3.55
Recommended Gears...???
Thread Starter
Racer
Joined: Apr 2001
Posts: 413
Likes: 0
From: Bluffdale Utah
Recommended Gears...???
I just got a Boetie Overdrives 2004R with 2200 stall torque converter for my 1981 Corvette. It has a ZZ4 with Hooker Super Comps, duel exhaust...no Y pipe. I'm interested in hearing from others, what rear gears would you recommend for my set up. BTW, I want to retain decent highway RPMs and fuel economy, but want the most out of the new tranny. I'm looking forward to your replies.
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
Too bad you went with the 200R4, the 700R4 has a lower first gear that would have worked well with your stock rear end and you might not even have found the need to change the gears.
I would go with a 3.55 with your current set up.
I would go with a 3.55 with your current set up.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Racer
Joined: Feb 2012
Posts: 390
Likes: 1
From: Livonia MI
You do realize that's like asking which oil to use, or which thermostat to use. You're going to get a bunch of opinions.
But since you mentioned that highway RPM's are important, I think the 3.55 recomendation is right on the nose. Perfect compromise between performance and highway drivability.
But since you mentioned that highway RPM's are important, I think the 3.55 recomendation is right on the nose. Perfect compromise between performance and highway drivability.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
For what you want, you need 3.55 gears in back. 3.70 would be best for performance, but highway mileage would suffer. Also, you don't want anything with with a lower ratio than 3.36. Below that ratio, your car will 'lug down' below 40 mph, because the rpm's are too low for overdrive at suburban speeds.
3.55 if you want good cruise and fairly good performance; 3.70 if you want better performance and decent cruise comfort.
3.55 if you want good cruise and fairly good performance; 3.70 if you want better performance and decent cruise comfort.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
For what you want, you need 3.55 gears in back. 3.70 would be best for performance, but highway mileage would suffer. Also, you don't want anything with with a lower ratio than 3.36. Below that ratio, your car will 'lug down' below 40 mph, because the rpm's are too low for overdrive at suburban speeds.
3.55 if you want good cruise and fairly good performance; 3.70 if you want better performance and decent cruise comfort.
3.55 if you want good cruise and fairly good performance; 3.70 if you want better performance and decent cruise comfort.
1980zz4, we don't know what your diff gears are right now, but I can tell you this: 2004r tranny has a 2.74:1 first gear, th350 has 2.52:1 first gear, th400 has a 2.48: first gear, so whatever your first gear final drive is now, the 2004r will increase it. I would say install the tranny, drive it around for awhile with the existing diff gears, and see how you like it. Then make the decision on where to go with the diff gear. What is your present diff gear, anyway?
Keep the shiny side up!
Scott
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Yes, you can reset the shift points. But, that means you have to drop the valve body and start digging into it. Not that easy or much fun...
And, below a 3.36 gear, you start losing performance significantly. So, why do it?
And, below a 3.36 gear, you start losing performance significantly. So, why do it?
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Thread Starter
Racer
Joined: Apr 2001
Posts: 413
Likes: 0
From: Bluffdale Utah
Thanks for the replies. I did expect a bunch of varying opinions and feel none of them are bad, but rather look to the supporting comments to help me make a decision that works for me. I have often thought that 3.54/3.55 would be a great combination with my trans with consideration to BOTH performance and economy.
Unfortunately, I don't know what gear ratio I have at this time, but highly suspect 3.07. I did expect to buy a new rear so I had no issue when I decided on using the 2004R rather than the 700R4. Either would have been fine, but I preferred the characteristics of the 2004R.
Unfortunately, I don't know what gear ratio I have at this time, but highly suspect 3.07. I did expect to buy a new rear so I had no issue when I decided on using the 2004R rather than the 700R4. Either would have been fine, but I preferred the characteristics of the 2004R.
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Thanks for the replies. I did expect a bunch of varying opinions and feel none of them are bad, but rather look to the supporting comments to help me make a decision that works for me. I have often thought that 3.54/3.55 would be a great combination with my trans with consideration to BOTH performance and economy.
Unfortunately, I don't know what gear ratio I have at this time, but highly suspect 3.07. I did expect to buy a new rear so I had no issue when I decided on using the 2004R rather than the 700R4. Either would have been fine, but I preferred the characteristics of the 2004R.
Unfortunately, I don't know what gear ratio I have at this time, but highly suspect 3.07. I did expect to buy a new rear so I had no issue when I decided on using the 2004R rather than the 700R4. Either would have been fine, but I preferred the characteristics of the 2004R.
You would be going from a first gear final drive of 7.23:1 to a 7.86:1 with the 2004r, better, but not much better. A 700r4 would give you 8.78:1. The deeper the gear the better for performance, until you get up to around 10:1, much past that, and the car starts to drive like a very powerful tractor.
2.74 x 3.54 = 9.70:1 which is probably about right.
Keep the shiny side up!
Scott