what gear do i have
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Thread Starter
Intermediate
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Le Mans Master
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From: Oxford MA-----You just lost the game!!!!
Anyway, here's how to figure out what your rearend ratio is: Put the back of the car on jackstands, make a chalk mark or a mark of some kind on one of the rear tires, and the driveshaft. Spin the tire one full revolution, while counting how many times the driveshaft turns. Just a hair over 3 turns? 3.08. Just about 3 and 3/4 turns? That's a 3.73. Get it? It's better than trying to figure out rearend ratio from rpm at speed, because there are variables like tire diameter, and how accurate the speedo is, stuff like that.
Scott
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LOL!!! "grammer" queens! I can dig the irony, man, and I can see that you have a sense of humor, but I'm not really sure what you're getting all upset about, I was just trying to clarify what it was you actually wanted to know. What are we supposed to do, just start throwing random information at you until we stumble onto what it is you actually want to know?
Anyway, here's how to figure out what your rearend ratio is: Put the back of the car on jackstands, make a chalk mark or a mark of some kind on one of the rear tires, and the driveshaft. Spin the tire one full revolution, while counting how many times the driveshaft turns. Just a hair over 3 turns? 3.08. Just about 3 and 3/4 turns? That's a 3.73. Get it? It's better than trying to figure out rearend ratio from rpm at speed, because there are variables like tire diameter, and how accurate the speedo is, stuff like that.
Scott
Anyway, here's how to figure out what your rearend ratio is: Put the back of the car on jackstands, make a chalk mark or a mark of some kind on one of the rear tires, and the driveshaft. Spin the tire one full revolution, while counting how many times the driveshaft turns. Just a hair over 3 turns? 3.08. Just about 3 and 3/4 turns? That's a 3.73. Get it? It's better than trying to figure out rearend ratio from rpm at speed, because there are variables like tire diameter, and how accurate the speedo is, stuff like that.
Scott
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From: Duvall, WA
Race Director
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Burning Brakes
Joined: Jan 2006
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From: Fort Wayne IN
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
Well, there ya go, according to your "dead on" speedometer, you have the ultra-rare 2.91 rearend ratio. Maybe your tach is not 100% accurate. Maybe your speedo is inaccurate. Maybe your clutch is slipping just a teeny-weeny bit. Maybe there is a loose nut behind the steering wheel. The only way to REALLY know, is to take the cover off and count the teeth. That's a pretty big job on a 'vette, so counting the driveshaft revolutions is the next best thing.
Scott
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Well, there ya go, according to your "dead on" speedometer, you have the ultra-rare 2.91 rearend ratio. Maybe your tach is not 100% accurate. Maybe your speedo is inaccurate. Maybe your clutch is slipping just a teeny-weeny bit. Maybe there is a loose nut behind the steering wheel. The only way to REALLY know, is to take the cover off and count the teeth. That's a pretty big job on a 'vette, so counting the driveshaft revolutions is the next best thing.
Scott
Scott
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
In 1973 we were well into emission controls .....and dealer inventory ordered cars would be the standard ratios as performance was already history....With 'OEM size tires a tach reading of 3000 RPM reads 60 MPH on the odometer and would be a 4.1 gear....which was not available in 73
Last edited by Ironcross; Jul 31, 2011 at 02:07 AM.