. The numbers will actually be stamped in the face of the pinion. Take the larger number and divide it by the smaller number and you've got your ratio.
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67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska |
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04-18-2003, 12:50 PM
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#8 |
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Registered User
Join Date: Apr 2000
Location: Frisco, Tx, USA
Posts: 606
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If I remember correctly, turning the wheel only works if you turn both tires at the same time (at least for an open diff).
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http://home.comcast.net/~r.landrum/w...tos.html-.html '68 C-10 LWB, '98 Z-71 350 w/accessories (Serpentine), Edelbrock Performer, Edelbrock 1405 (600cfm) carb, GM HEI, CompCam Extreme 4x4 roller cam, Thorley Headers, Carter Electric Fuel Pump, Vintage Air, 700r4, 3.73, disc brakes and power steering upgrades. |
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04-18-2003, 01:07 PM
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#9 | |
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Senior Member
 
Join Date: May 2002
Location: Hammond, WI
Posts: 1,795
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this place here will also help you figure out your tire diameter:
http://www.rx7turboturbo.com/robrobi...e_diameter.htm
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Mike 2001 Dakota R/T - Silver CC - 1 of 1671 •360 w/46RE •392 limited slip 1972 Chevy Suburban - Turquoise/Black 1969 Chevy C/10 - Blue LWB •350 w/ 700R4 •3.73 posi •PS PB A/C - SOLD  Using your turn signal is not "giving information to the enemy" 67-72 FAQ Quote:
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04-18-2003, 11:37 PM
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#10 |
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Registered User
Join Date: Aug 2002
Posts: 15
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Thanks for all the great help. Got it figured out. I have a 3.73 positraction.
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