What gear ratio is this? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RShaips · 04-03-2011, 09:43 PM

I bought a rear and front axle assembly from a guy and it was supposed to be from a 79 1/2 ton with 3.73 gears. I checked the ratio by spinning one tire one revolution and times it by 2 and the front and back came out as 3.73, at least that's what I thought! Well I take the rear apart and the ring gear is stamped 10.34. And i counted them and that's what it is. 3.40 gears? I have heard of 3.42 but 3.40?

69CSTDawg · 04-03-2011, 10:43 PM

its most likely 3.42

rayfinseats · 04-04-2011, 08:31 AM

10 34 is 3.2. You sure you got the right numbers off the ring gear? Put a mark on the tire and count how many times the pinion turns in one revolution of tire. What's this times two stuff for???? I have 2.73's in my 83. Which rear end is it? 10-bolt? Dana 60? 14 bolt?

3.4 what the F was I thinking?

**argonaut** · 04-04-2011, 03:53 PM

34 teeth on the ring / 10 teeth on the pinion = 3.4:1 ratio

68chevyfuelie · 04-07-2011, 11:35 PM

12 bolt chevy rears were a 3.40 ratio, they didn't offer a 3.42 12 bolt ratio.

04-03-2011, 09:43 PM	#1
RShaips Senior Member Join Date: Jun 2002 Location: Augusta Missouri Posts: 804	What gear ratio is this? I bought a rear and front axle assembly from a guy and it was supposed to be from a 79 1/2 ton with 3.73 gears. I checked the ratio by spinning one tire one revolution and times it by 2 and the front and back came out as 3.73, at least that's what I thought! Well I take the rear apart and the ring gear is stamped 10.34. And i counted them and that's what it is. 3.40 gears? I have heard of 3.42 but 3.40?

04-03-2011, 10:43 PM	#2
69CSTDawg Registered User Join Date: Dec 2010 Location: Conyers,Ga Posts: 24	Re: What gear ratio is this? its most likely 3.42

04-04-2011, 08:31 AM	#3
rayfinseats Registered User Join Date: Dec 2010 Location: sioux city, iowa Posts: 619	Re: What gear ratio is this? 10 34 is 3.2. You sure you got the right numbers off the ring gear? Put a mark on the tire and count how many times the pinion turns in one revolution of tire. What's this times two stuff for???? I have 2.73's in my 83. Which rear end is it? 10-bolt? Dana 60? 14 bolt? 3.4 what the F was I thinking? Last edited by rayfinseats; 04-08-2011 at 12:10 AM.

04-04-2011, 03:53 PM	#4
argonaut Senior Member Join Date: Aug 2008 Location: Long Beach, CA Posts: 1,813	Re: What gear ratio is this? 34 teeth on the ring / 10 teeth on the pinion = 3.4:1 ratio __________________ Jason M. @argonaut62 1972 K5 Blazer CST, Turquoise 1966 K20 Short Fleet Pickup, Big Ugly 1964 C10 Short Fleet, Gertrude 2001 Porsche 911 Carrera 1996 Ford Bronco XLT 1980 Jeep Wagoneer 2008 Honda CBR1000RR 2005 Honda RC51 1981 Honda CB750C No dis-assemble Johnny Five! No dis-assemble!

04-07-2011, 11:35 PM	#5
68chevyfuelie Registered User Join Date: Mar 2008 Location: Kitchener, Ontario Posts: 487	Re: What gear ratio is this? 12 bolt chevy rears were a 3.40 ratio, they didn't offer a 3.42 12 bolt ratio.



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