[C1] Axle ratios and Gear Ratios
#1
Racer
Thread Starter
Axle ratios and Gear Ratios
I'm "Corn Fused" (as my uncle Bill used to say. I have a 62 with a 327 - 340 HP - 4 speed positraction. The Corvette servicing guide (ST-12) on page 14-2 lists 3.36:1 regular ratio but it lists 6 different Positraction ratios. How do I determine what I have?
Also in the transmission section page (14-17) it lists 2 ratios for each of the first three gears. Again how do I tell what I have?
I know someone out there has the answer or can tell me how to calculate it. All help greatly appreciated, i've owned the car since 1968, but never payed much attention to the gearing, now i'm curious.
Also in the transmission section page (14-17) it lists 2 ratios for each of the first three gears. Again how do I tell what I have?
I know someone out there has the answer or can tell me how to calculate it. All help greatly appreciated, i've owned the car since 1968, but never payed much attention to the gearing, now i'm curious.
#2
Drifting
see this one of many threads
https://www.corvetteforum.com/forums...end-gears.html
also if rear is original it will have a cast date code and part# on drivers side on lateral front facing surface
opposide side there is a stamped code that reveals axle ratio. very difficult to see. scrub clean to see. find codes for vette on differernt vette websites.
codes for 62 chev may not match up with codes for 62 vette.
rear gears could have been changed so follow direction in suggested thread.
trans could be wide ratio
https://www.corvetteforum.com/forums...end-gears.html
also if rear is original it will have a cast date code and part# on drivers side on lateral front facing surface
opposide side there is a stamped code that reveals axle ratio. very difficult to see. scrub clean to see. find codes for vette on differernt vette websites.
codes for 62 chev may not match up with codes for 62 vette.
rear gears could have been changed so follow direction in suggested thread.
trans could be wide ratio
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62-C1 (02-12-2017)
#3
Race Director
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Assuming the speedometer gearing is correct for the installed axle.
In forth gear axle ratio = revs @ 60 / 760.
All 340/360 HP engines ordered with the optional four-speed received the close ratio version (2.20:1 first gear).
Duke
In forth gear axle ratio = revs @ 60 / 760.
All 340/360 HP engines ordered with the optional four-speed received the close ratio version (2.20:1 first gear).
Duke
Last edited by SWCDuke; 02-11-2017 at 09:40 AM.
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62-C1 (02-12-2017)
#4
Safety Car
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Simply turn rear wheels one revolution and count revolution of driveshaft. Revolution of driveshaft equals the ratio. Thus driveshaft turns 3.7 times, ratio is 3.70. This only works with positraction.
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62-C1 (02-12-2017)
#5
Melting Slicks
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2016 C1 of Year Finalist
Try what hope2 described.
I believe that typically the car with a close ratio trans (2.20 first gear) had a 3.70 rear gear. The 2.20 first gear and a 3.36 rear would be hard on the clutch and the driver.
Difficult to get the car moving.
I believe that typically the car with a close ratio trans (2.20 first gear) had a 3.70 rear gear. The 2.20 first gear and a 3.36 rear would be hard on the clutch and the driver.
Difficult to get the car moving.
Last edited by ohiovet; 02-16-2017 at 08:48 PM.
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62-C1 (02-12-2017)
#6
And if you don't have positraction differential, lock one rear wheel in place and turn the other rear wheel exactly two complete revolutions while counting how many times the pinion shaft/driveshaft yoke revolves and that will give you the gear ratio.
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62-C1 (02-12-2017)
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62-C1 (02-12-2017)
#8
Race Director
True that - that's the way my '67 was built. OTOH, I lived with it that way for about 35 years, until I put in a Tremec TKO 500 with a 3.27 1st gear and a .67 5th!
#9
Racer
Thread Starter
Have You installed the TKO 500 in your 62?
Thanks,
Marty
#10
Racer
Thread Starter
Bill I tried to send you a PM, obviously i'm doing something wrong.
Bill,
I spoke with 'Frankie the Fink" on the phone this afternoon he suggested I call you about the 5 speed transmission that you installed in your 62. He says it was from Silver Sport and that it shifts slicker then the Tremec TKO 600. I think he said it was an "RS" model. What is different about this transmission versus the TKO 600.
I am going thru the thought process of installing a five speed in place of my T-10 "Rock crusher".
How long did it take to install? What was the price comparison between the two kits? Thanks for your help.
Marty
Bill,
I spoke with 'Frankie the Fink" on the phone this afternoon he suggested I call you about the 5 speed transmission that you installed in your 62. He says it was from Silver Sport and that it shifts slicker then the Tremec TKO 600. I think he said it was an "RS" model. What is different about this transmission versus the TKO 600.
I am going thru the thought process of installing a five speed in place of my T-10 "Rock crusher".
How long did it take to install? What was the price comparison between the two kits? Thanks for your help.
Marty
#11
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2023 C1 of the Year Finalist - Modified
2015 C1 of the Year Finalist
2.20 is a CLOSE ratio
2.56 is a WIDE ratio
2.56 is a WIDE ratio
Last edited by DZAUTO; 02-16-2017 at 08:46 PM.