Noob tranny/rear end question
Thread Starter
Racer
Joined: Nov 2004
Posts: 319
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From: Sunnyvale CA
Noob tranny/rear end question
Question: My vette goes 65 in 4th gear at 3200RPMs. Is it just me, or is something wrong there??? Is this a popular thing??? I mean, I guess the back end is geared in such a way that it will go 8MPH when it's idling before I give it gas, and it doesn't seem like it could go very fast since it redlines at what, 5500 or so. Is this common??? What does it mean??? (I'm a noob so help me out 
)
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Race Director
Joined: Sep 2004
Posts: 11,874
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by 76mike
Question: My vette goes 65 in 4th gear at 3200RPMs. Is it just me, or is something wrong there??? Is this a popular thing??? I mean, I guess the back end is geared in such a way that it will go 8MPH when it's idling before I give it gas, and it doesn't seem like it could go very fast since it redlines at what, 5500 or so. Is this common??? What does it mean??? (I'm a noob so help me out )
)it means you have a ratio in the rear end that was designed for acceleration for example (i'm making these gear ratios up) 3.99 or 4.11 as opposed to a 3.08...all our vettes suffer from this....thats why the conversion to 5spds or in my case an overdrive Auto is so common place....there are websites that can calculate your rear end ratio based on tire circumference,engine rpm and speed
Team Owner
Joined: Sep 2003
Posts: 88,393
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From: eville in
Originally Posted by bobs77vet
it means you have a ratio in the rear end that was designed for acceleration for example (i'm making these gear ratios up) 3.99 or 4.11 as opposed to a 3.08...all our vettes suffer from this....thats why the conversion to 5spds or in my case an overdrive Auto is so common place....there are websites that can calculate your rear end ratio based on tire circumference,engine rpm and speed
Pro
Joined: Apr 2004
Posts: 687
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From: Atascadero Ca
Last edited by i885744; Dec 16, 2004 at 02:37 AM.
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,968
From: Connecticut, USA
Originally Posted by 76mike
No it's not the L82, it's the L48. Just seems odd to me, is this a standard vette rear end?
Gary
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Instructor
Joined: Jul 2004
Posts: 210
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From: Lakewood CO
You can check the casting numbers on the bottom of the pumpkin and it will tell you what was in there new. Other then that only calculations will tell you what what gear is currently in there.
Dave
Dave
Drifting
Joined: Nov 2002
Posts: 1,665
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From: Ontario
I have a 4 speed with a stock 3.36 rear end. My tires are 235/55-17 which have an approximate diameter of 27.2 inches. At 65mph my engine rpm is approx 3100.
Good tire size calculator
Good tire size calculator
Melting Slicks
Joined: Jul 2004
Posts: 3,248
Likes: 48
From: westland mi
Originally Posted by crazydalys
The tach in my '76 is broken, but I know the engine does rev pretty good on the highway. By 30 mph I'm already in 4th gear. You proabably have the 3:73 rear end.
Burning Brakes
Joined: Oct 2002
Posts: 1,228
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From: lancaster ma
That sounds about right. It will take some time to adjust and accept.
A nice aspect of the 4 speed is you can lug it down on back roads without having to shift all the time. If you do a lot of highway driving you might want to consider a transmission change.
A nice aspect of the 4 speed is you can lug it down on back roads without having to shift all the time. If you do a lot of highway driving you might want to consider a transmission change.
Melting Slicks
Joined: Jan 2004
Posts: 3,247
Likes: 210
From: Detroit MI
Originally Posted by Boofers
I have a 4 speed with a stock 3.36 rear end. My tires are 235/55-17 which have an approximate diameter of 27.2 inches. At 65mph my engine rpm is approx 3100.
Good tire size calculator
Good tire size calculator
Your numbers equate to a 3.86 gear.
mph=(rpm*tire dia")/(trans*gear*336)
No calculations are really necessary to know what gear you have...put the rear of the car on jack stands with the trans in neutral, mark the driveshaft and count how many turns of the driveshaft equates to one turn of the tire. That's your rear end ratio.
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Originally Posted by 69autoXr
Or, if you're speedo is inaccurate, you should be cruising along at 74.7 mph at 3100 RPM
Originally Posted by 69autoXr
put the rear of the car on jack stands with the trans in neutral, mark the driveshaft and count how many turns of the driveshaft equates to one turn of the tire. That's your rear end ratio.
